WorldWideScience

Sample records for mode-locked phosphate glass

  1. Integrated optics dissipative soliton mode-locked laser on glass

    Science.gov (United States)

    Charlet, Bertrand; Bastard, Lionel; Broquin, Jean-Emmanuel

    2011-01-01

    Mode-lock lasers have been studied a lot in the past years for producing pulses as short as possible. These devices have mostly been realized in bulk optics and they are consequently cumbersome and sensitive to vibrations. There are only a few studies on integrated optics mode-lock lasers, though this technology is very promising because of its stability, compactness and the possibility to integrate several functions on a single chip. In this paper, we present an ion-exchange passively mode-locked laser in dissipative soliton operation. One of the key characteristics of this structure is its mechanical stability. Indeed, no bulk optics is needed because the saturable absorber is hybridized on the top of the waveguide in order to interact with the evanescent part of the guided mode. Indeed, the device that has been obtained is composed of an ion-exchanged single mode waveguide realized in a Neodymium doped phosphate glass. The laser feedback is produced by a Fabry-Perot cavity realized with two multilayers dielectric mirrors stuck on the waveguides facets. We implemented a bis(4- dimethylaminodithiobenzil)nickel (BDN) dye included in a cellulose acetate thick film, which presents a saturable absorber behaviour around 1.06 μm. With this structure, pulses with repetition rates of 3.3 GHz and a single mode output have been measured. Moreover, the use of an autocorrelation set-up allowed us measuring picosecond pulse durations.

  2. Spectral development of pico second pulses of mode-locked Nd-glass lasers

    Energy Technology Data Exchange (ETDEWEB)

    Penzkofer, A.; Weinhardt, N.

    1983-04-01

    The spectra of single picosecond pulses of mode-locked Nd-glass lasers are investigated along the pulse train. In addition to self-phase modulation, the spectra are modified due to spectral hole burning in the inhomogeneous gain profile of the active medium.

  3. Characterization of nonlinear saturation and mode-locking potential of ionically-doped colored glass filter for short-pulse fiber lasers.

    Science.gov (United States)

    Zhang, M; Kelleher, E J R; Popov, S V; Taylor, J R

    2013-05-20

    The nonlinear saturable absorption of an ionically-doped colored glass filter is measured directly using a Z-scan technique. For the first time, we demonstrate the potential of this material as a saturable asborber in fiber lasers. We achieve mode-locking of an ytterbium doped system. Mode-locking of cavities with all-positive and net-negative group velocity dispersion are demonstrated, achieving pulse durations of 60 ps and 4.1 ps, respectively. This inexpensive and optically robust material, with the potential for broadband operation, could surplant other saturable absorber devices in affordable mode-locked fiber lasers.

  4. Nonlinear switching in a two-concentric-core chalcogenide glass optical fiber for passively mode-locking a fiber laser.

    Science.gov (United States)

    Nazemosadat, Elham; Mafi, Arash

    2014-08-15

    We propose an all-fiber mode-locking device, which operates based on nonlinear switching in a novel two-concentric-core fiber structure. The design is particularly attractive given the ease of fabrication and coupling to other components in a mode-locked fiber laser cavity. The nonlinear switching in this coupler is studied, and the relative power transmission is obtained. The analysis shows that this nonlinear switch is practical for mode-locking fiber lasers and is forgiving to fabrication errors.

  5. 220 fs Er-Yb:glass laser mode-locked by a broadband low-loss Si/Ge saturable absorber

    CERN Document Server

    Grawert, F J; Ilday, F O; Liu, J; Gopinath, J T; Shen, H M; Wada, K; Ippen, E P; Kimerling, L C; Kaertner, Franz X

    2004-01-01

    We demonstrate femtosecond performance of an ultra-broadband high-index-contrast saturable Bragg reflector consisting of a silicon/silicon-dioxide/germanium structure that is fully compatible with CMOS processing. This device offers a reflectivity bandwidth of over 700 nm and sub-picosecond recovery time of the saturable loss. It is used to achieve mode-locking of an Er-Yb:glass laser centered at 1540 nm, generating 220 fs pulses, with the broadest output spectrum to date.

  6. Near- infrared, mode-locked waveguide lasers with multi-GHz repetition rates

    Science.gov (United States)

    Choudhary, A.; Lagatsky, A. A.; Zhang, Z. Y.; Zhou, K. J.; Wang, Q.; Hogg, R. A.; Pradeesh, K.; Rafailov, E. U.; Resan, B.; Oehler, A. E. H.; Weingarten, K. J.; Sibbett, W.; Brown, C. T. A.; Shepherd, D. P.

    2014-02-01

    In this work, we discuss mode-locking results obtained with low-loss, ion-exchanged waveguide lasers. With Yb3+-doped phosphate glass waveguide lasers, a repetition rate of up to 15.2 GHz was achieved at a wavelength of 1047 nm with an average power of 27 mW and pulse duration of 811 fs. The gap between the waveguide and the SESAM introduced negative group velocity dispersion via the Gires Tournois Interferometer (GTI) effect which allowed the soliton mode-locking of the device. A novel quantum dot SESAM was used to mode-lock Er3+, Yb3+-doped phosphate glass waveguide lasers around 1500 nm. Picosecond pulses were achieved at a maximum repetition rate of 6.8 GHz and an average output power of 30 mW. The repetition rate was tuned by more than 1 MHz by varying the pump power.

  7. Resonance vector mode locking

    CERN Document Server

    Kolpakov, Stanislav A; Loika, Yuri; Tarasov, Nikita; Kalashnikov, Vladimir; Agrawal, Govind P

    2015-01-01

    A mode locked fibre laser as a source of ultra-stable pulse train has revolutionised a wide range of fundamental and applied research areas by offering high peak powers, high repetition rates, femtosecond range pulse widths and a narrow linewidth. However, further progress in linewidth narrowing seems to be limited by the complexity of the carrier-envelope phase control. Here for the first time we demonstrate experimentally and theoretically a new mechanism of resonance vector self-mode locking where tuning in-cavity birefringence leads to excitation of the longitudinal modes sidebands accompanied by the resonance phase locking of sidebands with the adjacent longitudinal modes. An additional resonance with acoustic phonons provides the repetition rate tunability and linewidth narrowing down to Hz range that drastically reduces the complexity of the carrier-envelope phase control and so will open the way to advance lasers in the context of applications in metrology, spectroscopy, microwave photonics, astronomy...

  8. Passively mode locked Raman laser

    CERN Document Server

    Liang, W; Savchenkov, A A; Matsko, A B; Seidel, D; Maleki, L

    2010-01-01

    We report on the observation of a novel mode locked optical comb generated at the Raman offset (Raman comb) in an optically pumped crystalline whispering gallery mode resonator. Mode locking is confirmed via measurement of the radio-frequency beat note produced by the optical comb on a fast photodiode. Neither the conventional Kerr comb nor hyper-parametric oscillation is observed when the Raman comb is present.

  9. Subharmonic Fourier domain mode locking.

    Science.gov (United States)

    Eigenwillig, Christoph M; Wieser, Wolfgang; Biedermann, Benjamin R; Huber, Robert

    2009-03-15

    We demonstrate a subharmonically Fourier domain mode-locked wavelength-swept laser source with a substantially reduced cavity fiber length. In contrast to a standard Fourier domain mode-locked configuration, light is recirculated repetitively in the delay line with the optical bandpass filter used as switch. The laser has a fundamental optical round trip frequency of 285 kHz and can be operated at integer fractions thereof (subharmonics). Sweep ranges up to 95 nm full width centred at 1317 nm are achieved at the 1/5th subharmonic. A maximum sensitivity of 116 dB and an axial resolution of 12 microm in air are measured at an average sweep power of 12 mW. A sensitivity roll-off of 11 dB over 4 mm and 25 dB over 10 mm is observed and optical coherence tomography imaging is demonstrated. Besides the advantage of a reduced fiber length, subharmonic Fourier domain mode locking (shFDML) enables simple scaling of the sweep speed by extracting light from the delay part of the resonator. A sweep rate of 570 kHz is achieved. Characteristic features of shFDML operation, such as power leakage during fly-back and cw breakthrough, are investigated.

  10. An automatic mode-locked system for passively mode-locked fiber laser

    Science.gov (United States)

    Li, Sha; Xu, Jun; Chen, Guoliang; Mei, Li; Yi, Bo

    2013-12-01

    This paper designs and implements one kind of automatic mode-locked system. It can adjust a passively mode-locked fiber laser to keep steady mode-locked states automatically. So the unsteadiness of traditional passively mode-locked fiber laser can be avoided. The system transforms optical signals into electrical pulse signals and sends them into MCU after processing. MCU calculates the frequency of the signals and judges the state of the output based on a quick judgment algorithm. A high-speed comparator is used to check the signals and the comparison voltage can be adjusted to improve the measuring accuracy. Then by controlling two polarization controllers at an angle of 45degrees to each other, MCU extrudes the optical fibers to change the polarization until it gets proper mode-locked output. So the system can continuously monitor the output signal and get it back to mode-locked states quickly and automatically. States of the system can be displayed on the LCD and PC. The parameters of the steady mode-locked states can be stored into an EEPROM so that the system will get into mode-locked states immediately next time. Actual experiments showed that, for a 6.238MHz passively mode-locked fiber lasers, the system can get into steady mode-locked states automatically in less than 90s after starting the system. The expected lock time can be reduced to less than 20s after follow up improvements.

  11. An investigation of iron phosphate glasses

    Science.gov (United States)

    Fang, Xiangyu

    The effect of melting history on the iron redox equilibrium, structure, crystallization and properties of a binary iron phosphate glass with a 40Fe 2O3-60P2O5, mol%, batch composition were investigated. The structure and properties of single and mixed alkali iron phosphate glasses were also studied. Mossbauer, Raman and infrared spectroscopy were used to determine the changes in the concentration of iron ions and phosphate units in the structure. Differential thermal analysis, X-ray diffraction and thermogravimetric analysis were used to investigate crystallization. Density, molar volume, thermal expansion, dc electrical conductivity and dielectric constant and loss tangent were measured. The heat capacity and glass transition behavior of the glasses was also measured by the differential scanning calorimeter method. The effect of the melting temperature is stronger than the melting time on the concentration of Fe2+ ions in iron phosphate glasses. The pyrophosphate network in iron phosphate glasses and their general properties do not change either with melting temperature and time or with adding up to 20 mol% of single and mixed alkali oxides. The dissolution rate (in deionized water) of these glasses is generally very low (˜10-9 g/cm2/min) and nearly independent of the relative concentration of Fe 2+ or Fe3+ ions. The dissolution rate of the iron phosphate glasses containing 20 mol% of single or mixed alkali oxide can be comparable to that of window glass. There is no mixed alkali effect in the iron phosphate glasses. The crystallization tendency indicates that the glass structure becomes closer to that of crystalline Fe3(P2O 7)2 with increasing concentration of Fe2+ ions in the glass. The large fragility parameters indicates that the iron phosphate glasses belong in the category of the fragile glass-forming liquids.

  12. Self-mode-locking semiconductor disk laser.

    Science.gov (United States)

    Gaafar, Mahmoud; Richter, Philipp; Keskin, Hakan; Möller, Christoph; Wichmann, Matthias; Stolz, Wolfgang; Rahimi-Iman, Arash; Koch, Martin

    2014-11-17

    The development of mode-locked semiconductor disk lasers received striking attention in the last 14 years and there is still a vast potential of such pulsed lasers to be explored and exploited. While for more than one decade pulsed operation was strongly linked to the employment of a saturable absorber, self-mode-locking emerged recently as an effective and novel technique in this field - giving prospect to a reduced complexity and improved cost-efficiency of such lasers. In this work, we highlight recent achievements regarding self-mode-locked semiconductor devices. It is worth to note, that although nonlinear effects in the active medium are expected to give rise to self-mode-locking, this has to be investigated with care in future experiments. However, there is a controversy whether results presented with respect to self-mode-locking truly show mode-locking. Such concerns are addressed in this work and we provide a clear evidence of mode-locking in a saturable-absorber-free device. By using a BBO crystal outside the cavity, green light originating from second-harmonic generation using the out-coupled laser beam is demonstrated. In addition, long-time-span pulse trains as well as radiofrequency-spectra measurements are presented for our sub-ps pulses at 500 MHz repetition rate which indicate the stable pulse operation of our device. Furthermore, a long-time-span autocorrelation trace is introduced which clearly shows absence of a pedestal or double pulses. Eventually, a beam-profile measurement reveals the excellent beam quality of our device with an M-square factor of less than 1.1 for both axes, showing that self-mode-locking can be achieved for the fundamental transverse mode.

  13. Iron phosphate glass containing simulated fast reactor waste: Characterization and comparison with pristine iron phosphate glass

    Science.gov (United States)

    Joseph, Kitheri; Asuvathraman, R.; Venkata Krishnan, R.; Ravindran, T. R.; Govindaraj, R.; Govindan Kutty, K. V.; Vasudeva Rao, P. R.

    2014-09-01

    Detailed characterization was carried out on an iron phosphate glass waste form containing 20 wt.% of a simulated nuclear waste. High temperature viscosity measurement was carried out by the rotating spindle method. The Fe3+/Fe ratio and structure of this waste loaded iron phosphate glass was investigated using Mössbauer and Raman spectroscopy respectively. Specific heat measurement was carried out in the temperature range of 300-700 K using differential scanning calorimeter. Isoconversional kinetic analysis was employed to understand the crystallization behavior of the waste loaded iron phosphate glass. The glass forming ability and glass stability of the waste loaded glass were also evaluated. All the measured properties of the waste loaded glass were compared with the characteristics of pristine iron phosphate glass.

  14. $\\mathcal{PT}$-symmetric mode-locking

    CERN Document Server

    Longhi, Stefano

    2016-01-01

    Parity-time ($\\mathcal{PT}$) symmetry is one of the most important accomplishments in optics over the past decade. Here the concept of $\\mathcal{PT}$ mode-locking of a laser is introduced, in which active phase locking of cavity axial modes is realized by asymmetric mode coupling in a complex time crystal. $\\mathcal{PT}$ mode-locking shows a transition from single to double pulse emission as the $\\mathcal{PT}$ symmetry breaking point is crossed. The transition can show a turbulent behavior, depending on a dimensionless modulation parameter that plays the same role as the Reynolds number in hydrodynamic flows.

  15. Integration of mode-locked diode lasers

    Science.gov (United States)

    Coleman, A. Catrina; Hou, Lianping; Marsh, John H.

    2016-03-01

    Monolithic mode-locked semiconductor lasers are attractive sources of short optical pulses with advantages over more conventional sources in compactness, robustness, performance stability, power consumption, and cost savings. The use of quantum well intermixing (QWI) to integrate passive sections and surface etched distributed Bragg reflectors (DBR) into monolithic laser cavity will be described. The performance of the devices will be presented.

  16. Soliton mode-locking in optical microresonators

    CERN Document Server

    Herr, T; Gorodetsky, M L; Kippenberg, T J

    2012-01-01

    The discovery of mode-locking via saturable absorbers has led to optical femto-second pulses with applications ranging from eye-surgery to the analysis of chemical reactions on ultra-short timescales. In the frequency domain a train of such optical pulses corresponds to a frequency comb (equidistant optical laser lines spaced by the pulse repetition rate), which find use in precision spectroscopy and optical frequency metrology. Not relying on mode-locking, frequency combs can also be generated in continuously driven high-Q Kerr-nonlinear optical microresonators via cascaded four-wave mixing. Over the past years these Kerr-combs have been demonstrated in a variety of microresonator geometries. Applying a pulse-shaping mode locking mechanism, could enable compact femto-second pulse generators. However, conventional saturable absorbers are challenging to apply to microresonators, as they affect the high-quality-factor. Here, we report on passive mode-locking in microresonators without saturable absorber. This m...

  17. Phase diagram and complexity of mode-locked lasers: from order to disorder

    CERN Document Server

    Leuzzi, L; Folli, V; Angelani, L; Ruocco, G

    2008-01-01

    We investigate mode-locking processes in lasers displaying a variable degree of structural randomness, from standard optical cavities to multiple-scattering media. By employing methods mutuated from spin-glass theory, we analyze the mean-field Hamiltonian and derive a phase-diagram in terms of the pumping rate and the degree of disorder. Three phases are found: i) paramagnetic, corresponding to a noisy continuous wave emission, ii) ferromagnetic, that describes the standard passive mode-locking, and iii) the spin-glass in which the phases of the electromagnetic field are frozen in a exponentially large number of configurations. The way the mode-locking threshold is affected by the amount of disorder is quantified. The results are also relevant for other physical systems displaying a random Hamiltonian, like Bose-Einstein condensates and nonlinear optical beams.

  18. Mode-locking via dissipative Faraday instability

    Science.gov (United States)

    Tarasov, Nikita; Perego, Auro M.; Churkin, Dmitry V.; Staliunas, Kestutis; Turitsyn, Sergei K.

    2016-08-01

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin-Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system--spectrally dependent losses--achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin-Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering.

  19. Mode-locking via dissipative Faraday instability.

    Science.gov (United States)

    Tarasov, Nikita; Perego, Auro M; Churkin, Dmitry V; Staliunas, Kestutis; Turitsyn, Sergei K

    2016-08-09

    Emergence of coherent structures and patterns at the nonlinear stage of modulation instability of a uniform state is an inherent feature of many biological, physical and engineering systems. There are several well-studied classical modulation instabilities, such as Benjamin-Feir, Turing and Faraday instability, which play a critical role in the self-organization of energy and matter in non-equilibrium physical, chemical and biological systems. Here we experimentally demonstrate the dissipative Faraday instability induced by spatially periodic zig-zag modulation of a dissipative parameter of the system-spectrally dependent losses-achieving generation of temporal patterns and high-harmonic mode-locking in a fibre laser. We demonstrate features of this instability that distinguish it from both the Benjamin-Feir and the purely dispersive Faraday instability. Our results open the possibilities for new designs of mode-locked lasers and can be extended to other fields of physics and engineering.

  20. Dark solitons in mode-locked lasers

    CERN Document Server

    Ablowitz, Mark J; Nixon, Sean D; Frantzeskakis, Dimitri J

    2010-01-01

    Dark soliton formation in mode-locked lasers is investigated by means of a power-energy saturation model which incorporates gain and filtering saturated with energy, and loss saturated with power. It is found that general initial conditions evolve into dark solitons under appropriate requirements also met in the experimental observations. The resulting pulses are well approximated by dark solitons of the unperturbed nonlinear Schr\\"{o}dinger equation. Notably, the same framework also describes bright pulses in anomalous and normally dispersive lasers.

  1. Mode-locking in nonlinear rotordynamics

    Science.gov (United States)

    van der Heijden, G. H. M.

    1995-05-01

    We present a computer-assisted study of the dynamics of two nonlinearly coupled driven oscillators with rotational symmetry which arise in rotordynamics (the nonlinearity coming from bearing clearance). The nonlinearity causes a splitting of the twofold degenerate natural frequency of the associated linear model, leading to three interacting frequencies in the system. Partial mode-locking then yields a biinfinite series of attracting invariant 2-tori carrying (quasi-) periodic motion. Due to the resonance nature, the (quasi-) periodic solutions become periodic in a corotating coordinate system. They can be viewed as entrainments of periodic solutions of the associated linear problem. One presumably infinite family is generated by (scaled) driving frequencies ω = 1+2/ n, n = 1,2,3,...; another one is generated by frequencies ω = m, m = 4,5,6,... Both integers n and m can be related to discrete symmetry properties of the particular periodic solutions. Under a perturbation that breaks the rotational symmetry, more complicated behavior is possible. In particular, a second rational relation between the frequencies can be established, resulting in fully mode-locked periodic motion.

  2. Surface chemistry studies of phosphate glasses

    Science.gov (United States)

    Barnes, Amy Suzanne

    This research examined the surface of an undoped and rare-earth doped sodium alumino metaphosphate glass after fracture or surface finishing and subsequent exposure to humid and aqueous environments. In addition, the adsorption of aminopropyl triethoxysilane (APS), and the dominant parameters controlling the structure of the deposited film, were studied. Typically, commercial glasses must be cut and polished into optical components for engineering applications. This process involves a series of aqueous treatments in both acidic and basic media. The experiments performed here on aluminophosphate glass showed that this results in dissolution, surface composition changes (depletion of Na) and surface pitting. In both alkaline detergent and acid etching solution, dissolution at a rate of approximately 4 x 10 -3 mol/m2/hr (0.2 mum/hr) occurs along with a drastic alteration of the surface morphology. When exposed to an environment of elevated humidity and temperature for an extended period of time, this aluminophosphate glass was observed to break down, forming a soluble phosphate gel that dissolves away from the surface. Simultaneously, the surface became enriched in silica, a trace contaminant in the glass, which eventually precipitated and coalesced into a dendritic pattern that covered the surface. The freshly powdered phosphate glass was found to contain surface hydroxyls weakly associated with one another, and some bound by a stronger hydrogen bond, likely to adjacent non-bridging oxygens. Most of these hydroxyls could be desorbed upon heating above the glass transition temperature to leave only a small concentration of weakly associated hydroxyls and free hydroxyls on the surface. The characterization of hydroxyls and water on the phosphate glass surface was used to understand the adsorption of aminopropyl tri-ethoxysilane (APS) also through the use of in-situ DRIFTS. The concentration of adsorbed APS was found to be independent of solution pH, but the measured

  3. Transition state to mode locking in a passively mode-locked erbium-doped fibre ring laser

    Institute of Scientific and Technical Information of China (English)

    Liu Jia-Rui; Xu Wen-Cheng; Luo Zhi-Chao; Luo Ai-Ping; Yin Hai-Sen

    2011-01-01

    The transition state between the continuous wave region and the mode-locked region in a passively mode-locked erbium-doped fibre ring laser has been experimentally observed by utilizing the nonlinear polarization rotation technique. When the pump power reaches the mode-locked threshold, the metastable pulse train with a tunable repetition rate is obtained in the transition from the continuous wave state to the passive mode-locked state via proper adjustment of the polarization controller. A simple model has been established to explain the experimental observation.

  4. Increased reliability of passive mode-locking a multi-atmosphere TE CO2 laser by injection mode-locking

    NARCIS (Netherlands)

    Goor, van F.A.

    1986-01-01

    By injection of manosecond pulses from an AM mode-locked TEA CO2 laser in a passive mode-locked multi-atmosphere TE CO2 laser the shot-to-shot reproducibility of the generated subnanosecond pulses was increased to almost 100%.

  5. Modelling aqueous corrosion of nuclear waste phosphate glass

    Science.gov (United States)

    Poluektov, Pavel P.; Schmidt, Olga V.; Kascheev, Vladimir A.; Ojovan, Michael I.

    2017-02-01

    A model is presented on nuclear sodium alumina phosphate (NAP) glass aqueous corrosion accounting for dissolution of radioactive glass and formation of corrosion products surface layer on the glass contacting ground water of a disposal environment. Modelling is used to process available experimental data demonstrating the generic inhibiting role of corrosion products on the NAP glass surface.

  6. Theory of Passively Mode-Locked Photonic Crystal Semiconductor Lasers

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Blaaberg, Søren; Mørk, Jesper

    2010-01-01

    We report the first theoretical investigation of passive mode-locking in photonic crystal mode-locked lasers. Related work has investigated coupled-resonator-optical-waveguide structures in the regime of active mode-locking [Opt. Express 13, 4539-4553 (2005)]. An extensive numerical investigation...... of the influence of key parameters of the active sections and the photonic crystal cavity on the laser performance is presented. The results show the possibility of generating stable and high quality pulses in a large parameter region. For optimized dispersion properties of the photonic crystal waveguide cavity......, the pulses have sub picosecond widths and are nearly transform limited....

  7. A racetrack mode-locked silicon evanescent laser.

    Science.gov (United States)

    Fang, Alexander W; Koch, Brian R; Gan, Kian-Giap; Park, Hyundai; Jones, Richard; Cohen, Oded; Paniccia, Mario J; Blumenthal, Daniel J; Bowers, John E

    2008-01-21

    By utilizing a racetrack resonator topography, an on-chip mode locked silicon evanescent laser (ML-SEL) is realized that is independent of facet polishing. This enables integration with other devices on silicon and precise control of the ML-SEL's repetition rate through lithographic definition of the cavity length. Both passive and hybrid mode-locking have been achieved with transform limited, 7 ps pulses emitted at a repetition rate of 30 GHz. Jitter and locking range are measured under hybrid mode locking with a minimum absolute jitter and maximum locking range of 364 fs, and 50 MHz, respectively.

  8. Monolithic Hybrid and Passive Mode-Locked 40GHz Quantum Dot Laser Diodes

    DEFF Research Database (Denmark)

    Thompson, M. G.; Larsson, David; Rae, A. R.

    2006-01-01

    For the first time hybrid and passive mode-locking jitter performance is investigated in 40GHz quantum-dot mode-locked lasers. Record low passive mode-locking jitter of 219fs is presented, along with promising hybrid mode-locking results of 124fs.......For the first time hybrid and passive mode-locking jitter performance is investigated in 40GHz quantum-dot mode-locked lasers. Record low passive mode-locking jitter of 219fs is presented, along with promising hybrid mode-locking results of 124fs....

  9. Monolithic Hybrid and Passive Mode-Locked 40GHz Quantum Dot Laser Diodes

    DEFF Research Database (Denmark)

    Thompson, M. G.; Larsson, David; Rae, A. R.;

    2006-01-01

    For the first time hybrid and passive mode-locking jitter performance is investigated in 40GHz quantum-dot mode-locked lasers. Record low passive mode-locking jitter of 219fs is presented, along with promising hybrid mode-locking results of 124fs.......For the first time hybrid and passive mode-locking jitter performance is investigated in 40GHz quantum-dot mode-locked lasers. Record low passive mode-locking jitter of 219fs is presented, along with promising hybrid mode-locking results of 124fs....

  10. Ultrafast pulse generation in a mode-locked Erbium chip waveguide laser

    CERN Document Server

    Khurmi, Champak; Zhang, Wen Qi; V., Shahraam Afshar; Chen, George; Genest, Jérôme; Monro, Tanya M; Lancaster, David G

    2016-01-01

    We report mode-locked ~1550 nm output of transform-limited ~180 fs pulses from a large mode-area (diameter ~ 50 {\\mu}m) guided-wave erbium fluorozirconate glass laser. The passively mode-locked oscillator generates pulses with 25 nm bandwidth at 156 MHz repetition rate and peak-power of 260 W. Scalability to higher repetition rate is demonstrated by transform-limited 410 fs pulse output at 1.3 GHz. To understand the origins of the broad spectral output, the laser cavity is simulated by using a numerical solution to the Ginzburg-Landau equation. This paper reports the widest bandwidth and shortest pulses achieved from an ultra-fast laser inscribed waveguide laser.

  11. Noise Effects in the Mode-Locked External Cavity Lasers

    Institute of Scientific and Technical Information of China (English)

    Nuran Dogru; M. Sadettin Ozyazici

    2003-01-01

    Effect of high level of spontaneous and carrier noise on mode-locked hybrid soliton pulse source and relative intensity noise is described. Transform limited pulses are not generated over a wide frequency range because of these noises.

  12. Mode-Locked Semiconductor Lasers for Optical Communication Systems

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Oxenløwe, Leif Katsuo

    2005-01-01

    We present investigations on 10 and 40 GHz monolithic mode-locked lasers for applications in optical communications systems. New all-active lasers with one to three quantum wells have been designed, fabricated and characterized.......We present investigations on 10 and 40 GHz monolithic mode-locked lasers for applications in optical communications systems. New all-active lasers with one to three quantum wells have been designed, fabricated and characterized....

  13. OPTICALLY HOMOGENEOUS PHOSPHATE GLASSES DOPED WITH METAL NANOPARTICLES

    OpenAIRE

    Shakhgil'dyan, Georgiy; Savinkov, Vitaliy; Konev, Denis; Paleari, A.; Sigaev, Vladimir

    2013-01-01

    The technique of batch preparation, melting, glass working and nanoscale modification of the structure of phosphate glass doped with gold nanoparticles was developed. Glass samples containing different amounts of phosphorus oxide were synthesized. Heat treatments of the samples were held in a gradient furnace. Physical, spectral-luminescent and nonlinear optical properties of the samples were studied.

  14. Tin-phosphate glass anode for sodium ion batteries

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Honma

    2013-11-01

    Full Text Available The electrochemical property of tin-phosphate (designate as GSPO glass anode for the sodium ion battery was studied. During the first charge process, sodium ion diffused into GSPO glass matrix and due to the reduction of Sn2+ to Sn0 state sodiated tin metal nano-size particles are formed in oxide glass matrix. After the second cycle, we confirmed the steady reversible reaction ∼320 mAh/g at 0–1 V cutoff voltage condition by alloying process in NaxSn4. The tin-phosphate glass is a promising candidate of new anode active material that realizes high energy density sodium ion batteries.

  15. Single-SectionFabry-Perot Mode-Locked Semiconductor Lasers

    Directory of Open Access Journals (Sweden)

    Weiguo Yang

    2011-01-01

    Full Text Available We present a review of the theoretical models and experimental verification of the single-section Fabry-Perot mode-locked semiconductor lasers based on multiple-spatial-mode (MSM coupling. The mode-locked operation at the repetition rates of 40 GHz and higher and the pulse width of a few picoseconds are confirmed by the intensity autocorrelation, the fast photo detection and RF spectrum, and the optical spectral interference measurement of ultrafast pulse. The spatial mode coupling theory of single-section Fabry-Perot mode-locked semiconductor lasers is also reviewed, and the results are compared with the experimental observations. The small signal modulation response of these lasers, which exhibits high-frequency responses well beyond the relaxation oscillation resonance limit, is also modeled theoretically, and the simulation is verified by the experimental measurements.

  16. Characterization of Fe$^{3+}$-doped silver phosphate glasses

    Indian Academy of Sciences (India)

    B P CHOUDHARY; N B SINGH

    2016-12-01

    The relationship among the composition, structure and selected properties for five series of silver phosphate glasses containing 0, 5, 10, 15 and 20wt% Fe$_2$O$_3$ has been investigated. The synthesized glasses have been characterized using different experimental techniques. X-ray diffraction studies revealed that the glasses are amorphous in nature. IR spectral studies have shown the presence of characteristic P–O–P linkages of linear phosphate chains,presence of O–P–O units in the phosphate tetrahedral and the formation of P–O–Fe bonds in the doped glass. It is also confirmed that due to doping of Fe$_2$O$_3$, loosening of glassy structure occurred and the glass became more disordered. Differential scanning calorimetric (DSC) studies revealed that glass transition temperature increased with Fe$_2$O$_3$ concentration. Scanning electron microscopic studies have shown that Fe$_2$O$_3$ doping modifies the microstructures of the glass and at lower concentration of dopant, a nanostructure is obtained. Electrical conductivity measurements from 303 to 373 K in a frequency range from 100 Hz to 5 MHz have indicated that all glasses are ionic conductors with Ag$^+$ ions as the charge carrier. Fe$_2$O$_3$ doping in silver phosphate glass increased the electrical conductivities. Results have shown that dielectric constants increased with the increase of temperature at all the frequencies; a.c. and d.c. conductivities have been separated and a Cole–Cole plot is also drawn. Dielectric losses in all the glasses decreased with frequency at a particular temperature. It is found that Ag$_2$O–P$_2$O$_5$ glass doped with 5wt% Fe$_2$O$_3$ gives high OCV value and the doped glass can be used as an electrolyte for solid-state batteries.

  17. Pulse properties of external cavity mode locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Kroh, Marcel; Mørk, Jesper

    2006-01-01

    The performance of an external-cavity mode-locked semiconductor laser is investigated both theoretically and experimentally. The optimization analysis focuses on the regimes of stable mode locking and the generation of sub-picosecond optical pulses. We demonstrate stable output pulses down to one...... picosecond duration with more than 30 dB trailing pulse suppression. The limiting factors to the device performance are investigated on the basis of a fully-distributed time-domain model.We find that ultrafast gain dynamics effectively reduce the pulse-shaping strength and inhibit the generation...

  18. Dual-polarization mode-locked Nd:YAG laser.

    Science.gov (United States)

    Thévenin, J; Vallet, M; Brunel, M

    2012-07-15

    A mode-locked solid-state laser containing a birefringent element is shown to emit synchronously two frequency combs associated to the two polarization eigenstates of the cavity. An analytical model predicts the polarization evolution of the pulse train, which is determined by the adjustable intracavity birefringence. Experiments realized with a Nd:YAG laser passively mode locked by a semiconductor saturable absorber mirror are in perfect agreement with the model. Locking between the two combs arises for particular values of their frequency difference, e.g., half the repetition rate, and the pulse train polarization sequence is then governed by the relative overall phase offset of the two combs.

  19. Graphene mode locked, wavelength-tunable, dissipative soliton fiber laser

    CERN Document Server

    Zhang, Han; Knize, R J; Zhao, Luming; Bao, Qiaoliang; Loh, Kian Ping

    2010-01-01

    Atomic layer graphene possesses wavelength-insensitive ultrafast saturable absorption, which can be exploited as a full-band mode locker. Taking advantage of the wide band saturable absorption of the graphene, we demonstrate experimentally that wide range (1570 nm - 1600nm) continuous wavelength tunable dissipative solitons could be formed in an erbium doped fiber laser mode locked with few layer graphene.

  20. Carbon nanotubes for mode-locking: polarization study

    Science.gov (United States)

    Afkhamiardakani, Hanieh; Kamer, Brian; Diels, Jean-Claude; Arissian, Ladan

    2016-03-01

    Mode-locked fiber lasers are the most promising lasers for intracavity phase interferometry,1 because they offer the possibility to have two orthogonally polarized pulses circulating independently in the cavity. The saturable absorbers based on polarization maintaining tapered fiber coated with carbon nanotubes are developed and analyzed for minimum coupling between the slow and fast axis of the fiber.

  1. Quasi mode-locking of coherent feedback random fiber laser

    Science.gov (United States)

    Ma, R.; Zhang, W. L.; Zeng, X. P.; Yang, Z. J.; Rao, Y. J.; Yao, B. C.; Yu, C. B.; Wu, Y.; Yu, S. F.

    2016-12-01

    Mode-locking is a milestone in the history of lasers that allows the generation of short light pulses and stabilization of lasers. This phenomenon is known to occur only in standard ordered lasers for long time and until recently it is found that it also occurs in disordered random lasers formed by nanoscale particles. Here, we report the realization of a so-called quasi mode-locking of coherent feedback random fiber laser which consists of a partially disordered linear cavity formed between a point reflector and a random distributed fiber Bragg grating array with an inserted graphene saturable absorber. We show that multi-groups of regular light pulses/sub-pulses with different repetition frequencies are generated within the quasi mode-locking regime through the so-called collective resonances phenomenon in such a random fiber laser. This work may provide a platform to study mode locking as well as pulse dynamic regulation of random lasing emission of coherent feedback disordered structures and pave the way to the development of novel multi-frequency pulse fiber lasers with potentially wide frequency tuning range.

  2. Modelling colliding-pulse mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Bischoff, Svend

    or to determine the optimum operation conditions. The purpose of this thesis is to elucidate some of the physics of interest in the field of semiconductor laser modelling, semiconductor optics and fiber optics. To be more specific we will investigate: The Colliding-Pulse Mode-Locked (CPM) Quantum Well (QW) laser...

  3. Dispersion-managed semiconductor mode-locked ring laser.

    Science.gov (United States)

    Resan, Bojan; Archundia, Luis; Delfyett, Peter J; Alphonse, Gerard

    2003-08-01

    A novel breathing-mode external sigma-ring-cavity semiconductor mode-locked laser is developed. Intracavity pulse compression and stretching produce linearly chirped pulses with an asymmetric exponential temporal profile. External dispersion compensation reduces the pulse duration to 274 fs (within 10% of the bandwidth limit).

  4. Film formation of CdSe quantum dot embedded phosphate glass on an FTO glass substrate

    Science.gov (United States)

    Han, Karam; Kim, Yoon Hwa; Im, Won Bin; Chung, Woon Jin

    2015-07-01

    A thick film with CdSe quantum dot (QD) embedded glass was formed on a fluorine-doped tin oxide (FTO) glass substrate. Phosphate glasses with different CdO and ZnSe concentrations were synthesized, and the heat treatment conditions were varied to determine the appropriate QD and film formation conditions. Phosphate glass with 1 mol. % CdO and 1.5 mol. % ZnSe showed controlled crystallization of CdSe QDs when they were heat treated at 550℃ for 1 hr. Absorption spectra and Raman spectroscopy identified the QD formation. Precursor glass was ground into powder and pasted onto FTO only and TiO2/FTO glass substrates via the screen printing method. Glass film embedded with QDs was successfully formed after sintering, thus demonstrating its potential for film applications. [Figure not available: see fulltext.

  5. Gain Characteristics of Er3+-Doped Phosphate Glass Fibres

    Institute of Scientific and Technical Information of China (English)

    XU Shan-Hui; YANG Zhong-Min; ZHANG Qin-Yuan; DENG Zai-De; JIANG Zhong-Hong

    2006-01-01

    @@ An erbium-doped phosphate glass fibre has been drawn by the rod-in-tube technique in our laboratory. The gain for the Er3+-doped phosphate glass fibre with different pump powers and with different input signal wavelengths is investigated. The 2.2-cm-long fibre, pumped by a single-mode 980-nm fibre-pigtailed laser diode, can provide a net gain per unit length greater than 1.8dB/cm. The pump threshold is about 50mW at the wavelength of 1534nm, and below 70mW at 1550nm. The gain linewidth of the Er3+-doped phosphate glass fibre is greater than 34 nm and can cover the C band in optical communication networks.

  6. Phosphate Nd:glass materials for femtosecond pulse generation

    Science.gov (United States)

    Agnesi, Antonio; Carrà, Luca; Reali, Giancarlo

    2008-08-01

    Two different phosphate Nd-doped glasses have been investigated in a diode-pumped femtosecond laser. To our knowledge, only Schott's phosphate glasses were previously used in femtosecond oscillators. A slightly different behaviour was observed in our experiments, with respect to earlier reports: clean sech 2-pulses with duration <400 fs were routinely generated with wavelength corresponding to the fluorescence peak ≈1054 nm, whereas shorter pulses occurred at red-shifted wavelengths near 1067 nm. With a single 1-W pump diode (broad area emitter), cw slope efficiency as high as 32% and 139-fs pulse generation were demonstrated.

  7. Erbium Doped Phosphate Glass For Optical Waveguide Amplifier

    Institute of Scientific and Technical Information of China (English)

    R.S.F.Wong; S.Q.Man; E.Y.B.Pun; P.S.Chung

    2000-01-01

    @@ Erbium (Er3+) doped phosphate glasses was prepared and the optical properties of these glasses were investigated. The emission parameters were calculated using the Judd-Ofelt treatment. The radiative lifetime of the 4I13/2 level is calculated to be 7.2ms. The fluorescence lifetime is measured to be 6ms, and the quantum efficiency is estimated to be 83%. Ion-exchanged optical waveguides were fabricated in these glasses by using pure KNO3 meet at 370℃, and diluted AgNO3 molten salt at 270℃. It was found that the lower temperature diluted AgNO3 molten salt is better for the ion exchange process. Planar waveguide with 5 modes at the 633nm and 2 modes at the 1550nm was demonstrated using the diluted AgNO3. Our results show that phosphate glass is a potential candidate for the 1.5μm optical amplifier device.

  8. Semiconductor Mode-Locked Lasers for Optical Communication Systems

    DEFF Research Database (Denmark)

    Yvind, Kresten

    2003-01-01

    The thesis deals with the design and fabrication of semiconductor mode-locked lasers for use in optical communication systems. The properties of pulse sources and characterization methods are described as well as requirements for application in communication systems. Especially, the importance of......, and ways to reduce high-frequency jitter is discussed. The main result of the thesis is a new design of the epitaxial structure that both enables simplified fabrication and improves the properties of monolithic lasers. 40 GHz monolithic lasers with record low jitter and high power is presented as well...... as the first 10 GHz all-active monolithic laser with both short pulses and low jitter.Results from external cavity mode-locked lasers are also reported along with an investigation of the influence of the operating conditions on the performance of the device. Antireflection coatings are a critical limiting...

  9. Self-induced transparency mode-locking, and area theorem

    CERN Document Server

    Arkhipov, R M; Babushkin, I

    2015-01-01

    Self-induced transparency mode-locking (or coherent mode-locking, CML) which is based on intracavity self-induced transparency soliton dynamics, allows potentially to achieve nearly single cycle intracavity pulse durations, much below the phase relaxation time $T_2$ in a laser, which, despite of great promise, has not yet been realized experimentally. We develop a diagram technique which allows to predict the main features of CML regimes in a generic two-section laser. We show that CML can arise directly at the first laser threshold if the phase relaxation time is large enough. Furthermore, CML regimes can be unconditionally stable. We also predict the existence of ``super-CML regimes``, with a pulse coupled to several Rabi oscillations in the nonlinear medium.

  10. High-Energy Passive Mode-Locking of Fiber Lasers

    Directory of Open Access Journals (Sweden)

    Edwin Ding

    2012-01-01

    Full Text Available Mode-locking refers to the generation of ultrashort optical pulses in laser systems. A comprehensive study of achieving high-energy pulses in a ring cavity fiber laser that is passively mode-locked by a series of waveplates and a polarizer is presented in this paper. Specifically, it is shown that the multipulsing instability can be circumvented in favor of bifurcating to higher-energy single pulses by appropriately adjusting the group velocity dispersion in the fiber and the waveplate/polarizer settings in the saturable absorber. The findings may be used as practical guidelines for designing high-power lasers since the theoretical model relates directly to the experimental settings.

  11. Chirp of monolithic colliding pulse mode-locked diode lasers

    DEFF Research Database (Denmark)

    Hofmann, M.; Bischoff, S.; Franck, Thorkild

    1997-01-01

    Spectrally resolved streak camera measurements of picosecond pulses emitted by hybridly colliding pulse mode-locked (CPM) laser diodes are presented in this letter. Depending on the modulation frequency both blue-chirped (upchirped) and red-chirped (downchirped) pulses can be observed. The two...... different regimes and the transition between them are characterized experimentally and the behavior is explained on the basis of our model for the CPM laser dynamics. (C) 1997 American Institute of Physics....

  12. Recent advances in phosphate laser glasses for high power applications

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.H.

    1996-05-14

    Recent advances in Nd-doped phosphate laser glasses for high-peak-power and high-average-power applications are reviewed. Compositional studies have progressed to the point that glasses can be tailored to have specific properties for specific applications. Non-radiative relaxation effects can be accurately modeled and empirical expressions have been developed to evaluate both intrinsic (structural) and extrinsic (contamination induced) relaxation effects. Losses due to surface scattering and bulk glass absorption have been carefully measured and can be accurately predicted. Improvements in processing have lead to high damage threshold (e.g. Pt inclusion free) and high thermal shock resistant glasses with improved edge claddings. High optical quality pieces up to 79 x 45 x 4cm{sup 3} have been made and methods for continuous melting laser glass are under development.

  13. Nonlinear high-order mode locking in stochastic sensory neurons

    Science.gov (United States)

    Rowe, Michael; Afghan, Muhammad; Neiman, Alexander

    2004-03-01

    Excitable systems demonstrate various mode locking regimes when driven by periodic external signals. With noise taken into account, such regimes represent complex nonlinear responses which depend crucially on the frequency and amplitude of the periodic drive as well as on the noise intensity. We study this using a computational model of a stochastic Hodgkin-Huxley neuron in combination with the turtle vestibular sensory system as an experimental model. A bifurcation analysis of the model is performed. Extracellular recordings from primary vestibular afferent neurons with two types of stimuli are used in the experimental study. First, mechanical stimuli applied to the labyrinth allow us to study the responses of the entire system, including transduction by the hair cells and spike generation in the primary afferents. Second, a galvanic stimuli applied directly to an afferent are used to study the responses of afferent spike generator directly. The responses to galvanic stimuli reveal multiple high-order mode locking regimes which are well reproduced in numerical simulation. Responses to mechanical stimulation are characterized by larger variability so that fewer mode-locking regimes can be observed.

  14. Multiwavelength arrays of mode-locked lasers for WDM applications

    Science.gov (United States)

    Davis, Lawrence J.; Young, Martin G.; Dougherty, David J.; Keo, Sam A.; Muller, Richard E.; Maker, Paul D.; Forouhar, Siamak

    1998-08-01

    The continued need for increased bandwidth is driving the pursuit of both increased speed in TDM and more channels in WDM for fiber optic communication systems. Multiwavelength arrays of monolithic mode-locked DBR lasers are an attractive source for future high bit rate (100 - 800 Gb/s) optical communication systems. Monolithic mode-locked lasers in the colliding-pulse mode-locked configuration have been fabricated, with DBR end mirrors for wavelength selection. A continuous gain region has been employed for ease of fabrication and the elimination of multiple reflections within the cavity. Arrays containing up to 9 wavelengths have been fabricated, with all the wavelengths within the erbium-doped fiber amplifier gain bandwidth. An RF signal is applied to the saturable absorber for synchronization to an external clock and reduction of the phase noise. For a 4.6 mm cavity, short (< 10 ps) optical pulses at high (approximately 18 GHz) repetition rates have been achieved. Low single side-band phase noise values (-107 dBc/Hz 100 kHz offset) have been demonstrated, nearly equal to that of the RF source.

  15. Sub-20-Attosecond Timing Jitter Mode-Locked Fiber Lasers

    CERN Document Server

    Kim, Hyoji; Song, Youjian; Yang, Heewon; Shin, Junho; Kim, Chur; Jung, Kwangyun; Wang, Chingyue; Kim, Jungwon

    2014-01-01

    We demonstrate 14.3-attosecond timing jitter [integrated from 10 kHz to 94 MHz offset frequency] optical pulse trains from 188-MHz repetition-rate mode-locked Yb-fiber lasers. In order to minimize the timing jitter, we shorten the non-gain fiber length to shorten the pulsewidth and reduce excessive higher-order nonlinearity and nonlinear chirp in the fiber laser. The measured jitter spectrum is limited by the amplified spontaneous emission limited quantum noise in the 100 kHz - 1 MHz offset frequency range, while it was limited by the relative intensity noise-converted jitter in the lower offset frequency range. This intrinsically low timing jitter enables sub-100-attosecond synchronization between the two mode-locked Yb-fiber lasers over the full Nyquist frequency with a modest 10-kHz locking bandwidth. The demonstrated performance is the lowest timing jitter measured from any free-running mode-locked fiber lasers, comparable to the performance of the lowest-jitter Ti:sapphire solid-state lasers.

  16. Quantum dot mode locked lasers for coherent frequency comb generation

    Science.gov (United States)

    Martinez, A.; Calò, C.; Rosales, R.; Watts, R. T.; Merghem, K.; Accard, A.; Lelarge, F.; Barry, L. P.; Ramdane, A.

    2013-12-01

    Monolithic semiconductor passively mode locked lasers (MLL) are very attractive components for many applications including high bit rate telecommunications, microwave photonics and instrumentation. Owing to the three dimensional confinement of the charge carriers, quantum dot based mode-locked lasers have been the subject of intense investigations because of their improved performance compared to conventional material systems. Indeed, the inhomogeneous gain broadening and the ultrafast absorption recovery dynamics are an asset for short pulse generation. Moreover, the weak coupling of amplified spontaneous emission with the guided modes plus low loss waveguide leads to low timing jitter. Our work concentrates on InAs quantum dash nanostructures grown on InP substrate, intended for applications in the 1.55 μm telecom window. InAs/InP quantum dash based lasers, in particular, have demonstrated efficient mode locking in single section Fabry-Perot configurations. The flat optical spectrum of about 12 nm, combined with the narrow RF beat note linewidth of about 10 kHz make them a promising technology for optical frequency comb generation. Coherence between spectral modes was assessed by means of spectral phase measurements. The parabolic spectral phase profile indicates that short pulses can be obtained provided the intracavity dispersion can be compensated by inserting a single mode fiber.

  17. Fiber Transmission Stabilization by Optical Heterodyning Techniques and Synchronization of Mode-Locked Lasers Using Two Spectral Lines

    CERN Document Server

    Staples, J W

    2005-01-01

    Stabilization of the transit time through a glass fiber using an optical heterodyne technique promises to provide jitter reduction down to the few femtosecond level using inexpensive commodity hardware. An acousto-optical frequency shifter provides the optical frequency offset that is used to downconvert phase shifts at optical frequency to equivalent phase shifts at radio frequency which are used to close a phase-lock loop driving a piezoelectric phase shifter. Using the stabilized fiber transmission medium, two spectral lines of a mode locked laser lock two low-power CW lasers which are transmitted to a receiver which phase locks the same spectral lines of a second mode-locked laser to the first. The optical transmission system operates at low power and is linear, providing excellent signal-to-noise ratio and allows many signals to be transmitted without mutual interference. Experimental results will be presented.

  18. Simultaneous Q-switching and mode-locking in the CW Nd:YAG laser

    Science.gov (United States)

    Kuizenga, D. J.; Phillion, D. W.; Siegman, A. E.; Lund, T.

    1973-01-01

    The theory of transient mode-locking for an active modulator in a laser with a homogeneously broadened line is presented. The theory is applied to simultaneously Q-switched and mode-locked Nd:YAG lasers and good agreement between theory and experiment is obtained. The main conclusion is that under usual Q-switched operating conditions the mode-locking process does not have sufficient time to build up to steady-state conditions. We also present a method to overcome this problem by allowing the laser to prelase before the Q-switch is opened. Mode-locked pulses whose width approaches the steady-state value are obtained. The transient mode-locking theory presented here also applies to actively mode-locking TEA CO2 lasers and to other types of simultaneously pulsed and mode-locked lasers.

  19. Cytocompatibility assessment of chemical surface treatments for phosphate glass to improve adhesion between glass and polyester.

    Science.gov (United States)

    S Hasan, M; Ahmed, I; Parsons, A J; Walker, G S; Scotchford, C A

    2013-11-01

    Fully resorbable phosphate glass fiber reinforced polymer composites have shown real potential for replacing some of the existing metallic bone fracture fixation devices. However, some of these composites have not provided suitable mechanical strength profiles over the required healing period for bone. Typically, it has been seen that these composites can lose up to 50% or more of their strength within the first week of degradation. Functionalizing the glass surface to promote polymer adhesion or to introduce hydrophobicity at the glass surface could potentially introduce control over the mechanical properties of the composite and their retention. In this study eight chemical agents namely, Glycerol 2-phosphate disodium salt; 3-phosphonopropionic acid; 3-aminopropyltriethoxy silane; etidronic acid; hexamethylene diisocyanate; sorbitol/sodium ended PLA oligomers and amino phosphonic acid, were selected to functionalise the bulk phosphate glass surface. Selected chemical agents had one functional group (-OH or O C N) to react with the glass and another functionality (either -OH, NH2, or Na) to react with the polymer matrix and/or produce hydrophobicity at the fiber surface. Bulk phosphate glass surface-treated with the above agents were assessed for the cytotoxicity of degradation products cell-material interaction in short- and long-term direct cytocompatibility studies. Results obtained from these cytocompatibility studies (using human osteosarcoma (MG63) and primary human osteoblast cell lines) revealed no cytotoxicity from the degradation products and a response comparable to controls in terms of cell functions (attachment, viability, metabolic activity, proliferation, and differentiation) and morphology.

  20. Structural and thermochemical properties of sodium magnesium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Oueslati Omrani, Refka [Université de Tunis El Manar, Faculté des Sciences de Tunis, Chemistry Department, LR01SE10 Applied Thermodynamics Laboratory, 2092 Tunis (Tunisia); Kaoutar, Abdeltif; El Jazouli, Abdelaziz [LCMS, URAC 17, Faculté des Sciences Ben M’Sik, UH2MC, Casablanca (Morocco); Krimi, Saida [LPCMI, Faculté des Sciences Aïn Chok, UH2C, Casablanca (Morocco); Khattech, Ismail, E-mail: ismail.khattech@fst.rnu.tn [Université de Tunis El Manar, Faculté des Sciences de Tunis, Chemistry Department, LR01SE10 Applied Thermodynamics Laboratory, 2092 Tunis (Tunisia); Jemal, Mohamed [Université de Tunis El Manar, Faculté des Sciences de Tunis, Chemistry Department, LR01SE10 Applied Thermodynamics Laboratory, 2092 Tunis (Tunisia); Videau, Jean-Jacques [ICMCB, Institut de Chimie de la matière condensée, Université de Bordeaux 1 (France); Couzi, Michel [Institut des Sciences Moléculaires, CNRS-Université de Bordeaux 1 (France)

    2015-05-25

    Highlights: • Phosphate glasses were prepared by met quenching technique. • Structural study is investigated using FTIR, Raman and {sup 31}PNMR spectroscopy. • A 4.5% weight of H{sub 3}PO{sub 4} solution has use for glass dissolution. • Dissolution is endothermic for lower MgO content and becomes exothermic when x rises. - Abstract: Ternary phosphate based glasses with the general formula (50−x/2)Na{sub 2}O–xMgO–(50−x/2)P{sub 2}O{sub 5} (0 ⩽ x ⩽ 42.8 mol%), where the O/P ratio was varied from 3 to 3.75, have been prepared using a conventional melt quenching technique. Samples were investigated by means of density measurements, Fourier-transformed infrared (FTIR), Raman and {sup 31}P solid state magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopies, differential scanning calorimetry (DSC), inductively coupled plasma atomic emission spectroscopy (ICP/AES) analysis and calorimetric dissolution. The depolymerization of metaphosphate chains are described by the decrease of Q{sup 2} tetrahedral sites allowing the formation of pyrophosphate groups (Q{sup 1}) revealed by spectroscopic investigations. As a result, the increase of density and glass transition temperature when x rises. Calorimetric study shows that the dissolution phenomenon is endothermic for a lower MgO content and becomes exothermic when magnesium oxide is gradually incorporated, suggesting the disruption of phosphate chains with increasing O/P ratio.

  1. Luminescence properties of Er3+-doped phosphate glasses

    Science.gov (United States)

    Hraiech, S.; Bouzidi, C.; Férid, M.

    2017-10-01

    Erbium doped phosphate glasses with composition P2O5 - Na2O - B2O3 -x Er2O3 were obtained using melt-quench method. The spectroscopic properties were analyzed using optical absorption and fluorescence spectra. Based on the absorption spectra and Judd-Ofelt theory, the Judd-Ofelt intensity parameters, Ω2, Ω4, and Ω6 were determined and then used to calculate the total spontaneous transition probability (Atot), radiative life time (τr) and the branching ratio (β), for various excited luminescent states. The spectroscopic quality factor Ω4/Ω6 has been calculated for the present Er3+ doped phosphate glasses (1.53, 1.69 and 1.02) and is found to be in the same order than the reported Er3+ glasses, that makes our glasses are suitable for various photonic applications. Optical band gap energy (Eopt) values through direct and indirect allowed transitions of the prepared Er3+ glasses have also been determined and compared with similar studies.

  2. Emission mechanism of radiophotoluminescence in Ag-doped phosphate glass

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Y., E-mail: miyamoto-y@c-technol.co.j [Oarai Research Center, Chiyoda Technol Corpration, 3681 Narita-cho, Oarai-machi Higashi-ibaraki-gun, Ibaraki-ken 311-1313 (Japan); Yamamoto, T., E-mail: yamamoto-ta@c-technol.co.j [Oarai Research Center, Chiyoda Technol Corpration, 3681 Narita-cho, Oarai-machi Higashi-ibaraki-gun, Ibaraki-ken 311-1313 (Japan); Kinoshita, K. [Advanced Materials, Science Research, Development Center, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusann-shi, Ishikawa-ken 924-0838 (Japan); Koyama, S., E-mail: s-koyama@neptune.kanazawa-it.ac.j [Advanced Materials, Science Research, Development Center, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusann-shi, Ishikawa-ken 924-0838 (Japan); Takei, Y., E-mail: takei@neptune.kanazawa-it.ac.j [Advanced Materials, Science Research, Development Center, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusann-shi, Ishikawa-ken 924-0838 (Japan); Nanto, H., E-mail: hnanto@neptune.kanazawa-it.ac.j [Advanced Materials, Science Research, Development Center, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusann-shi, Ishikawa-ken 924-0838 (Japan); Shimotsuma, Y., E-mail: yshimo@collon1.kuic.kyoto-u.ac.j [Department of Materials Chemistry, Graduate School of Engineering, Kyoto University, A3-119 Katsura, Kyoto-University, Nishikyo-ku, Kyoto-shi, Kyoto-hu 615-8510 (Japan); Sakakura, M., E-mail: masa@collon1.kuic.kyoto-u.ac.j [Department of Materials Chemistry, Graduate School of Engineering, Kyoto University, A3-119 Katsura, Kyoto-University, Nishikyo-ku, Kyoto-shi, Kyoto-hu 615-8510 (Japan); Miura, K., E-mail: kmiura@collon1.kuic.kyoto-u.ac.j [Department of Materials Chemistry, Graduate School of Engineering, Kyoto University, A3-119 Katsura, Kyoto-University, Nishikyo-ku, Kyoto-shi, Kyoto-hu 615-8510 (Japan)

    2010-03-15

    The objective of this study is to investigate the emission mechanism of radiophotoluminescence (RPL) in the Ag{sup +}-doped phosphate glass (glass dosimeter), which is now used as individual radiation dosimeter, because the emission mechanism of RPL in glass dosimeter was not fully understood. Optical properties such as optical absorption spectrum, RPL spectrum and change of RPL spectrum as a function of X-ray irradiation dose were measured for commercially available glass dosimeter. In this study, we discuss the emission mechanism of two RPL peaks at 460 nm and 560 nm, based on the fact that electrons and holes produced by X-ray irradiation are trapped at Ag{sup +} ions to produce Ag{sup 0} and Ag{sup 2+} ions, respectively, when the Ag{sup +}-doped phosphate glass is exposed to X-ray. We would like to propose the emission mechanism of RPL peaks at 460 nm and 560 nm, concerning with Ag{sup 2+} and Ag{sup 0} ions.

  3. Environmental stability of actively mode locked fibre lasers

    Science.gov (United States)

    Hill, Calum H.; Lee, Stephen T.; Reid, Derryck T.; Baili, Ghaya; Davies, John

    2016-10-01

    Lasers developed for defence related applications typically encounter issues with reliability and meeting desired specification when taken from the lab to the product line. In particular the harsh environmental conditions a laser has to endure can lead to difficulties. This paper examines a specific class of laser, namely actively mode-locked fibre lasers (AMLFLs), and discusses the impact of environmental perturbations. Theoretical and experimental results have assisted in developing techniques to improve the stability of a mode-locked pulse train for continuous operation. Many of the lessons learned in this research are applicable to a much broader category of lasers. The AMLFL consists of a fibre ring cavity containing a semiconductor optical amplifier (SOA), an isolator, an output coupler, a circulator, a bandpass filter and a modulator. The laser produces a train of 6-ps pulses at 800 nm with a repetition rate in the GHz regime and a low-noise profile. This performance is realisable in a laboratory environment. However, even small changes in temperature on the order of 0.1 °C can cause a collapse of mode-locked dynamics such that the required stability cannot be achieved without suitable feedback. Investigations into the root causes of this failure were performed by changing the temperature of components that constitute the laser resonator and observing their properties. Several different feedback mechanisms have been investigated to improve laser stability in an environment with dynamic temperature changes. Active cavity length control will be discussed along with DC bias control of the Mach-Zehnder modulator (MZM).

  4. Kerr-lens Mode Locking Without Nonlinear Astigmatism

    CERN Document Server

    Yefet, Shi; Pe'er, Avi

    2013-01-01

    We demonstrate a Kerr-lens mode locked folded cavity using a planar (non-Brewster) Ti:sapphire crystal as a gain and Kerr medium, thus cancelling the nonlinear astigmatism caused by a Brewster cut Kerr medium. Our method uses a novel cavity folding in which the intra-cavity laser beam propagates in two perpendicular planes such that the astigmatism of one mirror is compensated by the other mirror, enabling the introduction of an astigmatic free, planar-cut gain medium. We demonstrate that this configuration is inherently free of nonlinear astigmatism, which in standard cavity folding needs a special power specific compensation.

  5. Vector Dissipative Solitons in Graphene Mode Locked Fiber Lasers

    CERN Document Server

    Zhang, Han; Zhao, Luming; Bao, Qiaoliang; Loh, Kian Ping

    2010-01-01

    Vector soliton operation of erbium-doped fiber lasers mode locked with atomic layer graphene was experimentally investigated. Either the polarization rotation or polarization locked vector dissipative solitons were experimentally obtained in a dispersion-managed cavity fiber laser with large net cavity dispersion, while in the anomalous dispersion cavity fiber laser, the phase locked NLSE solitons and induced NLSE soliton were experimentally observed. The vector soliton operation of the fiber lasers unambiguously confirms the polarization insensitive saturable absorption of the atomic layer graphene when the light is incident perpendicular to its 2D atomic layer.

  6. Iron Phosphate Glass-Containing Hanford Waste Simulant

    Energy Technology Data Exchange (ETDEWEB)

    Sevigny, Gary J.; Kimura, Marcia L.; Fischer, Christopher M.; Schweiger, Michael J.; Kim, Dong-Sang

    2011-08-01

    Resolution of the nation’s high level tank waste legacy requires the design, construction, and operation of large and technically complex one-of-a-kind processing waste treatment and vitrification facilities. While the ultimate limits for waste loading and melter efficiency have yet to be defined or realized, significant reductions in glass volumes for disposal and mission life may be possible with advancements in melter technologies and/or glass formulations. This test report describes the experimental results from a small-scale test using the research scale melter (RSM) at Pacific Northwest National Laboratory (PNNL) to demonstrate the viability of iron phosphate-based glass with a selected waste composition that is high in sulfates (4.37 wt% SO3). The primary objective of the test was to develop data to support a cost-benefit analysis as related to the implementation of phosphate-based glasses for Hanford low activity waste (LAW) and/or other high-level waste streams within the U.S. Department of Energy complex. The testing was performed by PNNL and supported by Idaho National Laboratory, Savannah River National Laboratory, and Mo-Sci Corporation.

  7. Thermodynamic Development of Corrosion Rate Modeling in Iron Phosphate Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Schlesinger, Mark [Missouri Univ. of Science and Technology, Rolla, MO (United States); Brow, Richard [Missouri Univ. of Science and Technology, Rolla, MO (United States)

    2011-10-31

    A two-year research program investigated links between the thermodynamic properties of phosphate glasses and their corrosion rates in different solutions. Glasses in the Na2O-CaO-P2O5 and Na2O-Fe2O3-PO5 systems were prepared and characterized. These glasses were then exposed in bulk and powder form to acid (0.1M HCl), basic (0.1M KOH) and neutral (deionized water) solutions at varying exposure times and temperatures. Analysis of the solution and the glass after exposure determined the rate and type of corrosion that occurred. Simultaneously, efforts were made to determine the thermodynamic properties of solid iron phosphate compounds. This included measurement of low temperature (5-300 K) heat capacities, measured at Brigham Young University; the attempted use of a Parr calorimeter to measure ambient temperature enthalpies of formation; and attempted measurement of temperature heat capacities. Only the first of the three tasks was successfully accomplished. In lieu of experimental measurement of enthalpies of formation, first-principles calculation of enthalpies of formation was performed at Missouri S&T; these results will be used in subsequent modeling efforts.

  8. Iron Phosphate Glass-Containing Hanford Waste Simulant

    Energy Technology Data Exchange (ETDEWEB)

    Sevigny, Gary J.; Kimura, Marcia L.; Fischer, Christopher M.; Schweiger, M. J.; Rodriguez, Carmen P.; Kim, Dong-Sang; Riley, Brian J.

    2012-01-18

    Resolution of the nation's high-level tank waste legacy requires the design, construction, and operation of large and technically complex one-of-a-kind processing waste treatment and vitrification facilities. While the ultimate limits for waste loading and melter efficiency have yet to be defined or realized, significant reductions in glass volumes for disposal and mission life may be possible with advancements in melter technologies and/or glass formulations. This test report describes the experimental results from a small-scale test using the research-scale melter (RSM) at Pacific Northwest National Laboratory (PNNL) to demonstrate the viability of iron-phosphate-based glass with a selected waste composition that is high in sulfate (4.37 wt% SO3). The primary objective of the test was to develop data to support a cost-benefit analysis related to the implementation of phosphate-based glasses for Hanford low-activity waste (LAW) and/or other high-level waste streams within the U.S. Department of Energy complex. The testing was performed by PNNL and supported by Idaho National Laboratory, Savannah River National Laboratory, Missouri University of Science and Technology, and Mo-Sci Corporation.

  9. Iron phosphate glasses: Structure determination and radiation tolerance

    Science.gov (United States)

    Jolley, Kenny; Smith, Roger

    2016-05-01

    Iron phosphate glass (IPG) has gained recent interest for use in encapsulating radioactive waste for long term storage. In this work, we investigate 5 different compositions of iron phosphate glass. We consider amorphous structures of 3 known crystalline phases: Fe2+ Fe23+ (P2O7)2, Fe43 + (P2O7)3 and Fe3+(PO3)3, and structures of IPG (40 mol% Fe2O3 and 60 mol% P2O5), with 4% and 17% Fe2+ ion concentrations. Using constant volume molecular dynamics (MD), we quench a set of structures for each glass composition, to find the optimal density structure. We found that the lowest energy structures of IPG with 4% and 17% concentration of Fe2+, have a density of 3.25 and 3.28 g/cm3 respectively. This is slightly higher than the experimentally measured values of 2.9 and 2.95 g/cm3 respectively. We also estimate an upper and lower bound on the melting temperatures of each glass, then for each glass, we simulate radiation damage cascades at 4 keV. The cascade structures can be in the form of either a concentrated thermal spike or more diffuse with sub-cascade branching. We found that the glass compositions with a higher Fe/P atomic ratio, contained a greater number of displacements after the cascade. We also found that the IPG with 4% Fe2+, contained slightly fewer displacements than the IPG with 17% Fe2+. This is consistent with our previous work, which showed that the threshold displacement energies are lower for glasses with a lower Fe2+ content. In all the simulations, many PO4 polyhedra are destroyed during the early stages of irradiation, but recover strongly over a time scale of picoseconds, leaving very few over or under co-ordinated P atoms at the end of the ballistic phase. This is in contrast to recent work in apatite. The strong recovery indicates that phosphate glasses with a low Fe2+ content could be good materials for waste encapsulation.

  10. Active mode-locking via pump modulation in a Tm-doped fiber laser

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-10-01

    Full Text Available We propose and experimentally realize a new class of actively mode-locking technique using pump modulation for rare-earth doped fiber lasers. A Tm-doped fiber laser at 2 μm is mode-locked using the proposed active mode-locking via pump modulation technique. Low-threshold continuous-wave mode-locking is achieved with a transform-limited pulse width of 4.4 ps, a spectral bandwidth of 0.9 nm, and a repetition rate of 12.9 MHz. Second-harmonic mode-locking is also demonstrated by simply driving the pump current at an appropriate frequency. More importantly, we believe that this technique can be applied to mode-lock other rare-earth doped fiber laser systems such as erbium- and ytterbium-doped fiber lasers.

  11. Commercial mode-locked vertical external cavity surface emitting lasers

    Science.gov (United States)

    Lubeigt, Walter; Bialkowski, Bartlomiej; Lin, Jipeng; Head, C. Robin; Hempler, Nils; Maker, Gareth T.; Malcolm, Graeme P. A.

    2017-02-01

    In recent years, M Squared Lasers have successfully commercialized a range of mode-locked vertical external cavity surface emitting lasers (VECSELs) operating between 920-1050nm and producing picosecond-range pulses with average powers above 1W at pulse repetition frequencies (PRF) of 200MHz. These laser products offer a low-cost, easy-to-use and maintenance-free tool for the growing market of nonlinear microscopy. However, in order to present a credible alternative to ultrafast Ti-sapphire lasers, pulse durations below 200fs are required. In the last year, efforts have been directed to reduce the pulse duration of the Dragonfly laser system to below 200fs with a target average power above 1W at a PRF of 200MHz. This paper will describe and discuss the latest efforts undertaken to approach these targets in a laser system operating at 990nm. The relatively low PRF operation of Dragonfly lasers represents a challenging requirement for mode-locked VECSELs due to the very short upper state carrier lifetime, on the order of a few nanoseconds, which can lead to double pulsing behavior in longer cavities as the time between consecutive pulses is increased. Most notably, the design of the Dragonfly VECSEL cavity was considerably modified and the laser system extended with a nonlinear pulse stretcher and an additional compression stage. The improved Dragonfly laser system achieved pulse duration as short as 130fs with an average power of 0.85W.

  12. Quantum model for mode locking in pulsed semiconductor quantum dots

    Science.gov (United States)

    Beugeling, W.; Uhrig, Götz S.; Anders, Frithjof B.

    2016-12-01

    Quantum dots in GaAs/InGaAs structures have been proposed as a candidate system for realizing quantum computing. The short coherence time of the electronic quantum state that arises from coupling to the nuclei of the substrate is dramatically increased if the system is subjected to a magnetic field and to repeated optical pulsing. This enhancement is due to mode locking: oscillation frequencies resonant with the pulsing frequencies are enhanced, while off-resonant oscillations eventually die out. Because the resonant frequencies are determined by the pulsing frequency only, the system becomes immune to frequency shifts caused by the nuclear coupling and by slight variations between individual quantum dots. The effects remain even after the optical pulsing is terminated. In this work, we explore the phenomenon of mode locking from a quantum mechanical perspective. We treat the dynamics using the central-spin model, which includes coupling to 10-20 nuclei and incoherent decay of the excited electronic state, in a perturbative framework. Using scaling arguments, we extrapolate our results to realistic system parameters. We estimate that the synchronization to the pulsing frequency needs time scales in the order of 1 s .

  13. WS2 mode-locked ultrafast fiber laser

    Science.gov (United States)

    Mao, Dong; Wang, Yadong; Ma, Chaojie; Han, Lei; Jiang, Biqiang; Gan, Xuetao; Hua, Shijia; Zhang, Wending; Mei, Ting; Zhao, Jianlin

    2015-01-01

    Graphene-like two dimensional materials, such as WS2 and MoS2, are highly anisotropic layered compounds that have attracted growing interest from basic research to practical applications. Similar with MoS2, few-layer WS2 has remarkable physical properties. Here, we demonstrate for the first time that WS2 nanosheets exhibit ultrafast nonlinear saturable absorption property and high optical damage threshold. Soliton mode-locking operations are achieved separately in an erbium-doped fiber laser using two types of WS2-based saturable absorbers, one of which is fabricated by depositing WS2 nanosheets on a D-shaped fiber, while the other is synthesized by mixing WS2 solution with polyvinyl alcohol, and then evaporating them on a substrate. At the maximum pump power of 600 mW, two saturable absorbers can work stably at mode-locking state without damage, indicating that few-layer WS2 is a promising high-power flexible saturable absorber for ultrafast optics. Numerous applications may benefit from the ultrafast nonlinear features of WS2 nanosheets, such as high-power pulsed laser, materials processing, and frequency comb spectroscopy. PMID:25608729

  14. Large energy mode locking of an erbium-doped fiber laser with atomic layer graphene.

    Science.gov (United States)

    Zhang, H; Tang, D Y; Zhao, L M; Bao, Q L; Loh, K P

    2009-09-28

    We report on large energy pulse generation in an erbium-doped fiber laser passively mode-locked with atomic layer graphene. Stable mode locked pulses with single pulse energy up to 7.3 nJ and pulse width of 415 fs have been directly generated from the laser. Our results show that atomic layer graphene could be a promising saturable absorber for large energy mode locking.

  15. Study on Thermal Stability and Spectroscopic Properties of Nd3+ -Doped Phosphate Laser Glasses

    Institute of Scientific and Technical Information of China (English)

    Shi Qi; Lv Jingwen; Cheng Hong; Fu Xingguo; Sun Yu

    2004-01-01

    Fluorescence spectra, absorption spectra and thermal stability properties of Nd3 + -doped phosphate laser glasses were tested in this work. We calculated spectroscopic parameters of Nd3 + -doped phosphate laser glasses according to their absorption spectrum. Measuring and calculating linear thermal expansion coefficient, and analysising thermal stability of glasses show that this kind of Nd3 + -doped phosphate laser glasses has thermal expansion coefficient α = 38.75× 10 -7/℃ and optimal spectroscopic properties which extend application range of Nd +3-doped phosphate laser glasses.

  16. Passive harmonic mode locked all-normal-dispersion Yb-doped fibre lasers

    Institute of Scientific and Technical Information of China (English)

    Kong Ling-Jie; Xiao Xiao-Sheng; Yang Chang-Xi

    2011-01-01

    Passive harmonic mode-locking of dissipative solitons is demonstrated in all-normal dispersion Yb-doped fibre lasers. A difference equation model of the mode-locked fibre lasers is adopted to simulate the intra-cavity nonlinear dynamics. Hysteresis phenomena around the mode-locking threshold, and the effect of introducing linear phase bias are discussed. The passive harmonic mode-locking as one kind of multipulsing operations is revealed. Moreover, the simulation shows the bistability between multipulsing and single-pulse or period multiplication.

  17. Properties of InGaAs quantum dot saturable absorbers in monolithic mode-locked lasers

    DEFF Research Database (Denmark)

    Thompson, M.G.; Marinelli, C.; Chu, Y.

    Saturable absorbers properties are characterised in monolithic mode-locked InGaAs quantum dot lasers. We analyse the impact of weak quantum confined Stark effect, fast absorber recovery time and low absorber saturation power on the mode-locking performance.......Saturable absorbers properties are characterised in monolithic mode-locked InGaAs quantum dot lasers. We analyse the impact of weak quantum confined Stark effect, fast absorber recovery time and low absorber saturation power on the mode-locking performance....

  18. An extended topological model for binary phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Hermansen, Christian [Section of Chemistry, Aalborg University, 9220 Aalborg (Denmark); Rodrigues, Bruno P.; Wondraczek, Lothar [Otto Schott Institute of Materials Research, University of Jena, 07743 Jena (Germany); Yue, Yuanzheng, E-mail: yy@bio.aau.dk [Section of Chemistry, Aalborg University, 9220 Aalborg (Denmark); State Key Laboratory of Silicate Materials for Architecture, Wuhan University of Technology, Wuhan 430070 (China)

    2014-12-28

    We present a topological model for binary phosphate glasses that builds on the previously introduced concepts of the modifying ion sub-network and the strength of modifier constraints. The validity of the model is confirmed by the correct prediction of T{sub g}(x) for covalent polyphosphoric acids where the model reduces to classical constraint counting. The constraints on the modifying cations are linear constraints to first neighbor non-bridging oxygens, and all angular constraints are broken as expected for ionic bonding. For small modifying cations, such as Li{sup +}, the linear constraints are almost fully intact, but for larger ions, a significant fraction is broken. By accounting for the fraction of intact modifying ion related constraints, q{sub γ}, the T{sub g}(x) of alkali phosphate glasses is predicted. By examining alkali, alkaline earth, and rare earth metaphosphate glasses, we find that the effective number of intact constraints per modifying cation is linearly related to the charge-to-distance ratio of the modifying cation to oxygen.

  19. Passive mode-locking of fiber ring laser at the 337th harmonic using gigahertz acoustic core resonances.

    Science.gov (United States)

    Kang, M S; Joly, N Y; Russell, P St J

    2013-02-15

    We report the experimental demonstration of a passively mode-locked Er-doped fiber ring laser operating at the 337th harmonic (1.80 GHz) of the cavity. The laser makes use of highly efficient Raman-like optoacoustic interactions between the guided light and gigahertz acoustic resonances trapped in the micron-sized solid glass core of a photonic crystal fiber. At sufficient pump power levels the laser output locks to a repetition rate corresponding to the acoustic frequency. A stable optical pulse train with a side-mode suppression ratio higher than 45 dB was obtained at low pump powers (~60 mW).

  20. Material Engineering for Monolithic Semiconductor Mode-Locked Lasers

    DEFF Research Database (Denmark)

    Kulkova, Irina

    This thesis is devoted to the materials engineering for semiconductor monolithic passively mode-locked lasers (MLLs) as a compact energy-efficient source of ultrashort optical pulses. Up to the present day, the achievement of low-noise sub-picosecond pulse generation has remained a challenge....... This work has considered the role of the combined ultrafast gain and absorption dynamics in MLLs as a main factor limiting laser performance. An independent optimization of MLL amplifier and saturable absorber active materials was performed. Two promising approaches were considered: quantum dot (QD...... application in MLLs. Improved QW laser performance was demonstrated using the asymmetric barrier layer approach. The analysis of the gain characteristics showed that the high population inversion beneficial for noise reduction cannot be achieved for 10 GHz QW MLLs and would have required lowering the modal...

  1. Anapole nanolasers for mode-locking and ultrafast pulse generation

    KAUST Repository

    Gongora, Juan S. Totero

    2017-05-31

    Nanophotonics is a rapidly developing field of research with many suggestions for a design of nanoantennas, sensors and miniature metadevices. Despite many proposals for passive nanophotonic devices, the efficient coupling of light to nanoscale optical structures remains a major challenge. In this article, we propose a nanoscale laser based on a tightly confined anapole mode. By harnessing the non-radiating nature of the anapole state, we show how to engineer nanolasers based on InGaAs nanodisks as on-chip sources with unique optical properties. Leveraging on the near-field character of anapole modes, we demonstrate a spontaneously polarized nanolaser able to couple light into waveguide channels with four orders of magnitude intensity than classical nanolasers, as well as the generation of ultrafast (of 100 fs) pulses via spontaneous mode locking of several anapoles. Anapole nanolasers offer an attractive platform for monolithically integrated, silicon photonics sources for advanced and efficient nanoscale circuitry.

  2. Development and commercialization of mode-locked VECSELs

    Science.gov (United States)

    Hempler, Nils; Bialkowski, Bartlomiej; Hamilton, Craig J.; Maker, Gareth T.; Malcolm, Graeme P. A.

    2015-03-01

    This paper will describe the current state-of-the-art in commercial mode-locked Vertical External Cavity Surface Emitting Lasers (VECSEL) and demonstrate their efficacy in key applications. Based on indium gallium arsenide quantum well gain structures, our systems operate between 920 nm - 1050 nm with >1 W output powers, 200 MHz pulse repetition rate and duration. Crucially, the development issues that have been overcome to bring this promising technology to market will be discussed. These include: thermal management challenges, electronic control system development and robust mechanical design requirements. Having the potential to replace more conventional titanium sapphire laser technology where wavelength flexibility can be traded off against a significantly lower cost point and form factor, we will discuss the use of VECSELs in key applications such as nonlinear microscopy.

  3. Neutron scattering study of protonated and deuterated potassium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yamamuro, Osamu; Madokoro, Yasushi; Obara, Hideki; Harabe, Kouji; Matsuo, Takasuke [Department of Chemistry, Graduate School of Science, Osaka Univ., Toyonaka, Osaka (Japan); Kamiyama, Takashi [Graduate School of Engineering, Hokkaido Univ., Sappro, Hokkaido (Japan); Fukazawa, Hiroshi; Ikeda, Susumu [Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan)

    2001-03-01

    The incoherent inelastic neutron scattering from protonated potassium phosphate glass was measured on CAT at KENS and AGNES at ISSP (JRR-3M) over a wide energy range of 0.1-300 meV. The measurement of coherent inelastic scattering was also performed for the deuterated analogue in the energy range 3-90 meV and momentum transfer range 1-13 A{sup -1} by using MARI at ISIS. We have found a boson peak at around 4 meV and some interesting features of the acoustic and localized vibrations characteristic to the amorphous structure of the present materials. (author)

  4. Ytterbium-Phosphate Glass for Microstructured Fiber Laser

    Directory of Open Access Journals (Sweden)

    Ryszard Stępień

    2014-06-01

    Full Text Available In the paper, we report on the development of a synthesis and melting method of phosphate glasses designed for active microstructured fiber manufacturing. Non-doped glass synthesized in a P2O5-Al2O3-BaO-ZnO-MgO-Na2O oxide system served as the matrix material; meanwhile, the glass was doped with 6 mol% (18 wt% of Yb2O3, as fiber core. The glasses were well-fitted in relation to optical (refractive index and thermal proprieties (thermal expansion coefficient, rheology. The fiber with the Yb3+-doped core, with a wide internal photonic microstructure for a laser pump, as well as with a high relative hole size in the photonic outer air-cladding, was produced. The laser built on the basis of this fiber enabled achieving 8.07 W of output power with 20.5% slope efficiency against the launched pump power, in single-mode operation M2 = 1.59, from a 53 cm-long cavity.

  5. Intermediate- and extended-range order in phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Suzuya, Kentaro [Japan Atomic Research Institute, Ako, Hyogo (Japan)]|[Argonne National Lab., IL (United States); Price, D.L.; Loong, Chun-Keung [Argonne National Lab., IL (United States); Martin, S.W. [Iowa State Univ., Ames, IA (United States). Dept. of Materials Science and Engineering

    1997-08-01

    The structure of sodium ultraphosphate glasses, (Na{sub 2}O){sub x}(P{sub 2}O{sub 5}){sub 100-x} (x = 0, 10, 20), and alkali metaphosphate glasses, MePO{sub 3} (Me = Li, Na, K, Rb and Cs) have been studied by neutron diffraction. Structural features in the neutron structure factors S(Q) characteristic of intermediate-range (Q {approx_lt} 3 {angstrom}{sup -1}) order were identified. The feature of intermediate-range order in the pure phosphate glass (v-P{sub 2}O{sub 5}) is accounted for by the P{sub 4}O{sub 10} molecule packing model. The addition of the alkali metal modifier, Na, has drastic affect on the intermediate-range structure due to destruction of the PO{sub 4} network structure. Around x {approximately} 50 a new peak arises at lower Q than the intermediate-range order peak, which is found in the S(Q)`s of all alkali metaphosphate glasses, associated with extended-range order. The length scale of extended-range order increases with Me{sup +} size. These phenomena can be explained by the behavior of oxygen atoms. i.e. PO{sub 4} chain-like units ordering around the Me{sup +}.

  6. Independent tunability of the double-mode-locked cw dye laser.

    LENUS (Irish Health Repository)

    Bourkoff, E

    1979-06-01

    We report a new configuration that enables the double-mode-locked cw dye laser to be independently tunable. In addition, the output coupling at each of the two wavelengths can be independently specified. A series of oscillographs shows some interesting features unique to double mode locking and also shows the effects of varying the two cavity lengths with respect to each other.

  7. All-fiber passively mode-locked Ho-laser pumped by ytterbium fiber laser

    Science.gov (United States)

    Filatova, S. A.; Kamynin, V. A.; Zhluktova, I. V.; Trikshev, A. I.; Tsvetkov, V. B.

    2016-11-01

    We report an all-fiber mode-lock holmium-doped ring laser passively mode-locked by nonlinear polarization rotation without dispersion compensation. The laser produced picosecond pulses at 2.057 µm. The average output power was 4.5 mW.

  8. Repetition rate continuously tunable 10-GHz picosecond mode-locked fiber ring laser

    Institute of Scientific and Technical Information of China (English)

    Fang Wan; Ziyu Wang

    2006-01-01

    A couple of simple-structure phase modulators were used in active mode-locked fiber laser to implement repetition rate continuous tuning. The laser produces pulse as short as 5.7 ps whose repetition rate tuning can cover the spacing of the adjoining order mode-locking frequencies.

  9. Dynamic localization and Bloch oscillations in the spectrum of a frequency mode-locked laser.

    Science.gov (United States)

    Longhi, Stefano

    2005-04-01

    It is shown that a frequency mode-locked laser with a sinusoidal sweep of modulation frequency around a mode-locking condition represents an ideal optical system for observing in the spectral domain the phenomena of dynamic localization and Bloch oscillations of electrons in an ideal solid placed in an external ac electric field.

  10. Modeling of mode-locked coupled-resonator optical waveguide lasers

    DEFF Research Database (Denmark)

    Agger, Christian; Skovgård, Troels Suhr; Gregersen, Niels;

    2010-01-01

    Coupled-resonator optical waveguides made from coupled high-Q photonic crystal nanocavities are investigated for use as cavities in mode-locked lasers. Such devices show great potential in slowing down light and can serve to reduce the cavity length of a mode-locked laser. An explicit expression...

  11. Comparison of the noise performance of 10GHz QW and QD mode-locked laser diodes

    DEFF Research Database (Denmark)

    Carpintero, Guillermo; Thompson, Mark G.; Yvind, Kresten

    2010-01-01

    This paper reports the experimental characterization of the noise performance of a quantum dot and a quantum well 10GHz passive mode locked laser diodes.......This paper reports the experimental characterization of the noise performance of a quantum dot and a quantum well 10GHz passive mode locked laser diodes....

  12. Diode-Pumped Soliton and Non-Soliton Mode-Locked Yb:GYSO Lasers

    Institute of Scientific and Technical Information of China (English)

    HE Jin-Ping; LIANG Xiao-Yan; LI Jin-Feng; ZHENG Li-He; SU Liang-Bi; XU Jun

    2011-01-01

    @@ Diode-pumped soliton and non-soliton mode-locked Yb:(Gd1-xYx,)2SiO5 (x=0.5) lasers are demonstrated.Pulsesas short as 1.4 ps are generated for the soliton mode-locked operation, with a pair of SF10 prisms as the negativedispersion elements.The central wavelength is 1056nm and the repetition rate is 48 MHz.For the non-solitonmode locking, the output power could achieve ~1.2W and the pulse width is about 20ps.The critical pulseenergy in the soliton-mode locked operation against the Q-switched mode locking is much lower than the criticalpulse energy in the non-soliton mode-locked operation

  13. Active mode locking of quantum cascade lasers operating in external ring cavity

    CERN Document Server

    Revin, D G; Wang, Y; Cockburn, J W; Belyanin, A

    2015-01-01

    Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode locked operation remains a challenge despite dedicated effort. Here we report the first demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents of a standard commercial laser chip.

  14. Passive mode locking of lasers by crossed-polarization gain modulation.

    Science.gov (United States)

    Javaloyes, Julien; Mulet, Josep; Balle, Salvador

    2006-10-20

    We report on a novel approach for inducing passive mode locking of lasers without using any saturable absorber but exploiting the polarization degree of freedom of light. In our scheme, passive mode locking is achieved by crossed-polarization gain modulation caused by the reinjection of a polarization-rotated replica of the laser output after a time delay. The reinjection time delay defines resonance tongues that correspond to mode-locking operation. Numerical continuation reveals that the cw solution is destabilized through a Hopf bifurcation that defines the onset of multimode operation which evolves sharply into a mode-locked solution. Our approach can be applied to a large variety of laser systems. For vertical-cavity surface-emitting lasers, we demonstrate stable mode-locked pulses at repetition rates in the GHz range and pulse widths of few tens of picoseconds.

  15. Dielectric relaxation and ac conductivity of sodium tungsten phosphate glasses

    Indian Academy of Sciences (India)

    B Singh; P S Tarsikka; L Singh

    2002-10-01

    Studies of dielectric relaxation and ac conductivity have been made on three samples of sodium tungsten phosphate glasses over a temperature range of 77–420 K. Complex relative permittivity data have been analyzed using dielectric modulus approach. Conductivity relaxation frequency increases with the increase of temperature. Activation energy for conductivity relaxation has also been evaluated. Measured ac conductivity (m()) has been found to be higher than dc at low temperatures whereas at high temperature m() becomes equal to dc at all frequencies. The ac conductivity obeys the relation ac() = A over a considerable range of low temperatures. Values of exponent are nearly equal to unity at about 78 K and the values decrease non-linearly with the increase of temperature. Values of the number density of states at Fermi level ((F)) have been evaluated at 80 K assuming values of electron wave function decay constant to be 0.5 (Å)-1. Values of (F) have the order 1020 which are well within the range suggested for localized states. Present values of (F) are smaller than those for tungsten phosphate glasses.

  16. Phosphate-based glasses: Prediction of acoustical properties

    Energy Technology Data Exchange (ETDEWEB)

    El-Moneim, Amin Abd, E-mail: aminabdelmoneim@hotmail.com

    2016-04-15

    In this work, a comprehensive study has been carried out to predict the composition dependence of bulk modulus and ultrasonic attenuation coefficient in the phosphate-based glass systems PbO-P{sub 2}O{sub 5}, Li{sub 2}O-TeO{sub 2}-B{sub 2}O{sub 3}-P{sub 2}O{sub 5}, TiO{sub 2}-Na{sub 2}O-CaO-P{sub 2}O{sub 5} and Cr{sub 2}O{sub 3}-doped Na{sub 2}O-ZnO-P{sub 2}O{sub 5} at room temperature. The prediction is based on (i) Makishima-Mackenzie theory, which correlates the bulk modulus with packing density and dissociation energy per unit volume, and (ii) Our recently presented semi-empirical formulas, which correlate the ultrasonic attenuation coefficient with the oxygen density, mean atomic ring size, first-order stretching force constant and experimental bulk modulus. Results revealed that our recently presented semi-empirical formulas can be applied successfully to predict changes of ultrasonic attenuation coefficient in binary PbO-P{sub 2}O{sub 5} glasses at 10 MHz frequency and in quaternary Li{sub 2}O-TeO{sub 2}-B{sub 2}O{sub 3}-P{sub 2}O{sub 5}, TiO{sub 2}-Na{sub 2}O-CaO-P{sub 2}O{sub 5} and Cr{sub 2}O{sub 3}-Na{sub 2}O-ZnO-P{sub 2}O{sub 5} glasses at 5 MHz frequency. Also, Makishima-Mackenzie theory appears to be valid for the studied glasses if the effect of the basic structural units that present in the glass network is taken into account.

  17. Crystallization Behavior of Phosphate Glasses with Hydrophobic Coating Materials

    Directory of Open Access Journals (Sweden)

    Jaeyeop Chung

    2015-01-01

    Full Text Available We analyzed the effect of the addition of Li2O3, TiO2, and Fe2O3 on the crystallization behavior of P2O5–CaO–SiO2–K2O glasses and the effect of the crystallization behavior on the roughness and hydrophobicity of the coated surface. Exothermic behavior, including a strong exothermic peak in the 833–972 K temperature range when Fe2O3, TiO2, or Li2O3 was added, was confirmed by differential thermal analysis. The modified glass samples (PFTL1–3 showed diffraction peaks when heated at 1073 and 1123 K for 5 min; the crystallized phase corresponds to Fe3(PO42, that is, graftonite. We confirmed that the intensity of the diffraction peaks increases at high temperatures and with increasing Li2O3 content. In the case of the PFTL3 glass, a Li3Fe2(PO42 phase, that is, trilithium diiron(III tris[phosphate(V], was observed. Through scanning electron microscopy and the contact angles of the surfaces with water, we confirmed that the increase in surface roughness, correlated to the crystallization of the glass frit, increases hydrophobicity of the surface. The calculated values of the local activation energies for the growth of Fe3(PO42 on the PTFL1, PTFL2, and PFTL3 glass were 237–292 kJ mol−1, 182–258 kJ mol−1, and 180–235 kJ mol−1.

  18. Polaronic Transport in Phosphate Glasses Containing Transition Metal Ions

    Science.gov (United States)

    Henderson, Mark

    The goal of this dissertation is to characterize the basic transport properties of phosphate glasses containing various amounts of TIs and to identify and explain any electronic phase transitions which may occur. The P2 O5-V2O5-WO3 (PVW) glass system will be analyzed to find the effect of TI concentration on conduction. In addition, the effect of the relative concentrations of network forming ions (SiO2 and P2O5) on transport will be studied in the P2O5-SiO2-Fe2O 3 (PSF) system. Also presented is a numerical study on a tight-binding model adapted for the purposes of modelling Gaussian traps, mimicking TI's, which are arranged in an extended network. The results of this project will contribute to the development of fundamental theories on the electronic transport in glasses containing mixtures of transition oxides as well as those containing multiple network formers without discernible phase separation. The present study on the PVW follows up on previous investigation into the effect on mixed transition ions in oxide glasses. Past research has focused on glasses containing transition metal ions from the 3d row. The inclusion of tungsten, a 5d transition metal, adds a layer of complexity through the mismatch of the energies of the orbitals contributing to localized states. The data have indicated that a transition reminiscent of a metal-insulator transition (MIT) occurs in this system as the concentration of tungsten increases. As opposed to some other MIT-like transitions found in phosphate glass systems, there seems to be no polaron to bipolaron conversion. Instead, the individual localization parameter for tungsten noticeably decreases dramatically at the transition point as well as the adiabaticity. Another distinctive feature of this project is the study of the PSF system, which contains two true network formers, phosphorous pentoxide (P2O 5) and silicon dioxide (SiO2). It is not usually possible to do a reliable investigation of the conduction properties of

  19. Phosphate-bonded glass cements for geothermal wells. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rockett, T.J.

    1979-09-01

    Calcium aluminosilicate glasses were found to react with phosphoric acid in three ways depending upon silica content. Above 55% SiO/sub 2/ they are insoluble while below 50% they dissolve readily. The transition compositions release calcium and aluminum ions and a silica gel phase replaces the glass. Activation energies in the order of 10 kcal/mole are associated with the dissolution. Equilibrium studies in the systems CaO-P/sub 2/O/sub 5/-H/sub 2/O, Al/sub 2/O/sub 3/-P/sub 2/O/sub 5/-H/sub 2/O, and CaO-Al/sub 2/O/sub 3/-P/sub 2/O/sub 5/-H/sub 2/O were made to determine the phases which are stable at 200/sup 0/C in excess water. The CaO system shows hydroxylapatite, monetite and monocalcium orthophosphate are the stable phases. The Al/sub 2/O/sub 3/ system contains augelite, berlinite, and a high phosphate aluminum hydrate. The quaternary system shows the above phase plus a lime alumina hydrogarnet and crandallite. Cement made from a glass frit of the composition 45% SiO/sub 2/: 24% CaO: 24% Al/sub 2/O/sub 3/ has a compressive strength of 500 psi after several days in steam at 200/sup 0/C and 800 psi after months in steam. Bonding of cements to mild steel are discussed.

  20. Diode-Pumped Mode-Locked LiSAF Laser

    Energy Technology Data Exchange (ETDEWEB)

    None

    1996-02-01

    Under this contract we have developed Cr{sup 3+}:LiSrAlF{sub 6} (Cr:LiSAF, LiSAF) mode-locked lasers suitable for generation of polarized electrons for CEBAF. As 670 nm is an excellent wavelength for optical pumping of Cr:LiSAF, we have used a LIGHTWAVE developed 670 nm diode pump module that combines the output of ten diode lasers and yields approximately 2 Watts of optical power. By the use of a diffraction limited pump beam however, it is possible to maintain a small mode size through the length of the crystal and hence extract more power from Cr:LiSAF laser. For this purpose we have developed a 1 Watt, red 660nm laser (LIGHTWAVE model 240R) which serves as an ideal pump for Cr:LiSAF and is a potential replacement of costly and less robust krypton laser. This new system is to compliment LIGHTWAVE Series 240, and is currently being considered for commercialization. Partially developed under this contract is LIGHTWAVEs product model 240 which has already been in our production lines for a few months and is commercially available. This laser produces 2 Watts of output at 532 nm using some of the same technology developed for production of the 660nm red system. It is a potential replacement for argon ion lasers and has better current and cooling requirements and is an excellent pump source for Ti:Al{sub 2}O{sub 3}. Also, as a direct result of this contract we now have the capability of commercially developing a mode-locked 100MHz Cr:LiSAF system. Such a laser could be added to our 100 MHz LIGHTWAVE Series 131. The Series 131 lasers provide pico second pulses and were originally developed under another DOE SBIR. Both models of LIGHTWAVE Series 240 lasers, the fiber coupled pump module and the 100MHz LiSAF laser of Series 131 have been partially developed under this contract, and are commercially competitive products.

  1. The antimicrobial activity of as-prepared silver-loaded phosphate glasses and zirconium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Wang; Jiang, Ji Zhi; Yang, Yang; Yan, Zhao Chun; Yan, Wang Xiao [China Building Materials Academy, Beijing (China); He, Shui Zhong [Wuhan University of Technology, Wuhan (China)

    2016-03-15

    The antimicrobial activities of silver-loaded zirconium phosphate (JDG) and silver-loaded phosphate glasses (ZZB) against Escherichia coli were studied. Although the silver content in JDG was higher than that in ZZB, ZZB suspensions showed better antimicrobial property than JDG suspensions, especially at low concentrations. The antimicrobial activity was analyzed using minimum inhibitory concentrations, bacterial inhibition ring tests, and detection of silver ions in the suspensions. Furthermore, the amounts of silver ions in suspensions with/without bacterial cells were analyzed. Results revealed that only a portion of released silver ions could be adsorbed by E. coli cells, which are critical to cell death. The damaged microstructures of E. coli cells observed by transmission electron microscopy may further prove that the adsorbed silver ions play an important role in the antimicrobial process.

  2. Radiation Shielding Properties Comparison of Pb-Based Silicate, Borate, and Phosphate Glass Matrices

    Directory of Open Access Journals (Sweden)

    Suwimon Ruengsri

    2014-01-01

    Full Text Available Theoretical calculations of mass attenuation coefficients, partial interactions, atomic cross-section, and effective atomic numbers of PbO-based silicate, borate, and phosphate glass systems have been investigated at 662 keV. PbO-based silicate glass has been found with the highest total mass attenuation coefficient and then phosphate and borate glasses, respectively. Compton scattering has been the dominate interaction contributed to the different total attenuation coefficients in each of the glass matrices. The silicate and phosphate glass systems are more appropriate choices as lead-based radiation shielding glass than the borate glass system. Moreover, comparison of results has shown that the glasses possess better shielding properties than standard shielding concretes, suggesting a smaller size requirement in addition to transparency in the visible region.

  3. Characterization of a self-starting, passively mode-locked fiber ring laser that exploits nonlinear polarization evolution.

    Science.gov (United States)

    Matsas, V J; Richardson, D J; Newson, T P; Payne, D N

    1993-03-01

    A full characterization of a self-starting, passively mode-locked soliton ring fiber laser in terms of its various modes of mode-locked operation, cavity length, and type of fiber used is presented. Direct evidence, based on state-of-polarization measurements, that nonlinear polarization evolution is the responsible mode-locking mechanism is also given.

  4. Energy transfer between Gd3+ and Tb3+ in phosphate glass

    Institute of Scientific and Technical Information of China (English)

    HE Dongbing; YU Chunlei; CHENG Jimeng; LI Shunguang; HU Lili

    2011-01-01

    The phosphate glass doped with Gd3+,Tb3+ and Gd3+/Tb3+ were prepared by high temperature melting. The photo-luminescence behavior of Gd3+ and Tb3+ in phosphate glass were investigated by absorption, excitation, and emission spectroscopy. Energy transfer between Gd3+ and Tb3+ in phosphate glass was studied, and it was found that there were two energy transfer mechanisms between Gd3+ and Tb3+ in phosphate glass: one was from 4f7 level of Gd3+ to the 4f8 level of Tb3+, and the other was from 5d level of Tb3+ to 4f7 level of Gd3+. The new findings would be beneficial for the study of Tb3+-doped scintillating phosphate glass.

  5. Widely tunable Tm-doped mode-locked all-fiber laser

    Science.gov (United States)

    Yan, Zhiyu; Sun, Biao; Li, Xiaohui; Luo, Jiaqi; Shum, Perry Ping; Yu, Xia; Zhang, Ying; Wang, Qi Jie

    2016-06-01

    We demonstrated a widely tunable Tm-doped mode-locked all-fiber laser, with the widest tunable range of 136 nm, from 1842 to 1978 nm. Nonlinear polarization evolution (NPE) technique is employed to enable mode-locking and the wavelength-tunable operation. The widely tunable range attributes to the NPE-induced transmission modulation and bidirectional pumping mechanism. Such kind of tunable mode-locked laser can find various applications in optical communications, spectroscopy, time-resolved measurement, and among others.

  6. A wide bandwidth free-electron laser with mode locking using current modulation.

    Energy Technology Data Exchange (ETDEWEB)

    Kur, E.; Dunning, D. J.; McNeil, B. W. J.; Wurtele, J.; Zholents, A. A. (Accelerator Systems Division (APS)); (Univ. of California at Berkeley); (Univ. of Strathclyde); (STFC Daresbury Lab.); (LBNL)

    2011-01-20

    A new scheme for mode locking a free-electron laser amplifier is proposed based on electron beam current modulation. It is found that certain properties of the original concept, based on the energy modulation of electrons, are improved including the spectral brightness of the source and the purity of the series of short pulses. Numerical comparisons are made between the new and old schemes and between a mode-locked free-electron laser and self-amplified spontaneous emission free-electron laser. Illustrative examples using a hypothetical mode-locked free-electron laser amplifier are provided. The ability to generate intense coherent radiation with a large bandwidth is demonstrated.

  7. Long all-active monolithic mode-locked lasers with surface-etched bragg gratings

    OpenAIRE

    Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher

    2007-01-01

    We have fabricated 4.4-mm-long monolithic InAlGaAsP–InP mode-locked lasers with integrated deeply surface etched distributed Bragg reflector (DBR) mirrors. The lasers produce 3.7-ps transform-limited Gaussian pulses with 10-mW average output power and 250-fs absolute timing jitter. The performance of the DBR lasers is compared to the performance of Fabry–PÉrot mode-locked lasers from the same wafer and to the performance of earlier reported long monolithic DBR mode-locked lasers and is found ...

  8. Generation of the numerator=2 rational harmonic mode-locked pulses in fiber ring lasers

    Institute of Scientific and Technical Information of China (English)

    Pinghe Wang(汪平河); Li Zhan(詹黎); Qinghao Ye(叶庆好); Yuxing Xia(夏宇兴)

    2004-01-01

    In conventional rational harmonic mode-locking, optical pulse trains with the repetition rate of(pn + 1)fc are generated when the modulation frequency of the in-cavity modulator is set at fm=(n + 1/p)fc, where n and p are both integers, fc is the fundamental cavity frequency. In this paper, we report that rational harmonic mode locking phenomenon takes place in the fiber lasers when the modulation frequency is set at fm =(n + 2/p)fc. The pulse generations are experimentally demonstrated when the numerator of the rational corresponds to 2 in 5th and 7th order rational harmonic mode-locking.

  9. Equal-Amplitude Optical Pulse Generation from a Rational Harmonic Mode-Locked Fibre Laser

    Institute of Scientific and Technical Information of China (English)

    FENG Xin-Huan; YUAN Shu-Zhong; LI Yao; LIU Yan-Ge; KAI Gui-Yun; DONG Xiao-Yi

    2004-01-01

    A simple technique for the generation of equal-amplitude high repetition rate pulses from a rational harmonic mode-locked fibre ring laser is demonstrated. The principle is based on the combination of the nonlinear characteristics of the modulator and the effect of rational harmonic mode-locking. The two sources act on each other and the integrated effect eventually leads to the pulse amplitude-equalization. We obtain amplitude-equalized short pulses up to the fifth-order rational harmonic mode-locking with an optimum bias level and modulation depth of the modulator, which demonstrates the efficiency of this method.

  10. Long all-active monolithic mode-locked lasers with surface-etched bragg gratings

    DEFF Research Database (Denmark)

    Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher

    2007-01-01

    We have fabricated 4.4-mm-long monolithic InAlGaAsP–InP mode-locked lasers with integrated deeply surface etched distributed Bragg reflector (DBR) mirrors. The lasers produce 3.7-ps transform-limited Gaussian pulses with 10-mW average output power and 250-fs absolute timing jitter. The performance...... of the DBR lasers is compared to the performance of Fabry–PÉrot mode-locked lasers from the same wafer and to the performance of earlier reported long monolithic DBR mode-locked lasers and is found to be better....

  11. Passive mode locking of a Nd:KGW laser with hot-band diode pumping

    Science.gov (United States)

    Eibna Halim, M. Z.; Talukder, R. C.; Waritanant, T.; Major, A.

    2016-10-01

    Passive mode locking of a Nd:KGW laser with hot-band diode pumping at 910 nm was demonstrated. A semiconductor saturable absorber mirror was used as a mode locking mechanism. The laser generated 2.4 ps pulses at a repetition rate of ~83.8 MHz. An average output power of 87 mW was obtained at 1067 nm. To the best of our knowledge, this is the first report on passive mode locking of a Nd:KGW laser with low quantum defect pumping which holds great promise for further output power scaling.

  12. Radiation Shielding Properties Comparison of Pb-Based Silicate, Borate, and Phosphate Glass Matrices

    OpenAIRE

    Suwimon Ruengsri

    2014-01-01

    Theoretical calculations of mass attenuation coefficients, partial interactions, atomic cross-section, and effective atomic numbers of PbO-based silicate, borate, and phosphate glass systems have been investigated at 662 keV. PbO-based silicate glass has been found with the highest total mass attenuation coefficient and then phosphate and borate glasses, respectively. Compton scattering has been the dominate interaction contributed to the different total attenuation coefficients in each of th...

  13. The structure of mode-locking regions of piecewise-linear continuous maps: I. Nearby mode-locking regions and shrinking points

    Science.gov (United States)

    Simpson, D. J. W.

    2017-01-01

    The mode-locking regions of a dynamical system are subsets of parameter space within which there exists an attracting periodic solution. For piecewise-linear continuous maps, these regions have a distinctive chain structure with points of zero width called shrinking points. In this paper a local analysis about an arbitrary shrinking point is performed. This is achieved by studying the symbolic itineraries of periodic solutions in nearby mode-locking regions and performing an asymptotic analysis on one-dimensional centre manifolds in order to build a comprehensive theoretical framework for the local dynamics. The main results are universal quantitative descriptions for the shape of nearby mode-locking regions, the location of nearby shrinking points, and the key properties of these shrinking points. The results are applied to the three-dimensional border-collision normal form, a model of an oscillator subject to dry friction, and a model of a DC/DC power converter.

  14. Effect of MAE on the properties of phosphate edge-cladding glasses

    Institute of Scientific and Technical Information of China (English)

    Fenggang Zhao; Guonian Wang; Lili Hu

    2007-01-01

    Edge-cladding is a key factor in improving saturated small signal gain coefficient βs of large laser disc glass. In this paper, the glasses were melted with traditional method. The influences of mixed alkali effect (MAE) on refractive index, thermal expansion coefficient α, glass transition temperature Tg, dilatometer softening temperature Td, and relative chemical durability of phosphate edge-cladding glasses were studied.The results reveal that when Li/(Na + Li) = 0.5, Tg, Td, and dissolution rate (DR) reach a minimal value.These results are preferred in phosphate edge-cladding glasses.

  15. Neodymium Fluorescence Quenching by Hydroxyl Groups in Phosphate Laser Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ehrmann, P R; Carlson, K; Campbell, J H; Click, C A; Brow, R K

    2003-09-02

    Non-radiative losses due to OH fluorescence quenching of the Nd{sup 3+} {sup 4}F{sub 3/2} state are quantified over a range of OH concentrations from 4 x 10{sup 18}/cm{sup 3} to 4 x 10{sup 20}/cm{sup 3} and Nd doping levels from 0.4 to 9 x 10{sup 20}/cm{sup 3} in two K{sub 2}O-MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5} metaphosphate glasses having different K/Mg ratios ({approx}1/1 and 2/1). The quenching rate is found to vary linearly with the Nd and OH concentrations as predicted by Forster-Dexter theory. However, in contrast to theory the OH quenching rate extrapolates to a non-zero value at low Nd{sup 3+} doping levels. It is proposed that at low Nd{sup 3+} concentrations the OH is correlated with Nd sites in the glass. The quenching strength of OH on a per ion basis is found to be weak compared to other common transition metal impurities (e.g. Fe{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}). Nevertheless, OH dominates the Nd quenching in phosphate glass because under most processing conditions OH is present at concentrations 10{sup 2} to 10{sup 3} greater than transition metal ion impurities. A correlation of the quenching strength of OH and common metal impurity ions with the degree of spectral overlap of the impurity absorption bands and the four {sup 4}F{sub 3/2} to {sup 4}I{sub J} transitions shows good agreement.

  16. Enhanced Luminescent Properties in Tm3+/Dy3+ Co-doped Transparent Phosphate Glass Ceramic

    Directory of Open Access Journals (Sweden)

    Yao L. Q.

    2016-01-01

    Full Text Available Novel Tm3+/Dy3+ co-doped phosphate glass and glass ceramic samples for white light emitting diodes were prepared by melt quenching method. Under 353 nm excitation, the colors of the luminescence of the glass and glass ceramic samples are white. The CIE chromaticity coordinates (0.338, 0.328 of the emission from the glass ceramic is close to the standard white-light illumination (0.333, 0.333. Compared to the glass, the fluorescence intensity in the glass ceramic is greatly enhanced.

  17. Bismuth telluride topological insulator nanosheet saturable absorbers for q-switched mode-locked Tm:ZBLAN waveguide lasers

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiantao; Gross, Simon; Withford, Michael J.; Fuerbach, Alexander [Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) and MQ Photonics Research Centre, Dept. of Physics and Astronomy, Macquarie Univ., NSW (Australia); Zhang, Han; Guo, Zhinan [SZU-NUS Collaborative Innovation Centre for Optoelectronic Science and Technology, Key Lab. of Optoelectronic Devices and Systems of Ministry of Education, College of Optoelectronic Engineering, Shenzhen Univ. (China)

    2016-08-15

    Nanosheets of bismuth telluride (Bi{sub 2}Te{sub 3}), a topological insulator material that exhibits broadband saturable absorption due to its non-trivial Dirac-cone like energy structure, are utilized to generate short pulses from Tm:ZBLAN waveguide lasers. By depositing multiple layers of a carefully prepared Bi{sub 2}Te{sub 3} solution onto a glass substrate, the modulation depth and the saturation intensity of the fabricated devices can be controlled and optimized. This approach enables the realization of saturable absorbers that feature a modulation depth of 13% and a saturation intensity of 997 kW/cm{sup 2}. For the first time to our knowledge, Q-switched mode-locked operation of a linearly polarized mid-IR ZBLAN waveguide chip laser was realized in an extended cavity configuration using the topological insulator Bi{sub 2}Te{sub 3}. The maximum average output power of the laser is 16.3 mW and the Q-switched and mode-locked repetition rates are 44 kHz and 436 MHz, respectively. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Study of structural, electrical, and dielectric properties of phosphate-borate glasses and glass-ceramics

    Science.gov (United States)

    Melo, B. M. G.; Graça, M. P. F.; Prezas, P. R.; Valente, M. A.; Almeida, A. F.; Freire, F. N. A.; Bih, L.

    2016-08-01

    In this work, phosphate-borate based glasses with molar composition 20.7P2O5-17.2Nb2O5-13.8WO3-34.5A2O-13.8B2O3, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric, and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σac and σdc, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz-1 MHz.

  19. The effects of B/(B+Al) ratio on glass formation regions and properties of phosphate edge-cladding glasses

    Institute of Scientific and Technical Information of China (English)

    Fenggang Zhao; Qinglei Dong; Lili Hu

    2007-01-01

    The glass-forming region of P2O5-Al2O3-B2O3-ZnO-Na2O-CuCl system with different Al2O3 and B2O3 contents was studied. The dependence of glasses properties on B/(B+Al) ratio was investigated. The absorption coefficient of copper ion in a specific glass was measured. These results are very helpful to the designing of a cladding glass for large size neodymium phosphate glass.

  20. Doubly active Q switching and mode locking of an all-fiber laser.

    Science.gov (United States)

    Cuadrado-Laborde, Christian; Díez, Antonio; Cruz, Jose L; Andrés, Miguel V

    2009-09-15

    Simultaneous and independent active Q switching and active mode locking of an erbium-doped fiber laser is demonstrated using all-fiber modulation techniques. A magnetostrictive rod attached to the output fiber Bragg grating modulates the Q factor of the Fabry-Perot cavity, whereas active mode locking is achieved by amplitude modulation with a Bragg-grating-based acousto-optic device. Fully modulated Q-switched mode-locked trains of optical pulses were obtained for a wide range of pump powers and repetition rates. For a Q-switched repetition rate of 500 Hz and a pump power of 100 mW, the laser generates trains of 12-14 mode-locked pulses of about 1 ns each, within an envelope of 550 ns, an overall energy of 0.65 microJ, and a peak power higher than 250 W for the central pulses of the train.

  1. High frequency optoelectronic oscillators based on the optical feedback of semiconductor mode-locked laser diodes.

    Science.gov (United States)

    Haji, Mohsin; Hou, Lianping; Kelly, Anthony E; Akbar, Jehan; Marsh, John H; Arnold, John M; Ironside, Charles N

    2012-01-30

    Optical self seeding feedback techniques can be used to improve the noise characteristics of passively mode-locked laser diodes. External cavities such as fiber optic cables can increase the memory of the phase and subsequently improve the timing jitter. In this work, an improved optical feedback architecture is proposed using an optical fiber loop delay as a cavity extension of the mode-locked laser. We investigate the effect of the noise reduction as a function of the loop length and feedback power. The well known composite cavity technique is also implemented for suppressing supermode noise artifacts presented due to harmonic mode locking effects. Using this method, we achieve a record low radio frequency linewidth of 192 Hz for any high frequency (>1 GHz) passively mode-locked laser to date (to the best of the authors' knowledge), making it promising for the development of high frequency optoelectronic oscillators.

  2. Synchronization of Fourier-Synthesized Optical Pulses to a Mode-Locked Optical Clock

    Institute of Scientific and Technical Information of China (English)

    Masaharu; Hyodo; Kazi; Sarwal; Abedin; Noriaki; Onodera; Masayoshi; Watanabe

    2003-01-01

    A Fourier-synthesized 40-GHz optical pulse train was successfully synchronized to an 8-GHz optical clock generated from a mode-locked fiber ring laser. The measured timing jitter of the synchronization was 0.43 ps.

  3. Modelling and characterization of colliding-pulse mode-locked (CPM) quantum well lasers. [MPS1

    DEFF Research Database (Denmark)

    Bischoff, Svend; Brorson, S.D.; Franck, T.

    1996-01-01

    A theoretical and experimental study of passive colliding pulse mode-locked quantum well lasers is presented. The theoretical model for the gain dynamics is based on semi-classical density matrixequations. The gain dynamics are characterized exp...

  4. Sub-nanometer tuning of mode-locked pulse by mechanical strain on tapered fiber

    Science.gov (United States)

    Ahmad, Harith; Faruki, Md Jahid; Tiu, Zian Cheak; Thambiratnam, K.

    2017-03-01

    A tunable mode-locked fiber laser based on the non-linear polarization rotation (NPR) technique is proposed and demonstrated. A passively generated mode-locked output is obtained with a repetition rate of about 70 ns and an average output power of 0.7 mW, as well as a laser efficiency of 0.53%. The mode-locked pulses can be tuned over a span of 4.4 nm, from 1560.6 nm to 1556.2, corresponding to a stretching of the tapered fiber from 0 to 100 μm in 10 μm increments. The pulses have an average signal-to-noise ratio of about 41 dB in the frequency domain, indicating a highly stable mode-locked output. The system can repeat and reverse the generation of these pulses, a crucial criterion of many communications and sensing applications.

  5. 70-fs mode-locked erbium-doped fiber laser with topological insulator.

    Science.gov (United States)

    Liu, Wenjun; Pang, Lihui; Han, Hainian; Tian, Wenlong; Chen, Hao; Lei, Ming; Yan, Peiguang; Wei, Zhiyi

    2016-01-27

    Femtosecond optical pulses have applications in optical communication, astronomical frequency combs, and laser spectroscopy. Here, a hybrid mode-locked erbium-doped fiber (EDF) laser with topological insulator (TI) is proposed, for the first time to our best knowledge. The pulsed laser deposition (PLD) method is employed to fabricate the fiber-taper TI saturable absorber (TISA). By virtue of the fiber-taper TISA, the hybrid EDF laser is passively mode-locked using the nonlinear polarization evolution (NPE), and emits 70 fs pulses at 1542 nm, whose 3 dB spectral width is 63 nm with a repetition rate and transfer efficiency of 95.4 MHz and 14.12%, respectively. Our experiments indicate that the proposed hybrid mode-locked EDF lasers have better performance to achieve shorter pulses with higher power and lower mode-locking threshold in the future.

  6. Graphene oxide mode-locked femtosecond erbium-doped fiber lasers

    National Research Council Canada - National Science Library

    Xu, Jia; Liu, Jiang; Wu, Sida; Yang, Quan-Hong; Wang, Pu

    2012-01-01

    We demonstrated the femtosecond erbium-doped all-fiber lasers mode-locked with graphene oxide, which can be conveniently obtained from natural graphite by simple oxidation and ultra-sonication process...

  7. Modelling and characterization of colliding-pulse mode-locked (CPM) quantum well lasers. [MPS1

    DEFF Research Database (Denmark)

    Bischoff, Svend; Brorson, S.D.; Franck, T.;

    1996-01-01

    A theoretical and experimental study of passive colliding pulse mode-locked quantum well lasers is presented. The theoretical model for the gain dynamics is based on semi-classical density matrixequations. The gain dynamics are characterized exp...

  8. Molecular Dynamics Simulation of the Structure and Properties of Lithium Phosphate Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Liang, J-J; Cygan, R.T.; Alam, T.M.

    1999-07-09

    A new forcefield model was developed for the computer simulation of phosphate materials that have many important applications in the electronics and biomedical industries. The model provides a fundamental basis for the evaluation of phosphate glass structure and thermodynamics. Molecular dynamics simulations of a series of lithium phosphate glass compositions were performed using the forcefield model. A high concentration of three-membered rings (P{sub 3}O{sub 3}) occurs in the glass of intermediate composition (0.2 Li{sub 2}O {center_dot} 0.8P{sub 2}O{sub 5}) that corresponds to the minimum in the glass transition temperature curve for the compositional series. Molecular orbital calculations of various phosphate ring clusters indicate an increasing stabilization of the phosphate ring structure going from two- to four-membered rings.

  9. Short pulse generation in a passively mode-locked photonic crystal semiconductor laser

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Blaaberg, Søren; Mørk, Jesper

    2010-01-01

    We present a new type of passively mode-locked laser with quantum wells embedded in photonic crystal waveguides operating in the slow light regime, which is capable of emitting sub picosecond pulses with widely controllable properties......We present a new type of passively mode-locked laser with quantum wells embedded in photonic crystal waveguides operating in the slow light regime, which is capable of emitting sub picosecond pulses with widely controllable properties...

  10. Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements.

    Science.gov (United States)

    Olivier, Michel; Gagnon, Marc-Daniel; Habel, Joé

    2016-02-28

    When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

  11. Hybrid mode-locked ultrashort-pulse erbium-doped fiber laser

    Science.gov (United States)

    Lazarev, Vladimir A.; Sazonkin, Stanislav S.; Pniov, Alexey B.; Tsapenko, Konstantin P.; Krylov, Alexander A.; Obraztsova, Elena D.

    2014-03-01

    One of the implementations of fs-laser with CNT-film for mode-locking is considered. Scheme of single-pulse, self-starting, stable mode-locked laser generation by appropriate polarization controllers adjustment is suggested. The mechanism of cavity length stabilization for a femtosecond fiber laser based on the pump source modulation is considered. Bandwidth of the feedback frequency stabilization system based on pump source modulation method is defined.

  12. Research and development of neodymium phosphate laser glass for high power laser application

    Science.gov (United States)

    Hu, Lili; He, Dongbing; Chen, Huiyu; Wang, Xin; Meng, Tao; Wen, Lei; Hu, Junjiang; Xu, Yongchun; Li, Shunguang; Chen, Youkuo; Chen, Wei; Chen, Shubin; Tang, Jingping; Wang, Biao

    2016-12-01

    Neodymium phosphate laser glass is a key optical element for high-power laser facility. In this work, the latest research and development of neodymium phosphate laser glass at the Shanghai Institute of Optics and Fine Mechanics (SIOM), China, is addressed. Neodymium phosphate laser glasses, N31, N41, NAP2, and NAP4, for high peak power and high average power applications have been developed. The properties of these glasses are presented and compared to those of other commercial neodymium phosphate laser glass from the Schott and Hoya companies and the Vavilov State Optical Institute (GOI), Russia. Continuous melting and edge cladding are the two key fabrication techniques that are used for the mass production of neodymium phosphate laser glass slabs. These techniques for the fabrication of large-aperture N31 neodymium phosphate laser glass slabs with low stress birefringence and residual reflectivity have been developed by us The effect of acid etching on the microstructure, optical transmission, and mechanical properties of NAP2 glass is also discussed.

  13. Microscopic origins of the induced χ(2) in thermally poled phosphate glasses

    Science.gov (United States)

    Thamboon, P.; Krol, D. M.

    2009-06-01

    We have investigated the microscopic origins of the induced χ(2) in two phosphate glasses: a self-prepared lanthanum phosphate glass with molar composition 0.2La2O3 0.8P2O5 and a commercial sodium alumino phosphate glass (IOG-1, Schott Glass Technologies, Inc.) with molar composition 0.6P2O5 0.24Na2O 0.13Al2O3 0.03Ce2O3. The drastic difference in alkali content in these two phosphate glass systems results in different origins of their induced χ(2). For the poled lanthanum phosphate glass, the origin of the induced χ(2), which is directly proportional to the dc field established inside the glass, is the result of charge migration. A model that uses a single-positive-charge carrier with a nonblocking cathode describes the anodic surface χ(2) of 30μm thickness. For the poled sodium alumino phosphate glass, two mechanisms—dipole reorientation via the applied field and charge migration—are responsible for the origin of the bulk and the surface χ(2). Dipole reorientation via the applied field is suggested for the bulk contribution, while a charge migration model that involves multiple-charge carriers with nonblocking electrodes is appropriate for the surface χ(2).

  14. Research and development of neodymium phosphate laser glass for high power laser application

    Science.gov (United States)

    Hu, Lili; He, Dongbing; Chen, Huiyu; Wang, Xin; Meng, Tao; Wen, Lei; Hu, Junjiang; Xu, Yongchun; Li, Shunguang; Chen, Youkuo; Chen, Wei; Chen, Shubin; Tang, Jingping; Wang, Biao

    2017-01-01

    Neodymium phosphate laser glass is a key optical element for high-power laser facility. In this work, the latest research and development of neodymium phosphate laser glass at the Shanghai Institute of Optics and Fine Mechanics (SIOM), China, is addressed. Neodymium phosphate laser glasses, N31, N41, NAP2, and NAP4, for high peak power and high average power applications have been developed. The properties of these glasses are presented and compared to those of other commercial neodymium phosphate laser glass from the Schott and Hoya companies and the Vavilov State Optical Institute (GOI), Russia. Continuous melting and edge cladding are the two key fabrication techniques that are used for the mass production of neodymium phosphate laser glass slabs. These techniques for the fabrication of large-aperture N31 neodymium phosphate laser glass slabs with low stress birefringence and residual reflectivity have been developed by us The effect of acid etching on the microstructure, optical transmission, and mechanical properties of NAP2 glass is also discussed.

  15. Influence of addition of B2O3 on properties of Yb3+ -doped phosphate laser glass

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-jiang; LU An-xian; TANG Xiao-dong; HE Shao-bo

    2006-01-01

    The three host glasses doped with Yb3+ were prepared by means of conventional melt quenching technol ogy, and the influence on physical and spectral properties of phosphate glass due to addition of B2O3 was investigated and compared with silicate glass. The results show that due to the existence of OH- impurities which induce thenon-radiative route, the fluorescence lifetime of phosphate glass is shorter, so silicate glass has better spectral properties than phosphate glass. Silicate glass has more excellent thermal-mechanical properties than phosphate glass,but with the addition of B2O3, thermal-mechanical properties of phosphate glass are improved greatly without fluo rescence quenching effect, and this kind of borophosphate glass will be the candidate to be used in high average pow er solid state laser.

  16. Interference microscopy of femtosecond laser written waveguides in phosphate glass

    Science.gov (United States)

    Esser, D.; Mahlmann, D.; Wortmann, D.; Gottmann, J.

    2009-08-01

    By focusing fs-laser radiation in the volume of a transparent material the refractive index can be changed locally, leading to 3-dimensional waveguiding structures. Waveguides are written in phosphate glass (IOG from Schott) at a depth of 100 μm below the surface. The pulse energy and the scan velocity are varied. For the first time the optical path difference caused by the waveguides and therefore the refractive index distribution of the waveguides and their cross sections are determined using interference microscopy. The optical path difference measured in the written structures and their cross sections is analyzed by a phase-shift algorithm. Thus, the refractive index distribution both along a line perpendicular to the waveguide and in the plane of a cross section is determined. The results are visualized as 2-dimensional graphics. Several regions of opposite sign of the refractive index change are observed in the cross sections of waveguides generated by femtosecond laser pulses. The number and the size of these regions are increasing with increasing pulse energy and decreasing scan velocity.

  17. Simulation of alpha decay of actinides in iron phosphate glasses by ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Dube, Charu L., E-mail: dubecharu@gmail.com; Stennett, Martin C.; Gandy, Amy S.; Hyatt, Neil C.

    2016-03-15

    Highlights: • Alpha decay of actinides in iron phosphate glasses is simulated by employing ion irradiation technique. • FTIR and Raman spectroscopic measurements confirm modification of glass network. • The depolymerisation of glass network after irradiation is attributed to synergetic effect of nuclear and electronic losses. - Abstract: A surrogate approach of ion beam irradiation is employed to simulate alpha decay of actinides in iron phosphate nuclear waste glasses. Bismuth and helium ions of different energies have been selected for simulating glass matrix modification owing to radiolysis and ballistic damage due to recoil atoms. Structural modification and change in coordination number of network former were probed by employing Reflectance Fourier-Transform Infrared (FT-IR), and Raman spectroscopies as a consequence of ion irradiation. Depolymerisation is observed in glass sample irradiated at intermediate energy of 2 MeV. Helium blisters of micron size are seen in glass sample irradiated at low helium ion energy of 30 keV.

  18. Study of structural, electrical, and dielectric properties of phosphate-borate glasses and glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Melo, B. M. G.; Graça, M. P. F., E-mail: mpfg@ua.pt; Prezas, P. R.; Valente, M. A. [Physics Department (I3N), Aveiro University, Campus Universitário de Santiago, Aveiro (Portugal); Almeida, A. F.; Freire, F. N. A. [Mechanics Engineering Department, Ceará Federal University, Fortaleza (Brazil); Bih, L. [Equipe Physico-Chimie la Matière Condensée, Faculté des Sciences de Meknès, Meknès (Morocco)

    2016-08-07

    In this work, phosphate-borate based glasses with molar composition 20.7P{sub 2}O{sub 5}–17.2Nb{sub 2}O{sub 5}–13.8WO{sub 3}–34.5A{sub 2}O–13.8B{sub 2}O{sub 3}, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric, and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σ{sub ac} and σ{sub dc}, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz–1 MHz.

  19. Large aperture N31 neodymium phosphate laser glass for use in a high power laser facility

    Institute of Scientific and Technical Information of China (English)

    Lili; Hu; Shubin; Chen; Jingping; Tang; Biao; Wang; Tao; Meng; Wei; Chen; Lei; Wen; Junjiang; Hu; Shunguang; Li; Yongchun; Xu; Yasi; Jiang; Junzhou; Zhang; Zhonghong; Jiang

    2014-01-01

    Large aperture Nd:phosphate laser glass is a key optical element for an inertial confinement fusion(ICF) facility. N31,one type of neodymium doped phosphate glasses, was developed for high peak power laser facility applications in China. The composition and main properties of N31 glass are given, together with those of LHG-8, LG-770, and KGSS-0180 Nd:phosphate laser glasses, from Hoya and Schott, and from Russia. The technologies of pot melting, continuous melting, and edge cladding of large size N31 phosphate laser glass are briefly described. The small signal gain profiles of N31 glass slabs from both pot melting and continuous melting at various values of the pumping energy of the xenon lamp are presented. N31 glass is characterized by a stimulated emission cross section of 3.8 × 10-20cm2 at 1053 nm,an absorption coefficient of 0.10–0.15% cm-1at laser wavelength, small residual stress around the interface between the cladding glass and the laser glass, optical homogeneity of ~2 × 10-6in a 400 mm aperture, and laser damage threshold larger than 42 J/cm2 for a 3 ns pulse width at 1064 nm wavelength.

  20. Phosphate-based glass fiber vs. bulk glass: Change in fiber optical response to probe in vitro glass reactivity.

    Science.gov (United States)

    Massera, J; Ahmed, I; Petit, L; Aallos, V; Hupa, L

    2014-04-01

    This paper investigates the effect of fiber drawing on the thermal and structural properties as well as on the glass reactivity of a phosphate glass in tris(hydroxymethyl)aminomethane-buffered (TRIS) solution and simulated body fluid (SBF). The changes induced in the thermal properties suggest that the fiber drawing process leads to a weakening and probable re-orientation of the POP bonds. Whereas the fiber drawing did not significantly impact the release of P and Ca, an increase in the release of Na into the solution was noticed. This was probably due to small structural reorientations occurring during the fiber drawing process and to a slight diffusion of Na to the fiber surface. Both the powders from the bulk and the glass fibers formed a Ca-P surface layer when immersed in SBF and TRIS. The layer thickness was higher in the calcium and phosphate supersaturated SBF than in TRIS. This paper for the first time presents the in vitro reactivity and optical response of a phosphate-based bioactive glass (PBG) fiber when immersed in SBF. The light intensity remained constant for the first 48h after which a decrease with three distinct slopes was observed: the first decrease between 48 and 200h of immersion could be correlated to the formation of the Ca-P layer at the fiber surface. After this a faster decrease in light transmission was observed from 200 to ~425h in SBF. SEM analysis suggested that after 200h, the surface of the fiber was fully covered by a thin Ca-P layer which is likely to scatter light. For immersion times longer than ~425h, the thickness of the Ca-P layer increased and thus acted as a barrier to the dissolution process limiting further reduction in light transmission. The tracking of light transmission through the PBG fiber allowed monitoring of the fiber dissolution in vitro. These results are essential in developing new bioactive fiber sensors that can be used to monitor bioresponse in situ.

  1. High-Strength / High Alkaline Resistant Fe-Phosphate Glass Fibers as Concrete Reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Mariano Velez

    2008-03-31

    Calcium-iron-phosphate glasses were developed whose chemical durabilities in alkaline solutions (pH 13) were comparable or superior to those of commercial alkaline-resistant (AR) silica-based glasses. However, the tensile strength of Ca-Fe-phosphate fibers, after being exposed to alkaline environments, including wet Portland cement pastes, is lower than that of current AR silicate fibers. Another series of Ca-Fe-phosphate glasses were developed with excellent chemical durability in strong acidic solutions (H2SO4, HF), indicating potential applications where silica-based fibers degrade very quickly, including E-glass. The new Ca-Fe-phosphate glasses can be melted and processed 300 to 500°C lower than silica-based glasses. This offers the possibility of manufacturing glass fibers with lower energy costs by 40-60% and the potential to reduce manufacturing waste and lower gas emissions. It was found that Ca-Fe-phosphate melts can be continuously pulled into fibers depending on the slope of the viscosity-temperature curve and with viscosity ~100 poise, using multi-hole Pt/Rh bushings.

  2. Observation of self-mode-locked noise-like pulses from a net normal dispersion erbium-doped fiber laser

    Science.gov (United States)

    Li, Kexuan; Tian, Jinrong; Guoyu, Heyang; Xu, Runqin; Song, Yanrong

    2017-04-01

    Self-mode-locked noise-like pulses (NLPs) were experimentally investigated from a normal dispersion erbium-doped fiber laser. Different from noise-like pulses with a broadband spectrum, the self-mode-locked NLPs have a narrow optical spectrum of 1-2 nm and hundreds of nanoseconds duration. However, the intra-cavity maximum energy of NLPs is up to 560 nJ without pulse breaking. The higher pulse energy output is promising in the proposed fiber laser. To confirm whether self-mode-locked NLPs are caused by an invisible nonlinear polarization rotation (NPR) mechanism owing to slight residual polarization asymmetry of the fiber and components used, we compared the output characteristics between self-mode-locked NLPs and NPR mode-locked pulses in the same cavity. The experimental results show that the formation mechanism of such self-mode-locked NLPs could be related to a weak NPR effect.

  3. Hierarchy, dimension, attractor and self-organization -- dynamics of mode-locked fiber lasers

    CERN Document Server

    Wei, Huai; Shi, Wei; Zhu, Xiushan; Norwood, Robert A; Peyghambarian, Nasser; Jian, Shuisheng

    2016-01-01

    Mode-locked fiber lasers are one of the most important sources of ultra-short pulses. However, A unified description for the rich variety of states and the driving forces behind the complex and diverse nonlinear behavior of mode-locked fiber lasers have yet to be developed. Here we present a comprehensive theoretical framework based upon complexity science, thereby offering a fundamentally new way of thinking about the behavior of mode-locked fiber lasers. This hierarchically structured frame work provide a model with and changeable variable dimensionality resulting in a simple and elegant view, with which numerous complex states can be described systematically. The existence of a set of new mode-locked fiber laser states is proposed for the first time. Moreover, research into the attractors' basins reveals the origin of stochasticity, hysteresis and multistability in these systems. These findings pave the way for dynamics analysis and new system designs of mode-locked fiber lasers. The paradigm will have a w...

  4. Efficient graphene Q switching and mode locking of 1.34 μm neodymium lasers.

    Science.gov (United States)

    Xu, Jin-Long; Li, Xian-Lei; He, Jing-Liang; Hao, Xiao-Peng; Yang, Ying; Wu, Yong-Zhong; Liu, Shan-De; Zhang, Bai-Tao

    2012-07-01

    We demonstrate that few-layered graphene sheets used as a saturable absorber can provide efficient Q-switching and mode-locking modulation in 1.34 μm Nd:GdVO(4) bulk lasers. The minimum Q-switched pulses were 450 ns for 260 mW average power, 43 kHz repetition rate, and 2.5 μJ pulse energy. For the mode-locked laser, an average power of 1.29 W was achieved with 11 ps pulse duration and 13 nJ pulse energy. To our knowledge, this average power is the highest yet obtained from a graphene mode-locked laser, and the corresponding optical-optical efficiency of 23% is the best result among 1.3 μm neodymium mode-locked lasers. The quality factor M(2) of the Q-switched beam was 1.4 and 1.6 in the horizontal and longitudinal planes, respectively, and the M(2) of the mode-locked beam reached 1.1 and 1.0. These results clearly indicate the advantages of few-layered graphene as a saturable absorber.

  5. Er3+/Yb3+ Codoped Phosphate Glass for Ion-Exchanged Planar Waveguide Amplifiers

    Institute of Scientific and Technical Information of China (English)

    Shilong Zhao; Baoyu Chen; Zhuping Liu; Lili Hu

    2003-01-01

    A novel Er3+/Yb3+ codoped phosphate glass was developed, which exhibited good chemical durability in molten salts and excellent spectroscopic properties. Preliminary results of ion exchange at different time and temperature, and with varying melt concentrations indicated that WM4 glass was suitable for ion-exchange experiments and there was no deterioration of surface quality.

  6. Er~(3+)/Yb~(3+) Codoped Phosphate Glass for Ion-Exchanged Planar Waveguide Amplifiers

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel Er3+/Yb3+ codoped phosphate glass was developed, which exhibited good chemical durability in molten salts and excellent spectroscopic properties. Preliminary results of ion exchange at different time and temperature, and with varying melt concentrations indicated that WM4 glass was suitable for ion-exchange experiments and there was no deterioration of surface quality.

  7. Effects of phosphate buffer in parenteral drugs on particle formation from glass vials.

    Science.gov (United States)

    Ogawa, Toru; Miyajima, Makoto; Wakiyama, Naoki; Terada, Katsuhide

    2013-01-01

    The characteristics of inorganic particles generated in glass vials filled with phosphate buffer solutions were investigated. During storage, particles were visually detected in the phosphate buffer solution in particular glass vials which pass compendial tests of containers for injectable drugs. These particles were considered to be different from ordinal glass delamination, which has been reported in a number of papers because the particles were mainly composed of Al, P and O, but not Si. The formation of the particles accelerated at higher storage temperatures. Among the surface treatments tested for the glass vials, sulfur treatment showed a protective effect on the particle formation in the vials, whereas the SiO(2) coating did not have any protective effects. It was found that the elution ratio of Al and Si in the solution stored in the glass vials after the heating was similar to the ratio of Al and Si in borosilicate glass. However, the Al concentration decreased during storage (5°C, 6 months), and consequently, particle formation was observed in the solution. Adding citrate, which is a chelating agent for Al, effectively suppressed the particle formation in the heated solution. When 50 ppb and higher concentrations of Al ion were added to the phosphate buffer solution, the formation of white particles containing Al, P and O was detected. It is suggested that a phosphate buffer solution in a borosilicate glass vial has the ability to form particles due to interactions with the Al that is eluted from the glass during storage.

  8. Influence of Ag2O on crystallisation and structural modifications of phosphate glasses

    Science.gov (United States)

    Aravindan, Samickannian; Rajendran, Venkatachalam; Rajendran, Nallaiyan

    2012-07-01

    A series of phosphate glasses of composition 45P2O5-(40 - x)CaO-15Na2O-xAg2O (x = 0, 3, 6, 8, 10 and 12 mol%) with different Ag2O contents were prepared using the melt-quenching technique. The incorporated Ag2O highly influenced the increase of its transition tendency towards crystallisation and, on contrary, reduced the degree of glassification of phosphate glasses. The lowering of glass transition temperature and increase in thermal expansion were observed in glasses against Ag2O inclusions. The crystalline phase transitions of amorphous material during thermal treatment were confirmed by employing X-ray diffraction studies. As revealed by X-ray photoelectron spectroscopy, the incorporated silver oxide into phosphate glass exists in two different oxidation states, Ag2O and AgO. The pyrophosphate and metaphosphate units were predominantly occupied in glass and glass ceramics. The elastic moduli and Vicker's hardness values exhibited the decrease in phosphate glass structural compactness due to Ag2O-incorporation and these values were found to improve because of crystalline transitions.

  9. Structure and spectroscopy of rare earth – Doped lead phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pisarski, Wojciech A., E-mail: wojciech.pisarski@us.edu.pl [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Żur, Lidia [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland); Goryczka, Tomasz [University of Silesia, Institute of Materials Science, Bankowa 12, 40-007 Katowice (Poland); Sołtys, Marta; Pisarska, Joanna [University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice (Poland)

    2014-02-25

    Highlights: • Lead phosphate glasses doped with rare earth ions were prepared. • The local structure was examined using X-ray diffraction and spectroscopic methods. • Different structural phosphate groups are present in lead phosphate glasses. • The electron–phonon coupling strength and phonon energy of the glass host was determined. • Several observed emission bands are due to 4f–4f electronic transitions of rare earth ions. -- Abstract: Lead–gallium phosphate glasses doped with rare the earth ions (Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}, Er{sup 3+}) were synthesized. The structure of obtained glasses was examined by means of use: X-ray diffraction (XRD), nuclear magnetic resonance ({sup 207}Pb and {sup 31}P NMR), fourier transform infrared (FT-IR) and Raman spectroscopy. In contrast to fully amorphous Ln-doped samples (Ln = Eu, Dy, Tb), in Er-doped sample the GaPO{sub 4} crystalline phase was identified. It was found from the NMR, FT-IR and Raman spectroscopic techniques that, different structural phosphate groups were present in lead phosphate glasses. Based on absorption measurements, the UV–VIS cut-off wavelength for lead phosphate glass was determined and its value is close to 305 nm. Excitation and emission spectra of rare earths were also detected. From excitation spectra of Eu{sup 3+} the electron–phonon coupling strength and phonon energy of the glass host were determined. Due to 4f{sup 6}–4f{sup 6} (Eu{sup 3+}), 4f{sup 8}–4f{sup 8} (Tb{sup 3+}), 4f{sup 9}–4f{sup 9} (Dy{sup 3+}) and 4f{sup 11}–4f{sup 11} (Er{sup 3+}) electronic transitions of trivalent rare earth ions several luminescence bands were stated.

  10. Glass formation and structure of calcium antimony phosphate glasses and those doped with tellurium oxide

    Science.gov (United States)

    Li, Jun; Zhang, Yin; Nian, Shangjiu; Wu, Zhenning; Cao, Weijing; Zhou, Nianying; Wang, Danian

    2017-03-01

    An approximate glass-forming region in the P2O5-Sb2O3-CaO ternary system was determined. The properties and structure of two compositional series of (A) (75- x)P2O5- xSb2O3-25CaO ( x = 20, 25, 30, 35 mol%) and (B) 45P2O5-30Sb2O3-(25- x)CaO- xTeO2 ( x = 5, 10, 15, 20 mol%) were studied systematically. Thermal properties were investigated by means of differential scanning calorimetry (DSC). The densities of all samples were measured by Archimedes' method using distilled water as the immersion liquid. The water durability of the glasses was described by their dissolution rate (DR) in the distilled water at 90 °C for some time periods. Density, thermal stability and water durability were improved with the addition of Sb2O3 and TeO2. Structural studies were carried out by X-ray diffraction (XRD), infrared spectroscopy and Raman spectroscopy. The phosphate chain depolymerization occurred with the increase of Sb2O3 and the Q2 structural units transformed to the Q1 and Q0 structural units with the addition of TeO2.

  11. A semiconductor-based, frequency-stabilized mode-locked laser using a phase modulator and an intracavity etalon.

    Science.gov (United States)

    Davila-Rodriguez, Josue; Ozdur, Ibrahim; Williams, Charles; Delfyett, Peter J

    2010-12-15

    We report a frequency-stabilized semiconductor-based mode-locked laser that uses a phase modulator and an intracavity Fabry-Perot etalon for both active mode-locking and optical frequency stabilization. A twofold multiplication of the repetition frequency of the laser is inherently obtained in the process. The residual timing jitter of the mode-locked pulse train is 13 fs (1 Hz to 100 MHz), measured after regenerative frequency division of the photodetected pulse train.

  12. Automated mode locking in nonlinear polarization rotation fiber lasers by detection of a discontinuous jump in the polarization state.

    Science.gov (United States)

    Olivier, Michel; Gagnon, Marc-Daniel; Piché, Michel

    2015-03-09

    A strategy to align a mode-locked fiber laser with nonlinear polarization rotation is presented. This strategy is based on measurements of the output polarization state. It is shown that, as the angle of a motorized polarization controller inside the cavity is swept, the laser eventually reaches a mode-locked regime and the values of the Stokes parameters undergo an abrupt change. The sensing of this sudden variation is thus used to detect the mode-locking condition and a feedback mechanism drives the alignment of the polarization controller to force mode locking.

  13. Resonantly pumped continuous-wave mode-locked Ho:YAP laser

    Science.gov (United States)

    Duan, X. M.; Lin, W. M.; Cui, Z.; Yao, B. Q.; Li, H.; Dai, T. Y.

    2016-04-01

    In this paper, we report a continuous-wave mode-locked Ho:YAP laser for the first time to our knowledge. Mode-locked pulse was produced by using an acousto-optic modulator. A 1.91-μm Tm-fiber laser as the pump source, at incident pump power of 25.9 W, the maximum output power of 2.87 W at 2117.8 nm was achieved in continuous-wave mode-locked regime. Pulse as short as 254.8 ps was obtained at repetition frequency of 81.52 MHz. In addition, the beam quality factor M 2 value of 1.6 was obtained.

  14. Three types of pulses delivered from a nanotube-mode-locked fiber laser

    Science.gov (United States)

    Yao, X. K.

    2015-07-01

    Three types of pulses are experimentally investigated in a switchable normal-dispersion nanotube-mode-locked fiber laser by adjusting polarizer controller and pump power. They are a standard dissipative-soliton (DS), conventional soliton (CS)-like pulse, and noiselike pulse, which correspond to three mode-locking states. The standard DS with a rectangular spectrum possesses a Gaussian-shape pulse. The CS-like operation has a Lorenz shape, and the spectrum involves several sidebands similar to the CS case. For the noiselike pulse with a bell-shaped spectrum, a 317 fs peak rides upon the 132.5 ps pedestal in the autocorrelation trace. The spectra of these three pulse operations are centered at three close wavelengths. The generation of three such different types of pulses in one identical normal- dispersion laser cavity may find an important application for the future of mode-locked laser research.

  15. Harmonic Mode-Locked Fiber Laser based on Photonic Crystal Fiber Filled with Topological Insulator Solution

    Directory of Open Access Journals (Sweden)

    Yu-Shan Chen

    2015-04-01

    Full Text Available We reported that the photonic crystal fiber (PCF filled with TI:Bi2Te3 nanosheets solution could act as an effective saturable absorber (SA. Employing this TI-PCF SA device; we constructed an ytterbium-doped all-fiber laser oscillator and achieved the evanescent wave mode-locking operation. Due to the large cavity dispersion; the fundamental mode-locking pulse had the large full width at half maximum (FWHM of 2.33 ns with the repetition rate of ~1.11 MHz; and the radio frequency (RF spectrum with signal-to-noise ratio (SNR of 61 dB. In addition; the transition dynamics from a bunched state of pulses to harmonic mode-locking (HML was also observed; which was up to 26th order.

  16. Multiwavelength mode-locked cylindrical vector beam fiber laser based on mode selective coupler

    Science.gov (United States)

    Huang, Ping; Cai, Yu; Wang, Jie; Wan, Hongdan; Zhang, Zuxing; Zhang, Lin

    2017-10-01

    We propose and demonstrate a multiwavelength mode-locked fiber laser with cylindrical vector beam generation for the first time, to the best of our knowledge. The mode-locking mechanism is based on a nonlinear polarization rotation effect in fiber, and the multiwavelength operation is contributed to by an in-line birefringence fiber filter with periodic multiple passbands, formed by incorporating a section of polarization maintaining fiber into the laser cavity with a fiber polarizer. Furthermore, by using a home-made mode selective coupler, which acts as both a mode converter from fundamental mode to higher-order mode and an output coupler, multiwavelength mode-locked cylindrical vector beams have been obtained. This may have potential applications in mode-division multiplexing optical fiber communication and material processing.

  17. Harmonic mode locking in a high-Q whispering gallery mode microcavity

    Science.gov (United States)

    Tanabe, Takasumi; Kato, Takumi; Kobatake, Tomoya; Suzuki, Ryo; Chen-Jinnai, Akitoshi

    2016-03-01

    We present a numerical and experimental study of the generation of harmonic mode locking in a silica toroid microcavity. We use a generalized mean-field Lugiato-Lefever equation and solve it with the split-step Fourier method. We found that a stable harmonic mode-locking regime can be accessed when we reduce the input power after strong pumping even if we do not carefully adjust the wavelength detuning. This is due to the bistable nature of the nonlinear cavity system. The experiment agrees well with the numerical analysis, where we obtain a low-noise Kerr comb spectrum with a narrow longitudinal mode spacing by gradually reducing the input pump power after strong pumping. This finding clarifies the procedure for generating harmonic mode locking in such high-Q microcavity systems.

  18. Electronic control of nonlinear-polarization-rotation mode locking in Yb-doped fiber lasers.

    Science.gov (United States)

    Shen, Xuling; Li, Wenxue; Yan, Ming; Zeng, Heping

    2012-08-15

    We demonstrate a convenient approach to precisely tune the polarization state of a nonlinear-polarization-rotation mode-locked Yb-doped fiber laser by using an electronic polarization controller. It is shown to benefit self-starting of mode-locking states, with precise tuning of the spectral profile, pulse width, and carrier-envelope offset frequency. The pulse width changed linearly by 0.78 ps in the time domain, and the carrier-envelope offset frequency shifted ~77.5 MHz in the frequency domain with a slight change of the driving voltage of 30.7 mV applied on the controller, corresponding to a polarization rotation of 0.0135π. This facilitated precise and automatic regeneration of a particular mode-locking state by setting an accurate voltage at the polarization controller with a programmed microprocessor control unit.

  19. Hybrid mode-locked erbium-doped all-fiber soliton laser with a distributed polarizer.

    Science.gov (United States)

    Chernykh, D S; Krylov, A A; Levchenko, A E; Grebenyukov, V V; Arutunyan, N R; Pozharov, A S; Obraztsova, E D; Dianov, E M

    2014-10-10

    A soliton-type erbium-doped all-fiber ring laser hybrid mode-locked with a co-action of arc-discharge single-walled carbon nanotubes (SWCNTs) and nonlinear polarization evolution (NPE) is demonstrated. For the first time, to the best of our knowledge, boron nitride-doped SWCNTs were used as a saturable absorber for passive mode-locking initiation. Moreover, the NPE was introduced through the implementation of the short-segment polarizing fiber. Owing to the NPE action in the laser cavity, significant pulse length shortening as well as pulse stability improvement were observed as compared with a SWCNTs-only mode-locked laser. The shortest achieved pulse width of near transform-limited solitons was 222 fs at the output average power of 9.1 mW and 45.5 MHz repetition frequency, corresponding to the 0.17 nJ pulse energy.

  20. FTIR spectra and thermal properties of TiO2-doped iron phosphate glasses

    Science.gov (United States)

    Lu, Mingwei; Wang, Fu; Liao, Qilong; Chen, Kuiru; Qin, Jianfa; Pan, Sheqi

    2015-02-01

    Structure and thermal properties of xTiO2·(90 - x) (60P2O5-40Fe2O3)ṡ10CaF2 (x = 0, 5, 10, 15, 20 and 25 mol%) glasses are investigated in detail by Fourier Transform Infrared Spectrum (FTIR) and Differential Thermal Analysis (DTA), respectively. It is found that incorporation of TiO2 increase the density and glass transition temperature of iron phosphate system glass. The increment of doped-TiO2 can also strengthen phosphate network chains due to increasing O/P ratios and more orthophosphate (Q0) units formed in the glass structure at expense of pyrophosphate (Q1) units and metaphosphate (Q2) groups. Moreover, the structure of iron phosphate glass with TiO2 content contain distorted octahedral [TiO6] linked to phosphate unit through Psbnd Osbnd Ti bonds, thus enhanced structure cohesion and increased density obtained. The knowledge provides an improved understanding of the role of TiO2 in the structure of iron phosphate glasses.

  1. Graphite immobilisation in iron phosphate glass composite materials produced by microwave and conventional sintering routes

    Energy Technology Data Exchange (ETDEWEB)

    Mayzan, M.Z.H. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom); Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor (Malaysia); Stennett, M.C.; Hyatt, N.C. [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom); Hand, R.J., E-mail: r.hand@sheffield.ac.uk [Immobilisation Science Laboratory, Department of Materials Science and Engineering, The University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2014-11-15

    An investigation of microwave and conventional processing of iron phosphate based graphite glass composite materials as potential wasteforms for the immobilisation of irradiated graphite is reported. For the base iron phosphate glass, full reaction of the raw materials and formation of a glass melt occurs with consequent removal of porosity at 8 min microwave processing. When graphite is present, iron phosphate crystalline phases are formed with higher levels of residual porosity than in the sample prepared using conventional sintering under argon. It is found that graphite reacts with the microwave field when in powder form but this reaction is minimised when the graphite is incorporated into a pellet, and that the graphite also impedes sintering of the glass. Mössbauer spectroscopy indicates that reduction of iron also occurs with concomitant graphite oxidation. Conventionally sintered samples had lower porosities than the equivalent microwaved ones.

  2. Ultrasonic and Thermal Properties of Borate and Phosphate Glasses Containing Bismuth and Lead

    Science.gov (United States)

    Aziz, Sidek Hj. Abd.; Ahmad, Hamezan; Wahab, Zaidan A.; Sulaiman, Zainal Abidin; Talib, Zainal Abidin; Shaari, A. Halim; Senin, H. B.

    2007-05-01

    Systematic series of (B2O3,P2O5)-Bi2O3-PbO glasses have been successfully prepared by using the rapid quenching technique in which each oxide content changes for every series on the basis of its weight percentage. Their amorphous natures were confirmed earlier by the x-ray diffraction technique. The experimental results show that the density of both glasses, determined by using the Archimedes principle, increases with the glass modifier content. This is due to the replacement of Bi2O3 and PbO in the borate and phosphate glassy networks. The molar volume for borate glass increases with the addition of bismuth and lead oxides, but a reverse trend occurs for the phosphate glass. The longitudinal and shear ultrasound velocities, determined by the MBS 8000 system, of both lead bismuth borate and phosphate glasses show a decreasing trend as more PbO and Bi2O3 are added to the glass system. The increase in PbO/Bi2O3 content was probably related to the progressive increase in the concentration of non-bridging oxygen (NBOs). Thermal studies of the glass, using the Labsys DTA-Setaram machine, show that the value of the glass transition temperature (Tg) is closely related to the chemical bond in the system. In lead bismuth borate glasses, the addition of more Pb2+ and Bi3+ results in a more dominant ionic bond character in the system and hence decreases Tg of the sample. However, in lead bismuth phosphate glasses, the addition of Pb2+ and Bi3+ not only failed to weaken the covalent character in P-O-P bonds, but strengthened it further, leading to an increment in the values of Tg.

  3. Pulse formation and characteristics of the cw mode-locked titanium-doped sapphire laser

    Science.gov (United States)

    Zschocke, Wolfgang; Stamm, Uwe; Heumann, Ernst; Ledig, Mario; Guenzel, Uwe; Kvapil, Jiri; Koselja, Michael P.; Kubelka, Jiri

    1991-10-01

    We report on measurements of transient and steady-state pulse characteristics of an acousto- optically mode-locked titanium-doped sapphire laser. During the pulse evolution, oscillations in the pulse width and pulse energy are found. A steady state is reached after about 40 to 60 microsecond(s) . The steady-state pulse width is strongly influenced by the mode-locking loss as well as the intracavity bandwidth. Shortest pulses of typically 15 ps are obtained. The experiment is compared with results of a simple computer simulation.

  4. A 12.1-W SESAM mode-locked Yb:YAG thin disk laser

    Science.gov (United States)

    Yingnan, Peng; Zhaohua, Wang; Dehua, Li; Jiangfeng, Zhu; Zhiyi, Wei

    2016-05-01

    Pumped by a 940 nm fiber-coupled diode laser, a passively mode-locked Yb:YAG thin disk oscillator was demonstrated with a semiconductor saturable absorber mirror (SESAM). 12.1 W mode-locked pulses were obtained with pulse duration of 698 fs at the repetition rate of 57.43 MHz. Measurement showed that the beam quality was close to the diffraction limit. Project supported by the National Key Basic Research Program of China (Grant No. 2013CB922402), the National Major Instrument Program of China (Grant No. 2012YQ120047), and the National Natural Science Foundation of China (Grant No. 61210017).

  5. Tunable mode-locked laser with micro-air gap cavity

    Science.gov (United States)

    Ahmad, H.; Aidit, S. N.; Hassan, N. A.; Ooi, S. I.; Tiu, Z. C.

    2017-02-01

    A tunable mode-locked laser with a micro-air gap cavity acting as a high resolution tuning is proposed and demonstrated. The laser utilizes the nonlinear polarization technique in the cavity to obtain a reliable and stable mode locking over the whole tuning range at a resolution of 1 nm. The micro-air gap is constructed by aligning two fiber facets coaxially, and the variation of micro-air gap introduces a tuning mechanism where it changes the gain saturation compensation in the gain medium and thus induces wavelength shifting on the generated solitons.

  6. Novel design of low-jitter 10 GHz all-active monolithic mode-locked lasers

    DEFF Research Database (Denmark)

    Larsson, David; Yvind, Kresten; Christiansen, Lotte Jin

    2004-01-01

    Using a novel design, we have fabricated 10 GHz all-active monolithic mode-locked semiconductor lasers that generate 1.4 ps pulses with record-low timing jitter. The dynamical properties of lasers with 1 and 2 QWs are compared.......Using a novel design, we have fabricated 10 GHz all-active monolithic mode-locked semiconductor lasers that generate 1.4 ps pulses with record-low timing jitter. The dynamical properties of lasers with 1 and 2 QWs are compared....

  7. Comparative study on the temporal contrast of femtosecond mode-locked laser oscillators.

    Science.gov (United States)

    Stuart, Nicholas; Robinson, Timothy; Hillier, David; Hopps, Nick; Parry, Bryn; Musgrave, Ian; Nersisyan, Gagik; Sharba, Ahmed; Zepf, Matthew; Smith, Roland A

    2016-07-15

    We have investigated the temporal intensity contrast characteristics from a broad range of mode-locked short-pulse oscillators used for seeding high-power terawatt and petawatt-class laser systems. Saturable absorber (SESAM), Kerr lens (KLM), nonlinear polarization evolution (NPE) in optical fibers and synchronously pumped optical parametric oscillator (OPO) mode-locked sources have been measured using a third-order autocorrelator with up to 1010 dynamic range. We restricted the temporal characterization to features higher-order dispersion limits the performance of KLM and NPE sources up to the 105 contrast level, while >108 contrast was observed from the SESAM and OPO laser pulse trains.

  8. Polarization dynamics in dissipative soliton fiber lasers mode-locked by nonlinear polarization rotation.

    Science.gov (United States)

    Kong, Lingjie; Xiao, Xiaosheng; Yang, Changxi

    2011-09-12

    We numerically studied the polarization dynamics in dissipative soliton lasers mode-locked by nonlinear polarization rotation (NPR). It was found that the polarization states of the intracavity dissipative soliton vary with time across the pulse. Depending on output coupling ratios, the polarization states of the pulse peak before the polarizer can be either nearly circular or nearly linear polarizations. The polarization dependent component in NPR is found to play a role of spectral filter under high and medium output coupling. However, NPR may work as a weak optical limiter under low output coupling, when additional spectral filtering is necessary to maintain steady mode-locking state.

  9. Adjustable high-repetition-rate pulse trains in a passively-mode-locked fiber laser

    Science.gov (United States)

    Si Fodil, Rachid; Amrani, Foued; Yang, Changxi; Kellou, Abdelhamid; Grelu, Ph.

    2016-07-01

    We experimentally investigate multipulse regimes obtained within a passively-mode-locked fiber laser that includes a Mach-Zehnder (MZ) interferometer. By adjusting the time delay imbalance of the MZ, ultrashort pulse trains at multi-GHz repetition rates are generated. We compare the observed dynamics with high-harmonic mode locking, and show that the multi-GHz pulse trains display an inherent instability, which has been overlooked. By using a recirculation loop containing the MZ, we demonstrate a significant improvement of the pulse train stability.

  10. Effects of flake size on mode-locking behavior for flake-graphene saturable absorber mirrors

    CERN Document Server

    Hussain, M I; Booth, L S; Petrasiunas, M J; Brown, C L; Kielpinski, D

    2016-01-01

    After advent of graphene as a saturable absorber many experiments have been conducted to produce short pulse duration pulses. Here, we have measured the properties of flake-graphene saturable absorber mirrors of various flake sizes dependent on fabrication technique. These mirrors enabled us to obtain a large mode-locking bandwidth of 16nm in an erbium-doped fiber laser. Mirrors with large flake size and multi-layered thickness induce strong pulse shaping and reflect mode-locked train of pulses with very large bandwidths.

  11. Emergence of resonant mode-locking via delayed feedback in quantum dot semiconductor lasers.

    Science.gov (United States)

    Tykalewicz, B; Goulding, D; Hegarty, S P; Huyet, G; Erneux, T; Kelleher, B; Viktorov, E A

    2016-02-22

    With conventional semiconductor lasers undergoing external optical feedback, a chaotic output is typically observed even for moderate levels of the feedback strength. In this paper we examine single mode quantum dot lasers under strong optical feedback conditions and show that an entirely new dynamical regime is found consisting of spontaneous mode-locking via a resonance between the relaxation oscillation frequency and the external cavity repetition rate. Experimental observations are supported by detailed numerical simulations of rate equations appropriate for this laser type. The phenomenon constitutes an entirely new mode-locking mechanism in semiconductor lasers.

  12. Polarization dynamic patterns of vector solitons in a graphene mode-locked fiber laser.

    Science.gov (United States)

    Han, Mengmeng; Zhang, Shumin; Li, Xingliang; Zhang, Huaxing; Yang, Hong; Yuan, Ting

    2015-02-09

    Multiple polarization dynamic patterns of vector solitons, including fundamental solitons, bunched solitons, loosely or tightly bound states and harmonic mode locking have been observed experimentally in an erbium-doped fiber ring laser with graphene as a saturable absorber. By carefully adjusting the pump power and the orientation of the intra-cavity polarization controller, either polarization rotation or polarization locked operation have all been achieved for the above vector solitons. This is the first time that high order harmonic mode locking of polarization rotation vector solitons has been achieved. The signal to noise ratio of our system was ~51 dB, which indicates that the laser operated with high stability.

  13. Soliton mode locking fiber laser with an all-fiber polarization interference filter.

    Science.gov (United States)

    Yan, Zhijun; Wang, Hushan; Zhou, Kaiming; Wang, Yishan; Li, Cheng; Zhao, Wei; Zhang, Lin

    2012-11-01

    An erbium doped fiber ring laser achieving soliton mode locking by the use of an intra-cavity all-fiber polarization interference filter (AFPIF) has been demonstrated. To incorporate an AFPIF with relative narrow transmission bandwidth, the laser has produced clean soliton pulses of 1.2 ps duration at a repetition rate of 14.98 MHz with a polarization extinction ratio up to 25.7 dB. Moreover, we have demonstrated that the operating wavelength of the mode locking laser can be tuned over 20 nm range from 1545 to 1565 nm by thermally tuning the AFPIF cavity.

  14. A Q-switched, mode-locked fiber laser employing subharmonic cavity modulation.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Lee, Ju Han

    2011-12-19

    We present a new and simple approach for the generation of Q-switched, mode-locked pulses from a laser cavity. The approach is based on cavity loss modulation that employs a subharmonic frequency of the fundamental intermode frequency spacing. A range of experiments have been carried out using an erbium-doped fiber-based ring cavity laser in order to verify that this simple approach can readily produce high quality Q-switched, mode-locked pulses. An active tuning of the Q-switched envelope repetition rate is also shown to be easily achievable by adjusting the order of the applied subharmonic frequency.

  15. Time Domain Dynamic Analysis of 1550nm Monolithic Two Sections Mode Locked MQW Laser

    OpenAIRE

    DUMAN, Çağlar; ÇAKMAK, Bülent

    2015-01-01

    In this study, time domain dynamic model of a mode locked two sections DBR laser was obtained. Sort duration and high power optical pulse generation from a semiconductor laser was examined by using obtained model. For this aim, while one of the laser sections was thought as reverse biased and so acted as a saturable absorber, other section thought as forward biased with a DC current and so acted as a gain section. A semiconductor laser biased this way can produce mode locked pulses by suitabl...

  16. Figure-eight actively-passively mode-locked erbium-doped fiber laser

    Science.gov (United States)

    Wang, Zhaoying; Yu, Zhenhong; Ge, Chunfeng; Zhang, Ruifeng; Jia, Dongfang; Li, Shichen

    2003-03-01

    The advantages of using nonlinear optical loop mirror (NOLM) to compress pulse with slight amplitude fluctuation and reflected energy loss are analyzed in theory. Experimentally the NOLM is placed in an actively mode-locked erbium-doped fiber ring laser to form a figure-eight actively and passively modelocked fiber laser. 12 ps mode-locked pulses centered at 1.543 ?m were obtained with the modulation frequency of 2.498748700 GHz. 3.715 mW output power is achieved with 50 mW pump power.

  17. Graphene oxide mode-locked Yb:GAGG bulk laser operating in the femtosecond regime

    Science.gov (United States)

    Cui, Liang; Lou, Fei; Li, Yan-bin; Hou, Jia; He, Jing-Liang; Jia, Zhi-Tai; Liu, Jing-Quan; Zhang, Bai-Tao; Yang, Ke-Jian; Wang, Zhao-Wei; Tao, Xu-Tang

    2015-04-01

    High-quality graphene oxide saturable absorber (SA) is successfully fabricated with 1-2 layer graphene oxide. By employing this SA, we have demonstrated femtosecond pulse generation from a graphene oxide passively mode locked bulk laser for the first time to our best knowledge. With two Gires-Tournois interferometer mirrors for dispersion compensation, pulses as short as 493 fs with an average power of 500 mW are obtained at the central wavelength of 1035.5 nm. These results presented here indicate the great potential of GO for generating femtosecond mode-locked pulses in the bulk laser.

  18. Pulse shaping in mode-locked fiber lasers by in-cavity spectral filter.

    Science.gov (United States)

    Boscolo, Sonia; Finot, Christophe; Karakuzu, Huseyin; Petropoulos, Periklis

    2014-02-01

    We numerically show the possibility of pulse shaping in a passively mode-locked fiber laser by inclusion of a spectral filter into the laser cavity. Depending on the amplitude transfer function of the filter, we are able to achieve various regimes of advanced temporal waveform generation, including ones featuring bright and dark parabolic-, flat-top-, triangular- and saw-tooth-profiled pulses. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for controlling the dynamics of mode-locked fiber lasers.

  19. Pulse-shaping mechanism in colliding-pulse mode-locked laser diodes

    DEFF Research Database (Denmark)

    Bischoff, Svend; Sørensen, Mads Peter; Mørk, J.;

    1995-01-01

    The large signal dynamics of passively colliding pulse mode-locked laser diodes is studied. We derive a model which explains modelocking via the interplay of gain and loss dynamics; no bandwidth limiting element is necessary for pulse formation. It is found necessary to have both fast and slow...... absorber dynamics to achieve mode-locking. Significant chirp is predicted for pulses emitted from long lasers, in agreement with experiment. The pulse width shows a strong dependence on both cavity and saturable absorber length. (C) 1995 American Institute of Physics....

  20. Low jitter and high power all-active mode-locked lasers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin

    2003-01-01

    A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and fiber-coupled power of 7 mW.......A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and fiber-coupled power of 7 mW....

  1. Low jitter and high power all-active mode-locked lasers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin

    2003-01-01

    A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and -coupled power of 7 mW.......A novel epitaxial design leading to low loss and low gain saturation improves the properties of 40 GHz mode-locked lasers. We obtain 2.8 ps nearly chirp free pulses with 228 fs jitter and -coupled power of 7 mW....

  2. Study on the protection of Er-doped phosphate glass waveguide surface in ion-exchange processing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel method, sputtering K9 glass film, is proposed to solve the surface corrosion of Er-doped phosphate glass during ion-exchange processing for optical waveguide fabrication. The corrosion causes are analyzed to be the intrinsically weak stabilization of phosphate glass structure, hydrophile and weakly acidic property of phosphate radical. Experimental results show that the K9 glass film could not only protect the Er-doped phosphate glass surface from being corroded but also give no influence on the waveguide fabrication. The effect of thickness of K9 glass film on the optical property of waveguide is also investigated and the op- timal thickness is found to be 60―80 nm. It provides a good base for further fabri- cation of active phosphate glass optical waveguide devices.

  3. Effect of Network Modifiers on Spectroscopic Properties of Erbium-doped Phosphate Glasses

    Institute of Scientific and Technical Information of China (English)

    YANG Gangfeng; JIANG Zhonghong; DENG Zaide; YIN Bing; YING Tingzhao; FENG Zhouming

    2005-01-01

    The integrated absorption cross section Σabs, peak emission cross section σemi, Judd-Ofeld intensity parameters Ωt(t=2,4,6), and spontaneous emission probability AR of Er3+ ions were determined for Erbium doped alkali and alkaline earth phosphate glasses. It is found the compositional dependence of σemi is almost similar to that of Σabs, which is determined by the sum of Ωt (3Ω2+10Ω4+21Ω6). In addition, the compositional dependence of Ωt was studied in these glass systems. As a result, compared with Ω4 and Ω6, the Ω2 has a stronger compositional dependence on the ionic radius and content of modifiers. The covalency of Er-O bonds in phosphate glass is weaker than that in silicate glass, germanate glass, aluminate glass, and tellurate glass, since Ω6 of phosphate glass is relatively large. AR is affected by the covalency of the Er3+ ion sites and corresponds to the Ω6 value.

  4. Magneto-optical properties of transparent divalent iron phosphate glasses

    OpenAIRE

    Akamatsu, Hirofumi; FUJITA, KOJI; Murai, Shunsuke; Tanaka, Katsuhisa

    2008-01-01

    We have prepared glasses having xFeO·(100−x)P2O5 (mol %) (x=50.0, 54.0, 57.1) compositions by melting under mild reducing condition and found that these glasses exhibit fairly high transmittance in the visible range and large Faraday effect at the wavelength of about 400 nm. 57Fe Mössbauer spectra confirm that almost all the iron ions are present as Fe2+ in the glasses. A spin glass transition is observed at low temperatures in the temperature dependence of magnetic susceptibility. Intense op...

  5. Structure and properties of ZnO-containing lithium-iron-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yang Ruijuan; Liu Huali; Wang Yinghui [School of Materials Science and Engineering, University of Jinan, Jinan 250022, Shandong (China); Jiang Wanli; Hao Xiaopeng; Zhan Jie [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, Shandong (China); Liu Shiquan, E-mail: vctrliu@hotmail.com [School of Materials Science and Engineering, University of Jinan, Jinan 250022, Shandong (China)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Lithium-iron-phosphate glasses. Black-Right-Pointing-Pointer Substitution of Li{sub 2}O with ZnO. Black-Right-Pointing-Pointer Variation in structure and properties with ZnO substitutions. Black-Right-Pointing-Pointer Crystallization of LiFeP{sub 2}O{sub 7}. - Abstract: Lithium-iron-phosphate glasses with compositions of (20 - x)Li{sub 2}O{center_dot}xZnO{center_dot}30Fe{sub 2}O{sub 3}{center_dot}50P{sub 2}O{sub 5} (x = 0-7.2) have been prepared. The influences of the amount of ZnO on the structure, physical and chemical properties, and crystallization behavior of the glasses were investigated using Fourier transform infrared spectroscopy, differential thermal analysis and X-ray diffraction techniques. The density of glass was measured according to the Archimedes principle. The chemical stability was evaluated based on the weight loss after the glass particles were boiled in water. The results indicate that Zn{sup 2+} ions cross-linked the phosphate chains by forming P-O-Zn bridges when 2 mol% of ZnO was added. When the amount of ZnO was further increased, [ZnO{sub 4}] tetrahedra were formed and ZnO acted as a glass network former, integrating the phosphate glass network. The density, chemical stability and the activation energy of crystallization of the glasses increased with the amount of ZnO, whereas the glass transition temperature decreased. All thermally treated glasses showed surface crystallization with LiFeP{sub 2}O{sub 7} as the crystalline phase.

  6. A comparative property investigation of lithium phosphate glass melted in microwave and conventional heating

    Indian Academy of Sciences (India)

    AVIK HALDER; BISWAJIT MANDAL; SOURINDRA MAHANTY; RANJAN SEN; ASHIS KUMAR MANDAL

    2017-09-01

    The present study addresses the application of microwave (MW) energy for melting lithium phosphate glass. Acomparative analysis of the properties is presented with glasses melted in conventional resistance heating adopting standardmethods of characterization. The density of the glass was found less in MW heating. The glass transition temperature wasrecorded as 3–10$^{\\circ}$C lower in MW prepared glass than in conventional glass.Micro-hardness is found to be improved in caseof MW heating. Maximum forward power was recorded less than 2 kW with an average power $\\sim$1 kW during melting of40 g glass in MW furnace. MW forward and reflected power measured during melting in the MW cavity was elaborated.Total melting time was within 2 h 30 min in MW heating, whereas it was 6–7 h in resistive heating. Total power consumedwas $\\sim$5 kWh in MW heating and $\\sim$14 kWh in resistance heating.

  7. A model for phosphate glass topology considering the modifying ion sub-network

    DEFF Research Database (Denmark)

    Hermansen, Christian; Mauro, J.C.; Yue, Yuanzheng

    2014-01-01

    In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent with availa......In the present paper we establish a temperature dependent constraint model of alkali phosphate glasses considering the structural and topological role of the modifying ion sub-network constituted by alkali ions and their non-bonding oxygen coordination spheres. The model is consistent...... with available structural data by NMR and molecular dynamics simulation and dynamic data such glass transition temperature (Tg) and liquid fragility (m). Alkali phosphate glasses are exemplary systems for developing constraint model since the modifying cation network plays an important role besides the primary...... phosphate network. The proposed topological model predicts the changing trend of the Tg and m with increasing alkali oxide content for alkali phosphate glasses, including an anomalous minimum at around 20 mol% alkali oxide content. We find that the minimum in Tg and m is caused by increased connectivity...

  8. Simulation of alpha decay of actinides in iron phosphate glasses by ion irradiation

    Science.gov (United States)

    Dube, Charu L.; Stennett, Martin C.; Gandy, Amy S.; Hyatt, Neil C.

    2016-03-01

    A surrogate approach of ion beam irradiation is employed to simulate alpha decay of actinides in iron phosphate nuclear waste glasses. Bismuth and helium ions of different energies have been selected for simulating glass matrix modification owing to radiolysis and ballistic damage due to recoil atoms. Structural modification and change in coordination number of network former were probed by employing Reflectance Fourier-Transform Infrared (FT-IR), and Raman spectroscopies as a consequence of ion irradiation. Depolymerisation is observed in glass sample irradiated at intermediate energy of 2 MeV. Helium blisters of micron size are seen in glass sample irradiated at low helium ion energy of 30 keV.

  9. Incorporation of a controlled-release glass into a calcium phosphate cement.

    Science.gov (United States)

    Khairoun, I; Boltong, M G; Gil, F J; Driessens, F C; Planell, J A; Seijas, M M; Martínez, S

    1999-04-01

    A so-called controlled-release glass was synthesized occurring in the system CaO-Na2O-P2O5. A certain sieve fraction of this glass was incorporated in a calcium phosphate cement, of which the powder contained alpha-tricalcium phosphate (alpha-TCP), dicalcium phosphate (DCP) and precipitated hydroxyapatite (HA). The glass appeared to retard the cement setting slightly and it reduced considerably the compressive strength after aging in aqueous solutions which were continuously refreshed. Scanning electron microscope (SEM) pictures and X-ray diffraction (XRD) patterns of the samples after 5 weeks of aging showed that the glass was not dissolved but that large brushite crystals were formed. Thereby, aging in CaCl2 solutions resulted in more brushite formation than aging in NaCl solutions. The brushite crystals did not reinforce the cement. Neither was the aged glass-containing cement weaker than it was before the brushite formation right after complete setting. In conclusion, the incorporation of controlled-release glasses into a calcium phosphate cement and subsequent aging in aqueous solutions did not result in the formation of macropores in the cement structure, but that of brushite crystals. This incorporation reduced the compressive strength of the cement considerably.

  10. 35 GHz passive mode-locking of InGaAs/GaAs quantum dot lasers at 1.3 μm with Fourier-limited pulses

    DEFF Research Database (Denmark)

    Kuntz, M.; Fiol, G.; Laemmlin, M.;

    2004-01-01

    We report 35 GHz passive mode-locking and 20 GHz hybrid mode-locking of quantum dot (QD) lasers at 1.3 ìm. Our investigations show ultrafast absorber recovery times and for the first time transform-limited mode-locked pulses.......We report 35 GHz passive mode-locking and 20 GHz hybrid mode-locking of quantum dot (QD) lasers at 1.3 ìm. Our investigations show ultrafast absorber recovery times and for the first time transform-limited mode-locked pulses....

  11. Structural features of silver-doped phosphate glasses in zone of femtosecond laser-induced modification

    Energy Technology Data Exchange (ETDEWEB)

    Vasileva, A.A., E-mail: anvsilv@gmail.com [Saint-Petersburg State University, Institute of Chemistry, Saint-Petersburg (Russian Federation); Nazarov, I.A. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg (Russian Federation); Olshin, P.K.; Povolotskiy, A.V. [Saint-Petersburg State University, Institute of Chemistry, Saint-Petersburg (Russian Federation); Sokolov, I.A. [St.Petersburg State Polytechnical University, St.Petersburg (Russian Federation); LTD “AtomTjazhMash”, St.Petersburg (Russian Federation); Manshina, A.A. [Saint-Petersburg State University, Institute of Chemistry, Saint-Petersburg (Russian Federation)

    2015-10-15

    Femtosecond (fs) laser writing of two-dimensional microstructures (waveguides) is demonstrated in bulk phosphate glasses doped with silver ions. Silver-content phosphate and silver-content niobium–phosphate glasses with high concentration of silver oxide 55 mol% were used as samples for fs laser writing. The chemical network structure of the synthesized samples is analyzed through Raman spectroscopy and was found to be strongly sensitive to Nb incorporation. It was found that the direct laser writing process enables not only reorganization of glass network, but also formation of color centers and silver nanoparticles that are revealed in appearance of luminescence signal and plasmon absorption. The process of NPs' formation is more efficient for Nb-phosphate glass, while color centers are preferably formed in phosphate glass. - Graphical abstract: Formation of silver NPs on the surface of 0.5Ag{sub 2}O–0.4P{sub 2}O{sub 5}–0,1Nb{sub 2}O{sub 5} glass induced by CW laser irradiation. - Highlights: • The structure of 0.5Ag{sub 2}O–0.1Nb{sub 2}O{sub 5}–0.4P{sub 2}O{sub 5} and 0.55Ag{sub 2}O–0.45P{sub 2}O{sub 5} glasses was investigated by Raman spectroscopy. • Fs laser writing induces formation of silver NPs in investigated glasses. • Surface plasmon resonance in the absorption spectra confirms the formation of NP. • The possibility of CW laser induced formation of silver NPs on the surface of sample with niobium is shown.

  12. Direct femtosecond laser waveguide writing inside zinc phosphate glass

    NARCIS (Netherlands)

    Fletcher, L.; Witcher, J.J.; Troy, N.; Reis, S.T.; Brow, R.K.; Krol, D.M.

    2011-01-01

    We report the relationship between the initial glass composition and the resulting microstructural changes after direct femtosecond laser waveguide writing with a 1 kHz repetition rate Ti:sapphire laser system. A zinc polyphosphate glass composition with an oxygen to phosphorus ratio of 3.25 has dem

  13. Systematic investigation of the temperature behavior of InAs/InP quantum nanostructure passively mode-locked lasers

    DEFF Research Database (Denmark)

    Klaime, K.; Piron, R.; Grillot, F.

    2013-01-01

    This paper aims to investigate the effects of the temperature on the mode-locking capability of two section InAs/InP quantum nanostructure (QN) passively mode locked lasers. Devices are made with multi-layers of self-assembled InAs QN either grown on InP(100) (5 quantum dashes (QDashes) layers...

  14. 10-GHz 1.59-μm quantum dash passively mode-locked two-section lasers

    DEFF Research Database (Denmark)

    Dontabactouny, Madhoussoudhana; Rosenberg, C.; Semenova, Elizaveta

    2010-01-01

    This paper reports the fabrication and the characterisation of a 10 GHz two-section passively mode-locked quantum dash laser emitting at 1.59 μm. The potential of the device's mode-locking is investigated through an analytical model taking into account both the material parameters and the laser g...

  15. High-resolution microwave-photonic applications via precise synchronization between RF and mode-locked laser pulses (Conference Presentation)

    Science.gov (United States)

    Shi, Kebin; Lu, Xing; Lv, Zhiqiang

    2016-10-01

    Precise synchronization between radio frequency and mode-locked laser pulses provides a high resolution capability for detecting either time jitter in laser pulse train or phase noise in radio frequency. In this talk, we will present our recent progresses on radio frequency dissemination and fiber optical sensing based on sub-femtosecond level synchronization between radio frequency and mode-locked pulse train.

  16. Passively mode-locked fiber laser based on polarization rotation in a multiple-quantum-well waveguide.

    Science.gov (United States)

    Okhotnikov, O G; Salcedo, J R

    1995-01-01

    We give experimental evidence for a new type of mode-locking mechanism for Er-doped fiber lasers based on polarization evolution in an intracavity multiple-quantum-well waveguide. Experiments indicate that anisotropic properties of waveguides can continuously start the mode-locking process.

  17. The generation of femtosecond light pulses from a laser with combined mode locking with new saturable absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Bondarev, B.V.; Prokhorenko, V.I.; Rodionov, G.D.; Sorokin, V.B.; Slominskii, IU.L.

    1989-01-01

    Combined mode locking was studied experimentally using new 3492-y and 3490-y dyes. In a linear single-stream R6G laser, the 3490-y dye provides for stable mode locking throughout the 576-615 nm tuning range. The pulse duration varies over the tuning range from 180-250 fs, the lasing efficiency amounting to 17 percent. 10 refs.

  18. Monolithic mode-locked lasers with deeply dry etched Bragg mirror

    DEFF Research Database (Denmark)

    Larsson, David; Yvind, Kresten; Hvam, Jørn Märcher

    Background: Semiconductor mode-locked lasers are attractive as components in futureultra high-speed telecommunication systems (160-640Gb/s); as picosecond pulse sources,clock-recovery devices and for demultiplexing in Optical Time Division Multiplexing(OTDM) systems. We have recently designed, fa...

  19. Tunable mode-locked semiconductor laser with Bragg mirror external cavity

    DEFF Research Database (Denmark)

    Yvind, Kresten; Jørgensen, T.; Birkedal, Dan

    2002-01-01

    We present a simplified design for a wavelength tunable external cavity mode-locked laser by employing a wedged GaAs/AlGaAs Bragg mirror. The device emits 4-6 ps pulses at 10 GHz and is tunable over 15 nm. Although, in the present configuration, tunability is limited to 15 nm, however, we have...

  20. Mode-locked Pr3+-doped silica fiber laser with an external cavity

    DEFF Research Database (Denmark)

    Shi, Yuan; Poulsen, Christian; Sejka, Milan

    1994-01-01

    We present a Pr3+-doped silica-based fiber laser mode-locked by using a linear external cavity with a vibrating mirror. Stable laser pulses with a FWHM of less than 44 ps, peak power greater than 9 W, and repetition rate up to 100 MHz are obtained. The pulse width versus cavity mismatch ΔL and pump...

  1. Correlation coefficient measurement of the mode-locked laser tones using four-wave mixing.

    Science.gov (United States)

    Anthur, Aravind P; Panapakkam, Vivek; Vujicic, Vidak; Merghem, Kamel; Lelarge, Francois; Ramdane, Abderrahim; Barry, Liam P

    2016-06-01

    We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.

  2. Mode-locked 1.5 micrometers semiconductor optical amplifier fiber ring

    DEFF Research Database (Denmark)

    Pedersen, Niels V.; Jakobsen, Kaj Bjarne; Vaa, Michael

    1996-01-01

    The dynamics of a mode-locked SOA fiber ring are investigated experimentally and numerically. Generation of near transform-limited (time-bandwidth product=0.7) 1.5 μm 54 ps FWHM pulses with a peak power of 2.8 mW at a repetition rate of 960 MHz is demonstrated experimentally. The experimental res...

  3. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode

    Science.gov (United States)

    Auyeung, J. C.; Johnston, A. R.

    1982-01-01

    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  4. Development prospects and stability limits of mid-IR Kerr-lens mode-locked lasers

    CERN Document Server

    Kalashnikov, V L; Sorokina, I T

    2002-01-01

    The Kerr-lens mode locking stability and the ultrashort pulse characteristics are analyzed numerically for the Cr-doped ZnTe, ZnSe, ZnS active media. The advantages of these materials for the femtosecond lasing within 2 - 3 $\\mu$m spectral range are demonstrated

  5. Stable mode-locking in an Yb:YAG laser with a fast SESAM

    Institute of Scientific and Technical Information of China (English)

    Guifang Ju(居桂方); Lu Chai(柴路); Qingyue Wang(王清月); Zhigang Zhang(张志刚); Yonggang Wang(王勇刚); Xiaoyu Ma(马骁宇)

    2003-01-01

    Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor saturable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.

  6. Performance of external cavity mode-locked semiconductor lasers employing reverse biased saturable absorbers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Skovgaard, P.M.W.; Mørk, Jesper;

    2002-01-01

    We have experimentally investigated the performance of external cavity mode-locked semiconductor lasers employing reverse biased saturable absorbers. We have measured the magnitude of trailing pulses when varying the chip length and studied the pulse quality when changing the driving conditions...

  7. Monolithic Multi-Colour 40 GHz Mode-Locked Laser Array

    OpenAIRE

    Hou, Lianping; Eddie, Iain; Marsh, John

    2016-01-01

    The monolithic integration of four 40 GHz multi-colored mode-locked lasers with a 4×1 MMI, four electroabsorption modulators and an SOA has been demonstrated. The shortest pulse widths are between 2.63 and 2.85 ps.

  8. Stabilization of an AM mode-locked tea CO2 laser

    NARCIS (Netherlands)

    Goor, van F.A.

    1983-01-01

    An increased shot-to-shot reproducibility has been obtained by injection of radiation from a cw CO2 laser in an amplitude mode-locked TEA CO2 laser without additional pulse broadening. Stable pulses variable from 900 ps up to 4 ns have been generated with this new technique.

  9. An investigation of the spectral content of a mode-locked pulsed CO2 laser

    NARCIS (Netherlands)

    Bormans, B.J.M.; Olbertz, A.H.M.

    1980-01-01

    The frequency width of a pulse train in a pulsed mode-locked CO2 laser has been accurately measured by means of a Fabry-Perot interferometer. We succeeded in resolving the longitudinal mode structure. The results are in excellent agreement with the results of previous measurements of the line width

  10. Mode-Locked 1.5 um Semiconductor Optical Fiber Ring

    DEFF Research Database (Denmark)

    Pedersen, Niels Vagn; Jakobsen, Kaj Bjarne; Vaa, Michael

    1996-01-01

    The dynamics of a mode-locked SOA fiber ring are investigated experimentally and numerically. Generation of near transform-limited (time-bandwidth product = 0.7) 1.5 um 54 ps FWHM pulses with a peak power of 2.8 mW at a repetition rate of 960 MHz is demonstrated experimentally. The experimental...

  11. Bound soliton pulses in a passively mode-locked fibre ring laser

    Institute of Scientific and Technical Information of China (English)

    Zhang Shu-Min; Lü Fu-Yun; Gong Yan-Dong; Zhou Xiao-Qun; Yang Xiu-Feng; Lü Chao

    2005-01-01

    The bound solitons in a passively mode-locked fibre ring laser are observed and their formation mechanism is summarized in this paper. In order to obtain stable bound solitons, a strong CW laser field at the centre of the soliton spectral is necessary to suppress and synchronize the random soliton phase variations.

  12. Experimental studies of self-starting passive mode locking Er3 + -doped fiber ring soliton laser

    Institute of Scientific and Technical Information of China (English)

    刘东峰; 陈国夫; 王贤华

    1999-01-01

    The mechanism of femtosecond optical pulse generation in a self-starting Er3+-doped fiber ring solitonlaser and experimental research results are discussed. Using the nonlinear polarization rotation effect of the fiber for sat-urable absorbers (and then self-amplitude modulation) which acts as the mode locking mechanism in an Er3+-dopedfiber ring cavity laser, stable self-starting mode locking pulses have been generated. The shortest output pulse is 269 fs,with the central wavelength of 1.531 μm at the repetition rate of 21.37 MHz. The average output powers of the two terminators of the laser are 0.25 mW and 0.08 mW respectively. The threshold pump power which sustains the mode lock-ing is 15 mW. Under high pump power, the laser works in a high order harmonic mode locking state. The mode lockingpulse durations vs different cavity lengths are also studied.

  13. Quantum beats in forward scattering: subnanosecond studies with a mode-locked dye laser.

    Science.gov (United States)

    Harde, H; Burggraf, H; Mlynek, J; Lange, W

    1981-06-01

    Time-resolved polarization spectroscopy of transient coherent superpositions of atomic substates is extended to the picosecond time scale by using a synchronously pumped mode-locked dye laser. As a first demonstration, hyperfine beats in the sodium D(1) and D(2), lines were resolved. The ground-state splitting could be determined with an accuracy of better than 10(-3).

  14. Quantum beats in forward scattering - Subnanosecond studies with a mode-locked dye laser

    Science.gov (United States)

    Harde, H.; Burggraf, H.; Mlynek, J.; Lange, W.

    1981-06-01

    Time-resolved polarization spectroscopy of transient coherent superpositions of atomic substates is extended to the picosecond time scale by using a synchronously pumped mode-locked dye laser. As a first demonstration, hyperfine beats in the sodium D1 and D2 lines were resolved. The ground-state splitting could be determined with an accuracy of better than 0.001.

  15. Low-jitter and high-power 40 GHz all-active mode-locked lasers

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Christiansen, Lotte Jin

    2004-01-01

    A novel design strategy for the epitaxial structure of monolithic mode-locked semiconductor lasers is presented. Using an all-active design, we fabricate 40-GHz lasers generating 2.8-ps almost chirp-free pulses with record low high-frequency jitter and more than 7-mW fiber coupled output power....

  16. Fiberglass goes green: Developing phosphate glass for use in biodegradable composites

    Science.gov (United States)

    Arendt, Christina Lee

    Composite materials, such as the glass fiber reinforced polyester thermosets known as "fiberglass," are used in many applications. However, recycling processes for these materials are inefficient and not widely available. Specially engineered degradable polymers offer an opportunity to redesign these composites. Additionally, the composite could be tailored to be multi-use, such that upon degradation, the resulting products could be used as part of a zeoponic substrate (artificial soil) for growing plants. Such a material would be beneficial for long-duration space missions, terraforming, or in other agricultural applications. The research presented in this dissertation focuses on developing phosphate glass for use as the fiber reinforcement for such a composite. Due to the under-utilization of phosphate systems, there is a lack of thermodynamic data on these systems. The modified associate species method of phase diagram calculation was used in an attempt to gain more information about the desired system, as it is a good predictor of the phase relations in oxide melts, slags, and glasses and requires less data than other methods. Further research into the thermodynamic properties of phosphates is still needed to develop accurate phase diagrams and melting temperatures for this system. Seventeen glass formulations were developed and melted. Six of these formulations were chosen for dissolution testing. Of these six, Glass 17 was chosen for intensive testing and characterization. This glass was tested in water, hydrochloric acid solutions, and citric acid solutions. The weight loss was measured and ICP-OES was performed on the leachate solution. Scanning electron microscopy (SEM) and X-ray diffraction were performed on the tested specimens. Shrinking-core models were fit to the dissolution data. Fibers were drawn from the glass and characterized using SEM. The data shows that this glass is not dissolving congruently, as is expected of phosphate glasses. Instead

  17. Q-switched mode-locking of an erbium-doped fiber laser using cavity modulation frequency detuning.

    Science.gov (United States)

    Chang, You Min; Lee, Junsu; Jhon, Young Min; Lee, Ju Han

    2012-07-20

    We present the results of an investigation regarding a Q-switched mode-locked fiber laser scheme based on a cavity modulation frequency detuning technique. The approach is based on undamped laser relaxation oscillations occurring due to frequency detuning in the fundamental cavity resonance frequency. Through a range of experiments with an erbium-doped, fiber-based, ring-cavity laser, this approach has been shown to be capable of generating high-quality Q-switched mode-locked pulses from an optical fiber-based laser. The maximum frequency detuning range for a stable Q-switched mode-locking operation has been observed to vary depending on the pump power used. We found that the highest pulse peak power was obtained at the frequency detuning threshold at which the operation changed from the mode-locking to the Q-switched mode-locking regime.

  18. A precise length etalon generator controlled by femtosecond mode-locked laser

    Science.gov (United States)

    Šmid, Radek; Čip, Ondřej; Lazar, Josef

    2007-09-01

    The progress in the field of optical frequency standards is oriented to femtosecond mode-locked lasers stabilized by technique of the optical frequency synthesis. Such a laser produces a supercontinuum light, which is composed of a cluster of coherent frequency components in certain interval of wavelengths. A value of the repetition rate of femtosecond pulses determines (in the frequency domain) spacing of these coherent components. If we control the mode-locked laser by means of i.e. atomic clocks we ensure frequency of these components very stable. With respect to definition of SI unit "one meter" on basis of speed of light the stabilized mode-locked laser can be used for implementation of this definition by non-traditional way. In the work we present our proposal of a system, which converts excellent frequency stability of components generated by the mode-locked laser to a net of discrete absolute lengths represented by a distance of two mirrors of an optical resonator. On basis of theory, the optical resonator with a cavity length has a periodic frequency spectrum Similarly the frequency of i-th comb component could be written as: f i = f ceo + i f rep, where f ceo is the comb offset frequency and f rep is the repetition rate. For the simplicity we presume the offset frequency f ceo equals to zero. If the supercontinuum beam of the mode-locked laser illuminates the resonator and at the same time the cavity length L is adjusted to length L p = c / (2 p f rep ) then both spectra fit. The symbol 'p' is an integer value. It produces intensity maximum in the output of the cavity, which is detected by a photodetector and locked in the servo-loop. For absolute discrete values of cavity lengths L p that well satisfy the condition above we obtain precise etalons of length.

  19. LOW-Tg Bismuth Phosphate Glasses for Glass-Imprinting and Fabrication of 2d Sub-Wavelength Structure

    Science.gov (United States)

    Kitamura, Naoyuki; Fukumi, Kohei; Nakamura, Junichi; Hidaka, Tatsuo; Ikeda, Takurou; Hashima, Hidekazu; Nishii, Junji

    We have developed zinc-bismuth-phosphate glasses, which have deformation temperatures under 450°C and refractive indices higher than 1.7, in order to produce an antireflection structure on the surface by a glass-imprinting process. Two-dimensionally arrayed conical cavities of sub-wavelength size were fabricated on a SiC mold by electron lithography and dry etching techniques. The sub-wavelength periodic structure was transferred onto the glass surface by a glass-imprinting process using the mold. The sub-wavelength structure suppressed the reflectance by approximately 90%. A weak maximum was observed in the reflection spectra around 400-500 nm, which decreased in intensity and shifted toward shorter wavelengths with decreasing pitch.

  20. Biological performance of titania containing phosphate-based glasses for bone tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Abou Neel, Ensanya Ali, E-mail: eabouneel@kau.edu.sa [Division of Biomaterials, Conservative Dental Sciences Department, King Abdulaziz University, Jeddah (Saudi Arabia); Biomaterials Department, Faculty of Dentistry, Tanta University, Tanta (Egypt); Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, 256 Gray' s Inn Road, London WC1X 8LD (United Kingdom); Chrzanowski, Wojciech [The University of Sydney, Faculty of Pharmacy, Pharmacy and Bank Building, NSW2006 (Australia); Department of Nanobiomedical Science and BK21 Plus NBM Global Reserch Center for Regenerative Medicine, Dankook University, Cheonan 330-714 (Korea, Republic of); Knowles, Jonathan Campbell, E-mail: j.knowles@ucl.ac.uk [Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, 256 Gray' s Inn Road, London WC1X 8LD (United Kingdom); Department of Nanobiomedical Science and BK21 Plus NBM Global Reserch Center for Regenerative Medicine, Dankook University, Cheonan 330-714 (Korea, Republic of)

    2014-02-01

    The interplay between glass chemistry, structure, degradation kinetics, and biological activity provides flexibility for the development of scaffolds with highly specific cellular response. The aim of this study was therefore to investigate the role of titania inclusion into the phosphate-based glass on its ability to stimulate osteoblast-like human osteosarcoma (HOS) cells to adhere, proliferate and differentiate. In depth morphological and biochemical characterisation was performed on HOS cells cultured on the surface of glass discs. Cell proliferation was also studied in the presence of the glass extract. Cell differentiation, through osteoblast phenotype genes, alkaline phosphatase (ALP) activity and osteocalcin production, was carried out using normal or osteogenic media. Both Thermanox® and titania free glass were used as controls. The data demonstrated that titania inclusion provides desired cytocompatible surface that supported initial cell attachment, sustained viability, and increased cell proliferation similar or significantly higher than Thermanox®. The modified glasses regulated osteoblastic cell differentiation as detected by osteoblast phenotype gene transcription and upregulated ALP and osteocalcin expression. Using osteogenic media had no significant effect on ALP activity and osteocalcin expression. Therefore, titania modified phosphate glasses may have future use as bone tissue engineering scaffolds. - Highlights: • This study investigated the role of titania on the biological response of phosphate glasses. • Incorporation of titania improved HOS cell attachment, viability and proliferation. • Titania modified glasses regulated osteoblastic cell differentiation. • Using osteogenic media had no significant effect on cell differentiation. • Titania modified glasses may have future use as bone tissue engineering scaffolds.

  1. Calcium phosphates and glass composite coatings on zirconia for enhanced biocompatibility.

    Science.gov (United States)

    Kim, Hae-Won; Georgiou, George; Knowles, Jonathan C; Koh, Young-Hag; Kim, Hyoun-Ee

    2004-08-01

    Calcium phosphates (CaP) and phosphate-based glass (P-glass, xCaO-(0.55-x) Na(2)O-0.45P(2)O(5) composition) composite coatings were obtained on a strong ZrO(2) to improve biocompatibility, the mechanical strength and biological activity. Hydroxyapatite (HA) and P-glass mixed powder slurries were coated on the ZrO(2) substrate, and subsequently heat-treated to obtain CaP- and P-glass composite coatings. The effects of glass composition (x=0.3, 0.4, 0.5 mol), mixing ratio of glass to HA (30%, 40%, 50% wt/wt), and heat treatment temperature (800 degrees C, 900 degrees C, 1000 degrees C) on the coating properties were investigated. After heat treatment, additional calcium phosphates, i.e., dicalcium phosphate (DCP) and tricalcium phosphate (TCP), were crystallized, resulting in the formation of triphasic calcium phosphates (HA-TCP-DCP) surrounded by a glass phase. The relative amounts of the crystalline phases varied with coating variables. The higher heat treatment temperature and glass amount, and the lower CaO content in the glass composition rendered the composite coatings to retain the higher amounts of TCP and DCP while the initial HA decreased. These appearance of additional crystalline phases and reduction of HA amount were attributed to the combined effects, i.e., the melting-crystallization of P-glass and the reaction between glass liquid phase and HA powder during thermal treatment. As a result of the glass phase in the composite coatings, their microstructures became much denser when compared to the pure HA coating. In particular, a completely dense structure was obtained at coating conditions with large amount of glass addition (50 wt%) at the glass composition of lower CaO content (0.3 mol CaO), and the following heat treatment above 800 degrees C for 2h. As a result, the adhesion strengths of the composite coating layers were significantly improved when compared to the pure HA coating. The highest strength of the composite coating was approximately 40

  2. Structure and transport investigations on lithium-iron-phosphate glasses

    Science.gov (United States)

    Banday, Azeem; Sharma, Monika; Murugavel, Sevi

    2016-05-01

    Cathode materials for Lithium Ion Batteries (LIB's) are being constantly studied and reviewed especially in the past few decades. LiFePO4 (LFP) is one of the most potential candidates in the pedigree of cathode materials and has been under extensive study ever since. In this work, we report the synthesis of amorphous analogs of crystallite LFP by conventional melt quenching method. Thermal study by using differential scanning calorimetry (DSC) was used to determine the glass transition Tg and crystallization Tc temperatures on the obtained glass sample Fourier transform infrared (FTIR) absorption spectroscopy is being used to investigate the structural properties of the glass sample. The intrinsic electrical conductivity measurements were done using broad-band impedance spectroscopy with wide different temperature ranges. The conduction mechanism is described by non-adiabatic small polaron hopping between nearest neighbors. Based on the obtained results, we suggest that the glassy LFP is more suitable cathode material as compared to its crystalline counterpart.

  3. The effect of phosphate based glasses on the formation and viability of oral bacterial biofilms

    Science.gov (United States)

    Mulligan, April Miranda

    This study considered the antibacterial activity of a series of soluble phosphate-based glasses (based on the Na2O-CaO-P2O5 glass system) doped with increasing amounts of copper or silver against oral bacterial biofilms. Initially, a variety of phosphate-based glass compositions were produced. The dissolution rate of these glasses was determined, and the information obtained was used to decide which glass compositions would be investigated in future experiments for their antibacterial properties. Selected glass compositions were investigated for their antibacterial activity against Streptococcus sanguis biofilms and oral microcosm biofilms. These biofilms were produced on phosphate-based glass discs using a Constant Depth Film Fermenter (CDFF), which allows the conditions found in the oral cavity to be closely mimicked. Following disc removal from the CDFF, various analytical procedures were carried out. Under conditions designed to mimic the supragingival environment of the oral cavity, fewer viable cells of Streptococcus sanguis were detected on both copper and silver-containing glass discs than on control discs, during the initial stages of the experiments, the greatest reduction occurring on the silver-containing glasses. An increase in viable cell number was observed as the experiments continued. Under the same conditions, copper-containing glasses failed to reduce the viability of microcosm biofilms. Viable cell number was initially reduced on the silver-containing glasses, but by the end of the experiments the viability of microcosm biofilms was significantly similar to those observed on the controls. Attempts to determine the efficacy of silver-containing glasses at reducing the viability of microcosm biofilms, under conditions designed to mimic the subgingival environment of the oral cavity, were subsequently made. Viable cells were not detected on any type of disc, including the control discs. Various reasons for this were postulated. In conclusion, the

  4. Luminescence performance of Eu$^{3+}-doped lead-free zinc phosphate glasses for red emission

    Indian Academy of Sciences (India)

    Y C RATNAKARAM; V REDDY PRASAD; S BABU; V V RAVI KANTH KUMAR

    2016-08-01

    In this study, the luminescence performance of zinc phosphate glasses containing Eu$^{3+}$ ion with the chemical compositions $(60–x)NH_4H_2PO_4-20ZnO-10BaF_2-10NaF–x$ Eu$_2$O$_3$ (where $x = 0.2, 0.5, 1.0$ and 1.5 mol%) has been studied. These glasses were characterized by several spectroscopic techniques at room temperature. Allthe glasses showed relatively broad fluorescence excitation and luminescence spectra. Luminescence spectra of these glasses exhibit characteristic emission of Eu$^{3+}$ ion with an intense and most prominent red emission (614 nm), which is attributed to ${}^5$D$_0\\to {}^{7}$F$_2$ transition. Judd-Ofelt ($\\Omega_2$, $\\Omega_4$) parameters have been evaluated from the luminescence intensity ratios of ${}^5$D$_0\\to {}^{7}$F$_J$ (where $J = 2$ and 4) to ${}^5$D$_0\\to {}^{7}$F$_1$ transition. Using J-O parameters and excitationspectra, the radiative parameters are calculated for different Eu$^{3+}-doped glasses. Effect of $\\gamma$-irradiation at fixed dose has been studied for all the Eu$^{3+}$-doped glass matrices. The lifetimes of the excited level, ${}^{5}D$_0$, have been measured experimentally through decay profiles. The colour chromaticity coordinates are calculated and represented in the chromaticity diagram for Eu$^{3+}$-doped zinc phosphate glasses for all concentrations.

  5. Spectroscopic characterization of manganese-doped alkaline earth lead zinc phosphate glasses

    Indian Academy of Sciences (India)

    S Sreehari Sastry; B Rupa Venkateswara Rao

    2015-04-01

    Alkaline earth lead zinc phosphate glasses doped with Mn(II) are characterized by spectroscopic techniques like X-ray diffraction (XRD), UV–visible, differential scanning calorimetry (DSC), electron paramagnetic resonance (EPR), Fourier transform infrared (FTIR) and Raman. Optical absorption spectrum exhibits four bands which are characteristic of Mn(II) in distorted octahedral site symmetry. The crystal field parameter Dq and Racah interelectronic-repulsion parameters and have been evaluated. All investigated samples exhibit EPR signals which are characteristic to the Mn2+ ions. The shapes of spectra are also changed with varying alkaline earth ions content. FTIR spectra show specific vibrations of phosphate units. The characteristic Raman bands of these glasses due to stretching and bending vibrations were identified and analysed by varying alkaline earth content. The intensity and frequency variations for the characteristic phosphate group vibrations have been correlated with the changes of the structural units present in these glasses. Depolymerization of the phosphate chains in all the glasses is observed with replacement of alkaline earth content by spectroscopic studies. This leads to a strong decrease of the average chain length and a small decrease of the average P–O–P bridging angle with replacement of alkaline earth content.

  6. Wideband Erbium-Ytterbium Co-Doped Phosphate Glass Waveguide Amplifier

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new '(?)' type of wideband erbium-ytterbium co-doped phosphate glass waveguide amplifier integrated with medium thin film filter is proposed, Average gain about 15.5dB between 1530nm and 1570nm with gain difference of below 2 dB is obtained.

  7. Optical bistability in Er-Yb codoped phosphate glass microspheres at room temperature

    NARCIS (Netherlands)

    Warda, Jonathan M.; O'Shea, Danny G.; Shortt, Brian J.; Chormaic, Sile Nic

    2007-01-01

    We experimentally demonstrate optical bistability in Er(3+)-Yb(3+) phosphate glass microspheres at 295 K. Bistability is associated with both Er(3+) fluorescence and lasing behavior, and chromatic switching. The chromatic switching results from an intrinsic mechanism exploiting the thermal coupling

  8. Modeling of excimer laser radiation induced defect generation in fluoride phosphate glasses

    Science.gov (United States)

    Natura, U.; Ehrt, D.

    2001-03-01

    Fluoride phosphate (FP) glasses with low phosphate content are high-transparent in the deep ultraviolet (UV) range and attractive candidates for UV-optics. Their optical properties are complementary to fluoride crystals. The anomalous partial dispersion makes them desirable for optical lens designs to reduce the secondary spectrum. Their UV transmission is limited by trace impurities introduced by raw materials and decreases when exposed to UV-radiation (lamps, lasers). The experiments of the paper published previously in this journal were used in order to separate radiation induced absorption bands in the fluoride phosphate glass FP10. In this paper the generation mechanism of the phosphorus-oxygen related hole center POHC 2 is investigated in detail in glasses of various compositions (various phosphate and impurity contents) in order to predict the transmission loss in case of long-time irradiation. Experiments were carried out using ArF- and KrF-excimer lasers (ns-pulses). POHC 2 generation strongly depends on the phosphate content and on the content of Pb 2+. A model was developed on these terms. Rate equations are formulated, incorporating the influence of the Pb 2+-content on the defect generation, a two-step creation term including an energy transfer process and a one-photon bleaching term. This results in a set of coupled nonlinear differential equations. Absorption coefficients and lifetimes of the excited states were calculated as well. Experimental results compared well with the numerical analysis of the theoretical rate equations.

  9. Recent advances in phosphate laser glasses for high power applications. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.H.

    1996-05-01

    Recent advances in Nd-doped phosphate laser glasses for high-peak-power and high-average-power applications are reviewed. Compositional studies have progressed to the point that glasses can be tailored to have specific properties for specific applications. Non-radiative relaxation effects can be accurately modeled and empirical expressions have been developed to evaluate both intrinsic (structural) and extrinsic (contamination induced) relaxation effects. Losses due to surface scattering and bulk glass absorption have been carefully measured and can be accurately predicted. Improvements in processing have lead to high damage threshold (e.g. Pt inclusion free) and high thermal shock resistant glasses with improved edge claddings. High optical quality pieces up to 79 x 45 x 4 cm{sup 3} have been made and methods for continuous melting laser glass are under development.

  10. Low-temperature anodic bonding using thin films of lithium-niobate-phosphate glass

    Science.gov (United States)

    Woetzel, S.; Kessler, E.; Diegel, M.; Schultze, V.; Meyer, H.-G.

    2014-09-01

    This paper reports on the investigation of a low-temperature anodic bonding process with layers of a lithium-niobate-phosphate glass on chip level. The glass layers are deposited by means of rf sputtering. The applied glass is characterised by its high ion conductivity, enabling anodic bonding at room temperature. Results of the optimisation process concerning the intrinsic stress of the glass layers and the thermal exposure of the substrates through the deposition process are presented. The stoichiometry of the glass layers is verified through Rutherford backscattering spectroscopy (RBS). The bonding strength is measured by tensile tests. Microfabricated atomic vapour cells are used for hermeticity tests of the bonding by absorption measurements of the caesium D1 line.

  11. Preparation and optical spectroscopy of phosphate glasses containing divalent europium ions

    Institute of Scientific and Technical Information of China (English)

    Haiping Xia(夏海平); Hongwei Song(宋宏伟); Qiuhua Nie(聂秋华); Jianli Zhang(章践立); Jinhao Wang(王金浩); Jiwei Wang(王绩伟); Tiefeng Xu(徐铁峰); Jiaha Zhang(张家骅)

    2003-01-01

    P2O5.BaO.Na2O.K2O glasses doped with various content of Eu2O3 were prepared using high temperaturemelting method, and the Eu 2+ ions in the phosphate glasses were obtained with the aid of the reductiveaction of silicon powder. The fabricating conditions, fluorescence, excitation spectra of the glasses werethen studied. The glasses containing europium show a broad emission band at 450 nm and sharp bandsfrom 580 to 650 nm, and the co-existence of Eu2+ and Eu3+ is identified. Also, a good glass with adominant proportion and large quantity of Eu2+ ions can be obtained by the reductive action of siliconpowder and proper processing.

  12. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    Science.gov (United States)

    Sastry, S. Sreehari; Rao, B. Rupa Venkateswara

    2014-02-01

    In this paper spectroscopic investigation of Cu2+ doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR - X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu2+ state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu2+ is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P-O-P bonds and creating more number of new P-O-Cu bonds.

  13. Spectroscopic studies of copper doped alkaline earth lead zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, S. Sreehari, E-mail: sreeharisastry@yahoo.com [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Rao, B. Rupa Venkateswara [Department of Physics, Acharya Nagarjuna University, Nagarjunanagar 522510 (India); Department of Physics, V.R. Siddhartha Engineering College, Vijayawada 52007 (India)

    2014-02-01

    In this paper spectroscopic investigation of Cu{sup 2+} doped alkaline earth lead zinc phosphate glasses was done through the spectroscopic techniques like X-ray diffraction, Ultra Violet (UV) absorption Spectroscopy, Electron Paramagnetic Resonance (EPR – X band), Fourier Transform Infra Red (FTIR) and Raman Spectroscopy. Alkaline earth lead zinc phosphate glasses containing 0.1% copper oxide (CuO) were prepared by the melt quenching technique. Spectroscopic studies indicated that there is a greater possibility for the copper ions to exist in Cu{sup 2+} state in these glasses. The optical absorption spectra indicated that the absorption peak of Cu{sup 2+} is a function of composition. The maxima absorption peak was reported at 862 nm for strontium lead zinc phosphate glass. Bonding parameters were calculated for the optical and EPR data. All these spectral results indicated clearly that there are certain structural changes in the present glass system with different alkaline earth contents. The IR and Raman spectra noticed the breaking of the P–O–P bonds and creating more number of new P–O–Cu bonds.

  14. Dynamics of a Dispersion-Managed Passively Mode-Locked Er-Doped Fiber Laser Using Single Wall Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Norihiko Nishizawa

    2015-07-01

    Full Text Available We investigated the dynamics of a dispersion-managed, passively mode-locked, ultrashort-pulse, Er-doped fiber laser using a single-wall carbon nanotube (SWNT device. A numerical model was constructed for analysis of the SWNT fiber laser. The initial process of passive mode-locking, the characteristics of the output pulse, and the dynamics inside the cavity were investigated numerically for soliton, dissipative-soliton, and stretched-pulse mode-locking conditions. The dependencies on the total dispersion and recovery time of the SWNTs were also examined. Numerical results showed similar behavior to experimental results.

  15. Compact and high repetition rate Kerr-lens mode-locked 532 nm Nd:YVO4 laser

    Science.gov (United States)

    Li, Zuohan; Peng, Jiying; Yuan, Ruixia; Wang, Tongtong; Yao, Jianquan; Zheng, Yi

    2015-11-01

    A compact and feasible CW Kerr-lens-induced mode-locked 532 nm Nd:YVO4 laser system was experimentally demonstrated for the first time with theoretical analysis. Kerr-lens mode locking with intracavity second harmonic generation provides a promising method to generate a high-repetition-rate picosecond green laser. With an incident pump power of 6 W, the average output power of mode locking was 258 mW at a high repetition rate of 1.1 GHz.

  16. Theory of the ultrafast mode-locked GaN lasers in a large-signal regime

    CERN Document Server

    Smetanin, Igor V; Boiko, Dmitri L

    2011-01-01

    Analytical theory of the high-power passively mode-locked laser with a slow absorber is developed. In distinguishing from previous treatment, our model is valid at pulse energies well exceeding the saturation energy of absorber. This is achieved by solving the mode-locking master equation in the pulse energy-domain representation. The performances of monolithic sub-picosecond blue-violet GaN mode-locked diode laser in the high-power operation regime are analyzed using the developed approach.

  17. Tunable and switchable dual-wavelength Tm-doped mode-locked fiber laser by nonlinear polarization evolution.

    Science.gov (United States)

    Yan, Zhiyu; Li, Xiaohui; Tang, Yulong; Shum, Perry Ping; Yu, Xia; Zhang, Ying; Wang, Qi Jie

    2015-02-23

    We propose and demonstrate a tunable and switchable dual-wavelength ultra-fast Tm-doped fiber laser. The tunability is based on nonlinear polarization evolution (NPE) technique in a passively mode-locked laser cavity. The NPE effect induces wavelength-dependent loss in the cavity to effectively alleviate mode competition and enables the multiwavelength mode locking. The laser exhibits tunable dual-wavelength mode locking over a wide range from 1852 to 1886 nm. The system has compact structure and both the wavelength tuning and switching capabilities can be realized by controlling the polarization in the fiber ring cavity.

  18. High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large Tunability

    Directory of Open Access Journals (Sweden)

    Andreas Schmitt-Sody

    2008-01-01

    Full Text Available We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature.

  19. Self-stabilized and dispersion-compensated passively mode-locked Yb:Yttrium aluminum garnet laser

    Science.gov (United States)

    Agnesi, A.; Guandalini, A.; Reali, G.

    2005-04-01

    Self-stabilized passive mode-locking of a diode-pumped Yb:yttrium aluminum garnet laser with a semiconductor saturable absorber was achieved using an off-phase-matching second-harmonic crystal. According to the numerical model, such a condition is accomplished by self-defocusing in the nonlinear crystal in the presence of positive intracavity dispersion. Robust mode locking with Fourier-limited 1.0-ps pulses was obtained, whereas mode locking, unassisted by the nonlinear crystal, yielded 2.2-ps pulses, with the laser operating near the edge of the stability region in order to minimize the saturation energy of the semiconductor device.

  20. Experiment Study on Active-passive Mode-locking Using Cr4+∶YAG as Saturable Absorber

    Institute of Scientific and Technical Information of China (English)

    LENG Yuxin; LU Haihe; LIN Lihuang; XU Zhizhan

    2002-01-01

    Cr4+∶YAG crystal was used as a saturable absorber in an active-passive mode-locked Nd∶YAG laser. The stable and complete mode-locked pulse train was achieved at 1064 nm. The duration of ~0.8 ns to 2.4 ns for a single pulse was obtained by using Cr4+∶YAG crystals with the different initial transmissions, and there was a shortest pulse width. The mode-locking dynamic process of Cr4+∶YAG crystal was discussed to explain the experimental result, and the effect of excited-state absorption was considered.

  1. Mode-locking based on a zero-area pulse formation in a laser with a coherent absorber

    CERN Document Server

    Arkhipov, Mikhail V; Kalinichev, Alexey A; Babuskin, Ihar; Rosanov, Nikolai N; Arkhipov, Rostislav M

    2016-01-01

    We observe experimentally a mode-locking in a continuous narrow-band tunable dye laser with molecular iodine absorber cells, which transitions have large phase relaxation time T2. We show that the mode-locking arises due to coherent interaction of light with the absorbing medium leading to Rabi oscillations, so that zero-area (0{\\pi}-) pulses in the absorber are formed. Such mode-locking regime is different to most typical passive modelocking mechanisms where saturation plays the main role.

  2. Fabrication and Characterisation of Low-noise Monolithic Mode-locked Lasers

    DEFF Research Database (Denmark)

    Larsson, David

    2007-01-01

    This thesis deals with the fabrication and characterisation of monolithic semiconductor mode-locked lasers for use in optical communication systems. Other foreseeable applications may be as sources in microwave photonics and optical sampling. The thesis also deals with the design and fabrication...... of intracavity monolithically integrated filters. The common dnominator among the diffrent parts of the thesis is how to achieve and measure the lowest possible noise. Achieving low noise has been pinpointed as one of the most important and difficult challenges for semiconductor mode-locked lasers. The main...... result of this thesis are a fabrication process of a monolithic and deeply etched distributed Bragg reflector and a characterisation system for measurement of quantum limitid timing noise at high repetition rates. The Bragg reflector is a key component in achieving transform limited pulses with low noise...

  3. Hybrid mode-locked fiber ring laser using graphene and charcoal nanoparticles as saturable absorbers

    Science.gov (United States)

    Hu, Hongyu; Zhang, Xiang; Li, Wenbo; Dutta, Niloy K.

    2016-05-01

    A fiber ring laser which implements hybrid mode locking technique has been proposed and experimentally demonstrated to generate pulse train at 20 GHz repetition rate with ultrashort pulse width. Graphene and charcoal nano-particles acting as passive mode lockers are inserted into a rational harmonic mode-locked fiber laser to improve the performance. With graphene saturable absorbers, the pulse duration is shortened from 5.3 ps to 2.8 ps, and with charcoal nano-particles, it is shortened to 3.2 ps. The RF spectra show that supermode noise can be removed in the presence of the saturable absorbers. Numerical simulation of the pulse transmission has also been carried out, which shows good agreement with the experimental results.

  4. Long-term stable microwave signal extraction from mode-locked lasers

    Science.gov (United States)

    Kim, J.; Ludwig, F.; Felber, M.; Kärtner, F. X.

    2007-07-01

    Long-term synchronization between two 10.225 GHz microwave signals at +10 dBm power level, locked to a 44.26 MHz repetition rate passively mode-locked fiber laser, is demonstrated using balanced optical-microwave phase detectors. The out-of-loop measurement result shows 12.8 fs relative timing jitter integrated from 10 Hz to 10 MHz. Long-term timing drift measurement shows 48 fs maximum deviation over one hour, mainly limited by drift of the out-of-loop characterization setup itself. To the best of our knowledge, this is the first time to demonstrate long-term (>1 hour) 3 mrad-level phase stability of a 10.225 GHz microwave signal extracted from a mode-locked laser.

  5. Mode-locking external-cavity laser-diode sensor for displacement measurements of technical surfaces

    Science.gov (United States)

    Czarske, Jürgen; Möbius, Jasper; Moldenhauer, Karsten

    2005-09-01

    A novel laser sensor for position measurements of technical solid-state surfaces is proposed. An external Fabry-Perot laser cavity is assembled by use of an antireflection-coated laser diode together with the technical surface. Mode locking results from pumping the laser diode synchronously to the mode spacing of the cavity. The laser cavity length, i.e., the distance to the measurement object, is determined by evaluation of the modulation transfer function of the cavity by means of a phase-locked loop. The mode-locking external-cavity laser sensor incorporates a resonance effect that results in highly resolving position and displacement measurements. More than a factor-of-10 higher resolution than with conventional nonresonant sensing principles is achieved. Results of the displacement measurements of various technical surfaces are reported. Experimental and theoretical investigations are in good agreement.

  6. Experimental investigation of relaxation oscillations resonance in mode-locked Fabry-Perot semiconductor lasers

    CERN Document Server

    Roncin, Vincent; Hayau, Jean-François; Besnard, Pascal; Simon, Jean-Claude; Van Dijk, F; Shen, Alexandre; Duan, Guang-Hua

    2014-01-01

    We propose in this communication an experimental study of the relaxation oscillations behavior in mode-locked lasers. The semiconductor self-pulsating laser diode is composed by two gain sections, without saturable absorber. It is made of bulk structure and designed for optical telecommunication applications. This specific device allows two different regimes of optical modulation: the first one corresponds to the resonance of the relaxation oscillations and the second one, to the mode-locking regime at FSR value. This singular behavior leads us to characterize the self-pulsations which are coexisting in the laser and to describe two regimes of output modulation: the first one appears thanks to the resonance of the oscillation relaxation and the other one corresponds to the FSR of the Fabry-Perot laser at 40 GHz.

  7. Magneto-optic Crystal Polarization Controller Assisted Mode-Locked Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guang-Zhen; GUI Li-Li; XIAO Xiao-Sheng; YANG Chang-Xi

    2011-01-01

    We report a passively mode-locked erbium-doped fiber laser based on a compact magneto-optic crystal polarization controller. The length of the polarization controller consisting of four magneto-optic crystal rotators and two quarter wave-plates is only 10cm.Adjusting the polarization controller, central wavelength around 1559nm and repetition rate 21.10 MHz mode-locked pulse are obtained. Pulse duration and 3 dB spectrum width are 598.4fs and 6.24nm respectively. Single pulse energy is about 151.7pJ. Because of its small size, low insertion loss,good controllability and negligible dispersion, the magneto-optic crystal polarization controller could be an ideal polarization controller in fiber lasers.

  8. Q-switched and Mode-locked Characteristics of Cr4+:YAG Crystal

    Institute of Scientific and Technical Information of China (English)

    TIAN Wen-miao; YANG Feng; GAO Li-yan; WANG Guang-gang; LIU Shi-hua; LIU Jie

    2006-01-01

    The passively Q-switched and mode-locked(QML) characteristics in a diode-pumped Nd:GdVO4 laser with Cr4+:YAG saturable absorbers have been demonstrated. A maximum average output power of 710 mW has been obtained in the QML laser. The maximum energy of a single Q-switched pulse is 52.5 μJ,with the corresponding pulse width of 30 ns and the peak power of 1.75 kW,at the incident pump power of 7.75 W. The repetition rates of the Q-switched envelope and the mode-locked laser pulse are 16.7 kHz and 680 MHz,respectively.

  9. A novel numerical model for passively mode-locked solid-state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Leitner, A.; Aussenegg, F.; Lippitsch, M.; Roschger, E.

    1983-04-01

    Numerical computer models could be of high value in testing ideas for improving passive mode locking. Most of the known models for solid-state lasers lack realistic quantitative results, however. A new model is presented, using a rate-equation approach which has been refined to include interference effects by using field amplitudes and phases instead of energies. Also, the saturable absorber is treated by rate equations. With this model, a rather complete description of the pulse evolution is possible. The influence of various parameters on the mode-locking quality is calculated. The model is also capable of reliably describing processes based mainly on interference effects, like the action of external subresonators.

  10. Attosecond-resolution timing jitter characterization of free-running mode-locked lasers.

    Science.gov (United States)

    Kim, Jungwon; Chen, Jeff; Cox, Jonathan; Kärtner, Franz X

    2007-12-15

    Timing jitter characterization of optical pulse trains from free-running mode-locked lasers with attosecond resolution is demonstrated using balanced optical cross correlation in the timing detector and the timing delay configurations. In the timing detector configuration, the balanced cross correlation between two mode-locked lasers synchronized by a low-bandwidth phase-locked loop is used to measure the timing jitter spectral density outside the locking bandwidth. In addition, the timing delay configuration using a 325 m long timing-stabilized fiber link enables the characterization of timing jitter faster than the delay time. The limitation set by shot noise in this configuration is 2.2 x 10(-8) fs(2)/Hz corresponding to 470 as in 10 MHz bandwidth.

  11. Observation of soliton explosions in a passively mode-locked fiber laser

    CERN Document Server

    Runge, Antoine F J; Erkintalo, Miro

    2014-01-01

    Soliton explosions are among the most exotic dissipative phenomena studied in mode-locked lasers. In this regime, a dissipative soliton circulating in the laser cavity experiences an abrupt structural collapse, but within a few roundtrips returns to its original quasi-stable state. In this work we report on the first observation of such events in a fiber laser. Specifically, we identify clear explosion signatures in measurements of shot-to-shot spectra of an Yb-doped mode-locked fiber laser that is operating in a transition regime between stable and noise-like emission. The comparatively long, all-normal-dispersion cavity used in our experiments also permits direct time-domain measurements, and we show that the explosions manifest themselves as abrupt temporal shifts in the output pulse train. Our experimental results are in good agreement with realistic numerical simulations based on an iterative cavity map.

  12. Study Pulse Parameters versus Cavity Length for Both Dispersion Regimes in FM Mode Locked

    Directory of Open Access Journals (Sweden)

    Bushra Razooky Mhdi

    2015-03-01

    Full Text Available To demonstrate the effect of changing cavity length for  FM mode locked on pulse parameters and make comparison for both dispersion regime , a plot for each pulse parameter as Lr function are presented for normal and anomalous dispersion regimes. The analysis is based on the theoretical study and the results of numerical simulation using MATLAB. The effect of both normal and anomalous dispersion regimes on output pulses is investigate Fiber length effects on pulse parameters are investigated by driving the modulator into different values. A numerical solution for model equations using fourth-fifth order, Runge-Kutta method is performed through MATLAB 7.0 program. Fiber length effect on pulse parameters is investigated by driving the modulator into different values of lengths. Result shows that, the output pulse width from the FM mode locked equals to τ= 501ns anomalous regime and τ=518ns in normal regime.

  13. $CO_{2}$ laser ion source Comparison between mode-locked and free- running laser beams

    CERN Document Server

    Lisi, N; Scrivens, R

    2001-01-01

    The production of highly charged ions in a CO/sub 2/ laser-generated plasma is compared for different laser pulse-time structures. The work was performed at the CERN Laser Ion Source, which has the aim of developing a high current, high charge-state ion source for the Large Hadron Collider (LHC). When an intense laser pulse is focused onto a high-Z metal target, the ions expanding in the plasma plume are suitable for extraction from the plasma and matching into a synchrotron. For the first time, a comparison is made between free- running pulses with randomly fluctuating intensity, and mode-locked pulse trains with a reproducible structure and the same energy. Despite the lower power density with respect to the mode-locked pulse train, the free-running pulse provides higher charge states and higher yield. (10 refs).

  14. Pulse Evolution Characteristics in Self-Similar Mode-locked Fibre Laser

    Institute of Scientific and Technical Information of China (English)

    TU Cheng-Hou; LI Zhen; LEI Ting; LI Yong-Nan; GUO Wen-Gang; WEI Dai; ZHU Hui; ZHANG Shuang-Gen; LU Fu-Yun

    2007-01-01

    A self-similar mode locked fibre laser is studied based on a numerical model. By introducing a dimensionless factor k to characterize the pulse shape, the self-similar pulse evolution, formation and the temporal and spectral shape changes due to the elements in the cavity are investigated throughout the iaser cavity. The results show that in the self-similar mode locked fibre laser, self-similar pulse is first formed in the single-mode fibre, which is then amplified in the gain fibre. Gain bandwidth has a small influence on pulse shape, so high energy self-similar pulse can be obtained after amplification. Because net cavity dispersion directly influences the pulse width as well as peak power after compression by a pair of gratings, which can determine the pulse self-similar evolution, it is very important to control the net cavity dispersion to a certain range to obtain self-similar pulses.

  15. In-volume waveguides by fs-laser direct writing in rare-earth-doped fluoride glass and phosphate glass

    Science.gov (United States)

    Esser, D.; Wortmann, D.; Gottmann, J.

    2009-02-01

    Refractive index modifications are fabricated in the volume of rare-earth-doped glass materials namely Er- and Pr-doped ZBLAN (a fluoride glass consisting of ZrF4, BaF2, LaF3, AlF3, NaF), an Er-doped nano-crystalline glass-ceramic and Yb- and Er-doped phosphate glass IOG. Femtosecond laser radiation (τ=500fs, λ=1045nm, f=0.1-5MHz) from an Ybfiber laser is focused with a microscope objective in the volume of the glass materials and scanned below the surface with different scan velocities and pulse energies. Non-linear absorption processes like multiphoton- and avalanche absorption lead to localized density changes and the formation of color centers. The refractive index change is localized to the focal volume of the laser radiation and therefore, a precise control of the modified volume is possible. The width of the written structures is analyzed by transmission light microscopy and additionally with the quantitative phase microscopy (QPm) software to determine the refractive index distribution perpendicular to a waveguide. Structures larger than 50μm in width are generated at high repetition rates due to heat accumulation effects. In addition, the fabricated waveguides are investigated by far-field measurements of the guided light to determine their numerical apertures. Using interference microscopy the refractive index distribution of waveguide cross-sections in phosphate glass IOG is determined. Several regions with an alternating refractive index change are observed whose size depend on the applied pulse energies and scan velocities.

  16. Melting and freezing of light pulses and modes in mode-locked lasers.

    Science.gov (United States)

    Gordon, Ariel; Vodonos, Boris; Smulakovski, Vladimir; Fischer, Baruch

    2003-12-15

    We present a first experimental demonstration of melting of light pulses and freezing of lightwave modes by applying external noise which acts like temperature, verifying our recent theoretical prediction (Gordon and Fischer [1]). The experiment was performed in a fiber laser passively mode-locked by nonlinear rotation of polarization. The first order phase transition was observed directly in time domain and also by measurement of the quartic order parameter (RF power).

  17. Diode-pumped Yb,Y:CaF2 laser mode-locked by monolayer graphene

    Science.gov (United States)

    Zhu, Hongtong; Liu, Jie; Jiang, Shouzhen; Xu, Shicai; Su, Liangbi; Jiang, Dapeng; Qian, Xiaobo; Xu, Jun

    2015-12-01

    The large-area and high-quality monolayer graphene saturable absorber with a sandwich structure is prepared by the chemical vapor deposition technique. Using graphene saturable absorber, the mode locking operation of a diode-pumped Yb,Y:CaF2 laser is demonstrated. Without extra negative dispersion elements, 4.8 ps pulses are yielded at 1051 nm. The pulse repetition rate is 60 MHz.

  18. Wavelength and duration tunable soliton generation from a regeneratively mode-locked fiber laser

    Institute of Scientific and Technical Information of China (English)

    Bin Tan(谈斌); Zhiyong Li(李智勇); Zhaoying Wang(王肇颖); Chunfeng Ge(葛春风); Dongfang Jia(贾东方); Wenjun Ni(倪文俊); Shichen Li(李世忱)

    2004-01-01

    A 10-GHz soliton source with pulse duration between 4-8 ps and wavelength continuously tunable from 1530 to 1563 nm is presented. Using regeneratively mode-locking technology, the harmonically modelocked fiber ring laser could work without pulse dropout at room temperature when no cavity length or polarization maintaining mechanism is available. Applying only one 980-nm laser diode pump, the average output power reaches more than 4 mW.

  19. A stable, power scaling, graphene-mode-locked all-fiber oscillator

    Science.gov (United States)

    Popa, D.; Jiang, Z.; Bonacchini, G. E.; Zhao, Z.; Lombardi, L.; Torrisi, F.; Ott, A. K.; Lidorikis, E.; Ferrari, A. C.

    2017-06-01

    We report power tunability in a fiber laser mode-locked with a solution-processed filtered graphene film on a fiber connector. ˜370 fs pulses are generated with output power continuously tunable from ˜4 up to ˜52 mW. This is a simple, low-cost, compact, portable, all-fiber ultrafast source for applications requiring environmentally stable, portable sources, such as imaging.

  20. Structure and transport investigations on lithium-iron-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Banday, Azeem; Sharma, Monika; Murugavel, Sevi, E-mail: murug@physics.du.ac.in [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

    2016-05-23

    Cathode materials for Lithium Ion Batteries (LIB’s) are being constantly studied and reviewed especially in the past few decades. LiFePO{sub 4} (LFP) is one of the most potential candidates in the pedigree of cathode materials and has been under extensive study ever since. In this work, we report the synthesis of amorphous analogs of crystallite LFP by conventional melt quenching method. Thermal study by using differential scanning calorimetry (DSC) was used to determine the glass transition T{sub g} and crystallization T{sub c} temperatures on the obtained glass sample Fourier transform infrared (FTIR) absorption spectroscopy is being used to investigate the structural properties of the glass sample. The intrinsic electrical conductivity measurements were done using broad-band impedance spectroscopy with wide different temperature ranges. The conduction mechanism is described by non-adiabatic small polaron hopping between nearest neighbors. Based on the obtained results, we suggest that the glassy LFP is more suitable cathode material as compared to its crystalline counterpart.

  1. Mechanical behaviour of degradable phosphate glass fibres and composites-a review.

    Science.gov (United States)

    Colquhoun, R; Tanner, K E

    2015-12-23

    Biodegradable materials are potentially an advantageous alternative to the traditional metallic fracture fixation devices used in the reconstruction of bone tissue defects. This is due to the occurrence of stress shielding in the surrounding bone tissue that arises from the absence of mechanical stimulus to the regenerating bone due to the mismatch between the elastic modulus of bone and the metal implant. However although degradable polymers may alleviate such issues, these inert materials possess insufficient mechanical properties to be considered as a suitable alternative to current metallic devices at sites of sufficient mechanical loading. Phosphate based glasses are an advantageous group of materials for tissue regenerative applications due to their ability to completely degrade in vivo at highly controllable rates based on the specific glass composition. Furthermore the release of the glass's constituent ions can evoke a therapeutic stimulus in vivo (i.e. osteoinduction) whilst also generating a bioactive response. The processing of these materials into fibres subsequently allows them to act as reinforcing agents in degradable polymers to simultaneously increase its mechanical properties and enhance its in vivo response. However despite the various review articles relating to the compositional influences of different phosphate glass systems, there has been limited work summarising the mechanical properties of different phosphate based glass fibres and their subsequent incorporation as a reinforcing agent in degradable composite materials. As a result, this review article examines the compositional influences behind the development of different phosphate based glass fibre compositions intended as composite reinforcing agents along with an analysis of different potential composite configurations. This includes variations in the fibre content, matrix material and fibre architecture as well as other novel composites designs.

  2. Timing characterization of 100 GHz passively mode-locked discrete mode laser diodes

    CERN Document Server

    Bitauld, David; O'Brien, Stephen

    2011-01-01

    We report on the characterization of the timing stability of passively mode-locked discrete mode diode laser sources. These are edge-emitting devices with a spatially varying refractive index profile for spectral filtering. Two devices with a mode-locking frequency of 100 GHz are characterized. The first device is designed to support a comb of six modes and generates near Fourier limited 1.9 ps pulses. The second supports four primary modes resulting in a sinusoidal modulation of the optical intensity. Using a cross-correlation technique, we measured a 20 fs pulse to pulse timing jitter for the first device, while, for the second device, a mode-beating (RF) linewidth of 1 MHz was measured using heterodyne mixing in a semiconductor optical amplifier. Comparison of these results with those obtained for an equivalent Fabry-Perot laser indicates that the spectral filtering mechanism employed does not adversely affect the timing properties of these passively mode-locked devices.

  3. Multi-gigahertz repetition rate ultrafast waveguide lasers mode-locked with graphene saturable absorbers

    Science.gov (United States)

    Obraztsov, P. A.; Okhrimchuk, A. G.; Rybin, M. G.; Obraztsova, E. D.; Garnov, S. V.

    2016-08-01

    We report the development of an approach to build compact waveguide lasers that operate in the stable fundamental mode-locking regime with multigigahertz repetition rates. The approach is based on the use of depressed cladding multi- or single-mode waveguides fabricated directly in the active laser crystal using the femtosecond laser inscription method and a graphene saturable absorber. Using this approach we achieve the stable self-starting mode-locking operation of a diode-pumped waveguide Nd:YAG laser that delivers picosecond pulses at a repetition rate of up to 11.5 GHz with an average power of 12 mW at a central wavelength of 1064 nm. The saturable absorbers are formed through the chemical vapor deposition of single-layer graphene on the output coupler mirror or directly on the end facet of the laser crystal. The stable self-starting mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with an intracavity interferometer. The method developed for the creation of compact ultrashort pulse laser generators with gigahertz repetition rates can be extended further and applied for the development of compact high-repetition rate lasers that operate at a wide range of IR wavelengths.

  4. Techniques for increasing output power from mode-locked semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Mar, A.; Vawter, G.A.

    1996-02-01

    Mode-locked semiconductor lasers have drawn considerable attention as compact, reliable, and relatively inexpensive sources of short optical pulses. Advances in the design of such lasers have resulted in vast improvements in pulsewidth and noise performance, at a very wide range of repetition rates. An attractive application for these lasers would be to serve as alternatives for large benchtop laser systems such as dye lasers and solid-state lasers. However, mode-locked semiconductor lasers have not yet approached the performance of such systems in terms of output power. Different techniques for overcoming the problem of low output power from mode-locked semiconductor lasers will be discussed. Flared and arrayed lasers have been used successfully to increase the pulse saturation energy limit by increasing the gain cross section. Further improvements have been achieved by use of the MOPA configuration, which utilizes a flared semiconductor amplifier s amplify pulses to energies of 120 pJ and peak powers of nearly 30W.

  5. Black phosphorus saturable absorber for ultrafast mode-locked pulse laser via evanescent field interaction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kichul; Lee, Young Tack; Choi, Won-Kook; Song, Yong-Won [Center for Opto-electronic Materials and Devices, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Lee, Junsu; Lee, Ju Han [School of Electrical and Computer Engineering, University of Seoul (Korea, Republic of)

    2015-12-15

    Black phosphorus, or BP, has found a lot of applications in recent years including photonics. The most recent studies have shown that the material has an excellent optical nonlinearity useful in many areas, one of which is in saturable absorption for passive mode-locking. A direct interaction scheme for mode-locking, however, has a potential to optically cause permanent damage to the already delicate material. Evanescent field interaction scheme has already been proven to be a useful method to prevent such danger for other 2-dimensional nanomaterials. In this report, we have utilized the evanescent field interaction to demonstrate that the optical nonlinear characteristics of BP is sufficiently strong to use in such an indirect interaction method. The successful demonstration of the passive mode-locking operation has generated pulses with the pulse duration, repetition rate, and time bandwidth product of 2.18 ps, 15.59 MHz, and 0.336, respectively. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. RF spectral analysis for characterisation of mode-locked regimes in fibre lasers

    Science.gov (United States)

    Ivanenko, Alexey V.; Kobtsev, Sergey M.; Kokhanovskiy, Alexey; Smirnov, Sergey V.

    2016-10-01

    In this work, we present our results of RF spectral analysis applied to mode-locked lasers and propose a method of qualitative assessment of mode-locked operation, which allows differentiation of individual generation regimes by a parameter calculated from RF spectra of the fundamental and the n-th radiation harmonics. The proposed parameter is derived both from the signal-to-noise ratio and from width and amount of additional noise present in RF spectrum of inter-mode beats at the fundamental pulse repetition frequency and its harmonic. This work presents analysis of energy fluctuations and temporal instability of pulse train period for different regimes of pulse generation in Yb fibre laser mode locked due to nonlinear polarization evolution. The paper shows that energy fluctuations of single-scale ("conventional") pulses is about 1.6%, whereas for double-scale pulses energy fluctuations amount to 11.5%. Temporal instability of double-scale pulse train period is 1.5 times higher in comparison with single-scale pulse train period.

  7. Ultrafast erbium-doped fiber laser mode-locked with a black phosphorus saturable absorber

    Science.gov (United States)

    Ahmed, M. H. M.; Latiff, A. A.; Arof, H.; Harun, S. W.

    2016-09-01

    We experimentally demonstrate a passive mode-locked erbium-doped fiber laser (EDFL) using a multi-layer black phosphorus saturable absorber (BPSA). The BPSA is fabricated by mechanically exfoliating a BP crystal and sticking the acquired BP flakes onto scotch tape. A small piece of the tape is then placed between two ferrules and integrated into an EDFL cavity to achieve a self-started soliton mode-locked pulse operation at 1560.7 nm wavelength. The 3 dB bandwidth, pulse width, and repetition rate of the laser are 6.4 nm, 570 fs, and 6.88 MHz, respectively. The average output power is 5.1 mW at pump power of 140 mW and thus, the pulse energy and peak power are estimated at 0.74 nJ and 1.22 kW, respectively. The BPSA was constructed in a simple fabrication process and has a modulation depth of 7% to successfully produce the stable mode-locked fiber laser.

  8. Gamma ray interactions with V{sub 2}O{sub 5}-doped sodium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    ElBatal, F.H. [Glass Research Department, National Research Center, Cairo (Egypt); Hamdy, Y.M. [Spectroscopy Department, National Research Center, Cairo (Egypt)], E-mail: yousry_m_h@yahoo.com; Marzouk, S.Y. [Electron Microscope and Thin Film Department, National Research Center, Cairo (Egypt)

    2008-12-20

    Undoped and V{sub 2}O{sub 5}-doped sodium phosphate glasses of various compositions and with varying progressive V{sub 2}O{sub 5} contents were prepared. UV-vis and infrared, Raman and electron spin resonance spectroscopic studies were measured before and after successive gamma irradiation. Experimental results indicate that vanadium ions exist in three possible valencies in sodium phosphate glasses, namely, the trivalent, tetravalent and pentavalent states. The first two lower valencies are predominant in this glass system. The changes in UV-vis and infrared spectral data are discussed in relation to the structural evolution caused by the change in the V{sub 2}O{sub 5} content or glass composition. Raman and ESR measurements are taken as confirmative tools to support our assumptions relating to the states of vanadium and structural groups arrangements in the studied glasses. Gamma irradiation produces induced defects depending on the host glass and the concentration of V{sub 2}O{sub 5} content together with the sharing of unavoidable trace iron impurities. Vanadium ions when present in high doping level, have been found to exhibit a shielding behaviour towards the effects of progressive gamma irradiation causing a retardation of the growth of the induced defects caused by irradiation.

  9. Alkali-Phosphate Glasses Containing WO3 and Nb2O5

    Directory of Open Access Journals (Sweden)

    L. Bih

    2013-01-01

    Full Text Available New phosphate glasses in the quaternary system (50-x A2O-x WO3-10 Nb2O5-40 P2O5, with x = 0; 30 and A = Li or Na were prepared by the melt quenching method. The effect on the crystallization behaviour of the glass due to the introduction of WO3 into the glass composition and, consequently, the diminishing of the molar amount of the alkaline oxide and the decreasing of the molar ratio between network modifiers and network formers (M/F was studied. The prepared glasses were heat-treated in air, at 550°C, 600°C, and 650°C for 4 hours. The structure, of the obtained samples, was studied by differential thermal analysis (DTA, X-ray powder diffraction (XRD, and Raman spectroscopy and the morphology by scanning electron microscopy (SEM. It was found that the replacement of Li2O or Na2O by WO3 reduces the number of the crystallised phases. In the lithium-niobiophosphate glasses, the presence of WO3 promotes the formation of NbOPO4 instead of the LiNbO3 phase and reduces the formation of ortho- and pyro-phosphate phases. The thermal treatments affect the arrangements of the network structure of the AW40-glasses.

  10. Field-assisted patterned dissolution of silver nanoparticles in phosphate glass

    Energy Technology Data Exchange (ETDEWEB)

    Andreyuk, A., E-mail: alexmag25@gmail.com; Albert, J. [Department of Electronics, Carleton University, Ottawa, Ontario K1S 5B6 (Canada)

    2014-09-21

    Phosphate glass samples doped with silver ions through a Na⁺-Ag⁺ ion-exchange process were treated in a hydrogen atmosphere at temperatures near 430°C for durations ranging from 4 to 5 h. Such treatment causes metallic silver precipitation at the surface as well as nanoclustering of silver atoms under the surface under conditions very similar to those used for silicate glasses. The presence of silver clusters resulted in a characteristic coloring of the glass and was verified by the observation of a plasmon resonance peak near 410–420 nm in the absorption spectra. Applying a DC voltage between 1.4 and 2 kV at temperatures between 120 and 130°C led to dissolution of the clusters in the area under the positive electrode, thereby bleaching the glass color. The use of a patterned doped-silicon electrode further led to the formation of a 300 nm thick surface relief on the glass surface and of a volume complex permittivity grating extending at least 4 μm under the surface. Such volume complex refractive index gratings may find applications in passive or active (laser) photonic devices in rare-earth doped phosphate glasses, where conventional bulk grating formation techniques have limited applicability.

  11. Alkaline aluminum phosphate glasses for thermal ion-exchanged optical waveguide

    Science.gov (United States)

    Wang, Fei; Chen, Baojie; Pun, Edwin Yue Bun; Lin, Hai

    2015-04-01

    Alkaline aluminum phosphate glasses (NMAP) with excellent chemical durability for thermal ion-exchanged optical waveguide have been designed and investigated. The transition temperature Tg (470 °C) is higher than the ion-exchange temperature (390 °C), which is favorable to sustain the stability of the glass structure for planar waveguide fabrication. The effective diffusion coefficient De of K+-Na+ ion exchange in NMAP glasses is 0.110 μm2/min, indicating that ion exchange can be achieved efficiently in the optical glasses. Single-mode channel waveguide has been fabricated on Er3+/Yb3+ doped NMAP glass substrate by standard micro-fabrication and K+-Na+ ion exchange. The mode field diameter is 9.6 μm in the horizontal direction and 6.0 μm in the vertical direction, respectively, indicating an excellent overlap with a standard single-mode fiber. Judd-Ofelt intensity parameter Ω2 is 5.47 × 10-20 cm2, implying a strong asymmetrical and covalent environment around Er3+ in the optical glasses. The full width at half maximum and maximum stimulated emission cross section of the 4I13/2 → 4I15/2 are 30 nm and 6.80 × 10-21 cm2, respectively, demonstrating that the phosphate glasses are potential glass candidates in developing compact optoelectronic devices. Pr3+, Tm3+ and Ho3+ doped NMAP glasses are promising candidates to fabricate waveguide amplifiers and lasers operating at special telecommunication windows.

  12. The aluminium effect on the structure of silico-phosphate glasses studied by NMR and FTIR

    Science.gov (United States)

    Sitarz, Maciej; Fojud, Zbigniew; Olejniczak, Zbigniew

    2009-04-01

    Silico-phosphate glasses of NaCaPO 4-SiO 2 and NaCaPO 4-AlPO 4-SiO 2 system have been the subject of the presented investigations. Glasses of these systems are the basis for the preparation of glassy-crystalline biomaterials [R.D. Rawlings, Clin. Mater. 14 (1993) 155]. Detailed knowledge of the precursor glass structure is necessary for proper design of the glassy-crystalline biomaterials preparation procedure. Since there is no long-range ordering in glasses, spectroscopic methods which make it possible to study the short range ordering should be applied. MIR studies carried out in the work have allowed to establish that the glasses of the systems studied show domain composition [L.L. Hench, R.J. Splinter, T.K. Greenlee, W.C. Allen, J. Biol. Res. Symp. 2 (1971) 117; L.L. Hench, R.J. Splinter, W.C. Allen, T.K. Greenlee, J. Biol. Res. 5 (1972) 117]. Domain structure is close to that of the corresponding crystalline phases. It has been shown that even small amount of aluminium in the glass (5 mol.% of AlPO 4) significantly influences both, its texture (microscopic and EDX studies) and its structure (spectroscopic studies). 27Al NMR investigations have made it possible to establish unequivocally that aluminium occurs exclusively in tetrahedral coordination, i.e. it is involved in the formation of glass framework. Presence of aluminium results in significant changes in the [SiO 4] 4- and [PO 4] 3- tetrahedra environment which is reflected in 23Na, 31P and 29Si NMR spectra. Changes in the shapes and positions of the bands in the NMR spectra of glasses belonging to the NaCaPO 4-AlPO 4-SiO 2 system confirm great influence of aluminium on silico-phosphate glasses structure.

  13. White light emission of dysprosium doped lanthanum calcium phosphate oxide and oxyfluoride glasses

    Science.gov (United States)

    Luewarasirikul, N.; Kim, H. J.; Meejitpaisan, P.; Kaewkhao, J.

    2017-04-01

    Lanthanum calcium phosphate oxide and oxyfluoride glasses doped with dysprosium oxide were prepared by melt-quenching technique with chemical composition 20La2O3:10CaO:69P2O5:1Dy2O3 and 20La2O3:10CaF2:69P2O5:1Dy2O3. The physical, optical and luminescence properties of the glass samples were studied to evaluate their potential to using as luminescence materials for solid-state lighting applications. The density, molar volume and refractive index of the glass samples were carried out. The optical and luminescence properties were studied by investigating absorption, excitation, and emission spectra of the glass samples. The absorption spectra were investigated in the UV-Vis-NIR region from 300 to 2000 nm. The excitation spectra observed under 574 nm emission wavelength showed the highest peak centered at 349 nm (6H15/2 → 6P7/2). The emission spectra, excited with 349 nm excitation wavelength showed two major peaks corresponding to 482 nm blue emission (4F9/2 → 6H15/2) and 574 nm yellow emission (4F9/2 → 6H13/2). The experimental lifetime were found to be 0.539 and 0.540 for oxide and oxyfluoride glass sample, respectively. The x,y color coordinates under 349 nm excitation wavelength were (0.38, 0.43) for both glass samples, that be plotted in white region of CIE 1931 chromaticity diagram. The CCT values obtained from the glass samples are 4204 K for oxide glass and 4228 K for oxyfluoride glass corresponding to the commercial cool white light (3100-4500 K). Judd-Ofelt theory had also been employed to obtain the J-O parameters (Ω2, Ω4 and Ω6), oscillator strength, radiative transition possibility, stimulated emission cross section and branching ratio. The Ω2 > Ω4 > Ω6 trend of J-O parameters of both glass samples may indicate the good quality of a glass host for using as optical device application. Temperature dependence of emission spectra was studied from 300 K to 10 K and found that the intensity of the emission peak was found to be increased with

  14. Effect of Boron Addition on the Thermal, Degradation, and Cytocompatibility Properties of Phosphate-Based Glasses

    Directory of Open Access Journals (Sweden)

    Nusrat Sharmin

    2013-01-01

    Full Text Available In this study eight different phosphate-based glass compositions were prepared by melt-quenching: four in the (P2O545-(CaO16--(MgO24- system and four in the system (P2O550-(CaO16--(MgO24-, where and 10 mol%. The effect of B2O3 addition on the thermal properties, density, molar volume, dissolution rates, and cytocompatibility were studied for both glass systems. Addition of B2O3 increased the glass transition (, crystallisation (, melting (, Liquidus ( and dilatometric softening ( temperature and molar volume (. The thermal expansion coefficient (α and density ( were seen to decrease. An assessment of the thermal stability of the glasses was made in terms of their processing window (crystallisation onset, minus glass transition temperature, , and an increase in the processing window was observed with increasing B2O3 content. Degradation studies of the glasses revealed that the rates decreased with increasing B2O3 content and a decrease in degradation rates was also observed as the P2O5 content reduced from 50 to 45 mol%. MG63 osteoblast-like cells cultured in direct contact with the glass samples for 14 days revealed comparative data to the positive control for the cell metabolic activity, proliferation, ALP activity, and morphology for glasses containing up to 5 mol% of B2O3.

  15. All-fiber widely tunable mode-locked thulium-doped laser using a curvature multimode interference filter

    Science.gov (United States)

    Li, N.; Liu, M. Y.; Gao, X. J.; Zhang, L.; Jia, Z. X.; Feng, Y.; Ohishi, Y.; Qin, G. S.; Qin, W. P.

    2016-07-01

    We demonstrated a widely tunable mode-locked thulium doped fiber laser (TDFL) by using a homemade multimode interference filter (MMIF). The MMIF had a structure of single mode fiber (SMF)—multimode fiber (MMF)—SMF and three main transmission peaks at 1901.2, 1957.2 and 2043.2 nm. By mechanically bending the MMIF, the three main transmission peaks were tuned in the range of 1860-2024 nm due to multimode interference effect. By inserting the MMIF into a passively mode-locked TDFL cavity pumped by a 1570 nm fiber laser, a tunable mode-locked TDFL with a tuning range of 1919.6-2014.9 nm was achieved by adjusting the MMIF. To the best of our knowledge, such a tunable range is the largest among all-fiber tunable mode-locked TDFLs.

  16. High-power 200 fs Kerr-lens mode-locked Yb:YAG thin-disk oscillator.

    Science.gov (United States)

    Pronin, O; Brons, J; Grasse, C; Pervak, V; Boehm, G; Amann, M-C; Kalashnikov, V L; Apolonski, A; Krausz, F

    2011-12-15

    We demonstrate a power-scalable Kerr-lens mode-locked Yb:YAG thin-disk oscillator. It delivers 200 fs pulses at an average power of 17 W and a repetition rate of 40 MHz. At an increased (180 W) pump power level, the laser produces 270 fs 1.1 μJ pulses at an average power of 45 W (optical-to-optical efficiency of 25%). Semiconductor-saturable-absorber-mirror-assisted Kerr-lens mode locking (KLM) and pure KLM with a hard aperture show similar performance. To our knowledge, these are the shortest pulses achieved from a mode-locked Yb:YAG disk oscillator and this is the first demonstration of a Kerr-lens mode-locked thin-disk laser.

  17. Mode-locked laser realized by selective area growth for short pulse generation and optical clock recovery in TDM systems

    Science.gov (United States)

    Lach, Eugen; Baums, Dieter; Bouayad-Amine, Jamal; Hache, Claudia; Haisch, Hansjorg; Kuhn, Edgar; Satzke, Klaus; Schilling, Michael; Weber, Juergen; Zielinski, Erich

    1996-04-01

    We report on monolithically integrated active/passive coupled cavity mode locked lasers for 1.55 micrometer realized by selective area growth technology of InGaAs(P) quantum wells. Mode locked FP or DBR lasers are fabricated with an integrated cavity comprising up to three different band gaps. The devices emit short light pulses at around 10 GHz repetition rate with pulse width down to 8.7 ps. A time-bandwidth product of 0.5 is achieved for mode locked DBR lasers. Active/passive integrated mode locked laser is used for generation of optical 10 GHz clock signal from optical 10 Gb/s PRBS RZ data stream injected into the laser cavity.

  18. Low threshold diode-pumped picosecond mode-locked Nd:YAG laser with a semiconductor saturable absorber mirror

    Science.gov (United States)

    Eshghi, M. J.; Majdabadi, A.; Koohian, A.

    2017-01-01

    In this paper, a low threshold diode pumped passively mode-locked Nd:YAG laser has been demonstrated by using a semiconductor saturable absorber mirror. The threshold power for continuous-wave mode-locking is relatively low, about 3.2 W. The resonator stability across the pump power has been analytically examined. Moreover, the mode overlap between the pump beam and the laser fundamental mode has been simulated by MATLAB software. Adopting Z-shaped resonator configuration and suitable design of the resonator’s arm lengths, has enabled the author to prepare mode-locking conditions, and obtain 40 ps pulses with 112 MHz pulse repetition rate. The laser output was stable without any Q switched instability. To the best of our knowledge, this is the lowest threshold for CW mode-locking operation of a Nd:YAG laser.

  19. Mode-locking optimization with a real-time feedback system in a Nd:yttrium lithium fluoride laser cavity

    Science.gov (United States)

    Marengoni, C.; Canova, F.; Batani, D.; Benocci, R.; Librizzi, M.; Narayanan, V.; Gomareschi, M.; Lucchini, G.; Kilpio, A.; Shashkov, E.; Stuchebrukhov, I.; Vovchenko, V.; Chernomyrdin, V.; Krasuyk, I.; Hall, T.; Bittanti, S.

    2007-01-01

    We present a control system, which allows an automatic optimization of the pulse train stability in a mode-locked laser cavity. In order to obtain real-time corrections, we chose a closed loop approach. The control variable is the cavity length, mechanically adjusted by gear system acting on the rear cavity mirror, and the controlled variable is the envelope modulation of the mode-locked pulse train. Such automatic control system maintains the amplitude of the mode-locking pulse train stable within a few percent rms during the working time of the laser. Full implementation of the system on an Nd:yttrium lithium fluoride actively mode-locked laser is presented.

  20. Neutron scattering and ab initio molecular dynamics study of cross-linking in biomedical phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, A J; Ahmed, I; Rudd, C D [Division of Materials, Mechanics and Structures, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Cuello, G J; Pellegrini, E; Richard, D; Johnson, M R, E-mail: andrew.parsons@nottingham.ac.uk [Institut Laue-Langevin, BP 156, 38042 Grenoble (France)

    2010-12-08

    Details of the microscopic structure of phosphate glasses destined for biomedical applications, which include sodium, magnesium and calcium cations, have been obtained from the static structure factor measured by means of neutron scattering. A complementary, molecular dynamics study has been performed on a range of phosphate glasses using density functional theory methods, which allow structural fluctuations, including bond breaking, in the liquid phase before quenching to the glass phase. Good agreement between experiment and simulation allows the molecular dynamics trajectories to be analysed in detail. In particular, attention is focused on the cross-linking of divalent cations in contrast with the structural aspects associated with monovalent cations. Magnesium cations are found equidistant and bridging between the phosphorus atoms of different phosphate chains, leading to a shorter phosphorus-phosphorus second neighbour distance (that is, a more compact packing of neighbouring phosphate chains) compared to the effect of sodium cations. Calcium cations show behaviour intermediate between those of magnesium and sodium. Molecular dynamics simulations give access to the cation mobility, which is lowest for magnesium, reflecting its structural, cross-linking role.

  1. A Review of Iron Phosphate Glasses and Recommendations for Vitrifying Hanford Waste

    Energy Technology Data Exchange (ETDEWEB)

    Delbert E. Ray; Chandra S. Ray

    2013-11-01

    This report contains a comprehensive review of the research conducted, world-wide, on iron phosphate glass over the past ~30 years. Special attention is devoted to those iron phosphate glass compositions which have been formulated for the purpose of vitrifying numerous types of nuclear waste, with special emphasis on the wastes stored in the underground tanks at Hanford WA. Data for the structural, chemical, and physical properties of iron phosphate waste forms are reviewed for the purpose of understanding their (a) outstanding chemical durability which meets all current DOE requirements, (b) high waste loadings which can exceed 40 wt% (up to 75 wt%) for several Hanford wastes, (c) low melting temperatures, can be as low as 900°C for certain wastes, and (d) high tolerance for “problem” waste components such as sulfates, halides, and heavy metals (chromium, actinides, noble metals, etc.). Several recommendations are given for actions that are necessary to smoothly integrate iron phosphate glass technology into the present waste treatment plans and vitrification facilities at Hanford.

  2. The influence of SrO and CaO in silicate and phosphate bioactive glasses on human gingival fibroblasts.

    Science.gov (United States)

    Massera, J; Kokkari, A; Närhi, T; Hupa, L

    2015-06-01

    In this paper, we investigate the effect of substituting SrO for CaO in silicate and phosphate bioactive glasses on the human gingival fibroblast activity. In both materials the presence of SrO led to the formation of a CaP layer with partial Sr substitution for Ca. The layer at the surface of the silicate glass consisted of HAP whereas at the phosphate glasses it was close to the DCPD composition. In silicate glasses, SrO gave a faster initial dissolution and a thinner reaction layer probably allowing for a continuous ion release into the solution. In phosphate glasses, SrO decreased the dissolution process and gave a more strongly bonded reaction layer. Overall, the SrO-containing silicate glass led to a slight enhancement in the activity of the gingival fibroblasts cells when compared to the SrO-free reference glass, S53P4. The cell activity decreased up to 3 days of culturing for all phosphate glasses containing SrO. Whereas culturing together with the SrO-free phosphate glass led to complete cell death at 7 days. The glasses containing SrO showed rapid cell proliferation and growth between 7 and 14 days, reaching similar activity than glass S53P4. The addition of SrO in both silicate and phosphate glasses was assumed beneficial for proliferation and growth of human gingival fibroblasts due to Sr incorporation in the reaction layer at the glass surface and released in the cell culture medium.

  3. Energy transfer from Ce~(3+) to Tb~(3+) and Eu~(3+) in zinc phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    马崇庚; 江莎; 周贤菊

    2010-01-01

    Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h.The obtained glasses were homogeneous and transparent.The glasses without Ce3+ were colorless and those with Ce3+ showed slightly yellow.The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions.Strong energy transfer from Ce3+ to...

  4. Measuring a Fiber-Optic Delay Line Using a Mode-Locked Laser

    Science.gov (United States)

    Tu, Meirong; McKee, Michael R.; Pak, Kyung S.; Yu, Nan

    2010-01-01

    The figure schematically depicts a laboratory setup for determining the optical length of a fiber-optic delay line at a precision greater than that obtainable by use of optical time-domain reflectometry or of mechanical measurement of length during the delay-line-winding process. In this setup, the delay line becomes part of the resonant optical cavity that governs the frequency of oscillation of a mode-locked laser. The length can then be determined from frequency-domain measurements, as described below. The laboratory setup is basically an all-fiber ring laser in which the delay line constitutes part of the ring. Another part of the ring - the laser gain medium - is an erbium-doped fiber amplifier pumped by a diode laser at a wavelength of 980 nm. The loop also includes an optical isolator, two polarization controllers, and a polarizing beam splitter. The optical isolator enforces unidirectional lasing. The polarization beam splitter allows light in only one polarization mode to pass through the ring; light in the orthogonal polarization mode is rejected from the ring and utilized as a diagnostic output, which is fed to an optical spectrum analyzer and a photodetector. The photodetector output is fed to a radio-frequency spectrum analyzer and an oscilloscope. The fiber ring laser can generate continuous-wave radiation in non-mode-locked operation or ultrashort optical pulses in mode-locked operation. The mode-locked operation exhibited by this ring is said to be passive in the sense that no electro-optical modulator or other active optical component is used to achieve it. Passive mode locking is achieved by exploiting optical nonlinearity of passive components in such a manner as to obtain ultra-short optical pulses. In this setup, the particular nonlinear optical property exploited to achieve passive mode locking is nonlinear polarization rotation. This or any ring laser can support oscillation in multiple modes as long as sufficient gain is present to overcome

  5. Praseodymium ion doped phosphate glasses for integrated broadband ion-exchanged waveguide amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Shen, L.F. [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Chen, B.J. [Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Lin, H., E-mail: lhai8686@yahoo.com [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Pun, E.Y.B. [Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

    2015-02-15

    Highlights: • Effective near-infrared emission (1380-1525 nm) is observed in Pr{sup 3+}-doped phosphate glasses. • Effective bandwidth of {sup 1}D{sub 2} → {sup 1}G{sub 4} transition emission is obtained to be 124 nm. • Channel waveguides have been fabricated by K{sup +}-Na{sup +} ion-exchange method. • Pr{sup 3+}-doped phosphate glasses are promising in developing integrated broadband waveguide amplifier. - Abstract: Effective near-infrared emission covering the fifth optical telecommunication window (1380-1525 nm) has been observed in Pr{sup 3+}-doped phosphate (NMAP) glasses. Judd-Ofelt parameters Ω{sub 2} (6.38 × 10{sup −20} cm{sup 2}), Ω{sub 4} (20.30 × 10{sup −20} cm{sup 2}) and Ω{sub 6} (0.40 × 10{sup −20} cm{sup 2}) indicate a high inversion asymmetrical and strong covalent environment in the optical glasses. The effective bandwidth (Δλ{sub eff}) of the corresponding {sup 1}D{sub 2} → {sup 1}G{sub 4} transition emission is obtained to be 124 nm, and the maximum stimulated emission cross-section (σ{sub em-max}) at 1468 nm is derived to be 1.14 × 10{sup −20} cm{sup 2}. Channel waveguide was fabricated successfully by K{sup +}-Na{sup +} ion-exchange method with mode field diameter of 8.8 μm in the horizontal direction and 6.7 μm in the vertical direction. Broad effective bandwidth, large emission cross-section and perfect thermal ion-exchangeability indicate that Pr{sup 3+}-doped NMAP phosphate glasses are promising in developing integrated broadband waveguide amplifier, especially operating at E- and S-bands which belong to the fifth optical telecommunication window.

  6. Self-Mode-Locking in a Diode-Pumped Self-Q-Switched Nd3+,Cr4+:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    杨林; 冯宝华; 张治国; Volker Gaebler; 刘百宁; Hans J. Eichler; 张世文

    2002-01-01

    We report for the first time on the observation of self-mode-locking in a diode pumped self-Q-switched (SQS)Nd3+,Cr4+ : YA G laser. This phenomenon results from significant excited state absorption of the Cr4+ ions in theco-doped host during the SQS laser pulses. The self-mode-locking occurs already slightly above the SQS laserthreshold. Experiments using relatively low saturable intensity achieved a modulation depth of more than 40%.

  7. Scheme for independently stabilizing the repetition rate and optical frequency of a laser using a regenerative mode-locking technique.

    Science.gov (United States)

    Nakazawa, Masataka; Yoshida, Masato

    2008-05-15

    We have succeeded in achieving independent control of the repetition rate and optical frequency of a pulse laser by employing a regenerative mode-locking technique. By adopting a voltage-controlled microwave phase shifter or an optical delay line in a regenerative feedback loop we can control the repetition rate of the laser without directly disturbing the optical frequencies. We experimentally show how this independent control can be realized by employing a 40 GHz harmonically and regeneratively mode-locked fiber laser.

  8. Wavelength tunable stretched-pulse mode-locked all-fiber erbium ring laser with single polarization fiber.

    Science.gov (United States)

    Li, Shenping; Chen, Xin; Kuksenkov, Dmitri V; Koh, Joohyun; Li, Ming-Jun; Zenteno, Luis A; Nolan, Daniel A

    2006-06-26

    A wavelength tunable stretched-pulse mode-locked all-fiber ring laser using single polarization fiber (SPF) was demonstrated. In this laser, a segment of SPF was used simultaneously as a polarizer and a tunable filter in the laser cavity. Self-starting mode-locking with femtosecond output pulses was demonstrated. A wavelength tuning of ~20nm was achieved by bending the SPF with different radii.

  9. Sol-Gel Synthesis of Phosphate-Based Glasses for Hydrophilic Enamel Applications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae-Sung; Ryu, Bong-ki [Pusan National University, Busan (Korea, Republic of)

    2017-04-15

    In this study, quaternary phosphate-based sol-gel derived glasses were synthesized from a P{sub 2}O{sub 5}-CaO-Na{sub 2}O-TiO{sub 2} system with a high TiO{sub 2} content of up to 50 mol%. The sol-gel method was chosen because incorporating a high percentage of titanium into a phosphate network via traditional melt-quench methods is non-trivial. The structure and thermal properties of the obtained stabilized sol-gel glasses were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). The XRD results confirmed the amorphous nature of all of the stabilized sol–gel derived glasses. The FTIR results revealed that added TiO{sub 2} enters the network as (TiO{sub 6}), which likely acts as a modifier oxide. Consequently, the number of terminal oxygen atoms increases, leading to an increase in the number of P-OH bonds. In addition, DSC results confirmed a decrease in glass transition and crystallization temperatures with increasing TiO{sub 2} content. This is the first report of a sol-gel synthesis strategy combined with enameling to prepare glass at low processing temperatures and the first use of such a system for both hydrophilic and chemical resistance purposes.

  10. Emission and excitation mechanism of radiophotoluminescence in Ag{sup +}-activated phosphate glass

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, Y. [Oarai Research Center, Chiyoda Technol Corporation, 3681 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki-ken 311-1313 (Japan); Advanced Materials, Science Research and Development Center, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusann-shi, Ishikawa-ken 924-0838 (Japan); Kinoshita, K.; Koyama, S.; Takei, Y. [Advanced Materials, Science Research and Development Center, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusann-shi, Ishikawa-ken 924-0838 (Japan); Nanto, H., E-mail: hnanto@neptune.kanazawa-it.ac.j [Advanced Materials, Science Research and Development Center, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusann-shi, Ishikawa-ken 924-0838 (Japan); Yamamoto, T. [Oarai Research Center, Chiyoda Technol Corporation, 3681 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki-ken 311-1313 (Japan); Sakakura, M.; Shimotsuma, Y.; Miura, K.; Hirao, K. [Department of Materials Chemistry, Graduate School of Engineering, Kyoto University, A3-119 Katsura, Nishikyo-ku, Kyoto-shi, Kyoto-hu 615-8510 (Japan)

    2010-07-21

    The objective of this study is to investigate the emission mechanism of radiophotoluminescence (RPL) in the Ag{sup +}-doped phosphate glass (glass dosimeter), which is now used as the individual radiation dosimeter, because the emission mechanism of RPL in the glass dosimeter was not fully understood. Optical properties such as RPL emission and excitation spectra and change of RPL spectrum as a function of X-ray irradiation dose were measured for commercially available glass dosimeter. In this study, we discuss the emission mechanism of two RPL peaks at about 2.70 eV (460 nm) and 2.21 eV (560 nm), based on the fact that electrons and holes produced by X-ray irradiation are trapped at Ag{sup +} ions to produce Ag{sup 0} and Ag{sup 2+} ions, respectively, when the Ag{sup +}-doped phosphate glass is exposed to X-ray. We propose the emission mechanism of RPL peaks at about 2.70 and 2.21 eV, regarding Ag{sup 2+} and Ag{sup 0} ions.

  11. Melting Hanford LAW into Iron-Phosphate Glass in a CCIM

    Energy Technology Data Exchange (ETDEWEB)

    Nick Soelberg; Sharna Rossberg

    2011-09-01

    A vitrification test has been conducted using the cold crucible induction melter (CCIM) test system at the Idaho National Laboratory. The test was conducted to demonstrate the vitrification of a Hanford low activity waste (LAW) that contains relatively large amounts of sulfate and sodium, compared to other radioactive Hanford waste streams. The high sulfate content limits the potential loading of this waste stream in conventional borosilicate glass, so this test demonstrated how this waste stream could be vitrified in an iron-phosphate glass that can tolerate higher levels of sulfate.

  12. Optical planar waveguides in Yb3+-doped phosphate glasses produced by He+ ion implantation

    Institute of Scientific and Technical Information of China (English)

    Liu Chun-Xiao; Li Wei-Nan; Wei Wei; Peng Bo

    2012-01-01

    Optical planar waveguides in Yb3+-doped phosphate glasses are fabricated by implanting triple-energy helium ions.The guiding modes and the near-field intensity distribution are measured by using the prism-coupling method and the end-face coupling setup with a He-Ne laser at 633 nm The intensity calculation method (ICM) is used to reconstruct the refractive index profile of the waveguide.The absorption and the fluorescence investigations reveal that the glass bulk features are well preserved in the active volumes of the waveguides,suggesting the fabricated structures for possible applications as waveguide lasers.

  13. Instability of spin glass phase in divalent iron phosphate glass under a magnetic field

    Science.gov (United States)

    Nakatsuka, Yuko; Murai, Shunsuke; Fujita, Koji; Tanaka, Katsuhisa

    2017-01-01

    The spin glass behaviour of 50FeO · 50P2O5 (in mol%) glass has been examined under finite magnetic fields. The Sherrington-Kirkpatrick (SK) model, i.e. the mean field theory, is unsuitable for the interpretation of the frequency dependence of the ac magnetic susceptibility observed under an external field of 0.1 T; the critical exponent derived from the SK model is unphysically large. On the other hand, the droplet model explains well the frequency and field dependence of the spin-freezing temperature and the exponent of the thermally activated process is within the range defined by the droplet model. The results indicate that the spin glass phase of the 50FeO · 50P2O5 glass is unstable against magnetic fields.

  14. Concentration dependent spectroscopic properties of Dy3+ ions doped boro-phosphate glasses

    Science.gov (United States)

    Mariyappan, M.; Marimuthu, K.

    2016-05-01

    Dy3+ ions doped boro-phosphate glasses have been synthesized by melt quenching method and characterized through FTIR, absorption and luminescence spectral measurements. The presence of various stretching and bending vibrations of different borate and phosphate groups were identified from the FTIR spectra. In order to examine the electronic band structure of the studied glasses, Optical energy gap (Eopt) and Urbach energy (ΔE) values were estimated from the absorption spectra. The Judd-Ofelt (JO) intensity parameters were calculated to examine the symmetry of the ligand environment around the Dy3+ ions site. The emission spectra exhibit two intense emission bands at around 482 nm (blue) and 574 nm (yellow) corresponding to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions respectively. The emission spectra were characterized through Commission International d'Eclairage (CIE) 1931 chromaticity diagram to explore its suitability for WLED applications.

  15. Properties and solubility of chrome in iron alumina phosphate glasses containing high level nuclear waste

    Energy Technology Data Exchange (ETDEWEB)

    Huang, W. [School of Materials Science and Engineering, Tongji Univ., Shanghai, SH (China); Day, D.E.; Ray, C.S.; Kim, C.W.; Reis, S.T.D. [Univ. of Missouri-Rolla (United States). Graduate Center for Materials Research

    2004-10-01

    Chemical durability, glass formation tendency, and other properties of iron alumina phosphate glasses containing 70 wt% of a simulated high level nuclear waste (HLW), doped with different amounts of Cr{sub 2}O{sub 3}, have been investigated. All of the iron alumina phosphate glasses had an outstanding chemical durability as measured by their small dissolution rate (1 . 10{sup -9} g/(cm{sup 2} . min)) in deionized water at 90 C for 128 d, their low normalized mass release as determined by the product consistency test (PCT) and a barely measurable corrosion rate of <0.1 g/(m{sup 2} . d) after 7 d at 200 C by the vapor hydration test (VHT). The solubility limit for Cr{sub 2}O{sub 3} in the iron phosphate melts was estimated at 4.1 wt%, but all of the as-annealed melts contained a few percent of crystalline Cr{sub 2}O{sub 3} that had no apparent effect on the chemical durability. The chemical durability was unchanged after deliberate crystallization, 48 h at 650 C. These iron phosphate waste forms, with a waste loading of at least 70 wt%, can be readily melted in commercial refractory crucibles at 1250 C for 2 to 4 h, are resistant to crystallization, meet all current US Department of Energy requirements for chemical durability, and have a solubility limit for Cr{sub 2}O{sub 3} which is at least three times larger than that for borosilicate glasses. (orig.)

  16. Effect of GeO2 on the lasing performance of Yb: Phosphate glass fiber

    Science.gov (United States)

    Wang, Chao; Wang, Yajie; Zhang, Liyan; Chen, Danping

    2017-02-01

    A novel GeO2 modified Yb: phosphate glass with good luminescent properties has been demonstrated. P and PG fibers were fabricated by the stack-and-draw method. An output power of 6.4 W with slope efficiency of 46% was obtained from 40.5 cm long PG fiber, while 40.2 cm long P fiber had an output power of 2.7 W and 34% slope efficiency.

  17. A Novel Ce3+/Tb3+ Codoped Phosphate Glass as Down-Shifting Materials for Enhancing Efficiency of Solar Cells

    Institute of Scientific and Technical Information of China (English)

    HE Dong-Bing; YU Chun-Lei; CHENG Ji-Meng; LI Shun-Guang; HU Li-Li

    2010-01-01

    @@ For the purpose of improving conversion effciency of solar cells by applying the effect of the wavelength conversion of rare earth ions,photo-luminescence and excitation spectrums of Ce3+-Tb3+ doped phosphate glass are investigated.Results show that incorporating Cea+ ions to Tb3+-doped phosphate glass can greatly increase the absorption coefficient in the range 300-400 nm and then the energy transfer (ET) from Ce3+ to Tb3+ occurs.In addition,increasing Tb3+ concentration in Ce3+ /Tb3+ co-doped phosphate glass can greatly enhance the ET efffciency and 545 nm emission intensity.This shows that Ce3+ /Tb3+ co-doped phosphate glass would be a promising down-shifting material for enhancing the efficiency of solar cells.

  18. Spectroscopic properties of Nd-doped phosphate glass with a high emission cross section

    Institute of Scientific and Technical Information of China (English)

    毛艳丽; 孙真荣; 蒋秀丽; 邓佩珍; 干福熹

    2002-01-01

    Neodymium doped phosphate glasses have been prepared by the semi-continuous melting technique. Their ab-sorption and emission spectra have been recorded at room temperature. The Judd-Ofelt theory has been applied to ewluate the stimulated emission cross sections of 4F3/2→4I11/2 transition for Nd3+. The higher stimulated emission cross section, 4.0×10-20cm2, is obtained. The fluorescence decays of the 4F3/2→411/2 transition of Nd3+ are mea-sured for the samples doped (0.7-10) wt% of Nd2O3 at room temperature. The concentration quenching of Nd-doped phosphate glass is mainly attributed to cross-relaxation and energy migration. The site-dependent properties of fluores-cence spectra and the fluorescence lifetime of the Nd3+-doped phosphate glass (with 2.2wt% Nd2O3) are studied using laser-induced fluorescence line narrowing techniques, and the site-to-site variations of optical properties are observed at low temperature.

  19. Study on surface roughness evolvement of Nd-doped phosphate glass after IBF

    Science.gov (United States)

    Li, Furen; Xie, Xuhui; Zhou, Lin; Tie, Guipeng; Hu, Hao

    2016-10-01

    Nd doped phosphate glass is widely used as gain media in high power laser system. It is traditionally polished with the annular polishing technology. The edge effect is inevitable in annular polishing process and it results in the low manufacturing efficiency. Ion Beam Figuring (IBF) is a highly deterministic, non-contact method for the ultra-precision optics fabrication. So the edge effect is avoided. Nanometer and sub-nanometer precision is realizable in IBF. In this paper, Nd doped phosphate glass was polished with IBF, and the evolvement of surface roughness was emphasized. The roughness of surface polished with ion beam at normal and oblique incidence was researched. The oblique incident angle was 45°. The surface roughness was measured with the white light interferometer. No evident change was observed. This means that the pre-finish roughness can be preserved in IBF. The results denote that IBF is a feasible method to correct the contour errors of Nd doped phosphate glass, and the roughness will not be coarsened.

  20. Protein-adsorption and Ca-phosphate formation on chitosan-bioactive glass composite coatings

    Science.gov (United States)

    Wagener, V.; Boccaccini, A. R.; Virtanen, S.

    2017-09-01

    In the last years, chitosan-bioactive glass (BG) composites have been developed and investigated as bioactive coatings for orthopedic applications. The increase of bioactivity occurs due to the stimulation of calcium-phosphate/hydroxyapatite formation on the surface while the coating is degrading. In the present work, protein adsorption and its influence on calcium-phosphate precipitation was studied for the first time on such composite coatings. The experiments involved coating of 316L stainless steel substrates with chitosan (Ch) and chitosan-bioactive glass (Ch-BG) and immersion of the coated samples in two different bovine serum albumin (BSA) containing solutions, namely DI H2O (with pH adjusted to about 7.2 with diluted NaOH) and simulated body fluid (SBF). In order to investigate the influence of protein adsorption on calcium-phosphate precipitation, samples were also immersed in DI H2O and in SBF without BSA. Samples were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Surface analysis revealed that adsorption of BSA takes place on all studied samples and that protein adsorption is influenced by the presence of Ca2+ and PO43- ions. Bioactivity in the form of hydroxyapatite pre-stage formation is significantly increased on Ch-BG composite coating as compared with bare stainless steel surface. However, calcium-phosphate precipitation in SBF is reduced by the presence of BSA.

  1. Terahertz generation and detection using femtosecond mode-locked Yb-doped fiber laser

    Science.gov (United States)

    Kong, Moon Sik; Kim, Ji Su; Han, Sang-Pil; Kim, Namje; Moon, Ki Won; Park, Kyung Hyun; Jeon, Min Yong

    2016-02-01

    We successfully demonstrate a THz generation using an ytterbium (Yb)-doped mode-locked femtosecond fiber laser and a home-made low-temperature grown (LTG) InGaAs Photoconductive antenna (PCA) module for THz Time-domain spectroscopy (TDS) systems. The Yb-doped fiber ring laser consists of a pump laser diode (PLD), a wavelength division multiplexer (WDM) coupler, a single-mode fiber (SMF), a 25 cm-long highly Yb-doped fiber, two collimators, two quarter wave plates (QWPs), a half-wave plate (HWP), a 10 nm broadband band pass filter, an isolator, and a polarizing beam splitter (PBS). In order to achieve the passively mode-locked optical short pulse, the nonlinear polarization rotation (NPR) effect is used. The achieved center wavelength and the 3 dB bandwidth of the modelocked fiber laser are 1.03 μm and ~ 15.6 nm, respectively. It has 175 fs duration after pulse compression with 66.2 MHz repetition rate. The average output power of mode-locked laser has more than 275 mW. The LTG-InGaAs PCA modules are used as the emitter and receiver in order to achieve the THz radiation. The PCA modules comprise a hyper-hemispherical Si lens and a log-spiral antenna-integrated LTG-InGaAs PCA chip electronically contacted on a printed circuit board (PCB). An excitation optical average pumping and probing power were ~ 6.3 mW and 5 mW, respectively. The free-space distance between the emitter and the receiver in the THz-TDS system was 70 mm. The spectrum of the THz radiation is achieved higher than 1.5 THz.

  2. Second harmonic pico-second pulse generation with mode-locked 1064nm DBR laser diodes

    Science.gov (United States)

    Klehr, A.; Prziwarka, T.; Jedrzejczyk, D.; Brox, O.; Bugge, F.; Wenzel, H.; Paschke, K.; Erbert, G.; Tränkle, G.

    2014-02-01

    Detailed experimental investigations of the generation of high-energy short infrared and green pulses with a mode-locked multi-section distributed Bragg reflector (DBR) laser in dependence on the lengths of the gain section and the saturableabsorber (SA) section as well the corresponding input currents and reverse voltages, respectively, are presented. The laser under investigation is 3.5 mm long and has a 500 μm long DBR section. The remaining cavity was divided into four 50 μm, four 100 μm, two 200 μm and eight 250 μm long electrically separated segments so that the lengths of the gain and SA sections can be simply varied by bonding. Thus, the dependence of the mode-locking behavior on the lengths of the gain and SA sections can be investigated on the same device. Optimal mode-locking was obtained for absorber lengths between LAbs = 200 μm and 300 μm and absorber voltages between UAbs= -2 V and -3 V. A pulse length of τ ≍ 10 ps, a repetition frequency of 13 GHz and a RF line width of less than 100 kHz were measured. An infrared peak pulse power of 900 mW was reached. The FWHM of the optical spectrum was about 150 pm. With an 11.5 mm long periodically poled MgO doped LiNbO3 crystal having a ridge geometry of 5 μm width and 4 μm height green light pulses were generated. With an infrared pump peak power of 900 mW a green pulse energy of 3.15 pJ was reached. The opto-optical conversion efficiency was about 31%.

  3. Study of multicomponent fluoro-phosphate based glasses: Ho{sup 3+} as a luminescence center

    Energy Technology Data Exchange (ETDEWEB)

    Babu, S. [Department of Physics, Sri Venkateswara University, Tirupati, 517502 Andhra Pradesh (India); Seshadri, M. [Institute of Physics, University of Campinas, UNICAMP, P.O. Box 6165, Campinas 13083-970 (Brazil); Balakrishna, A.; Reddy Prasad, V. [Department of Physics, Sri Venkateswara University, Tirupati, 517502 Andhra Pradesh (India); Ratnakaram, Y.C., E-mail: ratnakaramsvu@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati, 517502 Andhra Pradesh (India)

    2015-12-15

    The multicomponent 49.5P{sub 2}O{sub 5}–10AlF{sub 3}–10BaF{sub 2}–10SrF{sub 2}–10PbO–10M (M=Li{sub 2}O, Na{sub 2}O, K{sub 2}O, ZnO and Bi{sub 2}O{sub 3}) glasses doped with 0.5 mol% holmium were prepared by melt quenching technique. Their thermal behavior was examined from differential scanning calorimetry (DSC). It is found that bismuth fluoro-phosphate glass matrix has good thermal stability. Their structures were characterized by the X-ray diffraction with SEM analysis, fourier transform infrared (FTIR), Raman spectroscopy and magic angle spinning (MAS) nuclear magnetic resonance (NMR) techniques. It was found that the phosphate network of these glasses was composed mainly of Q{sup 2} and Q{sup 3} phosphate tetrahedral units. The Judd–Ofelt parameters (J–O) (Ω{sub 2}, Ω{sub 4} and Ω{sub 6}) were evaluated from the intensities of the energy levels through optical absorption spectra. The most intense transitions are observed in the visible region of the spectrum. It is observed that the transition {sup 5}I{sub 8}→{sup 5}G{sub 6} is the hypersensitive transition for Ho{sup 3+} ion. With these J–O parameters, various radiative properties like the probabilities of radiative transitions, radiative lifetimes and branching ratios have been calculated for different fluoro-phosphate glasses. The luminescence kinetics from excited holmium levels have been studied upon selective excitation through photoluminescence measurements. Holmium produces two visible laser emissions i.e. one is green ({sup 5}F{sub 4}({sup 5}S{sub 2})→{sup 5}I{sub 8} ) and another one is red ({sup 5}F{sub 5}→{sup 5}I{sub 8}). The lifetimes of these levels have been experimentally determined through decay profile studies. The above results suggest that the prepared bismuth fluoro-phosphate glass system could be a suitable candidate for using it as a green laser source ({sup 5}F{sub 4}({sup 5}S{sub 2})→{sup 5}I{sub 8} ) in the visible region of the spectrum. - Highlights:

  4. Mode-locked pulse oscillation of a self-resonating enhancement optical cavity

    CERN Document Server

    Hosaka, Yuji; Kosuge, Atsushi; Omori, Tsunehiko; Sakaue, Kazuyuki; Takahashi, Tohru; Uesugi, Yuuki; Urakawa, Junji; Washio, Masakazu

    2016-01-01

    A power enhancement optical cavity is a compelling means of realizing a pulsed laser with a high peak power and a high repetition frequency, which is not feasible by using a simple amplifier scheme. However, a precise feedback system is necessary for maintaining the narrow resonance condition of the optical cavity, and has become a major technical issue in developing such cavities. We developed a new approach that does not require any active feedback system, by placing the cavity in the outer loop of a laser amplifier. We report on the first demonstration of a mode-locked pulse oscillation using the new system.

  5. 1700 nm dispersion managed mode-locked bismuth fiber laser

    OpenAIRE

    Teppo Noronen; Sergei Firstov; Evgeny Dianov; Okhotnikov, Oleg G.

    2016-01-01

    We demonstrate the first 1.7 μm bismuth-doped fiber laser generating ultrashort pulses via passive mode-locking. Pulse operation has been achieved for both anomalous and normal dispersion of the laser cavity owing to broadband characteristics of carbon nanotube saturable absorber. The laser delivered 1.65 ps pulses in net anomalous dispersion regime. In normal dispersion regime, the laser delivered 14 ps pulses which could be compressed to 1.2 ps using external fiber compressor.

  6. 1700 nm dispersion managed mode-locked bismuth fiber laser

    Science.gov (United States)

    Noronen, Teppo; Firstov, Sergei; Dianov, Evgeny; Okhotnikov, Oleg G.

    2016-04-01

    We demonstrate the first 1.7 μm bismuth-doped fiber laser generating ultrashort pulses via passive mode-locking. Pulse operation has been achieved for both anomalous and normal dispersion of the laser cavity owing to broadband characteristics of carbon nanotube saturable absorber. The laser delivered 1.65 ps pulses in net anomalous dispersion regime. In normal dispersion regime, the laser delivered 14 ps pulses which could be compressed to 1.2 ps using external fiber compressor.

  7. Cross-phase modulation instability in mode-locked laser based on reduced graphene oxide

    CERN Document Server

    Gaol, Lei; Liu, Min; Huang, Wei

    2014-01-01

    Cross-phase modulation instability (XPMI) is experimentally observed in a fiber ring cavity with net normal dispersion and mode-locked by long fiber taper. The taper is deposited with reduced graphene oxide, which can decrease the threshold of XPMI due to the enhanced nonlinearity realized by 8 mm evanescent field interaction length and strong mode confinement. Experimental results indicate that the phase matching conditions in two polarization directions are different, and sidebands with different intensities are generated. This phase matching condition can be satisfied even the polarization state of the laser varies greatly under different pump strengths.

  8. Mode-locked picosecond pulse generation from an octave-spanning supercontinuum

    CERN Document Server

    Kielpinski, D; Canning, J; Stevenson, M; Westbrook, P S; Feder, K S

    2011-01-01

    We generate mode-locked picosecond pulses near 1110 nm by spectrally slicing and reamplifying an octave-spanning supercontinuum source pumped at 1550 nm. The 1110 nm pulses are near transform-limited, with 1.7 ps duration over their 1.2 nm bandwidth, and exhibit high interpulse coherence. Both the supercontinuum source and the pulse synthesis system are implemented completely in fiber. The versatile source construction suggests that pulse synthesis from sliced supercontinuum may be a useful technique across the 1000 - 2000 nm wavelength range.

  9. Microwave signal extraction from femtosecond mode-locked lasers with attosecond relative timing drift.

    Science.gov (United States)

    Kim, Jungwon; Kärtner, Franz X

    2010-06-15

    We present a feedback-control method for suppression of excess phase noise in the optical-to-electronic conversion process involved in the extraction of microwave signals from femtosecond mode-locked lasers. A delay-locked loop based on drift-free phase detection with a differentially biased Sagnac loop is employed to eliminate low-frequency (e.g., locked laser with a relative rms timing jitter of 2.4 fs (integrated from 1 mHz to 1 MHz) and a relative rms timing drift of 0.84 fs (integrated over 8 h with 1 Hz bandwidth) between the optical pulse train and the extracted microwave signal.

  10. Analysis of timing jitter in external-cavity mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Mørk, Jesper

    2006-01-01

    processes, self-phase modulation, and spontaneous emission noise. Fluctuations of the mode-locked pulses are characterized from the fully distributed model using direct integration of noise-skirts in the phase-noise spectrum and the soliton perturbations introduced by Haus. We implement the model in order...... to investigate the performance of a MQW buried heterostructure laser. Results from numerical simulations show that the optimum driving conditions for achieving the shortest pulses with minimum timing jitter occur for large reverse bias in the absorber section at an optimum optical bandwidth limited by Gordon...

  11. Mode-locked Lasers Applied to Deflecting a Near Earth Object on Collision Course with Earth

    CERN Document Server

    Fork, Richard; Burgess, Luke; Bergstue, Grant

    2013-01-01

    We consider synchronized trains of sub-picosecond pulses generated by mode-locked lasers applied to deflection of near Earth objects (NEO) on collision course with Earth. Our method is designed to avoid a predicted collision of the NEO with Earth by at least the diameter of Earth. We estimate deflecting a 10,000 MT NEO, such as the asteroid which struck Earth near Chelyabinsk, Russia to be feasible within several months using average power in the ten kilowatt range. We see this deflection method as scalable to larger NEO to a degree not possible using continuous laser systems.

  12. Simultaneous picosecond and femtosecond solitons delivered from a nanotube-mode-locked all-fiber laser.

    Science.gov (United States)

    Han, D D; Liu, X M; Cui, Y D; Wang, G X; Zeng, C; Yun, L

    2014-03-15

    We propose a compact nanotube-mode-locked all-fiber laser that can simultaneously generate picosecond and femtosecond solitons at different wavelengths. The pulse durations of picosecond and femtosecond solitons are measured to be ∼10.6  ps and ∼466  fs, respectively. Numerical results agree well with the experimental observations and clearly reveal that the dynamic evolutions of the picosecond and femtosecond solitons are qualitatively distinct in the intracavity. Our study presents a simple, stable, low-cost, and dual-scale ultrafast-pulsed laser source suitable for practical applications in optical communications.

  13. Sub-picosecond ultra-low frequency passively mode-locked fiber laser

    Science.gov (United States)

    Cuadrado-Laborde, Christian; Cruz, José L.; Díez, Antonio; Andrés, Miguel V.

    2016-11-01

    We developed a nonlinear polarization rotation all-fiber mode-locked erbium-doped fiber laser, with the purpose to reach a sub-picosecond and sub-megahertz light pulse emission. In the process, we observed three different emission regimes as the net birefringence is changed, namely high-power dissipative soliton resonance, low-power soliton regime, and a mixed combination of both. In the pure solitonic regime, a 0.961 MHz train of chirp-free Gaussian pulses was obtained, with a time width of 0.919 ps at 1564.3 nm.

  14. Fourier domain mode-locked swept source at 1050 nm based on a tapered amplifier

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang;

    2010-01-01

    While swept source optical coherence tomography (OCT) in the 1050 nm range is promising for retinal imaging, there are certain challenges. Conventional semiconductor gain media have limited output power, and the performance of high-speed Fourier domain mode-locked (FDML) lasers suffers from...... achieved stable FDML operation, exploiting the full bandwidth of the tapered amplifier despite high dispersion. The light source operates at a repetition rate of 116 kHz with an effective average output power in excess of 30 mW. With a total sweep range of 70 nm, we achieved an axial resolution of 15 μm...

  15. Supercontinuum generation pumped by a regeneratively mode-locked fiber laser

    Institute of Scientific and Technical Information of China (English)

    JIA Dong-fang; TAN Bin; WANG Zhao-ying; GE Chun-feng; NI Wen-jun; LI Shi-chen

    2005-01-01

    Supercontinuum(SC) generation in a dispersion-shifted fiber(DSF) pumped by a 10 GHz regeneratively mode-locked fiber laser(RMLFL) is presented.Optimization of pump wavelength leads to a 20 dB bandwidth of 58.73 nm,which covers the whole C band and part of L band.Using an angle-tuning thin film filter,multi-wavelength and pico-second pulse trains of low chirp could be chosen from the SC spectrum.Amplified spontaneous emission(ASE) induced degeneration of the achieved pulse trains is observed and discussed.

  16. Polarisation effects in twin-core fibre: Application for mode locking in a fibre laser

    Science.gov (United States)

    Lobach, I. A.; Kablukov, S. I.; Podivilov, Evgenii V.; Babin, Sergei A.; Apolonski, A. A.

    2012-09-01

    We report the first measurements of the longitudinal power distribution in a twin-core optical fibre at different input light polarisations. Experimental evidence is presented that, because of the difference in birefringence between the cores, the power in them depends on which core the beam is launched into. Experimental data are interpreted in terms of a modified polarisation model for mode coupling in twin-core fibres which takes into account the birefringence of the cores. In addition, we demonstrate for the first time the use of the polarisation properties of a twincore fibre for mode locking in a fibre laser.

  17. Polarisation effects in twin-core fibre: Application for mode locking in a fibre laser

    Energy Technology Data Exchange (ETDEWEB)

    Lobach, I A; Kablukov, S I; Podivilov, Evgenii V; Babin, Sergei A; Apolonski, A A

    2012-09-30

    We report the first measurements of the longitudinal power distribution in a twin-core optical fibre at different input light polarisations. Experimental evidence is presented that, because of the difference in birefringence between the cores, the power in them depends on which core the beam is launched into. Experimental data are interpreted in terms of a modified polarisation model for mode coupling in twin-core fibres which takes into account the birefringence of the cores. In addition, we demonstrate for the first time the use of the polarisation properties of a twincore fibre for mode locking in a fibre laser. (optical fibres, lasers and amplifiers. properties and applications)

  18. Effects of resonator input power on Kerr lens mode-locked lasers

    Indian Academy of Sciences (India)

    S Kazempour; A Keshavarz; G Honarasa

    2015-07-01

    Using the ABCD matrix method, the common stability region between the sagittal and tangential planes of a four-mirror Kerr lens mode-locked (KLM) laser cavity is obtained for different ranges of input power. In addition, the effect of the input power on the Kerr lens sensitivity is investigated. Optimal input power and position for highest Kerr lens sensitivity in the stability region are presented and self-starting regime has been achieved. Results show that the resonator input power has a great influence on designing the KLM lasers which can be used in fabricating an optimal femtosecond laser.

  19. Evanescent-wave coupled right angled buried waveguide: Applications in carbon nanotube mode-locking

    Energy Technology Data Exchange (ETDEWEB)

    Mary, R.; Thomson, R. R.; Kar, A. K., E-mail: a.k.kar@hw.ac.uk [Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Brown, G. [Optoscribe Ltd, 0/14 Alba Innovation Centre, Alba Campus, Livingston EH54 7GA (United Kingdom); Beecher, S. J. [Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ (United Kingdom); Popa, D.; Sun, Z.; Torrisi, F.; Hasan, T.; Milana, S.; Bonaccorso, F.; Ferrari, A. C. [Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA (United Kingdom)

    2013-11-25

    We present an evanescent-field device based on a right-angled waveguide. This consists of orthogonal waveguides, with their points of intersection lying along an angled facet of the chip. Light guided along one waveguide is incident at the angled dielectric-air facet at an angle exceeding the critical angle, so that the totally internally reflected light is coupled into the second waveguide. By depositing a nanotube film on the angled surface, the chip is then used to mode-lock an Erbium doped fiber ring laser with a repetition rate of 26 MHz, and pulse duration of 800 fs.

  20. Trade-off between Linewidth and Slip Rate in a Mode-Locked Laser Model

    CERN Document Server

    Moore, Richard O

    2014-01-01

    We demonstrate a trade-off between linewidth and loss-of-lock frequency in a mode-locked laser employing active feedback to control the carrier-envelope offset phase difference. In frequency metrology applications, the linewidth translates directly to uncertainty in the measured frequency, while the impact of lock loss and recovery on the measured frequency is less well understood. We reduce the dynamics to stochastic differential equations, specifically diffusion processes, and compare the linearized linewidth to the rate of lock loss determined by the mean time to exit calculated from large deviation theory.

  1. Mode-locked 1.5 micrometers semiconductor optical amplifier fiber ring

    OpenAIRE

    Pedersen, Niels V.; Jakobsen, Kaj Bjarne; Vaa, Michael

    1996-01-01

    The dynamics of a mode-locked SOA fiber ring are investigated experimentally and numerically. Generation of near transform-limited (time-bandwidth product=0.7) 1.5 μm 54 ps FWHM pulses with a peak power of 2.8 mW at a repetition rate of 960 MHz is demonstrated experimentally. The experimental results agree well with the simulation results obtained using a transmission line laser model (TLLM) model, Both experiments and numerical simulations show how the RF power and the detuning affect the pu...

  2. Passively Mode-Locked Fiber Laser with a Sub-Megahertz Repetition Rate

    Institute of Scientific and Technical Information of China (English)

    CHEN Jiong; JIA Dong-Fang; WU Yong-Chao; WANG Chang-Le; WANG Zhao-Ying; YANG Tian-Xin

    2011-01-01

    We demonstrate an ultra-long cavity by which an all-fiber erbium-doped fiber laser is passively mode-locked by nonlinear polarization rotation.The length of the resonant cavity amounts to 466m,which can be achieved by incorporating a 420m highly nonlinear fiber.The laser generates stable mode-locked pulses with a 444 kHz fundamental repetition rate.A near transform-limited subpicosecond pulse is obtained without any dispersion compensation.The maximum average power of the output pulses is 5.16 mW,which corresponds to a per-pulse energy of 11.62nJ.A low-repetition-rate optical pulse train is required for many applications such as micromachining,biomedical diagnostics and lidar systems.[1-3] However,the repetition rate of conventional fiber lasers is normally tens of MHz.Pulse pickers such as Pockels cells or acousto-optic modulators are always used to lower the repetition rate,however,reduction in this way introduces significant energy losses,impairs the signal-to-noise ratio (SNR) and increases complexity.Because the pulse repetition rate of a modelocked laser is inversely proportional to its resonator length,longer cavities lead to lower pulse repetition rates and,consequently,to higher pulse energy at the same average power of radiation.%We demonstrate an ultra-long cavity by which an all-fiber erbium-doped fiber laser is passively mode-locked by nonlinear polarization rotation. The length of the resonant cavity amounts to 466 m, which can be achieved by incorporating a 420 m highly nonlinear fiber. The laser generates stable mode-locked pulses with a 444 kHz fundamental repetition rate. A near transform-limited subpicosecond pulse is obtained without any dispersion compensation. The maximum average power of the output pulses is 5.16mW, which corresponds to a per-pulse energy of 11.62 nJ.

  3. Wide-band residual phase-noise measurements on 40-GHz monolithic mode-locked lasers

    DEFF Research Database (Denmark)

    Larsson, David; Hvam, Jørn Märcher

    2005-01-01

    We have performed wide-band residual phase-noise measurements on semiconductor 40-GHz mode-locked lasers by employing electrical waveguide components for the radio-frequency circuit. The intrinsic timing jitters of lasers with one, two, and three quantum wells (QW) are compared and our design...... prediction, concerning noise versus number of QWs, for the first time corroborated by experiments. A minimum jitter of 44 fs is found, by extrapolating to the Nyquist frequency, for the one-QW device having nearly transform-limited pulses of 1.2 ps. This jitter is nearly three times lower than for a three...

  4. Eu{sup 3+} emission in phosphate glasses with high UV transparency

    Energy Technology Data Exchange (ETDEWEB)

    Silva, G.H. [Laboratório de Espectroscopia de Materiais (LEM), Departamento de Física, Universidade Federal de Juiz de Fora, CEP 36036-900 Juiz de Fora, MG (Brazil); Anjos, V., E-mail: virgilio@fisica.ufjf.br [Laboratório de Espectroscopia de Materiais (LEM), Departamento de Física, Universidade Federal de Juiz de Fora, CEP 36036-900 Juiz de Fora, MG (Brazil); Bell, M.J.V. [Laboratório de Espectroscopia de Materiais (LEM), Departamento de Física, Universidade Federal de Juiz de Fora, CEP 36036-900 Juiz de Fora, MG (Brazil); Carmo, A.P. [Instituto Federal Fluminense-Campus Cabo Frio, CP 112015, CEP 28909-971 Cabo Frio, RJ (Brazil); Pinheiro, A.S.; Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, CP 593, CEP 38400-902 Uberlândia, MG (Brazil)

    2014-10-15

    We report a study of the phosphate glass PZABP (P{sub 2}O{sub 5}–ZnO–Al{sub 2}O{sub 3}–BaO–PbO) doped with europium (Eu{sup 3+}) in different concentrations. Absorption, photoluminescence and time resolved photoluminescence were used to investigate the influence of increasing Eu{sup 3+} concentrations. The present glass exhibits Eu{sup 3+} absorption bands in the ultraviolet region (about 300 nm) due to the high transparency of the system compared to other phosphate glasses. In this way, it was possible to obtain the Judd–Ofelt parameters from the emission and absorption spectra. Moreover, a strong red emission attributed to the transition {sup 5}D{sub 0}→{sup 7}F{sub 2} of Eu{sup 3+} (611 nm) was observed. It was found that the radiative lifetime and the quantum efficiency of the Eu{sup 3+} level, {sup 5}D{sub 0}, do not suffer a significant change as the concentration of Eu{sup 3+} ions increases. - Highlights: • UV transparent glass matrix is used for Eu{sup 3+} doping. • Judd–Ofelt parameters from the emission and absorption spectra were obtained. • Red emission attributed to the transition {sup 5}D{sub 0}→{sup 7}F{sub 2} of Eu{sup 3+} (611 nm) was observed.

  5. Photosensitivity of ion-exchanged Er-doped phosphate glass using 248nm excimer laser radiation.

    Science.gov (United States)

    Pissadakis, Stavros; Ikiades, Aris; Hua, Ping; Sheridan, Anna; Wilkinson, James

    2004-07-12

    The photosensitivity to 248nm excimer laser radiation of Er-doped Schott IOG-1 phosphate glass is presented. The photosensitive mechanism is investigated by employing a grating recording process. Index changes of up to ~2.0x10(-3) were measured in silver ion-exchanged samples using diffraction efficiency measurements; whereas changes of only ~10(-5) were measured for non-ion-exchanged samples. Absorption measurements allowed the identification of specific color center bands, which were attributed to the glass matrix and to the silver ions. Investigation of the exposed ion-exchanged glass using scanning electron microscopy and energy dispersive x-ray microanalysis revealed that in addition to the color centers formed, silver ion migration and ionization contribute significantly to the UV-induced index changes.

  6. Luminescent properties of Bi-doped boro-alumino-phosphate glasses

    Science.gov (United States)

    Denker, B.; Galagan, B.; Osiko, V.; Sverchkov, S.; Dianov, E.

    2007-03-01

    A new Bi-doped boro-alumino-phosphate glass (BAP) composition was developed. Absorption and emission spectra and luminescence decay kinetics were investigated. The emission spectrum consists of two wide bands in the visible (0.6 0.8 μm) and near-infrared (˜1.0 1.5 μm) ranges. The luminescence decay curve investigation has revealed a complicated behavior dependent on both excitation and registration wavelengths. In contrast to earlier investigated Bi-doped glasses, Bi:BAP has good technological properties and can be easily scaled. This makes the developed glass composition interesting for broadband tunable (˜1.0 1.5 μm) lasers and amplifiers.

  7. Radiation damage induced by gamma irradiation on Ce sup 3 sup + doped phosphate and silicate scintillating glasses

    CERN Document Server

    Baccaro, S; Mihoková, E; Nikl, M; Nitsch, K; Polato, P; Zanella, G; Zannoni, R

    2002-01-01

    The effect of gamma irradiation on the optical properties of Ce sup 3 sup + -doped phosphate and silicate glasses is studied in the 1-250 Gy dose range. Results are discussed by taking into account the possible dependence of radiation-induced effects on the composition of the glass matrix.

  8. Modeling the absorption spectra of Er3+ and Yb3+ in a phosphate glass

    Science.gov (United States)

    Gruber, John B.; Sardar, Dhiraj K.; Zandi, Bahram; Hutchinson, J. Andrew; Trussell, C. Ward

    2003-10-01

    Absorption spectra of Er3+ and Yb3+ ions, codopants in a phosphate glass, are reported at 8 K and at wavelengths between 350 and 1600 nm. Detailed structure appearing in the spectra, associated with individual multiplet states, 2S+1LJ, of Er3+(4f11) and Yb3+(4f13) is interpreted using a ligand-field coordination sphere model to characterize the microscopic environment surrounding the rare earth ions in multiple sites. Inhomogeneous broadening of the spectra is likely due to different configurations of PO4 tetrahedra clustered about a caged rare earth ion in the amorphous host. Similarity between the Er3+ spectrum in the glass and in the spectrum of single-crystal LiErP4O12, where Er3+ occupies sites of C2 symmetry, suggests that an averaged site symmetry of C2 is a reasonable approximation for Er3+ and Yb3+ ions in the phosphate glass. Calculated splitting of multiplet states by the ligand-field cluster model are compared with energy levels derived from the observed absorption peaks and well-defined shoulders. Inhomogeneous broadening of the spectra limit the precision in establishing the energy of the multiplet splittings, but the analysis is useful for modeling studies of the Er:Yb:phosphate glass as an eye-safe laser (1.53 μm). The splitting of the Yb3+(4f13)2FJ states is determined using parameters obtained from the Er3+ set by means of the three-parameter theory. No adjustments were made to the Yb3+ parameters that predict multiplet splittings in reasonable agreement with experimental data.

  9. Development of large-scale production of Nd-doped phosphate glasses for megajoule-scale laser systems

    Science.gov (United States)

    Ficini, Gaelle; Campbell, Jack H.

    1996-08-01

    Nd-doped phosphate glasses are the preferred gain medium for high-peak-power lasers used for inertial confinement fusion research because they have excellent energy storage and extraction characteristics. In addition, these glasses can be manufactured defect-free in large sizes and a t relatively low cost. To meet the requirements of the future megajoule size lasers, advanced laser glass manufacturing methods are being developed that would enable laser glass to be continuously produced at the rate of several thousand large plates of glass per year. This represents more than a 10 to 100-fold improvement in the scale of the present manufacturing technology.

  10. Mode-locking neurodynamics predict human auditory brainstem responses to musical intervals.

    Science.gov (United States)

    Lerud, Karl D; Almonte, Felix V; Kim, Ji Chul; Large, Edward W

    2014-02-01

    The auditory nervous system is highly nonlinear. Some nonlinear responses arise through active processes in the cochlea, while others may arise in neural populations of the cochlear nucleus, inferior colliculus and higher auditory areas. In humans, auditory brainstem recordings reveal nonlinear population responses to combinations of pure tones, and to musical intervals composed of complex tones. Yet the biophysical origin of central auditory nonlinearities, their signal processing properties, and their relationship to auditory perception remain largely unknown. Both stimulus components and nonlinear resonances are well represented in auditory brainstem nuclei due to neural phase-locking. Recently mode-locking, a generalization of phase-locking that implies an intrinsically nonlinear processing of sound, has been observed in mammalian auditory brainstem nuclei. Here we show that a canonical model of mode-locked neural oscillation predicts the complex nonlinear population responses to musical intervals that have been observed in the human brainstem. The model makes predictions about auditory signal processing and perception that are different from traditional delay-based models, and may provide insight into the nature of auditory population responses. We anticipate that the application of dynamical systems analysis will provide the starting point for generic models of auditory population dynamics, and lead to a deeper understanding of nonlinear auditory signal processing possibly arising in excitatory-inhibitory networks of the central auditory nervous system. This approach has the potential to link neural dynamics with the perception of pitch, music, and speech, and lead to dynamical models of auditory system development.

  11. Electrical addressing and temporal tweezing of localized pulses in passively-mode-locked semiconductor lasers

    Science.gov (United States)

    Camelin, P.; Javaloyes, J.; Marconi, M.; Giudici, M.

    2016-12-01

    We show that the pumping current is a convenient parameter for manipulating the temporal localized structures (LSs), also called localized pulses, found in passively-mode-locked vertical-cavity surface-emitting lasers. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing one to control the position and the dynamics of LSs. We show that the localized pulse drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on a finite time scale and breaks the parity invariance along the cavity, thus leading to a different paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. Starting from a generic model of passive mode locking based upon delay differential equations, we deduce the effective equations of motion for these LSs in a time-dependent current landscape.

  12. An ultrafast optics undergraduate advanced laboratory with a mode-locked fiber laser

    Science.gov (United States)

    Schaffer, Andrew; Fredrick, Connor; Hoyt, Chad; Jones, Jason

    2015-05-01

    We describe an ultrafast optics undergraduate advanced laboratory comprising a mode-locked erbium fiber laser, auto-correlation measurements, and an external, free-space parallel grating dispersion compensation apparatus. The simple design of the stretched pulse laser uses nonlinear polarization rotation mode-locking to produce pulses at a repetition rate of 55 MHz and average power of 5.5 mW. Interferometric and intensity auto-correlation measurements are made using a Michelson interferometer that takes advantage of the two-photon nonlinear response of a common silicon photodiode for the second order correlation between 1550 nm laser pulses. After a pre-amplifier and compression, pulse widths as narrow as 108 fs are measured at 17 mW average power. A detailed parts list includes previously owned and common components used by the telecommunications industry, which may decrease the cost of the lab to within reach of many undergraduate and graduate departments. We also describe progress toward a relatively low-cost optical frequency comb advanced laboratory. NSF EIR #1208930.

  13. Kerr Lens Mode-locked Operation of Yb:KYW Laser

    Institute of Scientific and Technical Information of China (English)

    Falihati.Mejiti; V.L.Kalashnikov; I.G.Poloyko; Toran.Vajidi

    2002-01-01

    Using a modified ABCD-matrix approach accounting for nonlinear refraction in active medium,the ranges of cavity parameters that provide a mode-locking of Yb∶KYW-laser in usual z-fold cavity configuration are determined.Taking the cavity parameters that provide a most efficient mode locking and based on fluctuation model,a numerical simulation of laser operation is performed.In the calculations the side-band pump power of 6W at 982 nm is used in 1 cm length KYW crystal with 1 cm×0.005 cm beam cross section.Calculations show that self-starting operation is possible with these parameters and dispersion compensation allows for bandwidth-limited ultrashort pulse generation.The shortest pulse duration was determined to be about 200 fs with self-starting buid-up time of 130 μs.Such a built-up time is comparable and even shorter than that one for the lasers with semiconductor saturable absorbers.The region of negative dispersion provided by prism pair for a stable ultrashort pulse generation was determined to be (-17000~-42000)fs2.

  14. Modeling of mode-locking in a laser with spatially separate gain media

    CERN Document Server

    Oldenbeuving, R M; van Voorst, P D; Offerhaus, H L; Boller, K -J

    2010-01-01

    We present a novel laser mode-locking scheme and discuss its unusual properties and feasibility using a theoretical model. A large set of single-frequency continuous-wave lasers oscillate by amplification in spatially separated gain media. They are mutually phase-locked by nonlinear feedback from a common saturable absorber. As a result, ultra short pulses are generated. The new scheme offers three significant benefits: the light that is amplified in each medium is continuous wave, thereby avoiding issues related to group velocity dispersion and nonlinear effects that can perturb the pulse shape. The set of frequencies on which the laser oscillates, and therefore the pulse repetition rate, is controlled by the geometry of resonator-internal optical elements, not by the cavity length. Finally, the bandwidth of the laser can be controlled by switching gain modules on and off. This scheme offers a route to mode-locked lasers with high average output power, repetition rates that can be scaled into the THz range, ...

  15. Ultrafast non-equilibrium carrier dynamics in semiconductor laser mode-locking

    Science.gov (United States)

    Hader, J.; Scheller, M.; Laurain, A.; Kilen, I.; Baker, C.; Moloney, J. V.; Koch, S. W.

    2017-01-01

    Experimental and theoretical results on the mode-locking dynamics in vertical-external-cavity surface-emitting lasers with semiconductor and graphene saturable absorber mirrors are reviewed with an emphasis on the role of nonequilibrium carrier effects. The systems are studied theoretically using a fully microscopic many-body model for the carrier distributions and polarizations, coupled to Maxwell’s equations for the field propagation. Pump-probe measurements are performed with (sub-) 100 fs resolution. The analysis shows that the non-equilibrium carrier dynamics in the gain quantum-wells and saturable absorber medium significantly influences the system’s response and the resulting mode-locked pulses. The microscopic model is used to study the pulse build up from spontaneous emission noise and to determine the dependence of achievable pulse lengths and fluences on the amounts of saturable and non-saturable losses and the optical gain. The change of the group delay dispersion (GDD) on the pump level is examined and the dependence of the pulse lengths on the total amount of GDD is demonstrated experimentally. Theory-experiment comparisons are used to demonstrate the highly quantitative accuracy of the fully microscopic modeling.

  16. Multiple-Pulse Operation and Bound States of Solitons in Passive Mode-Locked Fiber Lasers

    Directory of Open Access Journals (Sweden)

    A. Komarov

    2012-01-01

    Full Text Available We present results of our research on a multiple-pulse operation of passive mode-locked fiber lasers. The research has been performed on basis of numerical simulation. Multihysteresis dependence of both an intracavity energy and peak intensities of intracavity ultrashort pulses on pump power is found. It is shown that the change of a number of ultrashort pulses in a laser cavity can be realized by hard as well as soft regimes of an excitation and an annihilation of new solitons. Bound steady states of interacting solitons are studied for various mechanisms of nonlinear losses shaping ultrashort pulses. Possibility of coding of information on basis of soliton trains with various bonds between neighboring pulses is discussed. The role of dispersive wave emitted by solitons because of lumped intracavity elements in a formation of powerful soliton wings is analyzed. It is found that such powerful wings result in large bounding energies of interacting solitons in steady states. Various problems of a soliton interaction in passive mode-locked fiber lasers are discussed.

  17. Towards monolithic integration of mode-locked vertical cavity surface emitting laser

    Science.gov (United States)

    Aldaz, Rafael I.

    2007-12-01

    The speed and performance of today's high end computing and communications systems have placed difficult but still feasible demands on off-chip electrical interconnects. However, future interconnect systems may need aggregate bandwidths well into the terahertz range thereby making electrical bandwidth, density, and power targets impossible to meet. Optical interconnects, and specifically compact semiconductor mode-locked lasers, could alleviate this problem by providing short pulses in time at 10s of GHz repetition rates for Optical Time Division Multiplexing (OTDM) and clock distribution applications. Furthermore, the characteristic spectral comb of frequencies of these lasers could also serve as a multi-wavelength source for Wavelength Division Multiplexing (WDM) applications. A fully integrated mode-locked Vertical Cavity Surface Emitting Laser (VCSEL) is proposed as a low-cost high-speed source for these applications. The fundamental laser platform for such a device has been developed and a continuous-wave version of these lasers has been fabricated and demonstrated excellent results. Output powers close to 60mW have been obtained with very high beam quality factor of M2 unassisted ultrafast QD saturable absorbers, without the need to incorporate high concentrations of non radiative recombination centers by either ion-implantation or low temperature growth.

  18. Optical 40 GHz pulse source module based on a monolithically integrated mode locked DBR laser

    Science.gov (United States)

    Huettl, B.; Kaiser, R.; Kroh, M.; Schubert, C.; Jacumeit, G.; Heidrich, H.

    2005-11-01

    In this paper the performance characteristics of compact optical 40 GHz pulse laser modules consisting of a monolithic mode-locked MQW DBR laser on GaInAsP/InP are reported. The monolithic devices were fabricated as tunable multi-section buried heterostructure lasers. A DBR grating is integrated at the output port of an extended cavity in order to meet the standardized ITU wavelength channels allocated in the spectral window around 1.55 μm in optical high speed communication networks. The fabricated 40 GHz lasers modules not only emit short optical pulses (< 1.5 ps) with very low amplitude noise (<1.5 %) and phase noise levels (timing jitter: 50 fs) but also enable good pulse-to-pulse phase and long-term stability. A wavelength tuning range of 6 nm is possible and large locking bandwidths between 100 ... 260 MHz are observed. All data have been achieved by operating the lasers in a hybrid mode-locking scheme with a required minimum micro-wave power of only 12 dBm for pulse synchronization. Details on laser chip architecture and module performance are summarized and the results of a stable and error free module performance in first 160 Gb/s (4 x 40 Gb/s OTDM) RZ-DPSK transmission experiments are presented.

  19. Wavelength-tunable 10 GHz actively harmonic mode-locked fiber laser based on semiconductor optical amplifier

    Science.gov (United States)

    Mao, Yan; Tong, Xinglin; Wang, Zhiqiang; Zhan, Li; Hu, Pan; Chen, Liang

    2015-12-01

    We demonstrate a widely wavelength-tunable actively mode-locked fiber laser based on semiconductor optical amplifier. Beneficiating from the actively mode-locking operation and the wavelength-tunable characteristics of a Fabry-Perot filter, different harmonic mode-locking orders, from the fundamental mode-locking order (18.9 MHz) to the 520th order (9.832 GHz), can be easily achieved. The spectral bandwidth corresponding to the fundamental repetition rate is 0.12 nm with the pulse duration of 9.8 ns, leading to the TBP value of 146, which is about 460 times the transform-limited value for soliton pulse. The highest repetition rate of the mode-locked pulses we obtained is 9.832 GHz, with a signal-to-noise ratio up to 50 dB. The theoretical transform-limited pulse duration is 21 ps. Meanwhile, the central wavelength can be continuously tuned over 43.4 nm range (1522.8-1566.2 nm). The higher repetition rate and the widely tuning wavelength range make the fiber laser to own great potential and promising prospects in areas such as optical communication and photonic analog-to-digital conversion (ADC).

  20. Macroporous glass monoliths prepared from powdered niobium phosphate glass by fast sintering

    Energy Technology Data Exchange (ETDEWEB)

    Lacerda Mauricio, Vitor; Alves, Oswaldo Luiz; Odone Mazali, Italo, E-mail: mazali@iqm.unicamp.br

    2011-03-15

    Macroporous monoliths were prepared by very fast sintering (between 3 and 15 min) of niobophosphate glass powders at low temperature (1018 K) using cellulose as a foaming agent. The porous materials were analyzed by thermal analysis, Raman spectroscopy, scanning electron microscopy and powder X-ray diffraction, and further investigated using X-ray microtomography, a non-destructive technique capable of reconstructing three-dimensional models of samples and providing structural measurements. The progression of the porosity of the monoliths depends on the sintering time (3 to 15 min) and the amount (up to 50% in mass) of cellulose used. The macroporous glass monoliths may find application in integrated chemical systems and in filtering processes.

  1. Optical properties of Yb{sup 3+}-doped phosphate laser glasses

    Energy Technology Data Exchange (ETDEWEB)

    Venkatramu, V. [Department of Physics, Yogi Vemana University, Kadapa 516 003 (India); Vijaya, R. [Department of Physics, Sri Venkateswara University, Tirupati 517 502, Andhra Pradesh (India); Leon-Luis, S.F. [MALTA Consolider Team, Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna, E-38200 San Cristobal de La Laguna, Santa Cruz de Tenerife (Spain); Babu, P. [Department of Physics, Govt. Degree and P.G. College, Wanaparthy 509 103 (India); Jayasankar, C.K., E-mail: ckjaya@yahoo.com [Department of Physics, Sri Venkateswara University, Tirupati 517 502, Andhra Pradesh (India); Lavin, V. [MALTA Consolider Team, Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna, E-38200 San Cristobal de La Laguna, Santa Cruz de Tenerife (Spain); Instituto Universitario de Estudios Avanzados en Atomica, Molecular y Fotonica (IUdEA), Universidad de La Laguna, E-38200 San Cristobal de La Laguna, Santa Cruz de Tenerife (Spain); Dhareshwar, L.J. [Laser and Neutron Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2011-04-21

    Graphical abstract: Display Omitted Research highlights: > The optical properties of Yb{sup 3+}-doped phosphate glasses exhibit better laser performance parameters. > The OH{sup -} concentration in glasses increases with increase of Yb{sub 2}O{sub 3} concentration. > The quenching of lifetime is purely diffusion limited at lower Yb{sub 2}O{sub 3} concentration. > The lifetime of {sup 2}F{sub 5/2} is proportional to inter-ionic distance between Yb{sup 3+} ions. - Abstract: Ytterbium-doped phosphate glasses have been prepared and studied their spectroscopic properties through absorption, emission and Fourier transform infrared (FTIR) spectral studies and time-resolved luminescence decay curves. The absorption cross-section has been found to vary with the variation of Yb{sub 2}O{sub 3} concentration. The results of the FTIR spectra show that the OH{sup -} content is increasing with increase of the Yb{sub 2}O{sub 3} concentration in these glasses. The decay curves of the {sup 2}F{sub 5/2} level of Yb{sup 3+} ions exhibit a single exponential nature for all the concentrations. The lifetimes of the {sup 2}F{sub 5/2} level of Yb{sup 3+} ions decreases from 1.04 to 0.27 ms when the Yb{sub 2}O{sub 3} concentration is increased from 0.1 to 6.0 mol%. The quenching of lifetimes has been found to vary directly with the inter-ionic distance between the Yb{sup 3+} ions. The concentration quenching of the lifetime has been analyzed using different energy transfer processes and no evidence of cooperative luminescence of Yb{sup 3+} ions has been found in these glasses, which reveals that the present glasses are useful for photonic device applications. The laser performance properties have also been evaluated for these glasses and compared with those of other reported Yb{sup 3+}-doped glass systems.

  2. Electron Paramagnetic Resonance and Optical Absorption Studies on Copper Ions in Mixed Alkali Cadmium Phosphate Glasses

    Institute of Scientific and Technical Information of China (English)

    G.Giridhar; M.Rangacharyulu; R.V.S.S.N.Ravikumar; P.Sambasiva Rao

    2009-01-01

    Electron paramagnetic resonance (EPR) and optical absorption studies were carried out at room temperature on copper doped mixed alkali cadmium phosphate (LiNaCdP) glasses to understand the nature and symmetry of dopant. Three samples with varying concentrations of alkali ions have been prepared. The spin Hamiltonian parameters obtained from room temperature EPR spectra are: g||=2.437, g⊥=2.096, A||=117×10-4 cm-1, A⊥=26×10-4 cm-1 for LiNaCdP1, g||=2.441, g⊥=2.088, A||=121×10-4 cm-1, A⊥=25×10-4 cm-1 for LiNaCdP2 and g||=2.433, g⊥=2.096, A||=125×10-4 cm-1, A⊥=32×10-4 cm-1 for LiNaCdP3. These EPR results indicate that the dopant Cu2+ ion enters the glass matrix into a tetragonally elongated octahedral site. The bonding parameters evaluated by correlating optical and EPR data suggest that bonding between the central metal ion and ligands is partially covalent. The mixed alkali effect in cadmium phosphate glasses was reported.

  3. Effect of the Addition of CeO2 to Iron Phosphate Glass for Catalytic Applications.

    Science.gov (United States)

    Chung, Jae-Yeop; Kim, Jong-Hwan; Choi, Su-Yeon; Ryu, Bong-Ki

    2015-10-01

    We investigated the effect of CeO2 content on the catalytic behavior and chemical properties of the (100 - x)(80P2O5-20Fe2O3)-xCeO2 (x = 0, 4, 8, 12, 16, 20 and 24 wt%) glass system. Using thermogravimetric analysis, we confirmed that the catalytic activity increased until a CeO2 content of 16 wt%, beyond which, it decreased. The reasons for the change in the catalytic properties of the glass samples were determined using Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and density analyses. It was confirmed using the FT-IR and XPS-01s spectra that CeO2 acts as a network modifier in iron phosphate glass. When the CeO2 content is above 16 wt%, the number of non-bridging oxygen atoms decreases with increasing CeO2 content. For these reasons, the catalytic properties decrease when the CeO2 content is more than 16 wt%. From the dissolution rate measurements, it can be observed that cerium-iron phosphate has a high water resistance. Also, as we expected, it can be confirmed that the chemical durability is improved with increasing CeO2 content.

  4. Luminescence properties of Dy3+ doped different fluoro-phosphate glasses for solid state lighting applications

    Science.gov (United States)

    Babu, S.; Reddy Prasad, V.; Rajesh, D.; Ratnakaram, Y. C.

    2015-01-01

    Dy3+ doped different fluoro-phosphate glasses are prepared and they are characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), Raman, optical absorption, and photoluminescence (PL) techniques. The structural characterization is accomplished by XRD, FTIR and Raman spectroscopy. The morphological analysis was performed by SEM. The absorption spectra have been analyzed using Judd-Ofelt theory and the intensity parameters have been evaluated. These parameters are used to calculate radiative properties such as emission probabilities (AR), radiative lifetimes (τR) and integrated absorption cross-sections (Σ) for different Dy3+ transitions. The PL spectra exhibit bands in the blue, yellow and red regions. Furthermore, the dependence of luminescence properties such as stimulated emission cross-sections (σp) and branching ratios (β) on different metal cations in these glasses is studied. From decay curve analysis, the lifetimes of the excited state 4F9/2 have been measured. The calorimetric property is also studied based on Commission International del'Eclairage (CIE) standards for Dy3+ doped different fluoro-phosphate glasses and discussed.

  5. New laser glass for short pulsed laser applications: the BLG80 (Conference Presentation)

    Science.gov (United States)

    George, Simi A.

    2017-03-01

    For achieving highest peak powers in a solid state laser (SSL) system, significant energy output and short pulses are necessary. For mode-locked lasers, it is well-known from the Fourier theorem that the largest gain bandwidths produce the narrowest pulse-widths; thus are transform limited. For an inhomogeneously broadened line width of a laser medium, if the intensity of pulses follow a Gaussian function, then the resulting mode-locked pulse will have a Gaussian shape with the emission bandwidth/pulse duration relationship of pulse ≥ 0.44?02/c. Thus, for high peak power SSL systems, laser designers incorporate gain materials capable of broad emission bandwidths. Available energy outputs from a phosphate glass host doped with rare-earth ions are unparalleled. Unfortunately, the emission bandwidths achievable from glass based gain materials are typically many factors smaller when compared to the Ti:Sapphire crystal. In order to overcome this limitation, a hybrid "mixed" laser glass amplifier - OPCPA approach was developed. The Texas petawatt laser that is currently in operation at the University of Texas-Austin and producing high peak powers uses this hybrid architecture. In this mixed-glass laser design, a phosphate and a silicate glass is used in series to achieve a broader bandwidth required before compression. Though proven, this technology is still insufficient for the future compact petawatt and exawatt systems capable of producing high energies and shorter pulse durations. New glasses with bandwidths that are two and three times larger than what is now available from glass hosts is needed if there is to be an alternative to Ti:Sapphire for laser designers. In this paper, we present new materials that may meet the necessary characteristics and demonstrate the laser and emission characteristics these through the internal and external studies.

  6. Exploring the self-mode-locked dynamics of cryogenic diode-pumped Nd:YLF lasers: switching of orthogonal polarizations

    Science.gov (United States)

    Huang, T. L.; Y Cho, C.; Liang, H. C.; Huang, K. F.; Chen, Y. F.

    2017-08-01

    The self-mode-locked output for cryogenic Nd:YLF laser at the temperature range of 90 K to 290 K is thoroughly investigated. Linearly polarized self-mode-locked lasing at 1047 nm (1053 nm) with a repetition rate up to 1.59 GHz and a pulse width as short as 52 ps can be realized at temperatures above 155 K (below 135 K). Orthogonally polarized self-mode-locked operation can be observed at temperatures near 145 K. During dual-polarization operation, it is found that the polarized component with higher output power is the fundamental transverse mode, whereas the other component with lower output power becomes the high-order transverse mode. The dominant polarized component can be either π- or σ-polarization, depending on the fine adjustment of the cavity.

  7. Diode end-pumped self-Q-switched and mode-locked Nd,Cr:YAG/KTP green laser

    Institute of Scientific and Technical Information of China (English)

    Du Shi-Feng; Wang Su-Mei; Zhang Dong-Xiang; Feng Bao-Hua; Zhang Chun-Yu; Zhang Ling; Zhang Zhi-Guo; Zhang Shi-Wen

    2006-01-01

    We first experimentally demonstrate a laser-diode end-pumped self-Q-switched and mode-locked Nd,Cr:YAG green laser with a KTP crystal as the intra- cavity frequency doubler. The device produces an average output power of 680 mW at 532 nm. The corresponding pulse width of the Q-switched envelope of the green laser is 170 ± 20 ns. The mode-locked pulses have a repetition rate of approximately 183 MHz and the average pulse duration is estimated to be around sub-nanosecond. It is found that the intra-cavity frequency doubling greatly improves the modulation depth and stability of the mode-locked pulses within the Q-switched envelope.

  8. Passive mode locking of a Nd:YAG laser with co-doped Nd, Cr:YAG as saturable absorber

    Institute of Scientific and Technical Information of China (English)

    Yang Lin(杨林); Feng Bao-Hua(冯宝华); Zhang Zhi-Guo(张治国); Gaebler Volker; Liu Bai-Ning(刘百宁); Eichler Hans

    2003-01-01

    We demonstrate the characteristics of relatively low saturation intensity using co-doped Nd, Cr:YAG as saturable absorber for passively mode locking the Nd:YAG laser. The difference of the saturation intensity between Q-switched and mode-locked operation in co-doped Nd, Cr:YAG was only one to two orders of magnitude, while Cr:YAG was generally reported at a difference of five orders of magnitude. More than 80% mode locking modulation depth was achieved at an incident pump power of 4.4W, corresponding to an intracavity intensity of 6 × 104W/cma2, using a 68cm long plano-concave cavity.

  9. Contrastive study of two SESAMs for passive mode-locking in Nd:YVO4 laser with low pump power

    Institute of Scientific and Technical Information of China (English)

    Yang Liu; Liqun Sun; Yonggang Wang; Qian Tian; Xiaoyu Ma; Zhigang Zhang

    2005-01-01

    Two semiconductor saturable absorber mirrors (SESAMs), of which one is coated with 50% reflection film on the top and the other is not, were contrastively studied in passively mode-locked solid-state lasers which were pumped by low output power laser diode (LD). Experiments have shown that reducing the modulation depth of SESAM by coating partial reflection film, whose reflectivity is higher than that between SESAM and air interface, is an effective method to get continuous wave (CW) mode-locking instead of Q-switched power LD, in which no water-cooling system was used, could obtain CW mode-locking by the 50% reflector coated SESAM with average output power of ~ 20 mW.

  10. Passive mode locking of ytterbium- and erbium-doped all-fiber lasers using graphene oxide saturable absorbers.

    Science.gov (United States)

    Chen, Hou-Ren; Tsai, Chih-Ya; Cheng, Hsin-Ming; Lin, Kuei-Huei; Hsieh, Wen-Feng

    2014-06-02

    Broadband graphene oxide/PVA films were used as saturable absorbers (SAs) for mode locking erbium-doped fiber laser (EDFL) and ytterbium-doped fiber laser (YDFL) at 1.06 μm and 1.55 μm. They provide modulation depths of 3.15% and 6.2% for EDFL and YDFL, respectively. Stable self-starting mode-locked pulses are obtained for both lasers, confirming that the graphene oxide is cost-effective. We have generated mode-locked pulses with spectral width, repetition rate, and pulse duration of 0.75 nm, 9.5 MHz, and 2.7 ps. This is the shortest pulse duration directly obtained from an all-normal-dispersion YDFL with graphene-oxide saturable absorber.

  11. Generation of sub-100 fs pulses from mode-locked Nd,Y:SrF2 laser with enhancing SPM

    Science.gov (United States)

    Zhu, Jiangfeng; Wei, Long; Tian, Wenlong; Liu, Jiaxing; Wang, Zhaohua; Su, Liangbi; Xu, Jun; Wei, Zhiyi

    2016-05-01

    A mode-locked laser using Nd,Y:SrF2 crystal as the gain medium is presented in this letter. By special design of the cavity for enhancing the self-phase modulation effect, femtosecond mode-locking with 97 fs pulse duration and 13.2 nm spectral width centered at 1061 nm is obtained at a repetition rate of 96 MHz. The average output power is 102 mW under 925 mW pump power, corresponding to the optical-to-optical efficiency of 11%. To the best of our knowledge, these are the first sub-100 fs pulses generated from a mode-locked Nd doped crystal laser.

  12. A comparative study on dual colour soft aperture cascaded second-order mode-locking with different nonlinear optical crystals

    Indian Academy of Sciences (India)

    Shyamal Mondal; Satya Pratap Singh; Sourabh Mukhopadhyay; Aditya Date; Kamal Hussain; Shouvik Mukherjee; Prasanta Kumar Datta

    2014-02-01

    A comparative study in terms of optimized output power and stability is made on cascaded second-order nonlinear optical mode-locking with KTP, BBO and LBO crystals for both 1064 nm and 532 nm. Large nonlinear optical phase shift achieved in a non-phase-matched second harmonic generating crystal, is transformed into amplitude modulation through soft aperturing the nonlinear cavity mode variation at the laser gain medium to mode-lock a Nd:YVO4 laser. The laser delivers stable dual wavelength cw mode-locked pulse train with pulse duration 10.3 ps and average power of 1.84 W and 255 mW at 1064 nm and 532 nm respectively for the optimum performance in type-II KTP crystal. The exceptional stability achieved with KTP is accounted by simulating the mode-size variation with phase mismatch.

  13. Optical response and magnetic characteristic of samarium doped zinc phosphate glasses containing nickel nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Azmi, Siti Amlah M.; Sahar, M.R., E-mail: mrahim057@gmail.com

    2015-11-01

    A magnetic glass of composition 40ZnO–(58−x) P{sub 2}O{sub 5}–1Sm{sub 2}O{sub 3}–xNiO, with x=0.0, 1.0, 1.5 and 2.0 mol% is prepared by melt-quenching technique. The glass is characterized by X-ray diffraction, high-resolution transmission electron microscope (HRTEM), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM) analysis. The X-rays diffraction confirms the amorphous nature of the glass while the HRTEM analysis reveals the presence of nickel nanoparticles in the glass samples. High-resolution TEM reveals that the lattice spacing of nickel nanoparticles is 0.35 nm at (100) plane. Photoluminescence emission shows the existence of four peaks that correspond to the transition from the upper level of {sup 4}G{sub 5/2} to the lower level of {sup 6}H{sub 5/2}, {sup 6}H{sub 7/2}, {sup 6}H{sub 9/2,} and {sup 6}H{sub 11/2.} It is observed that all peaks experience significant quenching effect with the increasing concentration of nickel nanoparticles, suggesting a strong energy transfer from excited samarium ions to the nickel ions. The glass magnetization and susceptibility at 12 kOe at room temperature are found to be in the range of (3.87±0.17×10{sup −2}–7.19±0.39×10{sup −2}) emu/g and (3.24±0.16×10{sup −6}–5.99±0.29×10{sup −6}) emu/Oe g respectively. The obtained hysteresis curve indicates that the glass samples are paramagnetic materials. The studied glass can be further used towards the development of magneto-optical functional glass. - Highlights: • Sm{sup 3+} doped zinc phosphate glass embedded with Ni NPs has been prepared. • The Laue pattern and lattice spacing of Ni NPs are confirmed by HRTEM image. • The magnetic response of glasses has been studied through VSM analysis. • Enhancement factor and decay half-lifetime are investigated.

  14. Bright-dark rogue wave in mode-locked fibre laser (Conference Presentation)

    Science.gov (United States)

    Kbashi, Hani; Kolpakov, Stanislav; Martinez, Amós; Mou, Chengbo; Sergeyev, Sergey V.

    2017-05-01

    Bright-Dark Rogue Wave in Mode-Locked Fibre Laser Hani Kbashi1*, Amos Martinez1, S. A. Kolpakov1, Chengbo Mou, Alex Rozhin1, Sergey V. Sergeyev1 1Aston Institute of Photonic Technologies, School of Engineering and Applied Science Aston University, Birmingham, B4 7ET, UK kbashihj@aston.ac.uk , 0044 755 3534 388 Keywords: Optical rogue wave, Bright-Dark rogue wave, rogue wave, mode-locked fiber laser, polarization instability. Abstract: Rogue waves (RWs) are statistically rare localized waves with high amplitude that suddenly appear and disappear in oceans, water tanks, and optical systems [1]. The investigation of these events in optics, optical rogue waves, is of interest for both fundamental research and applied science. Recently, we have shown that the adjustment of the in-cavity birefringence and pump polarization leads to emerge optical RW events [2-4]. Here, we report the first experimental observation of vector bright-dark RWs in an erbium-doped stretched pulse mode-locked fiber laser. The change of induced in-cavity birefringence provides an opportunity to observe RW events at pump power is a little higher than the lasing threshold. Polarization instabilities in the laser cavity result in the coupling between two orthogonal linearly polarized components leading to the emergence of bright-dark RWs. The observed clusters belongs to the class of slow optical RWs because their lifetime is of order of a thousand of laser cavity roundtrip periods. References: 1. D. R. Solli, C. Ropers, P. Koonath,and B. Jalali, Optical rogue waves," Nature, 450, 1054-1057, 2007. 2. S. V. Sergeyev, S. A. Kolpakov, C. Mou, G. Jacobsen, S. Popov, and V. Kalashnikov, "Slow deterministic vector rogue waves," Proc. SPIE 9732, 97320K (2016). 3. S. A. Kolpakov, H. Kbashi, and S. V. Sergeyev, "Dynamics of vector rogue waves in a fiber laser with a ring cavity," Optica, 3, 8, 870, (2016). 5. S. Kolpakov, H. Kbashi, and S. Sergeyev, "Slow optical rogue waves in a unidirectional fiber laser

  15. Diode-Pumped Self Q-Switched and Mode-Locking Nd3+,Cr4+:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    LI Chun-Yong; LI Ping-Xue; LI De-Hua; FENG Bao-Hua; FU Pan-Ming; ZHANG Zhi-Guo; ZHANG Shi-Wen

    2004-01-01

    @@ Using Nd3+,Cr4+ : YAG as a laser crystal and saturable absorber simultaneously, we obtain a self-Q-switched and mode-locking laser at 1.06 μm with straight cavity structure. Self mode-locking phenomenon was observed at an intracavity intensity of only about 2000 W/cm2. More than 90% modulation depth is achieved at an intracavity intensity of less than 3.0 × 104 W/cm2 for the first time. The Q-switched pulse width and repetition rate are found to be connected with the cavity length and the output power.

  16. Q-switched mode-locked diode-pumped Nd:YVO4 laser with a saturable Bragg reflector

    Institute of Scientific and Technical Information of China (English)

    Juan Du(杜鹃); Jingliang He(何京良); Jie Liu(刘杰); Qiuxia Jiang(姜秋霞); Sheng Liu(刘胜); Huitian Wang(王慧田)

    2004-01-01

    We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of ~230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of ~150 kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.

  17. Q-switched mode-locked diode-pumped Nd:YVO4 laser with a saturable Bragg reflector

    Institute of Scientific and Technical Information of China (English)

    杜鹃; 何京良; 刘杰; 姜秋霞; 刘胜; 王慧田

    2004-01-01

    We demonstrated a diode-pumped passively Q-switched mode-locked Nd:YVO4 laser by using a relaxed saturable Bragg reflector (SBR). Stable mode-locked pulse train with the repetition rate of ~230 MHz was achieved and the pulse train was modulated by the Q-switched envelope with the repetition rate of ~150kHz. The maximum output of 4 W was obtained under the pump power of 13.5 W. The optical-to-optical efficiency was 30%. We also discussed the transition of each process having emerged.

  18. Mode-locked InAs/InP quantum-dash-based DBR laser with monolithically integrated SOA

    Science.gov (United States)

    Joshi, Siddharth; Chimot, Nicolas; Barbet, Sophie; Accard, Alain; Lelarge, François

    2014-02-01

    We present the first demonstration of InAs/InP Quantum Dash based single-section frequency comb generator designed for use in photonic integrated circuits. The laser cavity is closed using a specific Bragg reflector without compromising the mode-locking performance of the laser. This enables the integration of single-section mode- locked laser on photonic integrated circuits as on-chip frequency comb source. As a demonstration, we integrate the Fabry Perot laser with a semiconductor optical amplifier. Such a device could be used for amplification or modulation of the frequency generated comb. We thus investigate the device operation to obtain a NRZ modulated comb.

  19. 1.34 µm picosecond self-mode-locked Nd:GdVO4 watt-level laser

    Science.gov (United States)

    Han, Ming; Peng, Jiying; Li, Zuohan; Cao, Qiuyuan; Yuan, Ruixia

    2017-01-01

    With a simple linear configuration, a diode-pumped, self-mode-locked Nd:GdVO4 laser at 1.34 µm is experimentally demonstrated for the first time. Based on the aberrationless theory of self-focusing and thermal lensing effect, through designing and optimizing the resonator, a pulse width as short as 9.1 ps is generated at a repetition rate of 2.0 GHz and the average output power is 2.51 W. The optical conversion efficiency and the slope efficiency for the stable mode-locked operation are approximately 16.7% and 19.2%, respectively.

  20. Low-loss flake-graphene saturable absorber mirror for laser mode-locking at sub-200-fs pulse duration

    CERN Document Server

    Cunning, B V; Kielpinski, D

    2011-01-01

    Saturable absorbers are a key component for mode-locking femtosecond lasers. Polymer films containing graphene flakes have recently been used in transmission as laser mode-lockers, but suffer from high nonsaturable loss, limiting their application in low-gain lasers. Here we present a saturable absorber mirror based on a film of pure graphene flakes. The device is used to mode lock an erbium-doped fiber laser, generating pulses with state-of-the-art, sub-200-fs duration. The laser characteristic indicate that the film exhibits low nonsaturable loss (13% per pass) and large absorption modulation depth (45% of low-power absorption).

  1. Mode-locked Yb-doped fiber laser emitting broadband pulses at ultra-low repetition rates

    CERN Document Server

    Bowen, Patrick; Provo, Richard; Harvey, John D; Broderick, Neil G R

    2016-01-01

    We report on an environmentally stable, Yb-doped, all-normal dispersion, mode-locked fibre laser that is capable of creating broadband pulses with ultra-low repetition rates. Specifically, through careful positioning of fibre sections in an all-PM-fibre cavity mode-locked with a nonlinear amplifying loop mirror, we achieve stable pulse trains with repetition rates as low as 506 kHz. The pulses have several nanojules of energy and are compressible down to ultrashort (< 500 fs) durations.

  2. 177 fs erbium-doped fiber laser mode locked with a cellulose polymer film containing single-wall carbon nanotubes

    Science.gov (United States)

    Tausenev, A. V.; Obraztsova, E. D.; Lobach, A. S.; Chernov, A. I.; Konov, V. I.; Kryukov, P. G.; Konyashchenko, A. V.; Dianov, E. M.

    2008-04-01

    A mode-locked soliton erbium-doped fiber laser generating 177fs pulses is demonstrated. The laser pumped by a 85mW, 980nm laser diode emits 7mW at 1.56μm at a pulse repetition rate of 50MHz. Passive mode locking is achieved with a saturable absorber made of a high-optical quality film based on cellulose derivative with dispersed carbon single-wall nanotubes. The film is prepared with the original technique by using carbon nanotubes synthesized by the arc-discharge method.

  3. Large net-normal dispersion Er-doped fibre laser mode-locked with a nonlinear amplifying loop mirror

    CERN Document Server

    Bowen, Patrick; Broderick, Neil G R

    2016-01-01

    We report on an environmentally stable, all-PM-fibre, Er-doped, mode-locked laser with a central wavelength of 1550 nm. Significantly, the laser possesses large net-normal dispersion such that its dynamics are comparable to that of an all-normal dispersion fibre laser at 1 {\\mu}m with an analogous architecture. The laser is mode-locked with a nonlinear amplifying loop mirror to produce pulses that are externally compressible to 500 fs. Experimental results are in good agreement with numerical simulations.

  4. Comparative study between conventional and diffusion-bonded Nd-doped vanadate crystals in the passively mode-locked operation.

    Science.gov (United States)

    Huang, Y J; Huang, Y P; Liang, H C; Su, K W; Chen, Y F; Huang, K F

    2010-04-26

    We design a reliable linear three-element cavity to make a comparative study between the conventional and diffusion-bonded Nd:GdVO(4) crystals in the passively mode-locked operation. Experimental investigations reveal that the mode-locked pulse width obtained with the diffusion-bonded crystal is considerably broader than that obtained with the conventional crystal, even though the diffusion-bonded crystal can significantly reduce the thermal effects. The pulse broadening is experimentally verified to come from the length of the undoped part that brings in a reduction of the spatial-hole-burning (SHB) effect.

  5. X-ray photoelectron spectroscopy (XPS) and FTIR studies of vanadium barium phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Majjane, Abdelilah [Laboratoire de Physico-Chimie des Matériaux Vitreux et Cristallisés, Université Ibn Tofail, Faculté des Sciences, Kénitra 14090 (Morocco); Chahine, Abdelkrim, E-mail: abdelkrimchahine@gmail.com [Laboratoire de Physico-Chimie des Matériaux Vitreux et Cristallisés, Université Ibn Tofail, Faculté des Sciences, Kénitra 14090 (Morocco); Et-tabirou, Mohamed [Laboratoire de Physico-Chimie des Matériaux Vitreux et Cristallisés, Université Ibn Tofail, Faculté des Sciences, Kénitra 14090 (Morocco); Echchahed, Bousselham [Laboratoire d' Electrochimie, Corrosion et Environnement, Université Ibn Tofail, Faculté des Sciences, Kénitra (Morocco); Do, Trong-On [Département de génie chimique, Université Laval, G1K 7P4 (Canada); Breen, Peter Mc [Département de chimie, Université Laval, G1K 7P4 (Canada)

    2014-01-15

    Barium vanadophosphate glasses, having composition 50BaO–xV{sub 2}O{sub 5}–(50 − x)P{sub 2}O{sub 5}, (x = 0–50 mol%), were prepared by conventional melt quench method. Density, molar volume and glass transition temperature (T{sub g}) were measured as a function of V{sub 2}O{sub 5} content. Structural investigation was done using XPS and FTIR spectroscopy. First, substitution of the P{sub 2}O{sub 5} by the V{sub 2}O{sub 5} in the metaphosphate 50BaO–50P{sub 2}O{sub 5} glass increases the density and T{sub g} and decreases the molar volume. When the amount of V{sub 2}O{sub 5} increases, all these properties show a reverse trend. XPS measurement found in the O1s, P2p, and V2p core level spectra indicate the presence of primarily P–O–P, P–O–V and V–O–V structural bonds, the asymmetry in the P 2p spectra indeed arises from the spin-orbit splitting of P 2p core level, and more than one valence state of V ions being present. IR spectroscopy reveals the depolymerization of the phosphate glass network by systematic conversion of metaphosphate chains into pyrophosphate groups and then orthophosphate groups. Even though metaphosphate to pyrophosphate conversion is taking place due to breaking of P–O–P linkages, formation of P–O–V and P–O–Ba linkages provide cross linking between short P-structural units, which make the glass network more rigid. Above 10–20 mol% V{sub 2}O{sub 5} content, network is highly depolymerized due to the formation of orthophosphate units and V–O–V bridge bonds, resulting in poor cross-linking, making the glass network less rigid. - Highlights: • Barium–vanadium–phosphate glasses. • Structure has been investigated by XPS and IR spectra. • Variation in structure and properties with substitution of V{sub 2}O{sub 5} for P{sub 2}O{sub 5}. • Conversion of metaphosphate to pyrophosphate and finally to orthophosphate. • Substitution of P–O–P linkages by P–O–V, P–O–Ba and V–O–V linkages.

  6. Side-pumped short rectangular Nd-doped phosphate glass fiber lasers

    Institute of Scientific and Technical Information of China (English)

    Yulong Tang; Yong Yang; Jianqiu Xu

    2008-01-01

    Watt-level short fiber lasers side-pumped through fiber-to-waveguide couplers are demonstrated. The fiber lasers are fabricated from Nd-doped phosphate glass with large numerical aperture of 0.2 and rectangular cross section of 1.5 × 0.5 (mm). Single transverse mode output is achieved by the gain-guiding effect. Average power of 1 W is generated from a 4.0-cm-long fiber laser with a slope efficiency of 10%.

  7. Molecular dynamic simulations of the lithium coordination environment in phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    ALAM,TODD M.; LIANG,JIANJIE; CYGAN,RANDALL T.

    2000-06-07

    A molecular dynamics (MD) study of the lithium ultraphosphate glass series, xLi{sub 2}O{center_dot}(1{minus}x)P{sub 2}O{sub 5} (0 {le} x < 0.5) was used to investigate the changes in the Li environment with increasing modifier concentration. The results from the MD simulations indicate that no major structural variations in the Li coordination environment are observed. Changes in the type of oxygen coordinated to the modifier are observed and correlate with the T{sub g} minimum. Additionally, changes in the number of shared phosphorus vertices are observed with increasing modifier concentration, in support of recent models involving the role of the modifier in the extended range structure of phosphate glasses. Empirical calculations of the {sup 6}Li NMR chemical shifts directly from the MD simulation structures is also reported and compared to recent experimental solid-state NMR results.

  8. Effect of silver concentration on the silver-activated phosphate glass

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, S.M. [Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan (China); Yung, S.W., E-mail: hwyang@nuu.edu.tw [Department of Materials Science and Engineering, National United University, 1, Lin Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China); Brow, R.K. [Graduate Center for Materials Research, Missouri University of Science and Technology, Rolla, MO 65401 (United States); Hsu, W.L.; Lu, C.C.; Wu, F.B. [Department of Materials Science and Engineering, National United University, 1, Lin Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China); Ching, S.H. [City University of Hong Kong (Hong Kong)

    2010-09-01

    The effects of silver concentration on the structure and properties of silver-activated phosphate glasses, with the nominal molar compositions xAg{sub 2}O.(1 - x)(30Na{sub 2}O.10Al{sub 2}O{sub 3}.60P{sub 2}O{sub 5}) and 0 {<=} x {<=} 10 mol%, were studied. Increasing the Ag{sub 2}O-content decreases the glass transition temperature (T{sub g}), increases the thermal expansion coefficient (TEC) and increases the glass dissolution rate in water. {sup 31}P nuclear magnetic resonance (NMR) and Raman spectroscopies indicate that the addition of Ag{sub 2}O leads to the formation of chain-terminating P-tetrahedra, and {sup 27}Al NMR spectra indicate that Al-octahedra are the preferred structural moiety. Optical spectroscopy indicates that Ag{sub 2}O-additions shift the UV-absorption edge to longer wavelengths. Irradiating glasses with {<=}1.0 mol% Ag{sub 2}O with {sup 60}Co {gamma}-rays creates a photoluminescence (PL) center that emits near 605 nm when excited with UV light (337.1 nm). The intensity of this PL center is proportional to the radiation dosage (up to 200 Gy), and the relative sensitivity is maximized in glasses with 0.05 mol% Ag{sub 2}O. When x > 1 mol% Ag{sub 2}O, a second PL center, emitting at 470 nm, is activated. The formation of this second PL center is associated with the loss of radiation sensitivity for glasses with greater Ag{sub 2}O-contents.

  9. Er3+ and Yb3+ Codoped Phosphate Laser Glass for High Power Flashlamp Pumping

    Institute of Scientific and Technical Information of China (English)

    FANG Yong-Zheng; JIN Ming-Lin; WEN Lei; LI Shun-Guang; HU Li-Li

    2007-01-01

    A novel Yb3+-Er3+ codoped phosphate glass for high power flashlamp pumping and high repetition rate laser at 1.54 μm, designated EAT5-2, is developed. The weight-loss rate of is 1.3×10-5 gcm-2h-l in boiling water, which is comparable to Kigre's QX-Er glass. Some spectroscopic parameters are analysed by Judd-Ofelt theory and McCumber theory. The emission cross section is calculated to be 0.73×10-20 cm2. The thermo-mechanical properties of EAT5-2 are modified after an ion-exchange chemical strengthening process in a KNO3/NaNO3 molten salt bath. The thresholds for optical damage from the nashlamp pumping are tested on glass rods. A repetition rate of 15 Hz is achieved for chemically strengthened glass. The laser experimental results at 1.54 μm from nashlamp pumping are also reported.

  10. 4.5 W mid-infrared supercontinuum generation in a ZBLAN fiber pumped by a Q-switched mode-locked Tm3+- doped fiber laser

    Science.gov (United States)

    Kneis, C.; Donelan, B.; Berrou, A.; Manek-Hönninger, I.; Cadier, B.; Robin, T.; Poulain, M.; Joulain, F.; Eichhorn, M.; Kieleck, C.

    2015-02-01

    The generation of mid-infrared (mid-IR) supercontinuum (SC) radiation, ranging from 2 - 5 μm, is subject of intense research due to its wide range of applications. A very popular host media for mid-IR SC generation are soft glass fibers owing to their low-loss transmission in the mid-IR wavelength regime, particularly fluoride fibers are very attractive for high-power operation. In this research study, a diode-pumped Q-switched mode-locked (QML) thulium (Tm3+)-doped double-clad silica fiber laser is used to pump a ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fiber for mid-IR SC generation. The QML regime of the fiber laser is actively generated by two acousto-optic modulators. The Tm3+-fiber laser provided up to 23.5 W (26 W) of average output power in QML (continuous wave) regime with a slope efficiency of 36 % (32 %). The measured beam quality has been close to the diffraction-limit in QML regime. The system delivered mode-locked pulses with a duration of 7.5 ps, measured with a commercial autocorrelator system, at a repetition rate of 46 MHz. The Q-switched envelopes had a width between 50 and 150 ns depending on the output power level and the adjustable repetition rate. Mid-IR SC with an average output power in all spectral bands of 4.5 W have been achieved with more than 3 W/ 1.7 W/ 1 W/ 0.36 W after a long-wave-pass filter with a 3 dB-edge at 2.15 μm/ 2.65 μm/ 3.1 μm/ 3.5 μm.

  11. Modeling and analysis of polarization effects in Fourier domain mode-locked lasers.

    Science.gov (United States)

    Jirauschek, Christian; Huber, Robert

    2015-05-15

    We develop a theoretical model for Fourier domain mode-locked (FDML) lasers in a non-polarization-maintaining configuration, which is the most widely used type of FDML source. This theoretical approach is applied to analyze a widely wavelength-swept FDML setup, as used for picosecond pulse generation by temporal compression of the sweeps. We demonstrate that good agreement between simulation and experiment can only be obtained by including polarization effects due to fiber bending birefringence, polarization mode dispersion, and cross-phase modulation into the theoretical model. Notably, the polarization dynamics are shown to have a beneficial effect on the instantaneous linewidth, resulting in improved coherence and thus compressibility of the wavelength-swept FDML output.

  12. Microwave emission by nonlinear crystals irradiated with a high-intensity, mode-locked laser

    CERN Document Server

    Borghesani, A F; Guarise, M

    2016-01-01

    We report on the experimental investigation of the efficiency of some nonlinear crystals to generate microwave (RF) radiation as a result of optical rectification (OR) when irradiated with intense pulse trains delivered by a mode-locked laser at $1064\\,$nm. We have investigated lithium triborate (LBO), lithium niobate (LiNbO$_3$), zinc selenide (ZnSe), and also potassium titanyl orthophosphate (KTP) for comparison with previous measurements. The results are in good agreement with the theoretical predictions based on the form of the second-order nonlinear susceptibility tensor. For some crystals we investigated also the second harmonic generation (SHG) to cross check the theoretical model. We confirm the theoretical prediction that OR leads to the production of higher order RF harmonics that are overtones of the laser repetition rate.

  13. Investigation of Kerr-lens mode locking in lasers with composite active media

    Science.gov (United States)

    Trunov, V. I.; Kirpichnikov, A. V.; Pestryakov, Efim V.; Petrov, V. V.; Komarov, A. K.; Komarov, Konstantin P.

    2001-03-01

    One of the possible methods of realization of active medium with anomalously wide bandwidth has been described. Composite active medium, consisting of several laser active centers with overlapping gainbands in common resonator has been created. In this case gain contour has complex shape with local extremums. Method of numerical simulation of the formation dynamics of ultrashort pulse at passive mode locking in laser with arbitrary spectral gain contour has been performed. The main parameters for the generation of ultrashort pulse in a laser with a composite active medium are obtained and investigated. The conditions of realization of stationary regime in the form of ultrashort pulse generation with duration determined by combined gain bandwidth are calculated.

  14. Dynamics of soliton explosions in passively mode-locked fiber lasers

    CERN Document Server

    Runge, Antoine F J; Erkintalo, Miro

    2015-01-01

    A soliton explosion is an instability whereby a dissipative soliton undergoes a sudden structural collapse, but remarkably returns back to its original shape after a short transient. We recently reported the first experimental observation of this effect in a fiber laser (A. F. J. Runge et al., Optica 2, 36 (2015)). Here, we expand on our initial work, presenting a more detailed experimental and numerical study of the characteristics and dynamics of soliton explosions in passively mode-locked fiber lasers. Specifically, we explore different cavity configurations and gain levels, observing and characterizing explosion events using spectral and temporal real-time single-shot techniques. Our results highlight that the explosion characteristics observed in experiments depend critically on the position in the cavity where the output coupler is located. Furthermore, we find that the frequency at which explosions occur can be controlled by adjusting the pump power. We also identify a new kind of ``partial'' explosion...

  15. Wavelength Spacing Tunable, Multiwavelength Q-switched Fiber Laser Mode-locked by Graphene Oxide

    CERN Document Server

    Gao, Lei

    2014-01-01

    We demonstrate a wavelength spacing tunable, multiwavelength Q-switched mode-locked fiber laser (QML) based on a fiber taper deposited with graphene oxide. The operation of the laser can be understood in terms of the formation of bunches of QMLs which possess small temporal intervals, and multiwavelength spectra are generated due to the Fourier transformation. We find that the temporal spacing of the QMLs is highly sensitive to the pump power, and as a result, the wavelength spacing can be easily tuned by varying the pump power. Our experimental laser provides a wavelength spacing tuning range from ~0.001 nm to 0.145 nm with a pump power variation less than 10 mW. The laser could be developed into a low lost wavelength spacing tunable optical source for a wide range of applications, such as spectroscopy, microwave/terahertz signal generation, optical metrology, optical communications and sensing.

  16. Silicon Photonics WDM Transceiver with SOA and Semiconductor Mode-Locked Laser

    CERN Document Server

    Moscoso-Mártir, Alvaro; Hauck, Johannes; Chimot, Nicolas; Setter, Rony; Badihi, Avner; Rasmussen, Daniel E; Garreau, Alexandre; Nielsen, Mads; Islamova, Elmira; Romero-García, Sebastián; Shen, Bin; Sandomirsky, Anna; Rockman, Sylvie; Li, Chao; Azadeh, Saeed Sharif; Lo, Guo-Qiang; Mentovich, Elad; Merget, Florian; Lelarge, François; Witzens, Jeremy

    2016-01-01

    We demonstrate a complete Silicon Photonics WDM link relying on a single section semiconductor mode-locked laser and a single SOA to support up to 12 multiplexed channels with a bit error rate of 1e-12 at serial data rates of 14 Gbps without channel pre-emphasis, equalization or forward error correction. Individual channels reach error free operation at 25 Gbps and multi-channel operation at 25 Gbps is shown to be compatible with standard 7% overhead hard decision forward error correction. Silicon Photonics transmitter and receiver chips are hybridly integrated with driver and receiver electronics. A detailed link model is derived and verified. Particular emphasis is placed on accurate system level modeling of laser RIN, SOA amplified spontaneous emission noise and receiver noise. The impact of the electrical receiver bandwidth and non-Gaussian statistics on level dependent amplified spontaneous emission noise are investigated in detail. The channel count scalability as limited by SOA saturation is further an...

  17. Femtosecond pulse generation from a Topological Insulator mode-locked fiber laser

    CERN Document Server

    Liu, Hao; Liu, Meng; Zhao, Nian; Luo, Ai-Ping; Luo, Zhi-Chao; Xu, Wen-Cheng; Zhang, Han; Zhao, Chu-Jun; Wen, Shuang-Chun

    2014-01-01

    We reported on the generation of femtosecond pulse in an anomalous-dispersion fiber ring laser by using a polyvinyl alcohol (PVA)-based Topological Insulator (TI), Bi2Se3 saturable absorber (SA). The PVA-TI composite has a low saturable optical intensity of 12 MW/cm2 and a modulation depth of ~3.9%. By incorporating the fabricated PVA-TISA into a fiber laser, mode-locking operation could be achieved at a low pump threshold of 25 mW. After an optimization of the cavity parameters, optical pulse with ~660 fs centered at 1557.5 nm wavelength had been generated. The experimental results demonstrate that the PVA could be an excellent host material for fabricating high-performance TISA, and also indicate that the filmy PVA-TISA is indeed a good candidate for ultrafast saturable absorption device.

  18. Multi-pass oscillator layout for high-energy mode-locked thin-disk lasers

    CERN Document Server

    Schuhmann, K; Antognini, A

    2016-01-01

    A novel optical layout for a multi-pass resonator is presented paving the way for pulse energy scaling of mode-locked thin-disk lasers. The multi-pass resonator we are proposing consists of a concatenation of nearly identical optical segments. Each segment corresponds to a round-trip in an optically stable cavity containing an active medium exhibiting soft aperture effects. This scheme is apt for energy and power scaling because the stability region of this multi-pass resonator contrarily to the 4f-based schemes does not shrink with the number of passes. We conclude proposing a simple way to double the stability region of the state-of-the-art layouts used in the industry achievable by a minimal rearrangement of the used optical components.

  19. Intra-cavity frequency-doubled mode-locked semiconductor disk laser at 325 nm.

    Science.gov (United States)

    Bek, Roman; Baumgärtner, Stefan; Sauter, Fabian; Kahle, Hermann; Schwarzbäck, Thomas; Jetter, Michael; Michler, Peter

    2015-07-27

    We present a passively mode-locked semiconductor disk laser (SDL) emitting at 650nm with intra-cavity second harmonic generation to the ultraviolet (UV) spectral range. Both the gain and the absorber structure contain InP quantum dots (QDs) as active material. In a v-shaped cavity using the semiconductor samples as end mirrors, a beta barium borate (BBO) crystal is placed in front of the semiconductor saturable absorber mirror (SESAM) for pulsed UV laser emission in one of the two outcoupled beams. Autocorrelation (AC) measurements at the fundamental wavelength reveal a FWHM pulse duration of 1.22ps. With a repetition frequency of 836MHz, the average output power is 10mW per beam for the red emission and 0.5mW at 325nm.

  20. Comparison of different Kerr-lens mode locking laser design techniques

    Science.gov (United States)

    Moreno-Larios, José Agustín.; Rosete-Aguilar, Martha; Garduño-Mejía, Jesús

    2016-04-01

    Three numerical methods for the design of Kerr Lens Mode-Locking (KLML) ultrashort pulse cavities that use a solid state Brewster-cut nonlinear gain medium are compared. The nonlinear medium is modeled first deploying a matrix approximation that considers non-coupled (tangential analysis is independent of sagittal analysis) Kerr and thermal self-focusing; and second with a differential equation that relates the real and imaginary parts of the inverse of the complex Gaussian beam parameter. The third comparison is against a matrix analysis method that considers the coupling between the sagittal and tangential modes inside the nonlinear medium in order to determine the impact of this effect. The three methods search the self-consistency condition for the complex beam parameter and the results are compared.

  1. Flattop pulse generation based on the combined action of active mode locking and nonlinear polarization rotation.

    Science.gov (United States)

    Fang, Xiaohui; Wai, P K A; Lu, Chao; Chen, Jinhua

    2014-02-10

    A pulse-width-tunable 10 GHz flattop pulse (FTP) train is generated based on the combined action of active mode locking and nonlinear polarization rotation pulse shaping. Although the setup was previously used for other applications, the mechanism of FTP generation based on it is first analyzed and confirmed in the experiment. An FTP with pulse width tunable from 12 to 20 ps by changing polarization controllers is generated within the wavelength tuning range of 20 nm. The generated pulse reveals good stability, with the side mode suppression ratio of 65 dB, timing jitter of 92 fs, and amplitude fluctuation of 0.36%.

  2. Passively harmonic mode-locked fiber laser based on ReS2 saturable absorber

    Science.gov (United States)

    Lu, Feifei

    2017-06-01

    We demonstrate the generation of harmonic mode-locking (HML) in an erbium-doped fiber laser with a microfiber-based rhenium disulfide (ReS2) saturable absorber (SA). Taking advantages of both saturable absorption and large third-order nonlinear effect of ReS2, HML pulse with 318.5 MHz repetition rate can be obtained, corresponding to 168th harmonic of fundamental repetition frequency of 1.896 MHz. When the pump power is increased gradually, the pulse interval remains constant, while the output power increases linearly. At the pump power of 450 mW, the output power is ˜12 mW. The proposed high-repetition-rate pulse lasers would attract considerable attention due to its potential applications in soliton communications and frequency combs.

  3. Graphene oxide mode-locked femtosecond erbium-doped fiber lasers.

    Science.gov (United States)

    Xu, Jia; Liu, Jiang; Wu, Sida; Yang, Quan-Hong; Wang, Pu

    2012-07-02

    We demonstrated the femtosecond erbium-doped all-fiber lasers mode-locked with graphene oxide, which can be conveniently obtained from natural graphite by simple oxidation and ultra-sonication process. With proper dispersion management in an all-fiber ring cavity, the laser directly generated 200 fs pulses at a repetition rate of 22.9 MHz and the average output power was 5.8 mW. With the variation of net cavity dispersion, output pulses with pulse width of 0.2~3 ps were obtained at a repetition rate of 22.9~0.93 MHz. These results are comparable with those of graphene saturable absorbers and the superiority of easy fabrication and hydrophilic property of graphene oxide will facilitate its potential applications for ultrafast photonics.

  4. Intra-cavity gain shaping of mode-locked Ti:Sapphire laser oscillations

    CERN Document Server

    Yefet, Shai; Pe'er, Avi

    2015-01-01

    The gain properties of an oscillator strongly affect its behavior. When the gain is homogeneous, different modes compete for gain resources in a `winner takes all' manner, whereas with inhomogeneous gain, modes can coexist if they utilize different gain resources. We demonstrate precise control over the mode competition in a mode locked Ti:sapphire oscillator by manipulation and spectral shaping of the gain properties, thus steering the competition towards a desired, otherwise inaccessible, oscillation. Specifically, by adding a small amount of spectrally shaped inhomogeneous gain to the standard homogeneous gain oscillator, we selectively enhance a desired two-color oscillation, which is inherently unstable to mode competition and could not exist in a purely homogeneous gain oscillator. By tuning the parameters of the additional inhomogeneous gain we flexibly control the center wavelengths, relative intensities and widths of the two colors.

  5. Electrical Addressing and Temporal Tweezing of Localized Pulses in Passively Mode-Locked Semiconductor Lasers

    CERN Document Server

    Camelin, P; Marconi, M; Giudici, M

    2016-01-01

    We show that the pumping current is a convenient parameter for manipulating the temporal Localized Structures (LSs), also called localized pulses, found in passively mode-locked Vertical-Cavity Surface-Emitting Lasers. While short electrical pulses can be used for writing and erasing individual LSs, we demonstrate that a current modulation introduces a temporally evolving parameter landscape allowing to control the position and the dynamics of LSs. We show that the localized pulses drifting speed in this landscape depends almost exclusively on the local parameter value instead of depending on the landscape gradient, as shown in quasi-instantaneous media. This experimental observation is theoretically explained by the causal response time of the semiconductor carriers that occurs on an finite timescale and breaks the parity invariance along the cavity, thus leading to a new paradigm for temporal tweezing of localized pulses. Different modulation waveforms are applied for describing exhaustively this paradigm. ...

  6. Supercontinuum Generation in DSF Pumped by Actively Mode-Locked Fiber Laser

    Institute of Scientific and Technical Information of China (English)

    JIA Dongfang; WANG Zhaoying; LI Shichen

    2005-01-01

    The supercontinuum (SC) generation at the repetition rate of 10 GHz is presented. The SC is generated in a 4.2 km conventional dispersion-shifted fiber ( DSF), which is produced with nonlinear effects and group velocity dispersion. The DSF is pumped by an actively mode-locked Er3+ -doped fiber laser with pulse width of 7.97 ps. A novel SC pulse source with a bandwidth up to 125 nm is obtained, which covers the whole C, L bands and part of S band. The stable, narrow pulses with mean pulse-width of 9.7 ps and time-bandwidth product of 0.48 are filtered out across the whole SC bandwidth. This supercontinuum pulse source is suitable for future high-speed optical communications.

  7. 152 fs nanotube-mode-locked thulium-doped all-fiber laser

    Science.gov (United States)

    Wang, Jinzhang; Liang, Xiaoyan; Hu, Guohua; Zheng, Zhijian; Lin, Shenghua; Ouyang, Deqin; Wu, Xu; Yan, Peiguang; Ruan, Shuangchen; Sun, Zhipei; Hasan, Tawfique

    2016-07-01

    Ultrafast fiber lasers with broad bandwidth and short pulse duration have a variety of applications, such as ultrafast time-resolved spectroscopy and supercontinuum generation. We report a simple and compact all-fiber thulium-doped femtosecond laser mode-locked by carbon nanotubes. The oscillator operates in slightly normal cavity dispersion at 0.055 ps2, and delivers 152 fs pulses with 52.8 nm bandwidth and 0.19 nJ pulse energy. This is the shortest pulse duration and the widest spectral width demonstrated from Tm-doped all-fiber lasers based on 1 or 2 dimensional nanomaterials, underscoring their growing potential as versatile saturable absorber materials.

  8. Switchable dual-wavelength all-fiber laser mode-locked by carbon nanotubes

    Science.gov (United States)

    Kong, Y. C.; Yang, H. R.; Li, W. L.; Chen, G. W.

    2015-01-01

    We have proposed a compact dual-wavelength all-fiber pulse laser based on a single-walled carbon nanotube and chirped fiber Bragg gratings (CFBGs). A transmission filter is composed of a circulator and two CFBGs and is capable of controlling the operation of the proposed fiber laser. Mode-locking operations can be switched between 1551.2 and 1548.6 nm with the appropriate adjustment of polarization controller. Our laser delivers the pulses with the spectral bandwidth of about 0.6 nm and the pulse duration of about 7 ps. This work provides a low-cost, stable, and dual-wavelength ultrafast-pulsed laser source suitable for practical applications.

  9. Broadband Fourier domain mode-locked laser for optical coherence tomography at 1060 nm

    DEFF Research Database (Denmark)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang

    2012-01-01

    , enable acquisition of densely sampled three-dimensional datasets covering a wide field of view. However, semiconductor optical amplifiers (SOAs)-the typical laser gain media for swept sources-for the 1060nm band could until recently only provide relatively low output power and bandwidth. We have......Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human posterior eye segment (retina, choroid, sclera) due to low absorption in water and deep penetration into the tissue. Rapidly tunable light sources, such as Fourier domain mode-locked (FDML) lasers...... implemented an FDML laser using a new SOA featuring broad gain bandwidth and high output power. The output spectrum coincides with the wavelength range of minimal water absorption, making the light source ideal for OCT imaging of the posterior eye segment. With a moderate SOA current (270 mA) we achieve up...

  10. Design considerations for multi-core optical fibers in nonlinear switching and mode-locking applications

    CERN Document Server

    Nazemosadat, Elham

    2014-01-01

    We explore the practical challenges which should be addressed when designing a multi-core fiber coupler for nonlinear switching or mode-locking applications. The inevitable geometric imperfections formed in these fiber couplers during the fabrication process affect the performance characteristics of the nonlinear switching device. Fabrication uncertainties are tolerable as long as the changes they impose on the propagation constant of the modes are smaller than the linear coupling between the cores. It is possible to reduce the effect of the propagation constant variations by bringing the cores closer to each other, hence, increasing the coupling. However, higher coupling translates into a higher switching power which may not be desirable in some practical situations. Therefore, fabrication errors limit the minimum achievable switching power in nonlinear couplers.

  11. Report on first masing and single mode locking in a prebunched beam FEM oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M.; Eichenbaum, A.; Kleinman, H. [Tel-Aviv Univ., Ramat-Aviv (Israel)] [and others

    1995-12-31

    Radiation characteristics of a table-top free electron maser (FEM) are described in this paper. The FEM employs a prebunched electron beam and is operated as an oscillator in the low-gain collective (Raman) regime. Using electron beam prebunching single mode locking at any one of the possible oscillation modes was obtained. The electron beam is prebunched by a microwave tube section before it is injected into the wiggler. By tuning the electron beam bunching frequency, the FEM oscillation frequency can be locked to any eigen frequency of the resonant waveguide cavity which is within the frequency band of net gain of the FEM. The oscillation build up process is sped up, when the FEM operates with a prebunched electron beam, and the build-up time of radiation is shortened significantly. First measurements of masing with and without prebunching and characterization of the emitted radiation are reported.

  12. Higher Fe{sup 2+}/total Fe ratio in iron doped phosphate glass melted by microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Ashis K., E-mail: ashis@cgcri.res.in [CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata 700032 (India); Sinha, Prasanta K. [CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata 700032 (India); Das, Dipankar [UGC-DAE Consortium for Scientific Research, Kolkata 700098 (India); Guha, Chandan [Department of Chemical Engineering, Jadavpur University, Kolkata 700032 (India); Sen, Ranjan [CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata 700032 (India)

    2015-03-15

    Highlights: • Iron doped phosphate glasses prepared using microwave heating and conventional heating under air and reducing atmosphere. • Presence of iron predominantly in the ferrous oxidation state in all the glasses. • Significant concentrations of iron in the ferrous oxidation state on both octahedral and tetrahedral sites in all the glasses. • Ratio of Fe{sup 2+} with total iron is found higher in microwave prepared glasses in comparison to conventional prepared glasses. - Abstract: Iron doped phosphate glasses containing P{sub 2}O{sub 5}–MgO–ZnO–B{sub 2}O{sub 3}–Al{sub 2}O{sub 3} were melted using conventional resistance heating and microwave heating in air and under reducing atmosphere. All the glasses were characterised by UV–Vis–NIR spectroscopy, Mössbauer spectroscopy, thermogravimetric analysis and wet colorimetry analysis. Mössbauer spectroscopy revealed presence of iron predominantly in the ferrous oxidation state on two different sites in all the glasses. The intensity of the ferrous absorption peaks in UV–Vis–NIR spectrum was found to be more in glasses prepared using microwave radiation compared to the glasses prepared in a resistance heating furnace. Thermogravimetric analysis showed increasing weight gain on heating under oxygen atmosphere for glass corroborating higher ratio of FeO/(FeO + Fe{sub 2}O{sub 3}) in glass melted by direct microwave heating. Wet chemical analysis also substantiated the finding of higher ratio Fe{sup +2}/ΣFe in microwave melted glasses. It was found that iron redox ratio was highest in the glasses prepared in a microwave furnace under reducing atmosphere.

  13. Concentration effect on the spectroscopic behavior of Tb{sup 3+} ions in zinc phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kesavulu, C.R., E-mail: crkesavulu2005@gmail.com [Instituto de Fisica de São Carlos, Universidade de São Paulo, Avenida Trabalhador Sãocarlense 400, São Carlos, SP (Brazil); Almeida Silva, Anielle Christine [Laboratorio de Novos Materials Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberândia, MG (Brazil); Dousti, M.R. [Instituto de Fisica de São Carlos, Universidade de São Paulo, Avenida Trabalhador Sãocarlense 400, São Carlos, SP (Brazil); Dantas, Noelio Oliveira [Laboratorio de Novos Materials Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberândia, MG (Brazil); Camargo, A.S.S. de; Catunda, Tomaz [Instituto de Fisica de São Carlos, Universidade de São Paulo, Avenida Trabalhador Sãocarlense 400, São Carlos, SP (Brazil)

    2015-09-15

    Zinc phosphate glasses (PZABPTb) in the compositional system: P{sub 2}O{sub 5}–ZnO–Al{sub 2}O{sub 3}–BaO–PbO doped with variable Tb{sup 3+} concentrations (1–5 wt% Tb{sub 2}O{sub 3}) were prepared and characterized through absorption, excitation, emission and intensity decay rate measurements. The Judd–Ofelt model has been adopted to evaluate the radiative properties of the {sup 5}D{sub 4}→{sup 7}F{sub 6–3} emission transitions. The effect of Tb{sup 3+} ion concentration on the emissions from the {sup 5}D{sub 3,4} excited levels is discussed in detail. Analysis of the intensity decay curves corresponding to blue and green emissions from levels {sup 5}D{sub 3} and {sup 5}D{sub 4}, respectively, allowed determination of effective lifetimes, which confirmed the Tb{sup 3+} ion concentration quenching of the blue emission in these glasses. The decay curves for the {sup 5}D{sub 3} level are found to be non-exponential in nature for all the studied concentrations due to ion–ion energy transfer through cross-relaxation. In an attempt to identify the origin of the energy transfer mechanism, the decay curves were well fitted to the Inokuti–Hirayama model for S=6, which indicates that the energy transfer process is of dipole–dipole type. The optical band gap energy (E{sub opt}) has been evaluated taking into account the ultraviolet edge of absorption spectra. - Highlights: • Tb{sup 3+}-doped zinc phosphate glasses have been prepared by melt quenching technique. • Spectroscopic parameters were evaluated using the Judd–Ofelt theory. • Effects of Tb{sup 3+} concentration on luminescence of the glasses were studied. • Strong intense laser transition for Tb{sup 3+} ion in PZABPTb glasses is {sup 5}D{sub 4}→{sup 7}F{sub 5} (0.54 μm). • PZABPTb glasses could be used in the development of green color display devices and solid state visible lasers.

  14. Magnesium Coated Bioresorbable Phosphate Glass Fibres: Investigation of the Interface between Fibre and Polyester Matrices

    Directory of Open Access Journals (Sweden)

    Xiaoling Liu

    2013-01-01

    Full Text Available Bioresorbable phosphate glass fibre reinforced polyester composites have been investigated as replacement for some traditional metallic orthopaedic implants, such as bone fracture fixation plates. However, composites tested revealed loss of the interfacial integrity after immersion within aqueous media which resulted in rapid loss of mechanical properties. Physical modification of fibres to change fibre surface morphology has been shown to be an effective method to improve fibre and matrix adhesion in composites. In this study, biodegradable magnesium which would gradually degrade to Mg2+ in the human body was deposited via magnetron sputtering onto bioresorbable phosphate glass fibres to obtain roughened fibre surfaces. Fibre surface morphology after coating was observed using scanning electron microscope (SEM. The roughness profile and crystalline texture of the coatings were determined via atomic force microscope (AFM and X-ray diffraction (XRD analysis, respectively. The roughness of the coatings was seen to increase from 40±1 nm to 80±1 nm. The mechanical properties (tensile strength and modulus of fibre with coatings decreased with increased magnesium coating thickness.

  15. Sensitization of Sn2+ on Tb3+ luminescence for deep UV excitation in phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    Lei Li; Yang Wang; Duojin Wang; Jian Qi; Fanshu Xia; Huidan Zeng; Guorong Chen

    2016-01-01

    Tb3+ and Sn2+ co-doped strontium phosphate glasses are prepared and their unique photoluminescence (PL) properties for deep UV excitation are investigated.With the co-doped Sn2+ ions,Tb3+ keeps the original PL behaviors under near UV excitation while its PL action for deep UV excitation is enhanced tremendously.PL emission and excitation spectra demonstrate the sensitization role of Sn2+ on the Tb3+ emissions for deep UV excitation that is associated with the strong deep UV absorption of Sn2+ for greatly enhancing the resonance of the Tb3+ excitation with the deep UV light source.The decay curves of Sn2+ and Tb3+ emissions for both singly doped and co-doped samples are single exponentially well fitted with almost the same emission lifetime (τ) values in the microsecond and millisecond time regimes,respectively,confirming that Sn2+ and Tb3+ act as an independent activator in the present phosphate glass matrix while an involved energy transfer from Sn2+ to Tb3+ is radiative.Moreover,Sn2+ and Tb3+ can be co-excited with deep UV light to emit tunable light from blue to green with the definite CIE chromaticity coordinate for different applications.

  16. In Vitro Investigation of Bioactive Glass-Ceramic Composites Based on Biogenic Hydroxyapatite or Synthetic Calcium Phosphates

    Science.gov (United States)

    Pinchuk, Nataliia; Parkhomey, Oleksandr; Sych, Olena

    2017-02-01

    This in vitro investigation of the behavior of two types of calcium phosphate glass ceramics on the basis of phosphates of biogenic or synthetic origin prepared from initial mixtures with different particle size has revealed that some different factors affect the behavior, namely the phase composition of composite, fraction of open porosity, and average diameter of pore channels. It was established that the solubility of the composites on the basis of synthetic calcium phosphates and glass after 2 and 7 days contact with saline composites is the highest among the materials under study. First of all, this fact is related to the peculiarities of their phase composition, high fraction of open porosity, and high permeability. As for biogenic hydroxyapatite/glass materials, their solubility is several times lower in spite of close total porosity. The particle size of initial mixture practically does not affect the material solubility; the latter is only slightly lower for smaller particles.

  17. Red light generation through the lead boro-telluro-phosphate glasses activated by Eu3+ ions

    Science.gov (United States)

    Selvi, S.; Marimuthu, K.; Suriya Murthy, N.; Muralidharan, G.

    2016-09-01

    Lead boro-telluro-phosphate glasses containing 0.05 to 2.0 wt% of Eu3+ ions were prepared through melt quenching technique. Structural characteristics of title glasses were identified through XRD, FTIR and Raman studies. The optical properties of the prepared glasses were studied using UV-Vis-NIR absorption and photoluminescence spectra. From the resultant spectra, we have obtained the bonding parameters (δ), nephelauxetic ratio (β), direct and indirect band gaps and Urbach energy (ΔE) values. A deep red luminescence due to 5D0 → 7F2 transition of Eu3+ ions could be observed for the title glasses. The local site symmetry around the Eu3+ ions and the degree of Eu3+-O2- covalence were assessed from the luminescence intensity ratio of 5D0 → 7F2/5D0 → 7F1 transitions. Judd-Ofelt intensity parameters, calculated from the luminescence spectra, were used to estimate the radiative parameters like transition probability (A), branching ratio (βexp, βcal) and stimulated emission cross-section (σPE) concerning the 5D0 → 7FJ (J = 0, 1, 2, 3 and 4) transitions. The important laser parameters, gain bandwidth and optical gain are also estimated. The decay curves associated with the transition from 5D0 state was found to be single-exponential at all Eu3+ ion concentrations. CIE colour coordinates and colour purity of the prepared glasses were estimated from the CIE chromaticity diagram.

  18. Investigations of repetition rate stability of a mode-locked quantum dot semiconductor laser in an auxiliary optical fiber cavity

    DEFF Research Database (Denmark)

    Breuer, Stefan; Elsässer, Wolfgang; McInerney, J.G.

    2010-01-01

    We have investigated experimentally the pulse train (mode beating) stability of a monolithic mode-locked multi-section quantum-dot laser with an added passive auxiliary optical fiber cavity. Addition of the weakly coupled (¿ -24dB) cavity reduces the current-induced shift d¿/dI of the principal...

  19. Amplification of short pulses from a mode-locked diode laser in an ytterbium-doped fiber

    NARCIS (Netherlands)

    Hekelaar, M.G.; Adhimoolam, B.; Gross, P.; Lindsay, I.D.; Boller, Klaus J.

    2005-01-01

    We report the first mode-locked diode laser at 1.04 µm with subsequent amplification of the pulses in an ytterbium-doped fiber amplifier. The generated pulses have a pulse duration of 70ps and peak power of 50W.

  20. Rate equation dynamics of passively mode-locked quasi-continuous lasers: pulse stability and dynamic pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    New, G.H.C.; Orkney, K.E.; Nock, M.J.W.

    1976-09-01

    New theoretical results connected with the stability of multiple pulsing in a passively mode-locked quasicontinuous laser in the rate equation approximation are presented. Together with earlier results, these allow the number of pulses per cavity transit to be predicted and a qualitative estimate made of the pulse duration for any combination of parameters. The results are illustrated by computer evolutions.

  1. Q-Switched and Mode Locked Short Pulses from a Diode Pumped, YB-Doped Fiber Laser

    Science.gov (United States)

    2009-03-26

    500fs.pdf. 43. H. Leblond, M. Salhi, A. Hideur, T. Chartier , M. Brunel, F. Sanchez, "Experimental and theoretical study of the passively mode...locked ytterbium-doped double-clad fiber laser", Physical Review A, Vol. 65 063811 (2002) pp 1-9. 44. B. Ortac, A. Hideur, M. Brunel, T. Chartier , M

  2. Pulse bundles and passive harmonic mode-locked pulses in Tm-doped fiber laser based on nonlinear polarization rotation.

    Science.gov (United States)

    Wang, Xiong; Zhou, Pu; Wang, Xiaolin; Xiao, Hu; Liu, Zejin

    2014-03-10

    We demonstrate the nanosecond-level pulses in Tm-doped fiber laser generated by passively harmonic mode-locking. Nonlinear polarization rotation performed by two polarization controllers (PCs) is employed to induce the self-starting harmonic mode-locking. The fundamental repetition rate of the laser is 448.8 kHz, decided by the length of the cavity. Bundles of pulses with up to 17 uniform subpulses are generated due to the split of pulse when the pump power increases and the PCs are adjusted. Continuous harmonic mode-locked pulse trains are obtained with 1st to 6th and even more than 15th order when the positions of the PCs are properly fixed and the pump power is scaled up. The widths of all the uniform individual pulses are mostly 3-5 ns, and pulse with width of 304 ns at fundamental repetition rate can also be generated by adjusting the PCs. Hysteresis phenomenon of the passively harmonic mode-locked pulses' repetition frequency versus pump power is observed. The rather wide 3dB spectral bandwidth of the pulse train (25 nm) indicates that they may resemble noise-like pulses.

  3. Suppression of continuous lasing in a carbon nanotube polyimide film mode-locked erbium-doped fiber laser.

    Science.gov (United States)

    Gui, Lili; Yang, Xin; Zhao, Guangzhen; Yang, Xu; Xiao, Xiaosheng; Zhu, Jinsong; Yang, Changxi

    2011-01-01

    We demonstrated an erbium-doped mode-locked fiber laser using a single-walled carbon nanotube-dispersed polyimide (SWNT-PI) film. Different mode-locking operations were compared and analyzed utilizing SWNT-PI films with different concentrations (2, 1, and 0.25 wt.%, respectively). It was found that the continuous single-pulse mode-locking operation was often accompanied by a continuous wave oscillation part for the 1 and 0.25 wt.% SWNT-PI films, whereas the 2 wt.% SWNT-PI film presented the most excellent mode-locking performance, thanks to sufficient modulation depth. Using the 2 wt.% SWNT-PI film, a stable pulse train with a pulse width of 840 fs and a repetition rate of 15.3 MHz was achieved. The average output power was 0.33 mW at the pump power of 155 mW under an output coupling ratio of 10%. Operational performance of the laser cavity when employing the 2 wt.% SWNT-PI film was also demonstrated.

  4. Laser-diode pumped self-mode-locked praseodymium visible lasers with multi-gigahertz repetition rate.

    Science.gov (United States)

    Zhang, Yuxia; Yu, Haohai; Zhang, Huaijin; Di Lieto, Alberto; Tonelli, Mauro; Wang, Jiyang

    2016-06-15

    We demonstrate efficient laser-diode pumped multi-gigahertz (GHz) self-mode-locked praseodymium (Pr3+) visible lasers with broadband spectra from green to deep red for the first time to our knowledge. With a Pr3+-doped GdLiF4 crystal, stable self-mode-locked visible pulsed lasers at the wavelengths of 522 nm, 607 nm, 639 nm, and 720 nm have been obtained with the repetition rates of 2.8 GHz, 3.1 GHz, 3.1 GHz, and 3.0 GHz, respectively. The maximum output power was 612 mW with the slope efficiency of 46.9% at 639 nm. The mode-locking mechanism was theoretically analyzed. The stable second-harmonic mode-locking with doubled repetition frequency was also realized based on the Fabry-Perot effect formed in the laser cavity. In addition, we find that the polarization directions were turned with lasing wavelengths. This work may provide a new way for generating efficient ultrafast pulses with high- and changeable-repetition rates in the visible range.

  5. Diode array pumped, non-linear mirror Q-switched and mode-locked Nd : YVO4 laser – a good tool for powder SHG measurement

    Indian Academy of Sciences (India)

    P K Datta; Chandrajit Basu; S Mukhopadhyay; S K Das; G K Samanta; Antonio Agnesi

    2004-11-01

    A non-linear mirror consisting of a lithium triborate crystal and a dichroic output coupler are used to mode-lock (passively) an Nd : YVO4 laser, pumped by a diode laser array. The laser can operate both in cw mode-locked and simultaneously Q-switched and mode-locked (QML) regime. The peak power of the laser while operating in QML regime is much higher but pulses suffers from poor amplitude stability. The incorporation of an acousto-optic modulator as an active Q-switch enhances the stability of the QML pulse envelope. The second-order non-linearity of powdered crystalline urea is conclusively measured with respect to KDP while the laser is operating in passively Q-switched and passively mode-locked regime as well as in actively Q-switched and passively mode-locked regime.

  6. Phosphate glass core/silica clad fibres with a high concentration of active rare-earth ions

    Science.gov (United States)

    Egorova, O. N.; Galagan, B. I.; Denker, B. I.; Sverchkov, S. E.; Semjonov, S. L.

    2016-12-01

    We report a study of silica-clad composite optical fibres having a phosphate glass core doped with active rare-earth elements. The phosphate glass core allows a high concentration of active rare-earth ions to be obtained, and the silica cladding ensures high mechanical strength and facilitates fusion splicing of such fibres to silica fibres. Owing to the high concentration of active rare-earth ions, this type of fibre is potentially attractive for applications where a small cavity length and high lasing efficiency are needed.

  7. Structural and optical studies of Yb3+, Er3+ and Er3+/Yb3+ co-doped phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    S.Hraiech; M.Ferid; Y.Guyot; G.Boulon

    2013-01-01

    Phosphate glass samples with various Yb2O3 and Er2O3 contents were synthesized by the conventional melt quenching technique and characterized by X-ray diffraction,IR absorption spectroscopy and Raman scattering spectroscopy.The absorption,emission spectra and fluorescence decay studies were carried out both at low and room temperatures.Results showed the existence of several sites occupied by the rare earth ions in the phosphate glass.Up-conversion and cooperative fluorescence were also discussed.

  8. Novel Chemically Stable Er3+-Yb3+ Codopded Phosphate Glass for Ion-Exchanged Active Waveguide Devices

    Institute of Scientific and Technical Information of China (English)

    陈宝玉; 赵士龙; 胡丽丽

    2003-01-01

    A novel Er3+-Yb3+ codoped phosphate glass,which combines good chemical durability with good spectroscopic properties,is developed for the ion-exchange process.The relevant properties of this glass are presented for reference in the design and modelling of ion-exchanged active waveguide devices.The weight-loss rate of this glass is 1.45 × 10-5 g.cm-2.h-1 in boiling water,which is comparable to that of Kigre's Q-246 silicate glass.The emission cross section of Er3+ in this glass is calculated to be 0.72 × 10-20 cm2 using the McCumber theory.It is found that a planar waveguide with three modes at 632.8 nm is readily realized in this glass from our primary ion-exchange experiments.

  9. Investigations on optical properties of Sm{sup 3+} ion doped boro-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, R.; Suthanthirakumar, P.; Karthikeyan, P.; Marimuthu, K., E-mail: mari-ram2000@yahoo.com [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram – 624302 (India)

    2015-06-24

    The Sm{sup 3+} doped Boro-phosphate glasses with the chemical composition 60H{sub 3}BO{sub 3}+20Li{sub 2}CO{sub 3}+10ZnO+(10−x) H{sub 6}NO{sub 4}P+xSm{sub 2}O{sub 3} (where x= 0.1, 0.5, 1 and 2 in wt%) have been prepared by melt quenching technique. The prepared glasses were characterized through optical absorption and luminescence spectral measurements. The band gap energies corresponding to the direct and indirect allowed transitions and the Urbach’s energy values were estimated from the absorption spectra. Judd-Ofelt intensity parameters have been derived to predict the radiative properties of the various emission transitions. In order to identify the emission color of the prepared glasses, the emission intensities were analyzed using CIE 1931 color chromaticity diagram. The energy transfer process takes place between Sm{sup 3+}−Sm{sup 3+} ions through cross-relaxation mechanism have also been investigated and the results were discussed and reported.

  10. Application of Cu{sub 2}O-doped phosphate glasses for bandpass filter

    Energy Technology Data Exchange (ETDEWEB)

    Elhaes, H. [Physics Department, Faculty of Women for Arts, Science and Education, Ain Shams University, 11757 Cairo (Egypt); Attallah, M., E-mail: m_atallah94@yahoo.com [Basic Science Department, Higher Technological Institute, 10th of Ramadan City (Egypt); Elbashar, Y.; El-Okr, M. [Physics Department, Faculty of Science, Al Azhar University, Cairo (Egypt); Ibrahim, M. [Spectroscopy Department, National Research Centre, 12311 Dokki, Cairo (Egypt)

    2014-09-15

    Phosphate glasses doped with copper ions having general composition 42P{sub 2}O{sub 5}–39ZnO–(18−x) Na{sub 2}O–1CaO–xCu{sub 2}O [x=2, 4, 6, 8, 10 mol%] were prepared using a conventional melt-quench technique. Physical and chemical properties of the glasses were investigated using X-ray diffraction technique and UV–visible optical absorption. The density was measured by Archimedes' method, and molar volume (V{sub M}) was calculated. It is found that density and molar volume show opposite trend by increasing Cu{sub 2}O content. Absorbance and transmittance at the normal incidence are measured by a spectrophotometer in the spectral range of 190–1100 nm. Analyses of the obtained results were considered in the frame of current theories. Absorption data were used for absorption coefficient, the optical band gap (E{sub opt}), the cutoff in UV and IR bands to the bandpass filter, which confirmed the optical properties of this type of filter. E{sub opt} values for different glass samples are found to decrease with increasing Cu{sub 2}O content.

  11. Application of Cu2O-doped phosphate glasses for bandpass filter

    Science.gov (United States)

    Elhaes, H.; Attallah, M.; Elbashar, Y.; El-Okr, M.; Ibrahim, M.

    2014-09-01

    Phosphate glasses doped with copper ions having general composition 42P2O5-39ZnO-(18-x) Na2O-1CaO-xCu2O [x=2, 4, 6, 8, 10 mol%] were prepared using a conventional melt-quench technique. Physical and chemical properties of the glasses were investigated using X-ray diffraction technique and UV-visible optical absorption. The density was measured by Archimedes' method, and molar volume (VM) was calculated. It is found that density and molar volume show opposite trend by increasing Cu2O content. Absorbance and transmittance at the normal incidence are measured by a spectrophotometer in the spectral range of 190-1100 nm. Analyses of the obtained results were considered in the frame of current theories. Absorption data were used for absorption coefficient, the optical band gap (Eopt), the cutoff in UV and IR bands to the bandpass filter, which confirmed the optical properties of this type of filter. Eopt values for different glass samples are found to decrease with increasing Cu2O content.

  12. Conversion of borate-based glass scaffold to hydroxyapatite in a dilute phosphate solution.

    Science.gov (United States)

    Liu, Xin; Pan, Haobo; Fu, Hailuo; Fu, Qiang; Rahaman, Mohamed N; Huang, Wenhai

    2010-02-01

    Porous scaffolds of a borate-based glass (composition in mol%: 6Na2O, 8K2O, 8MgO, 22CaO, 36B2O3, 18SiO2, 2P2O5), with interconnected porosity of approximately 70% and pores of size 200-500 microm, were prepared by a polymer foam replication technique. The degradation of the scaffolds and conversion to a hydroxyapatite-type material in a 0.02 M K2HPO4 solution (starting pH = 7.0) at 37 degrees C were studied by measuring the weight loss of the scaffolds, as well as the pH and the boron concentration of the solution. X-ray diffraction, scanning electronic microscopy and energy dispersive x-ray analysis showed that a hydroxyapatite-type material was formed on the glass surface within 7 days of immersion in the phosphate solution. Cellular response to the scaffolds was assessed using murine MLO-A5 cells, an osteogenic cell line. Scanning electron microscopy showed that the scaffolds supported cell attachment and proliferation during the 6 day incubation. The results indicate that this borate-based glass could provide a promising degradable scaffold material for bone tissue engineering applications.

  13. Using graphene nano-particle embedded in photonic crystal fiber for evanescent wave mode-locking of fiber laser.

    Science.gov (United States)

    Lin, Yung-Hsiang; Yang, Chun-Yu; Liou, Jia-Hong; Yu, Chin-Ping; Lin, Gong-Ru

    2013-07-15

    A photonic crystal fiber (PCF) with high-quality graphene nano-particles uniformly dispersed in the hole cladding are demonstrated to passively mode-lock the erbium-doped fiber laser (EDFL) by evanescent-wave interaction. The few-layer graphene nano-particles are obtained by a stabilized electrochemical exfoliation at a threshold bias. These slowly and softly exfoliated graphene nano-particle exhibits an intense 2D band and an almost disappeared D band in the Raman scattering spectrum. The saturable phenomena of the extinction coefficient β in the cladding provides a loss modulation for the intracavity photon intensity by the evanescent-wave interaction. The evanescent-wave mode-locking scheme effectively enlarges the interaction length of saturable absorption with graphene nano-particle to provide an increasing transmittance ΔT of 5% and modulation depth of 13%. By comparing the core-wave and evanescent-wave mode-locking under the same linear transmittance, the transmittance of the graphene nano-particles on the end-face of SMF only enlarges from 0.54 to 0.578 with ΔT = 3.8% and the modulation depth of 10.8%. The evanescent wave interaction is found to be better than the traditional approach which confines the graphene nano-particles at the interface of two SMF patchcords. When enlarging the intra-cavity gain by simultaneously increasing the pumping current of 980-nm and 1480-nm pumping laser diodes (LDs) to 900 mA, the passively mode-locked EDFL shortens its pulsewidth to 650 fs and broadens its spectral linewidth to 3.92 nm. An extremely low carrier amplitude jitter (CAJ) of 1.2-1.6% is observed to confirm the stable EDFL pulse-train with the cladding graphene nano-particle based evanescent-wave mode-locking.

  14. Antibacterial effect of gallium and silver on Pseudomonas aeruginosa treated with gallium-silver-phosphate-based glasses.

    Science.gov (United States)

    Valappil, Sabeel P; Higham, Susan M

    2014-01-01

    Gallium and silver incorporated phosphate-based glasses were evaluated for antibacterial effect on the growth of Pseudomonas aeruginosa, which is a leading cause of opportunistic infections. The glasses were produced by conventional melt quenching methods at 1100°C for 1 h. Glass degradation studies were conducted by weight loss method. Disc diffusion assay and cell viability assay displayed statistically significant (p ≤ 0.0005) effect on P. aeruginosa growth which increased with decreasing calcium content in the glasses. The gallium ion release rates (1.83, 0.69 and 0.48 ppm·h(-1)) and silver ion release rates (2.97, 2.84 and 2.47 ppm·h(-1)) were found to account for this variation. Constant depth film fermentor was used to evaluate the anti-biofilm properties of the glasses. Both gallium and silver in the glass contributed to biofilm growth inhibitory effect on P. aeruginosa (up to 2.68 reduction in log 10 values of the viable counts compared with controls). The glasses were found to deliver gallium and silver in a controlled way and exerted cumulative antibacterial action on planktonic and biofilm growth of P. aeruginosa. The antibacterial, especially anti-biofilm, properties of the gallium and silver incorporated phosphate-based glasses make them a potential candidate to combat infections caused by P. aeruginosa.

  15. Cooperative energy transfer in Tm3+ and Yb3+ co-doped phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    XU Bo; YANG Bin; ZHANG Yuepin; XIA Haiping; WANG Jinhao

    2013-01-01

    An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated,which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+to Yb3+ ions.Judd-Ofelt (J-O) theory was used to calculate the intensity parameters (Ω2,Ω4,Ω6),the radiative transition rates (Ar),and radiative transition lifetime (τrad) of Tm3+.Based on Inokuti-Hirayama's model,the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system.Quantum efficiency related to Yb3+concentration was calculated,and the maximum QE efficiency reached 169.8%.

  16. Nanoscale mechanochemical wear of phosphate laser glass against a CeO2 particle in humid air

    Science.gov (United States)

    Yu, Jiaxin; He, Hongtu; Zhang, Yafeng; Hu, Hailong

    2017-01-01

    Using an atomic force microscope, the friction and wear of phosphate laser glass against a CeO2 particle were quantitatively studied both in humid air and in vacuum, to reveal the water molecules induced mechanochemical wear mechanism of phosphate laser glass. The friction coefficient of the glass/CeO2 pair in air was found to be 5-7 times higher than that in vacuum due to the formation of a capillary water bridge at the friction interface, with a contribution of the capillary-related friction to the total friction coefficient as high as 65-79%. The capillary water bridge further induced a serious material removal of glass and CeO2 particle surfaces, while supplying both a local liquid water environment to corrode the glass surface and a high shearing force to assist the stretching of the Cesbnd Osbnd P bond, accelerating the reaction between water and the glass/CeO2 pair. In vacuum, however, no discernable wear phenomena were observed, but the phase images captured by AFM tapping mode suggested the occurrence of potential strain hardening in the friction area of the glass surface.

  17. In vitro bioactivity of soda lime borate glasses with substituted SrO in sodium phosphate solution

    Directory of Open Access Journals (Sweden)

    Mohamed A. Marzouk

    2014-09-01

    Full Text Available Borate glasses with the basic composition 0.6B2O3·0.2Na2O·0.2CaO and SrO progressively substituting CaO were prepared and characterized for their bone-bonding ability. The obtained glasses were thermally treated and converted to their glass-ceramic derivatives. In this study, FTIR spectral analyses were done for the prepared glasses and glass-ceramics before and after immersion in a sodium phosphate solution for extended times. The appearance of two IR bands within the spectral range 550–680 cm-1 after immersion confirms the formation of hydroxyapatite. X-ray diffraction studies and scanning electron microscope analysis supported the obtained infrared spectroscopy results. The solubility test (measurements of the weight loss in aqueous sodium phosphate solution was conducted for measuring the dissolution of both glassy and crystalline derivatives to find out the role of SrO. The corrosion behaviour of the glasses and glass-ceramics indicate the increase of weight loss with the increase of SrO content. Different suggested proposals were introduced to explain this abnormal behaviour.

  18. Investigating the use of coupling agents to improve the interfacial properties between a resorbable phosphate glass and polylactic acid matrix.

    Science.gov (United States)

    Hasan, Muhammad Sami; Ahmed, Ifty; Parsons, Andrew J; Rudd, Chris D; Walker, Gavin S; Scotchford, Colin A

    2013-09-01

    Eight different chemicals were investigated as potential candidate coupling agents for phosphate glass fibre reinforced polylactic acid composites. Evidence of reaction of the coupling agents with phosphate glass and their effect on surface wettability and glass degradation were studied along with their principle role of improving the interface between glass reinforcement and polymer matrix. It was found that, with an optimal amount of coupling agent on the surface of the glass/polymer, interfacial shear strength improved by a factor of 5. Evidence of covalent bonding between agent and glass was found for three of the coupling agents investigated, namely: 3-aminopropyltriethoxysilane; etidronic acid and hexamethylene diisocyanate. These three coupling agents also improved the interfacial shear strength and increased the hydrophobicity of the glass surface. It is expected that this would provide an improvement in the macroscopic properties of full-scale composites fabricated from the same materials which may also help to retain these properties for the desired length of time by retarding the breakdown of the fibre/matrix interface within these composites.

  19. The Microleakage of Polycarboxylate, Glass Ionomer and Zinc Phosphate Cements for Stainless Steel Crowns of Pulpotomized Primary Molars

    Directory of Open Access Journals (Sweden)

    Mahkameh Mirkarimi

    2013-01-01

    Full Text Available Background: Microleakage in Stainless Steel Crowns (SSC margins leads to seepage of oral fluids and bacteria and it is one of the reasons for treatments failures. The aim of this study was to assess the effect of zinc phosphate, glass Ionomer and polycarboxylate cements on microleakage of stainless steel crowns for primary pulpotomized molar teeth. Materials and Methods: In this experimental in vitro study, 60 extracted primary molar teeth were randomly divided in to three groups (n=20. Stainless steel crowns were fitted for each tooth after pulpotomy procedures. Crowns were luted with a zinc phosphate, glass ionomer or polycarboxylate cement. All specimens were stored in 100% humidity at 37o C for 1 hour and termocycled 500 times (5ºC to 55ºC with a 30 seconds dwell time and then immersed in 0.5% basic fuschin solution for 24 hours. The specimens were sectioned buccolingually and each section was evaluated for microleakage under a stereomicroscope.Results: In zinc phosphate group 45% of spicemens and in glass ionomer group there was 5% of spicemens showed leakage extending on to occlusal aspect and in polycarboxylate group none of the spicemens had this situation. According to the kruskal wallis test in all groups there were significant differences in microleakage (p< 0.001.Conclusion: The use of zinc phosphate cement resulted in the highest percentage of microleakage. The microleakage of SSCs cemented with polycarboxylate and glass ionomer were similar.

  20. Development of large scale production of Nd-doped phosphate glasses for megajoule-scale laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Ficini, G. [Centre d`Etudes de Limeil-Valenton, Villeneuve, St. Georges (France); Campbell, J.H. [Lawrence Livermore National Lab., CA (United States)

    1996-05-01

    Nd-doped phosphate glasses are the preferred gain medium for high-peak-power lasers used for Inertial Confinement Fusion research because they have excellent energy storage and extraction characteristics. In addition, these glasses can be manufactured defect-free in large sizes and at relatively low cost. To meet the requirements of the future mega-joule size lasers, advanced laser glass manufacturing methods are being developed that would enable laser glass to be continuously produced at the rate of several thousand large (790 x 440 x 44 mm{sup 3}) plates of glass per year. This represents more than a 10 to 100-fold improvement in the scale of the present manufacturing technology.

  1. CsPbBr3 nanocrystal saturable absorber for mode-locking ytterbium fiber laser

    Science.gov (United States)

    Zhou, Yan; Hu, Zhiping; Li, Yue; Xu, Jianqiu; Tang, Xiaosheng; Tang, Yulong

    2016-06-01

    Cesium lead halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr3 nanocrystal films and characterize their physical properties. Broadband linear absorption from ˜0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr3 saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr3 liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm2, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ˜216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ˜1076 nm. This work shows that CsPbBr3 films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.

  2. Influence of kinetic hole filling on the stability of mode-locked semiconductor disk lasers

    Science.gov (United States)

    Moloney, Jerome V.; Kilen, Isak; Hader, Jorg; Koch, Stephan W.

    2016-03-01

    Microscopic many-body theory is employed to analyze the mode-locking dynamics of a vertical external-cavity surface-emitting laser with a saturable absorber mirror. The quantum-wells are treated microscopically through the semiconductor Bloch equations and the light field using Maxwell's equations. Higher order correlation effects such as polarization dephasing and carrier relaxation at the second Born level are included and also approximated using effective rates fitted to second-Born-Markov evaluations. The theory is evaluated numerically for vertical external cavity surface emitting lasers with resonant periodic gain media. For given gain, the influence of the loss conditions on the very-short pulse generation in the range above 100 fs is analyzed. Optimized operational parameters are identified. Additionally, the fully microscopic theory at the second Born level is used to carrier out a pump-probe study of the carrier recovery in individual critical components of the VECSEL cavity such as the VECSEL chip itself and semiconductor or graphene saturable absorber mirrors.

  3. Switchable repetition rate bound solitons passively mode-locked fiber laser

    Science.gov (United States)

    Wang, Xuqin; Yao, Yong

    2016-11-01

    We present a kind of a switchable repetition rate mode-locked of bound-state solitons in a fiber laser based on Bi2Se3 saturable absorber (SA). In the fiber laser, two forms of the bound-state optical spectrum with central wavelength of 1532 nm are observed. The fiber laser is operate at the abnormal group velocity dispersion and the bound state pulses are equally distributed to the temporal domain. The fundamental cavity repetition-rate is 1.11 MHz with a pulse duration of 2.27 ps. The output average power and the pulse peak energy are 1.53 mW and 607 W respectively, which the pump power is 267 mW. The different repetition-rates are also achieved by changing the pump power or adjusting the angle of polarization controller. In the experiment, the repetition-rate is switched from 1.11 MHz to 41.32 MHz (37th-order, the highest repetition-rate).

  4. CsPbBr{sub 3} nanocrystal saturable absorber for mode-locking ytterbium fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yan; Li, Yue; Xu, Jianqiu; Tang, Yulong, E-mail: yulong@sjtu.edu.cn [Key Laboratory for Laser Plasmas (MOE), Department of Physics and Astronomy, Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240 (China); Hu, Zhiping; Tang, Xiaosheng [Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2016-06-27

    Cesium lead halide perovskite nanocrystals (CsPbX{sub 3}, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr{sub 3} nanocrystal films and characterize their physical properties. Broadband linear absorption from ∼0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr{sub 3} saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr{sub 3} liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm{sup 2}, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ∼216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ∼1076 nm. This work shows that CsPbBr{sub 3} films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.

  5. Monolithic mode locked DBR laser with multiple-bandgap MQW structure realized by selective area growth

    Energy Technology Data Exchange (ETDEWEB)

    Schilling, M.; Bouayad-Amine, J.; Feeser, T.; Haisch, H.; Kuehn, E.; Lach, E.; Satzke, K.; Weber, J.; Zielinski, E. [Alcatel Telecom, Stuttgart (Germany). Research Div.

    1996-12-31

    The realization of novel monolithically integrated multiple-segment pulse laser sources in InGaAsP MQW technology is reported. The MQW layers for all functional sections of these devices, the modulator, the active (gain) and the passive waveguide, as well as the Bragg section were grown in a single selective area growth (SAG) step by LP-MOVPE on SiO{sub 2} patterned 2 inch InP substrates. Due to a properly selected pattern geometry 3 different bandgap regions with smooth interfaces are thereby formed along the laser cavity. The more than 4 mm long DBR lasers which exhibit a threshold current as low as 30 mA were mode locked by an intra-cavity electroabsorption modulator applying a sinusoidal voltage at around 10 GHz. In this way an optical pulse train with pulse widths < 13 ps (measured with a streak camera) and high extinction ratio was generated. A time-bandwidth product of 0.5 close to the Fourier limit is obtained. This device is very attractive for signal generation in 40 Gb/s OTDM transmission systems at 1.55 {micro}m wavelength.

  6. Mode-Locked CO Laser for Isotope Separation of Uranium Employing Condensation Repression

    Directory of Open Access Journals (Sweden)

    Igor Y. Baranov

    2010-01-01

    Full Text Available In the present work, we have suggested a technical solution of a CO laser facility for industrial separation of uranium used in the production of fuel for nuclear power plants. There has been used a method of laser isotope separation of uranium, employing condensation repression in a free jet. The laser operation with nanosecond pulse irradiation can provide acceptable efficiency in the separating unit and the high effective coefficient of the laser with the wavelength of 5.3 μm. Receiving a uniform RF discharge under medium pressure and high Mach numbers in the gas stream solves the problem of an electron beam and cryogenic cooler of CO lasers. The laser active medium is being cooled while it is expanding in the nozzle; a low-current RF discharge is similar to a non-self-sustained discharge. In the present work, we have developed a calculation model of optimization and have defined the parameters of a mode-locked CO laser with an RF discharge in the supersonic stream. The CO laser average power of 3 kW is sufficient for efficient industrial isotope separation of uranium at one facility.

  7. Picosecond pulses from wavelength-swept continuous-wave Fourier domain mode-locked lasers.

    Science.gov (United States)

    Eigenwillig, Christoph M; Wieser, Wolfgang; Todor, Sebastian; Biedermann, Benjamin R; Klein, Thomas; Jirauschek, Christian; Huber, Robert

    2013-01-01

    Ultrafast lasers have a crucial function in many fields of science; however, up to now, high-energy pulses directly from compact, efficient and low-power semiconductor lasers are not available. Therefore, we introduce a new approach based on temporal compression of the continuous-wave, wavelength-swept output of Fourier domain mode-locked lasers, where a narrowband optical filter is tuned synchronously to the round-trip time of light in a kilometre-long laser cavity. So far, these rapidly swept lasers enabled orders-of-magnitude speed increase in optical coherence tomography. Here we report on the generation of ~60-70 ps pulses at 390 kHz repetition rate. As energy is stored optically in the long-fibre delay line and not as population inversion in the laser-gain medium, high-energy pulses can now be generated directly from a low-power, compact semiconductor-based oscillator. Our theory predicts subpicosecond pulses with this new technique in the future.

  8. Passively mode-locked soliton femtosecond pulses employing graphene saturable absorber

    Science.gov (United States)

    Lau, K. Y.; Muhammad, F. D.; Latif, A. A.; Abu Bakar, M. H.; Yusoff, Z.; Mahdi, M. A.

    2017-09-01

    We demonstrate a passively mode-locked fiber laser incorporating graphene thin film (GTF) as saturable absorber (SA). The SA is fabricated by sandwiching the GTF between two single mode fiber ferrules through a fiber adaptor. The transmission loss at 1560 nm and non-linear saturation absorption modulation depth for GTF-SA are 0.8 dB and 2.90%, respectively. An erbium-doped fiber laser cavity is constructed to verify the functionality of GTF-SA and is designed to have net anomalous dispersion. It generates large spectral width of 4.99 nm with pulse repetition rate of 9.655 MHz and pulse width of 670 fs. Net anomalous dispersion and time bandwidth product higher than the sech2 transform-limited pulse validate the experimental result. In short, we demonstrate high performance GTF-SA that is able to generate ultrafast pulse duration in femtosecond range effortlessly with simple and green SA fabrication procedures.

  9. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers.

    Science.gov (United States)

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-12-19

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing.

  10. Simple optical frequency comb generation using a passively mode-locked quantum dot laser

    Science.gov (United States)

    Liu, Li; Zhang, Xiupu; Xu, Tiefeng; Dai, Zhenxiang; Liu, Taijun

    2017-08-01

    A simple and quasi-tunable optical frequency comb (OFC) generator is proposed and experimentally demonstrated using a C-band passively Fabry-Pérot quantum dot mode-locked laser and a dual-driven LiNbO3 Mach-Zehnder modulator. A 16-nm bandwidth OFC with 81, 58 and 30 comb lines at frequency interval of 23.3 GHz, 35 GHz and 70 GHz respectively is obtained experimentally. Measured average optical signal to noise ratio of 10-dB bandwidth OFCs is 36.3 dB, 38.5 dB and 40.8 dB at frequency interval of 23.3 GHz, 35 GHz and 70 GHz, respectively. Besides, single-sideband phase noise of the 23.3 GHz and 35 GHz frequency comb is -110 dBc/Hz and -102 dBc/Hz at an offset of 1 kHz, respectively. RF linewidth of the 23.3 GHz and 35 GHz OFC is about from 275 Hz to 289 Hz. This is considered a very simple OFC generator with a broadband and seamless spectrum.

  11. Isolator-free switchable uni- and bidirectional hybrid mode-locked erbium-doped fiber laser.

    Science.gov (United States)

    Chernysheva, Maria; Araimi, Mohammed Al; Kbashi, Hani; Arif, Raz; Sergeyev, Sergey V; Rozhin, Aleksey

    2016-07-11

    An Erbium-doped fibre ring laser hybrid mode-locked with single-wall carbon nanotubes (SWNT) and nonlinear polarisation evolution (NPE) without an optical isolator has been investigated for various cavity conditions. Precise control of the state of polarisation (SOP) in the cavity ensures different losses for counter-propagating optical fields. As the result, the laser operates in quasi-unidirectional regime in both clockwise (CW) and counter-clockwise (CCW) directions with the emission strengths difference of the directions of 22 dB. Furthermore, by adjusting the net birefringence in the cavity, the laser can operate in a bidirectional generation. In this case, a laser pumped with 75 mW power at 980 nm generates almost identical 790 and 570 fs soliton pulses with an average power of 1.17 and 1.11 mW. The operation stability and pulse quality of the soliton pulses in both unidirectional regimes are highly competitive with those generated in conventional ring fibre lasers with isolator in the cavity. Demonstrated bidirectional laser operation can find vital applications in gyroscopes or precision rotation sensing technologies.

  12. Artificial Neuron Based on Integrated Semiconductor Quantum Dot Mode-Locked Lasers

    Science.gov (United States)

    Mesaritakis, Charis; Kapsalis, Alexandros; Bogris, Adonis; Syvridis, Dimitris

    2016-12-01

    Neuro-inspired implementations have attracted strong interest as a power efficient and robust alternative to the digital model of computation with a broad range of applications. Especially, neuro-mimetic systems able to produce and process spike-encoding schemes can offer merits like high noise-resiliency and increased computational efficiency. Towards this direction, integrated photonics can be an auspicious platform due to its multi-GHz bandwidth, its high wall-plug efficiency and the strong similarity of its dynamics under excitation with biological spiking neurons. Here, we propose an integrated all-optical neuron based on an InAs/InGaAs semiconductor quantum-dot passively mode-locked laser. The multi-band emission capabilities of these lasers allows, through waveband switching, the emulation of the excitation and inhibition modes of operation. Frequency-response effects, similar to biological neural circuits, are observed just as in a typical two-section excitable laser. The demonstrated optical building block can pave the way for high-speed photonic integrated systems able to address tasks ranging from pattern recognition to cognitive spectrum management and multi-sensory data processing.

  13. Fourier domain mode-locked swept source at 1050 nm based on a tapered amplifier.

    Science.gov (United States)

    Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang; Biedermann, Benjamin R; Hsu, Kevin; Hansen, Kim P; Sumpf, Bernd; Hasler, Karl-Heinz; Erbert, Götz; Jensen, Ole B; Pedersen, Christian; Huber, Robert; Andersen, Peter E

    2010-07-19

    While swept source optical coherence tomography (OCT) in the 1050 nm range is promising for retinal imaging, there are certain challenges. Conventional semiconductor gain media have limited output power, and the performance of high-speed Fourier domain mode-locked (FDML) lasers suffers from chromatic dispersion in standard optical fiber. We developed a novel light source with a tapered amplifier as gain medium, and investigated the FDML performance comparing two fiber delay lines with different dispersion properties. We introduced an additional gain element into the resonator, and thereby achieved stable FDML operation, exploiting the full bandwidth of the tapered amplifier despite high dispersion. The light source operates at a repetition rate of 116 kHz with an effective average output power in excess of 30 mW. With a total sweep range of 70 nm, we achieved an axial resolution of 15 microm in air (approximately 11 microm in tissue) in OCT measurements. As our work shows, tapered amplifiers are suitable gain media for swept sources at 1050 nm with increased output power, while high gain counteracts dispersion effects in an FDML laser.

  14. Developing high energy mode-locked fiber laser at 2 micron

    CERN Document Server

    Huang, C; Shang, W; Tang, Y; Xu, J

    2015-01-01

    While dissipative soliton operation has successfully improved the pulse energy of 1 {\\mu}m and 1.5 {\\mu}m fiber lasers to tens of nanojoules, it is still hard to scale the pulse energy of dissipative solitons at 2 {\\mu}m due to the anomalous dispersion of the gain fiber. Based on theoretical simulation, we analyze intracavity dynamics of dissipative solitons (DSs) and propose that gain fiber should be condensed to short length in order to scale the pulse energy of 2 {\\mu}m DSs. The simulation predicts pulse energy of over 10 nJ for 2 {\\mu}m dissipative solitons, comparable to that achieved in the 1 {\\mu}m and 1.5 {\\mu}m regimes. Experimental operation generates stable 2 {\\mu}m DSs from a linear cavity with pulse energy of 4.9 nJ and dechirped pulse duration of 579 fs. These results advance our understanding of mode-locked fiber laser at different wavelengths and lay an important step in achieving high energy ultrafast laser pulses from anomalous dispersion gain media at 2 {\\mu}m.

  15. Nanotube-mode-locked linear-cavity fiber laser delivering switchable ultrafast solitons

    Science.gov (United States)

    Han, X. X.

    2015-02-01

    We propose a linear-cavity switchable fiber laser based on a single-wall carbon nanotube mode-locker for the first time to the best of our knowledge. Two chirped fiber Bragg gratings (CFBGs) in series and an optical circulator are employed as end mirrors of the linear cavity. The linear-cavity fiber laser is simple and cost-efficient. By adjusting the polarization controllers, a switchable mode-locking operation is obtained at 1551.3 and 1557.9 nm respectively, corresponding to the central wavelengths of two series-wound CFBGs. The pulse duration and spectral bandwidth of ultrafast solitons are ~4.4 ps and ~0.65 nm for the short wavelength operation at 1551.3 nm and ~3.9 ps and ~0.71 nm for the long wavelength operation at 1557.9 nm, respectively. Our experimental observations are well confirmed by the numerical results. The linear-cavity all-fiber laser reduces the cost and is very attractive for ultrafast optics.

  16. Effect of PbO on the spectral and thermo-optical properties of Nd3+-doped phosphate laser glass

    Science.gov (United States)

    Yin, Qianwen; Kang, Shuai; Wang, Xue; Li, Shunguang; He, Dongbing; Hu, Lili

    2017-04-01

    Nd3+-doped P2O5-K2O-Al2O3-BaO-PbO phosphate glasses with various PbO/BaO ratios were synthesized using the melt quenching technique. Raman, absorption, and emission spectra were measured to investigate the effects of PbO/BaO ratios on the structures and spectroscopic properties of the glasses. The emission cross-sections of the Nd3+-doped phosphate glasses were calculated using the Judd-Ofelt theory, and were found to increase from 4.37 × 10-20 to 4.50 × 10-20 cm2 as the PbO/BaO ratio increased. In addition, thermo-optical properties were measured using an interferometric technique. The thermo-optical coefficients, which were -1.49 × 10-6, -1.65 × 10-6, and -1.64 × 10-6 K-1, respectively, were all largely negative values. The thermal expansion coefficients of the three glass samples varied within a small range. The results showed that increasing the PbO/BaO ratio of phosphate glasses can improve the laser properties while maintaining their good thermo-optical properties.

  17. Structural and luminescence properties of Dy3+ doped bismuth phosphate glasses for greenish yellow light applications

    Science.gov (United States)

    Damodaraiah, S.; Reddy Prasad, V.; Babu, S.; Ratnakaram, Y. C.

    2017-05-01

    Different compositions of (5, 10, 15 and 20 mol%) of bismuth and different concentrations (0.5, 1.0, 1.5 and 2.0 mol%) of Dy3+ ion doped bismuth phosphate (BiP) glasses were synthesized by melt-quenching technique. The structural characterization was accomplished by XRD, SEM with EDS, FTIR, FT-Raman and 31P MAS NMR spectroscopy. The optical properties were studied using absorption and photoluminescence spectroscopy. Different structural groups were identified using FTIR and FT-Raman spectra. The depolymerization of metaphosphate chains are described by the decrease of Q2 tetrahedral sites allowing the formation of pyrophosphate groups (Q1) revealed by 31P MAS NMR spectroscopic investigations. Judd-Ofelt intensity parameters Ωλ (λ = 2, 4 and 6) were evaluated from absorption spectra. Radiative parameters such as radiative lifetimes (τR), integrated absorption cross-sections (Σ) and branching ratios (βR) were calculated using Judd-Ofelt intensity parameters. From photoluminescence spectra, experimental branching ratios (βexp) and stimulated emission cross-sections (σP) were calculated for all the observed emission transitions of prepared glasses. The decay profiles for 4F9/2 level were recorded and fit exponential for 0.5 mol% and non-exponential for higher concentrations of Dy3+ due to non-radiative energy transfer among excited Dy3+ ions. The CIE chromaticity co-ordinates have been calculated from the luminescence spectra which confirmed greenish yellow light emission.

  18. Influence of MgO on structure and optical properties of alumino-lithium-phosphate glasses

    Science.gov (United States)

    Jlassi, I.; Elhouichet, H.; Ferid, M.

    2016-07-01

    MgO doped lithium alumino phosphate glasses (PLA: P2O5+Li2O+Al2O3+MgO) were prepared by melt quenching technique. Raman spectra display three significant peaks at 698, 1164 and 1383 cm-1 attributed to: symmetric stretching vibrations of the bridging oxygen (BO) in the P-O-P chains, symmetric stretching vibrations of the PO2 groups, and the asymmetric vibrations vas(PO2) of the non-bridging oxygen (NBO) atoms, respectively. Also, the density, molar volumes and ion concentration have been discussed and correlated with the structural changes within the glassy matrix. Some optical constants such as refractive index and dispersion parameters (Eo: single-oscillator energy and Ed: dispersive energy) of the glasses were determined. Finally, the values of the optical band gap for direct and indirect allowed transitions have been determined from the absorption edge studies. It is deduced that the values of Eopt increase with increasing MgO content. It was assigned to structural changes induced from the formation of non-bridging oxygen. The Urbach energy (ΔE) was found to decrease from 0.578 to 0.339 eV with increasing MgO content from 0.5 to 2 mol.

  19. In Situ Wire Drawing of Phosphate Glass in Polymer Matrices for Material Extrusion 3D Printing

    Directory of Open Access Journals (Sweden)

    J. Gilberto Siqueiros

    2017-01-01

    Full Text Available A strategy to increase the amount of materials available for additive manufacturing platforms such as material extrusion 3D printing (ME3DP is the creation of printable thermoplastic composites. Potential limiters to the incorporation of filler materials into a thermoplastic resin include agglomeration of the filler materials, which can compromise the mechanical properties of the material system and a static morphology of the filler material. A potential solution to these issues is the use of filler materials with low glass transition temperatures allowing for a change in morphology during the extrusion process. Here, we successfully demonstrate the drawing of phosphate glass particles into a wire-like morphology within two polymeric systems: (1 a rubberized acrylonitrile butadiene styrene (ABS blend and (2 polylactic acid (PLA. After applying a normalization process to account for the effect of air gap within the 3D printed test specimens, an enhancement in the mechanical properties was demonstrated where an increase in strength was as high as 21% over baseline specimens. Scanning electron microanalysis was used to characterize the fracture surface and wire drawing efficacy. Factors affecting the ability to achieve wire drawing such as polymer viscosity and print temperature are also highlighted.

  20. Titanium phosphate glass microcarriers induce enhanced osteogenic cell proliferation and human mesenchymal stem cell protein expression

    Directory of Open Access Journals (Sweden)

    Nilay J Lakhkar

    2015-11-01

    Full Text Available In this study, we have developed 50- to 100-µm-sized titanium phosphate glass microcarriers (denoted as Ti5 that show enhanced proliferation of human mesenchymal stem cells and MG63 osteosarcoma cells, as well as enhanced human mesenchymal stem cell expression of bone differentiation markers, in comparison with commercially available glass microspheres at all time points. We also demonstrate that these microcarriers provide superior human mesenchymal stem cell proliferation with conventional Dulbecco’s Modified Eagle medium than with a specially developed commercial stem cell medium. The microcarrier proliferative capacity is revealed by a 24-fold increase in MG63 cell numbers in spinner flask bioreactor studies performed over a 7-day period, versus only a 6-fold increase in control microspheres under the same conditions; the corresponding values of Ti5 and control microspheres under static culture are 8-fold and 7-fold, respectively. The capability of guided osteogenic differentiation is confirmed by ELISAs for bone morphogenetic protein-2 and osteopontin, which reveal significantly greater expression of these markers, especially osteopontin, by human mesenchymal stem cells on the Ti5 microspheres than on the control. Scanning electron microscopy and confocal laser scanning microscopy images reveal favorable MG63 and human mesenchymal stem cell adhesion on the Ti5 microsphere surfaces. Thus, the results demonstrate the suitability of the developed microspheres for use as microcarriers in bone tissue engineering applications.

  1. Measurement of the figure of merit of indigenously developed Nd-doped phosphate laser glass rods for use in high power lasers

    Indian Academy of Sciences (India)

    A P Kulkarni; S Jain; M P Kamath; A S Joshi; P A Naik; P D Gupta; K Annapurna; A K Mandal; B Karmakar; R Sen

    2014-01-01

    High energy, high power (HEHP) Nd:glass laser systems are used for inertial confinement fusion and equation of state (EOS) studies of materials at high temperature and pressure. A program has been undertaken for the indigenous development of Nd-doped phosphate laser glass rods and discs for HEHP lasers. In this paper, we report the characterization of the Nd-doped phosphate laser glass rods produced under this program and compare the indigenously developed laser glass to LHG-8 laser glass of M/s Hoya, Japan. We experimentally measured the values of the stimulated emission cross-section () and coefficient of intensity-dependent refractive index (2) and hence the figure of merit = /2 of the indigenous phosphate laser glass rods. This value of figure of merit is found comparable to the reported value of identically doped Nd:glass rods.

  2. Luminescence properties of Tb3+-doped zinc phosphate glasses for green laser application

    Science.gov (United States)

    Juárez-Batalla, J.; Meza-Rocha, A. N.; Muñoz H., G.; Camarillo, I.; Caldiño, U.

    2016-08-01

    Tb3+-doped zinc phosphate glasses of composition in mol%: (100.0 - x)Zn(PO3)2 - xTb2O3, x = 0.6, 1.0, 2.0 and 5.0, were prepared by conventional melt quenching technique and characterized by photoluminescence and decay time spectroscopy. The integrated intensities of the 5D4 → 7F5 (green at 541 nm) and 5D3 → 7F4 (blue at 435 nm) emissions and their intensity ratios IG/IB upon 350 nm excitation have been evaluated as function of Tb3+ concentration. The CIE1931 color of the glasses excited at 350 nm varies from turquoise to green by increasing the Tb3+ content. The increased IG/IB ratio up to a factor of 364 for the phosphor with the highest Tb3+ content (ZP5Tb) is consistent with the observed shift toward the green region in the CIE coordinates, so that the ZP5Tb glass exhibits a green color purity of 66.9% with chromaticity coordinates (0.290, 0.581), being very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. This interesting feature of the ZP5Tb phosphor, together with an experimental branching ratio larger than 60% of the 5D4 → 7F5 green emission, highlights its capability as solid state green laser pumped by AlGaN (350 nm) LEDs. The decay time profiles of the 5D3 level resulted to be non-exponential for all the studied concentrations due to energy transfer between Tb3+ ions through cross-relaxation. Such decay profiles were well fitted to the Inokuti-Hirayama model for S = 6, which indicates that an electric dipole-dipole interaction might be the dominant mechanism in the cross-relaxation energy transfer occurring in Tb3+ ion clusters.

  3. Synthesis, characterization and bioactivity of a calcium-phosphate glass-ceramics obtained by the sol-gel processing method.

    Science.gov (United States)

    Jmal, Nouha; Bouaziz, Jamel

    2017-02-01

    In this work, a calcium-phosphate glass-ceramics was successfully obtained by heat treatment of a mixture of 26.52 in wt.% of fluorapatite (Fap) and 73.48 in wt.% of 77S (77 SiO214 CaO9 P2O5 in wt.%) gel. The calcium phosphate-glass-ceramics was prepared by sol-gel process with tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate and fluorapatite. The synthesized powders were characterized by some commonly used tools such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), (31)P magic angle spinning nuclear magnetic resonance (MAS-NMR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thin-film X-ray diffraction (TF-XRD). The obtained results seemed to confirm the nucleation and growth of hydroxyapatite (Hap) nano-phase in the glass. Moreover, an in-vitro evaluation of the glass-ceramic was performed. In addition, to assess its bioactive capacity, it was soaked in simulated body fluid (SBF) at different time intervals. The SEM, EDS and TF-XRD analyses showed the deposition of hydroxyapatite on the surface of the specimens after three days of immersion in SBF solution. The mechanical properties of the obtained material such as rupture strength, Vickers hardness and elastic modulus were measured. In addition, the friction coefficient of calcium phosphate-glass-ceramics was tested. The values of the composite of rupture strength (24MPa), Vickers hardness (214Hv), Young's modulus (52.3GPa), shear modulus (19GPa) and friction coefficient (0.327) were obtained. This glass-ceramics can have useful applications in dental prostheses. Indeed, this material may have promising applications for implants because of its content of fluorine, the effective protector against dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Post cementation sensitivity evaluation of glass Ionomer, zinc phosphate and resin modified glass Ionomer luting cements under class II inlays: An in vivo comparative study

    Directory of Open Access Journals (Sweden)

    Chandrasekhar V

    2010-01-01

    Full Text Available Objective: This study aims to compare the patient-perceived post-cementation sensitivity of class II metal restorations preoperatively, immediately after cementation, one week after cementation and one month after cementation with (1 Glass Ionomer luting cement (2 Zinc Phosphate cement and (3 Resin-modified Glass Ionomer luting cement. Materials and Methods: A total of 60 patients, irrespective of sex, in the age group of 15-50 years were selected and the teeth were randomly divided into three groups of 20 each. Twenty inlay cast restorations were cemented with three different luting cements. The criteria adapted to measure tooth sensitivity in the present study were objective examination for sensitivity.(1 Cold water test (2 Compressed air test and (3 Biting pressure test. Results: The patients with restorations cemented with Resin-modified Glass ionomer demonstrated the least postoperative sensitivity when compared with Glass Ionomer and zinc phosphate cement at all different intervals of time evaluated by different tests. Conclusion: The patients with restorations cemented with resin-modified Glass ionomer demonstrated the least postoperative sensitivity.

  5. Femtosecond mode-locking of an ytterbium-doped fiber laser using self-assembled gold nanorods

    Science.gov (United States)

    Lee, J.; Koo, J.; Lee, J. H.

    2017-09-01

    We experimentally demonstrate the use of a saturable absorber (SA) based on self-assembled gold nanorods (GNRs) for femtosecond mode-locking of an ytterbium-doped fiber-based 1 µm laser. A novel type of SA was made by implementation of an end-to-end GNRs self-assembly technique through hot-air induced rapid drying of the GNRs in a deionized water suspension, which enabled us to enhance optical absorption in the 1.06 µm wavelength region. By incorporating this novel SA into an ytterbium-doped fiber-based ring cavity under dispersion-managed conditions, we were able to readily generate mode-locked, soliton pulses having a temporal width of 840 fs at 1063.9 nm. To the best of our knowledge, this is the first demonstration of the effectiveness of a GNRs-based SA for the generation of femtosecond soliton pulses operating in the 1 µm range.

  6. Rational harmonic mode-locked laser using a bismuth-oxide-based highly nonlinear erbium-doped fiber

    Science.gov (United States)

    Fukuchi, Yutaka; Hirata, Kouji; Muraguchi, Masahiro; Maeda, Joji

    2017-01-01

    We report a rational harmonic mode-locked fiber laser employing a bismuth-oxide-based highly nonlinear erbium-doped fiber (Bi-HNL-EDF) with a length of 1.5 m. The Bi-HNL-EDF is used as a broadband gain medium and as a noise suppressor based on self-phase modulation. The amplitude of the rational harmonic mode-locked pulses can be regulated by properly tuning the modulation parameters of the intracavity modulator. The cavity length as short as 6 m enables generation of stable and clean short pulses with a repetition frequency up to 40 GHz over the wavelength range covering both the conventional and the longer bands.

  7. Hysteresis in the tearing mode locking/unlocking due to resonant magnetic perturbations in EXTRAP T2R

    Science.gov (United States)

    Fridström, R.; Frassinetti, L.; Brunsell, P. R.

    2015-10-01

    The physical mechanisms behind the hysteresis in the tearing mode locking and unlocking to a resonant magnetic perturbation (RMP) are experimentally studied in EXTRAP T2R reversed-field pinch. The experiments show that the electromagnetic and the viscous torque increase with increasing perturbation amplitude until the mode locks to the wall. At the wall-locking, the plasma velocity reduction profile is peaked at the radius where the RMP is resonant. Thereafter, the viscous torque drops due to the relaxation of the velocity in the central plasma. This is the main reason for the hysteresis in the RMP locking and unlocking amplitude. The increased amplitude of the locked tearing mode produces further deepening of the hysteresis. Both experimental results are in qualitative agreement with the model in Fitzpatrick et al (2001 Phys. Plasmas 8 4489)

  8. Generation of femtosecond optical vortex beams in all-fiber mode-locked fiber laser using mode selective coupler

    CERN Document Server

    Wang, Teng; Shi, Fan; Pang, Fufei; Huang, Sujuan; Wang, Tingyun; Zeng, Xianglong

    2016-01-01

    We experimentally demonstrated a high-order optical vortex pulsed laser based on a mode selective all-fiber fused coupler composed of a single-mode fiber (SMF) and a few-mode fiber (FMF). The fused SMF-FMF coupler inserted in the cavity not only acts as mode converter from LP01 mode to LP11 or LP21 modes with a broadband width over 100 nm, but also directly delivers femtosecond vortex pulses out of the mode locked cavity. To the best of our knowledge, this is the first report on the generation of high-order pulse vortex beams in mode-locked fiber laser. The generated 140 femtosecond vortex beam has a spectral width of 67 nm centered at 1544 nm.

  9. The characteristics of Kerr-lens mode-locked self-Raman Nd:YVO4 1176 nm laser

    Science.gov (United States)

    Li, Zuohan; Peng, Jiying; Yao, Jianquan; Han, Ming

    2017-03-01

    In this paper we report on a compact and feasible dual-concave cavity CW Kerr-lens mode-locked self-Raman Nd:YVO4 laser. A self-starting diode-pumped picosecond Nd:YVO4 1176 nm laser is demonstrated without any additional components, where the stimulated Stokes Raman scattering and Kerr-lens-induced mode locking are operated in the same crystal. With an incident pump power of 12 W, the average output power at 1176 nm is up to 643 mW. Meanwhile, the repetition rate and the pulse width of the fundamental laser are measured to be 1.53 GHz and 8.6 ps, respectively. In addition, the yellow laser output at 588 nm is realized by frequency doubling with a LiB3O5 crystal.

  10. WS2 as a saturable absorber for ultrafast photonic applications of mode-locked and Q-switched lasers

    CERN Document Server

    Wu, Kan; Wang, Jun; Li, Xing; Chen, Jianping

    2014-01-01

    Two-dimensional (2D) nanomaterials, especially the transition metal sulfide semiconductors, have drawn great interests due to their potential applications in viable photonic and optoelectronic devices, such as saturable absorbers (SAs) and optical switches, etc. In this work, tungsten disulfide (WS2) based SA for ultrafast photonic applications was demonstrated. WS2 nanosheets were prepared using liquid-phase exfoliation method and embedded in polyvinyl alcohol (PVA) thin film for the practical usage. Saturable absorption was observed in the WS2-PVA SA at the telecommunication waveband near 1550 nm. By incorporating WS2-PVA SA into a fiber laser cavity, both stable mode locking operation and Q-switching operation were achieved. In the mode locking operation, the laser obtained femtosecond output pulse width and high spectral purity in the radio frequency spectrum. In the Q-switching operation, the laser had tunable repetition rate and output pulse energy of a few tens of nano joule. Our findings suggest that ...

  11. Structure of picosecond pulses of a Q-switched and mode-locked diode-pumped Nd:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Donin, V I; Yakovin, D V; Gribanov, A V [Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2015-12-31

    The pulse duration of a diode-pumped Nd:YAG laser, in which Q-switching with mode-locking (QML regime) is achieved using a spherical mirror and a travelling-wave acousto-optic modulator, is directly measured with a streak camera. It is found that the picosecond pulses can have a non-single-pulse structure, which is explained by excitation of several competing transverse modes in the Q-switching regime with a pulse repetition rate of 1 kHz. In the case of cw mode-locking (without Q-switching), a new (auto-QML) regime is observed, in which the pulse train repetition rate is determined by the frequency of the relaxation oscillations of the laser field while the train contains single picosecond pulses. (control of laser radiation parameters)

  12. Kerr-Lens Self-Mode-Locked Laser Characteristics of Yb:Lu2SiO5 Crystal

    Institute of Scientific and Technical Information of China (English)

    LIU Jie; YANG Ji-Min; WANG Wei-Wei; ZHENG Li-He; SU Liang-Bi; Xu Jun

    2011-01-01

    A diode-pumped Kerr-lens self-mode-locked laser is achieved by using Yb:Lu2Si05 (Yb:LSO) crystal without additional components.Under the incident pump power of 14.44 W,a self-mode-locked output power of 2.98 W is obtained in the five-mirror cavity,corresponding to an optical-optical efficiency of 20.6%.Pulses as short as 8.2ps are realized at 1059 nm,with the corresponding pulse energy and peak power of 28.9 nJ and 3.5 k W,respectively.A pair of SF10 prisms are inserted into the laser cavity to compensate for the group velocity dispersion. The pulse width is compressed to 2.2 ps with an average output power of 1.25 W.

  13. Black phosphorus mode-locked Er-doped ZBLAN fiber laser at 2.8 um wavelength

    CERN Document Server

    Qin, Zhipeng; Zhao, Chujun; Wen, Shuangchun; Yuan, Peng; Qian, Liejia

    2015-01-01

    Mid-infrared saturable absorber mirror is successfully fabricated by transferring the mechanically exfoliated black phosphorus onto the gold-coated mirror. With the as-prepared black phosphorus saturable absorber mirror, a continuous-wave passively mode-locked Er:ZBLAN fiber laser is demonstrated at the wavelength of 2.8 um, which delivers a maximum average output power of 613 mW, a repetition rate of 24 MHz and a pulse duration of 42 ps. To the best of our knowledge, it is the first time to demonstrate black phosphorus mode-locked laser at 2.8 um wavelength. Our results demonstrate the feasibility of black phosphorus flake as a new two-dimensional material for application in mid-infrared ultrafast photonics.

  14. Passively mode-locking erbium-doped fiber lasers with 0.3 nm single-walled carbon nanotubes.

    Science.gov (United States)

    Xu, Xintong; Zhai, Jianpang; Li, Ling; Chen, Yanping; Yu, Yongqin; Zhang, Min; Ruan, Shuangchen; Tang, Zikang

    2014-10-24

    We demonstrate a passively mode-locked erbium-doped fiber laser (EDFL) by using the smallest single-walled carbon nanotubes (SWNTs) with a diameter of 0.3 nm as the saturable absorber. These ultrasmall SWNTs are fabricated in the elliptical nanochannels of a ZnAPO₄-11 (AEL) single crystal. By placing an AEL crystal into an EDFL cavity pumped by a 980 nm laser diode, stable passive mode-locking is achieved for a threshold pump power of 280 mW, and 73 ps pulses at 1563.2 nm with a repetition rate of 26.79 MHz.

  15. Mode-locked Erbium-doped fiber laser generation using hybrid ZnO/GO saturable absorber

    Science.gov (United States)

    Hassan, H.; Ariannejad, M. M.; Safaei, R.; Amiri, I. S.; Ahmad, H.

    2017-06-01

    Mode-locked generation of erbium-doped fiber laser (EDFL) with hybrid zinc oxide/graphene oxide (ZnO/GO) thin film as saturable absorber (SA) is proposed and practically demonstrated. The SA shows the modulation depth of 18.69% and it has been sandwiched between the fiber ferrules. Mode-locked pulse occurred at pump power of 14.8 mW and by varying the pump power to maximum threshold 27.43 mW, the repetition rate of the pulse fixed at 19.98 MHz at 1563 nm of central wavelength. The pulse width is estimated as 0.90 ps, whereas the pulse energy is calculated as 27.0 nJ.

  16. Sub-100 fs mode-locked erbium-doped fiber laser using a 45°-tilted fiber grating.

    Science.gov (United States)

    Zhang, Zuxing; Mou, Chengbo; Yan, Zhijun; Zhou, Kaiming; Zhang, Lin; Turitsyn, Sergei

    2013-11-18

    We demonstrate generation of sub-100 fs pulses at 1.5 µm in a mode-locked erbium-doped fiber laser using a 45°-tilted fiber grating element. The laser features a genuine all-fiber configuration. Based on the unique polarization properties of the 45°-tilted fiber grating, we managed to produce sub-100 fs laser pulses through proper dispersion management. To the best of our knowledge, this is the shortest pulse generated from mode-locked lasers with fiber gratings. The output pulse has an average power of 8 mW, with a repetition rate of 47.8 MHz and pulse energy of 1.68 nJ. The performance of laser also matches well the theoretical simulations.

  17. Tunable graphene Q-switched erbium-doped fiber laser with suppressed self-mode locking effect.

    Science.gov (United States)

    Zhou, Da-Peng; Wei, Li; Liu, Wing-Ki

    2012-05-10

    Self-mode locking effect in a wideband tunable graphene-based passively Q-switched erbium-doped fiber laser has been observed experimentally. Q-switching is achieved by using graphene as a saturable absorber, while a tunable bandpass filter with a narrow bandwidth is used to obtain wideband tunability. We propose to suppress the modulation on each pulse from self-mode locking by introducing three subring resonators constructed with three 3 dB couplers into the laser ring cavity. Moreover, the laser output characteristics with respect to pump power are studied in detail. A stable Q-switched erbium-doped fiber laser with a tunable range from 1522 nm to 1568 nm is demonstrated experimentally.

  18. Passively mode-locked stretched-pulse erbium-doped fiber ring laser with a regenerative feedback

    Science.gov (United States)

    Roy, Vincent; Lamonde, Martin; Babin, Francois; Piche, Michel

    2003-02-01

    A polarization additive pulse mode-locked stretched-pulse erbium-doped fiber ring laser with a regenerative feedback producing near transform-limited femtosecond pulses is reported. The regenerative feedback makes use of an intensity modulator driven at twice the fundamental repetition rate of the passively mode-locked fiber laser. The laser is self-starting for a limited range of pump power. The de-chirped pulses have a duration of 90 fs (FWHM) and a pulse time-bandwidth product of 0.44. The pulse energy amounts to 0.3 nJ. Pulses with nearly twice that energy could be obtained, though without self-starting capability. The laser RF power spectrum measurement yields an amplitude noise as low as 0.15% (rms) and a pulse timing jitter of 150 fs (rms). In addition, RF spectra show no relaxation oscillation in the self-starting regime.

  19. Simple synchronization technique of a mode-locked laser for Laser-Compton scattering γ-ray source

    Science.gov (United States)

    Mori, Michiaki; Kosuge, Atsushi; Kiriyama, Hiromitsu; Hajima, Ryoichi; Kondo, Kiminori

    2016-06-01

    We propose a simple and effective synchronization technique between a reference electrical oscillator and a mode-locked laser for a narrowband picosecond Laser-Compton scattering γ-ray source by using a commercial-based 1-chip frequency synthesizer, which is widely used in radio communication. The mode-locked laser has been successfully synchronized in time with a jitter of 180 fs RMS for 10 Hz-100 kHz bandwidth. A good stability of 640 μHz at 80 MHz repetition rate for 10 h operation has also been confirmed. We discuss in detail the design and performance of this technique (in terms of timing jitter, stability, and validity).

  20. Development of continuous glass melting for production of Nd-doped phosphate glasses for the NIF and LMJ laser system

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J. H.; Ficini-Dorn, G.; Hawley-Fedder, R.; McLean, M. J.; Suratwala, T.; Trombert, J. H.

    1998-08-14

    The NIF and LMJ laser systems require about 3380 and 4752 Nd-doped laser glass slabs, respectively. Continuous laser glass melting and forming will be used for the first time to manufacture these slabs. Two vendors have been chosen to produce the glass: Hoya Corporation and Schott Glass Technologies. The laser glass melting systems that each of these two vendors have designed, built and tested are arguably the most advanced in the world. Production of the laser glass will begin on a pilot scale in the fall of 1999.

  1. Development of continuous glass melting for production of Nd-doped phosphate glasses for the NIF and LMJ laser systems

    Science.gov (United States)

    Campbell, Jack H.; McLean, M. J.; Hawley-Fedder, Ruth A.; Suratwala, Tayyab I.; Ficini-Dorn, G.; Trombert, Jean-Hugues

    1999-07-01

    The NIF and LMJ laser systems require about 3380 and 4752 Nd-doped laser glass slabs, respectively. Continuous laser glass melting and forming will be used for the first time to manufacture these slabs. Two vendors have been chosen to produce the glass: Hoya Corporation and Schott Glass Technologies. The laser glass melting systems that each of these two vendors have designed, built and tested are arguably the most advanced in the world. Production of the laser glass will begin on a pilot scale in the fall of 1998.

  2. Mode-locked semiconductor laser system with intracavity spatial light modulator for linear and nonlinear dispersion management.

    Science.gov (United States)

    Balzer, Jan C; Döpke, Benjamin; Brenner, Carsten; Klehr, Andreas; Erbert, Götz; Tränkle, Günther; Hofmann, Martin R

    2014-07-28

    We analyze the influence of second and third order intracavity dispersion on a passively mode-locked diode laser by introducing a spatial light modulator (SLM) into the external cavity. The dispersion is optimized for chirped pulses with highest possible spectral bandwidth that can be externally compressed to the sub picosecond range. We demonstrate that the highest spectral bandwidth is achieved for a combination of second and third order dispersion. With subsequent external compression pulses with a duration of 437 fs are generated.

  3. Passive mode locking in a flash-pumped Al sub 2 O sub 3 :Ti(3+) laser

    Energy Technology Data Exchange (ETDEWEB)

    Demchuk, M.I.; Demidovich, A.A.; Zhavoronkov, N.I.; Mikhailov, V.P.; Shkadarevich, A.P. (Belorusskii Gosudarstvennyi Universitet, Minsk (Belorussian SSR))

    1990-02-01

    Passive mode locking was achieved in an Al2O3:Ti(3+) laser pumped by a flashlamp. The Al2O3Ti(3+) crystal used in the experiment (0.1 percent Ti by mass) had been grown by the Czochralski method and measured 7 x 80 mm. The pulse width in the tunable ranges 750-765 and 780-790 nm was 25 picoseconds.

  4. Mid-infrared supercontinuum generation in tapered ZBLAN fiber with a standard Erbium mode-locked fiber laser

    DEFF Research Database (Denmark)

    Kubat, Irnis; Moselund, Peter M.; Bang, Ole

    2013-01-01

    . commercially available), core diameter Dc=7 μm, and ZDW=1.5 μm, is pumped with TFWHM=10 ps and P0=10 kW pulses from an Er mode-locked laser with a 40 MHz repetition rate and 4W average power. The resulting MIR SC seen in Fig. 1(b) is based on Modulation Instability breakup of the pump pulse, which generates...

  5. Self-starting mode-locked picosecond Ti:sapphire laser by using of a fast SESAM

    Institute of Scientific and Technical Information of China (English)

    Zhu Jiang-Feng; Tian Jin-Rong; Wang Peng; Ling Wei-Jun; Li De-Hua; Wei Zhi-Yi

    2006-01-01

    A stable continuous wave mode-locked picosecond Ti:sapphire laser by using a fast semiconductor saturable absorber mirror (SESAM) is demonstrated. The laser delivers pulse width of 20 ps at a central wavelength of 813 nm and a repetition rate of 100 MHz. The maximum output power is 1.34 W with pump power of 7 W which corresponds to an optical-optical conversion efficiency of 19.1%.

  6. Monolithic strained-InGaAsP multiple-quantum-well lasers with integrated electroabsorption modulators for active mode locking

    Science.gov (United States)

    Sato, Kenji; Wakita, Koichi; Kotaka, Isamu; Kondo, Yasuhiro; Yamamoto, Mitsuo; Takada, Atsushi

    1994-07-01

    Active mode locking by monolithic lasers with integrated electroabsorption modulators using strained-InGaAsP multiple quantum wells is described. The electroabsorption modulator acts as a short optical gate when a sinusoidal voltage is driven at a deep bias point. Pulse widths as short as 2 ps have been obtained at a repetition rate of 16.3 GHz for a 2.5-mm-long monolithic laser.

  7. Effect of pyrophosphate ions on the conversion of calcium-lithium-borate glass to hydroxyapatite in aqueous phosphate solution.

    Science.gov (United States)

    Fu, Hailuo; Rahaman, Mohamed N; Day, Delbert E; Huang, Wenhai

    2010-10-01

    The conversion of glass to a hydroxyapatite (HA) material in an aqueous phosphate solution is used as an indication of the bioactive potential of the glass, as well as a low temperature route for preparing biologically useful materials. In this work, the effect of varying concentrations of pyrophosphate ions in the phosphate solution on the conversion of a calcium-lithium-borate glass to HA was investigated. Particles of the glass (150-355 μm) were immersed for up to 28 days in 0.25 M K(2)HPO(4) solution containing 0-0.1 M K(4)P(2)O(7). The kinetics of degradation of the glass particles and their conversion to HA were monitored by measuring the weight loss of the particles and the ionic concentration of the solution. The structure and composition of the conversion products were analyzed using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. For K(4)P(2)O(7) concentrations of up to 0.01 M, the glass particles converted to HA, but the time for complete conversion increased from 2 days (no K(4)P(2)O(7)) to 10 days (0.01 M K(4)P(2)O(7)). When the K(4)P(2)O(7) concentration was increased to 0.1 M, the product consisted of an amorphous calcium phosphate material, which eventually crystallized to a pyrophosphate product (predominantly K(2)CaP(2)O(7) and Ca(2)P(2)O(7)). The consequences of the results for the formation of HA materials and devices by the glass conversion route are discussed.

  8. Compact optical displacement sensing by detection of microwave signals generated from a monolithic passively mode-locked laser under feedback

    Science.gov (United States)

    Simos, Christos; Simos, Hercules; Nikas, Thomas; Syvridis, Dimitris

    2015-05-01

    A monolithic passively mode-locked laser is proposed as a compact optical sensor for displacements and vibrations of a reflecting object. The sensing principle relies on the change of the laser repetition frequency that is induced by optical feedback from the object under measurement. It has been previously observed that, when a semiconductor passively mode locked laser receives a sufficient level of optical feedback from an external reflecting surface it exhibits a repetition frequency that is no more determined by the mode-locking rule of the free-running operation but is imposed by the length of the external cavity. Therefore measurement of the resulting laser repetition frequency under self-injection permits the accurate and straightforward determination of the relative position of the reflecting object. The system has an inherent wireless capability since the repetition rate of the laser can be wirelessly detected by means of a simple antenna which captures the microwave signal generated by the saturable absorber and is emitted through the wiring of the laser. The sensor setup is very simple as it requires few optical components besides the laser itself. Furthermore, the deduction of the relative position of the reflecting object is straightforward and does not require any processing of the detected signal. The proposed sensor has a theoretical sub-wavelength resolution and its performance depends on the RF linewidth of the laser and the resolution of the repetition frequency measurement. Other physical parameters that induce phase changes of the external cavity could also be quantified.

  9. Passively Q-switched and mode-locked erbium doped fiber laser based on N-doped graphene saturable absorber

    Science.gov (United States)

    Ahmad, H.; Aidit, S. N.; Ooi, S. I.; Rezayi, M.; Tiu, Z. C.

    2017-10-01

    A passively Q-switched and mode-locked erbium-doped fiber laser based on a nitrogen-doped graphene saturable absorber is demonstrated. The N-doped graphene based saturable absorber has a modulation depth of 37.88% and a saturation intensity of 0.016 73 MW cm‑2. By integrating the N-doped graphene saturable absorber into the laser cavity, a stable Q-switched operation with a centre wavelength of 1561.1 nm is obtained with a pulse energy of up to 29.0 nJ. As the pump power increases, the Q-switching operation transits into a mode-locking operation. The mode-locking operation is achieved with a centre wavelength of 1560 nm, a pulse width of 0.98 ps, a repetition rate of 28.5 MHz and a signal to noise ratio of up to 40 dB in the RF spectrum.

  10. Pulse width shaping of passively mode-locked soliton fiber laser via polarization control in carbon nanotube saturable absorber.

    Science.gov (United States)

    Jeong, Hwanseong; Choi, Sun Young; Rotermund, Fabian; Yeom, Dong-Il

    2013-11-04

    We report the continuous control of the pulse width of a passively mode-locked fiber laser via polarization state adjustment in a single-walled carbon nanotube saturable absorber (SWCNT-SA). The SWCNT, coated on the side-polished fiber, was fabricated with optimized conditions and used for stable mode-locking of the fiber laser without Q-switching instabilities for any polarization state of the laser intra-cavity. The 3-dB spectral bandwidth of the mode-locked pulses can be continuously tuned from 1.8 nm to 8.5 nm with the polarization control for a given laser cavity length and applied pump power. A pulse duration varying from 470 fs to 1.6 ps was also observed with a change in the spectral bandwidth. The linear and the nonlinear transmission properties of the SA were analyzed, and found to exhibit different modulation depths depending on the input polarization state in the SA. The largest modulation depth of the SA was observed at the polarization state of the transverse electric mode that delivers shortest pulses at the laser output.

  11. Self-amplitude and self-phase modulation of the charcoal mode-locked erbium-doped fiber lasers.

    Science.gov (United States)

    Lin, Yung-Hsiang; Lo, Jui-Yung; Tseng, Wei-Hsuan; Wu, Chih-I; Lin, Gong-Ru

    2013-10-21

    With the intra-cavity nano-scale charcoal powder based saturable absorber, the 455-fs passive mode-locking of an L-band erbium-doped fiber laser (EDFL) is demonstrated. The size reduction of charcoal nano-particle is implemented with a simple imprinting-exfoliation-wiping method, which assists to increase the transmittance up to 0.91 with corresponding modulation depth of 26%. By detuning the power gain from 17 to 21 dB and cavity dispersion from -0.004 to -0.156 ps² of the EDFL, the shortening of mode-locked pulsewidth from picosecond to sub-picosecond by the transformation of the pulse forming mechanism from self-amplitude modulation (SAM) to the combining effect of self-phase modulation (SPM) and group delay dispersion (GDD) is observed. A narrower spectrum with 3-dB linewidth of 1.83-nm is in the SAM case, whereas the spectral linewidth broadens to 5.86 nm with significant Kelly sideband pair can be observed if the EDFL enters into the SPM regime. The mode-locking mechanism transferred from SAM to SPM/GDD dominates the pulse shortening procedure in the EDFL, whereas the intrinsic defects in charcoal nano-particle only affect the pulse formation at initial stage. The minor role of the saturable absorber played in the EDFL cavity with strongest SPM is observed.

  12. Narrow bandwidth passively mode locked picosecond Erbium doped fiber laser using a 45° tilted fiber grating device.

    Science.gov (United States)

    Wang, Tianxing; Yan, Zhijun; Mou, Chengbo; Liu, Zuyao; Liu, Yunqi; Zhou, Kaiming; Zhang, Lin

    2017-07-10

    An all-fiber passively picosecond mode locked Erbium doped laser using a 45° tilted fiber grating (45° TFG) and a fiber Bragg grating (FBG) is reported in this work. Due to the strong polarization dependent loss (PDL) of 45° TFG and narrow 3-dB bandwidth of FBG, the Erbium doped fiber laser (EDFL) can generate picosecond mode locked pulse based on the nonlinear polarization rotation (NPR) effect. The laser features a repetition rate of 9.67 MHz, a pulse duration of 33 ps, a signal-to-noise ratio (SNR) of 70 dB, an average output power of 1.2 mW, and a single pulse energy of 124 pJ under the pump power of 102 mW. Besides, the central wavelength of the laser can be continuously adjusted from 1550.65 nm to 1551.44 nm. The technique of using a 45° TFG to generate picosecond pulses can be readily extended to other wavelength such as mid-infrared (mid-IR) where fiber polarizing components are either expensive or not available. To the best of our knowledge, the spectral width is the narrowest among all-fiber passively mode locked Erbium-doped laser based on NPR.

  13. Multilayer graphene for Q-switched mode-locking operation in an erbium-doped fiber laser

    Science.gov (United States)

    Wang, Zhiteng; Zhu, Shou-En; Chen, Yu; Wu, Man; Zhao, Chujun; Zhang, Han; Janssen, G. C. A. M.; Wen, Shuangchun

    2013-07-01

    We report the laser operation of Q-switched mode-locking (QML) in an erbium-doped fiber laser by using a multilayer graphene saturable absorber (SA), which consists of 22-layer of graphene fabricated by the chemical vapor deposition method. Based on our balanced twin detector measurement, the graphene sample is confirmed to show a saturable intensity of 3.375 MW/cm2 and an absolute modulation depth of 40.27%. It is demonstrated that this graphene SA can readily produce high quality QML pulses. At the pump power of 391.9 mW, the stable mode-locked pulse train with the Q-switched envelope repetition rate of 16.98 kHz and the envelope width of 13.84 μs are achieved. The maximal main pulse peak power can reach up to 35.89 W. This verifies that the multilayer graphene can be still applied as an effective saturable absorber for passively Q-switched mode-locked operation.

  14. Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

    Directory of Open Access Journals (Sweden)

    Sonia Boscolo

    2015-11-01

    Full Text Available We review our recent progress on the realisation of pulse shaping in passively-mode-locked fibre lasers by inclusion of an amplitude and/or phase spectral filter into the laser cavity. We numerically show that depending on the amplitude transfer function of the in-cavity filter, various regimes of advanced waveform generation can be achieved, including ones featuring parabolic-, flat-top- and triangular-profiled pulses. An application of this approach using a flat-top spectral filter is shown to achieve the direct generation of high-quality sinc-shaped optical Nyquist pulses with a widely tunable bandwidth from the laser oscillator. We also present the operation of an ultrafast fibre laser in which conventional soliton, dispersion-managed soliton (stretched-pulse and dissipative soliton mode-locking regimes can be selectively and reliably targeted by adaptively changing the dispersion profile and bandwidth programmed on an in-cavity programmable filter. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for achieving a high degree of control over the dynamics and output of mode-locked fibre lasers.

  15. Phase equilibrium and preparation, crystallization and viscous sintering of glass in the alumina-silica-lanthanum phosphate system

    Science.gov (United States)

    He, Feng

    The phase equilibrium, viscosity of melt-quenched glasses, and processing of sol-gel glasses of the alumina-silica-lanthanum phosphate system were studied. These investigations were directed towards serving the objective of synthesizing nano-structured ceramic-matrix-composites via controlled crystallization of glass precursors. The thermal stability, phase equilibrium, and liquidus temperatures of the alumina- and mullite-lanthanum phosphate systems are determined. An iridium wire heater was constructed to anneal samples up to 2200°C. Phosphorus evaporation losses were significant at high temperatures, especially over 1800°C. The tentative phase diagrams of the two quasi-binary systems were presented. The viscosity of the melt-quenched mullite-lanthanum phosphate glasses was measured by three different methods, including viscous sintering of glass powder compacts, neck formation between two Frenkel glass beads, and thermal analysis of the glass transition. Improved methodologies were developed for applying the interpretative mathematical models to the results of the sintered powder and thermal analytical experiments. Good agreement was found between all three methods for both absolute values and temperature dependence. A sol-gel process was developed as a low temperature route to producing glasses. A unique, single phase mullite gel capable of low temperature (575°C) mullitization was made from tetraethoxysilane and aluminum isopropoxide at room temperature in three days. Low temperature crystallization was attributed to the avoidance of phase segregation during gel formation and annealing. This was greatly enhanced by a combination of low temperature preheating in the amorphous state, a high heating rate during crystallization and low water content. The Al2O3 content in mullite (61-68 mol%) depended on the highest annealing temperature. Two mullite-lanthanum phosphate gels were made based upon modifying the chemical procedures used for the homogeneous single

  16. Titanium Dioxide (TiO2) film as a new saturable absorber for generating mode-locked Thulium-Holmium doped all-fiber laser

    Science.gov (United States)

    Mohd Rusdi, Muhammad Farid; Latiff, Anas Abdul; Paul, Mukul Chandra; Das, Shyamal; Dhar, Anirban; Ahmad, Harith; Harun, Sulaiman Wadi

    2017-03-01

    We report the generation of mode-locked thulium-holmium doped fiber laser (THDFL) at 1979 nm. This is a first demonstration of mode-locked by using Titanium Dioxide (TiO2) film as a saturable absorber (SA). A piece of 1 mm×1 mm TiO2 film was sandwiched in between two fiber ferrule in the cavity. Fabrication process of TiO2 film incorporated a TiO2 and a polyvinyl alcohol (PVA). The stable 9 MHz repetition rate of mode-locked mode operation with 58 dB SNR was generated under pump power of 902-1062 mW. At maximum pump power, the mode-locked THDFL has output power and pulse energy of 15 mW and 1.66 nJ, respectively. Our results demonstrate the TiO2 can be used promisingly in ultrafast photonics applications.

  17. Comparative studies of semiconductor saturable absorber mirror mode-locking dynamics in pulsed diode-end-pumped picosecond Nd:GdVO4 and Nd:YAG lasers

    Institute of Scientific and Technical Information of China (English)

    Bingyuan Zhang; Gang Li; Meng Chen; Guoju Wang; Yonggang Wang

    2006-01-01

    Ultrashort pulses were generated in passively mode-locked Nd:YAG and Nd:GdVO4 lasers pumped by a pulsed laser diode with 10-Hz repetition rate. Stable mode-locked pulse trains were produced with the pulse width of 10 ps. The evolution of the mode-locked pulse was observed in the experiment and was discussed in detail. Comparing the pulse evolutions of Nd:YAG and Nd:GdVO4 lasers, we found that the buildup time of the steady-state mode-locking with semiconductor saturable absorber mirrors (SESAMs) was relevant to the upper-state lifetime and the emission cross-section of the gain medium.

  18. Generation of 30  fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO4 laser.

    Science.gov (United States)

    Ma, Jie; Huang, Haitao; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2016-03-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode-locked 8.43 optical-cycle pulses have a spectral bandwidth of ∼50  nm and a pulse repetition frequency of ∼113.5  MHz. To the best of our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique for directly generating few-cycle optical pulses from a laser oscillator.

  19. Generation of 30 fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO_4 laser

    Science.gov (United States)

    Ma, Jie; Huang, Haitao; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2016-03-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode locked 8.43 optical-cycle pulses have a spectral bandwidth of ~ 50 nm and a pulse repetition frequency of ~ 113.5 MHz. To our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique to generate few-cycle optical pulses directly from a laser oscillator.

  20. Generation of 30-fs pulses from a diode-pumped graphene mode-locked Yb:CaYAlO4 laser

    CERN Document Server

    Ma, Jie; Ning, Kaijie; Xu, Xiaodong; Xie, Guoqiang; Qian, Liejia; Loh, Kian Ping; Tang, Dingyuan

    2015-01-01

    Stable 30 fs pulses centered at 1068 nm (less than 10 optical cycles) are demonstrated in a diode pumped Yb:CaYAlO4 laser by using high-quality chemical vapor deposited monolayer graphene as the saturable absorber. The mode locked 8.43 optical-cycle pulses have a spectral bandwidth of ~ 50 nm and a pulse repetition frequency of ~ 113.5 MHz. To our knowledge, this is the shortest pulse ever reported for graphene mode-locked lasers and mode-locked Yb-doped bulk lasers. Our experimental results demonstrate that graphene mode locking is a very promising practical technique to generate few-cycle optical pulses directly from a laser oscillator.

  1. Characterization of timing jitter spectra in free-running mode-locked lasers with 340 dB dynamic range over 10 decades of Fourier frequency

    CERN Document Server

    Jung, Kwangyun

    2014-01-01

    We demonstrate a method that enables accurate timing jitter spectral density characterization of free-running mode-locked laser oscillators over more than 10-decade of Fourier frequency from mHz to tens MHz range. The method is based on analyzing both the input voltage noise to the slave laser and the output voltage noise from the balanced optical cross- correlator (BOC), when two mode-locked lasers are synchronized in repetition rate by the BOC. As a demonstration experiment, timing jitter spectrum of a free-running mode-locked Er-fiber laser with a dynamic range of >340 dB is measured over Fourier frequency ranging from 1 mHz to 38.5 MHz (Nyquist frequency). The demonstrated method can resolve different noise mechanisms that cause specific jitter characteristics in free-running mode-locked laser oscillators for a vast range of time scales from 1000-s.

  2. Comparison of the noise performance of 10 GHz repetition rate quantum-dot and quantum well monolithic mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Carpintero, G.; Thompson, M. G.; Yvind, Kresten

    2011-01-01

    Mode-locked lasers are commonly used in carrier-wave signal generation systems because of their excellent phase noise performance. Owing to the importance of this key parameter, this study presents a like-for-like comparison of the noise performance of the passive mode-locked regime of two devices...... and the shape of the noise pedestals, both depending on the passive mode-locked bias conditions. Nevertheless, the dominant contribution of the RF linewidth to the phase noise, which is significantly narrower for the QD laser, makes this material more suitable for optical generation of low-noise millimetre...... fabricated with different material gain systems, one quantum well and the other quantum dot (QD), both with a monolithic all-active two-section mode-locked structure. Two important factors are identified as having a significant effect on the noise performance, the RF linewidth of the first harmonic...

  3. Compact graphene mode-locked wavelength-tunable erbium-doped fiber lasers: from all anomalous dispersion towards all normal dispersion

    CERN Document Server

    Zhang, Han; Zhao, Luming; Bao, Qiaoliang; Loh, Kian Ping; Lin, Bo; Tjin, Swee Chuan

    2010-01-01

    Soliton operation and soliton wavelength tuning of erbium-doped fiber lasers mode locked with atomic layer graphene was experimentally investigated under various cavity dispersion conditions. It was shown that not only wide range soliton wavelength tuning but also soltion pulse width variation could be obtained in the fiber lasers. Our results show that the graphene mode locked erbium-doped fiber lasers provide a compact, user friendly and low cost wavelength tunable ultrahsort pulse source.

  4. Active mode locking at 50 GHz repetition frequency by half-frequency modulation of monolithic semiconductor lasers integrated with electroabsorption modulators

    Science.gov (United States)

    Sato, Kenji; Kotaka, Isamu; Kondo, Yasuhiro; Yamamoto, Mitsuo

    1996-10-01

    Active mode locking achieved at a 50 GHz repetition frequency by modulation at half (25 GHz) the cavity resonance frequency using a monolithic mode-locked InGaAsP laser integrated with an electroabsorption modulator is described. A pulse width of around 3 ps and a high suppression ratio of more than 33 dB of the intensity modulation at the driving frequency are obtained.

  5. Influence of CuO and ZnO addition on the multicomponent phosphate glasses: Spectroscopic studies

    Science.gov (United States)

    Szumera, Magdalena; Wacławska, Irena; Sułowska, Justyna

    2016-06-01

    The spectra of phosphate-silicate glasses from the P2O5-SiO2-K2O-MgO-CaO system modified with the addition of CuO or ZnO have been studied by means of FTIR, Raman and 31P MAS NMR spectroscopy. All glasses were synthesized by the conventional melt-quenching technique and their homogeneous chemical composition was controlled and confirmed. By using the aforementioned research techniques, the presence of structural units with various degrees of polymerization was shown in the structure of analyzed phosphate-silicate glasses: Q3, Q2, Q1 and Q0. It was found that an increase in the content of CuO or ZnO in the composition of analyzed glasses, which are introduced at the expense of decreasing amounts of CaO and MgO, has a different influence on the phospho-oxygen network. It was shown that copper ions cause its gradual polymerization, while zinc ions cause its depolymerization. At the same time, polymerization of the silico-oxygen subnetwork was found. Additionally, in the case of glasses containing increasing amounts of ZnO, a change of the role of zinc ions in the vitreous matrix was confirmed (from the modifier to a structure-forming component).

  6. Planar waveguides formed in a new chemically stable Er3+/Yb3+ co-doped phosphate glass

    Institute of Scientific and Technical Information of China (English)

    Shilong Zhao; Baoyu Chen; Junjiang Hu; Lili Hu

    2005-01-01

    @@ A new Er3+/Yb3+ co-doped phosphate glass has been prepared, which exhibits good chemical durability and spectral properties. Planar graded index waveguides have been fabricated in the glass by Ag+-Na+ ion exchange in a mixed melt of silver nitrate and potassium nitrate. Ion exchange is carried out by varying the process parameters such as temperature, diffusion time, and molten salt compositions. The diffusion parameters, diffusion coefficients, and activation energy are determined by the guidelines of fabricated waveguides, which are determined by the input prism coupling technique.

  7. Effect of gamma irradiation on X-ray absorption and photoelectron spectroscopy of Nd-doped phosphate glass.

    Science.gov (United States)

    Rai, V N; Rajput, Parasmani; Jha, S N; Bhattacharyya, D; Raja Shekhar, B N; Deshpande, U P; Shripathi, T

    2016-11-01

    X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS) of Nd-doped phosphate glasses have been studied before and after gamma irradiation. The intensity and the location of the white line peak of the L3-edge XANES of Nd are found to be dependent on the ratio O/Nd in the glass matrix. Gamma irradiation changes the elemental concentration of atoms in the glass matrix, which affects the peak intensity of the white line due to changes in the covalence of the chemical bonds with Nd atoms in the glass (structural changes). Sharpening of the Nd 3d5/2 peak profile in XPS spectra indicates a deficiency of oxygen in the glasses after gamma irradiation, which is supported by energy-dispersive X-ray spectroscopy measurements. The ratio of non-bridging oxygen to total oxygen in the glass after gamma radiation has been found to be correlated to the concentration of defects in the glass samples, which are responsible for its radiation resistance as well as for its coloration.

  8. Characterization of iron phosphate glasses prepared by microwave heating; Obtencao de vidros fosfatos contendo ferro por meio do aquecimento em fornos de microondas

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Fabio Jesus Moreira de

    2006-07-01

    Phosphate glasses have been investigated since the fifties, because they are relatively easy to prepare, have low melting temperatures (1000 deg C - 1200 deg C), and low glass transition. However, these glasses were very sensitive to humidity, showing a very low chemical durability. Iron phosphate glasses have been prepared by melting inorganic precursors in conventional electric furnaces and induction furnaces. By adding iron, phosphate glasses became chemical resistant and were thought to be used as nuclear waste forms or mechanical resistance fibers. The use of microwaves has been investigated because it makes possible a fast and homogeneous heating of the materials. Microwave promotes the self-heating of the material by the interaction of the external electromagnetic field with the molecules and ions of the material. Niobium phosphate glasses was also produced already through the heating of precursors in microwave ovens. Other glasses containing iron in theirs structure was produced by conventional furnaces and they had your structures analyzed. But even so, it was not still published synthesis of iron phosphate glasses starting from the melting of precursors materials in microwave ovens. In the present work mixtures of (NH{sub 4}){sub 2}HPO{sub 4} and Fe{sub 3}O{sub 4} or (NH{sub 4}){sub 2}HPO{sub 4} and Fe{sub 2}O{sub 3} were exposed to microwave energy with electromagnetic waves of 2,45 GHz. It was proposed that the absorption of this radiation for the material causes the heating from room temperature to melting temperature. The obtained iron phosphate glasses was analyzed by X-ray diffraction, Moessbauer spectroscopy, and Differential Thermal Analysis. Iron phosphate glasses were also produced in electrical furnaces for comparison. (author)

  9. Bioresorbable screws reinforced with phosphate glass fibre: manufacturing and mechanical property characterisation.

    Science.gov (United States)

    Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

    2013-01-01

    Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ∼80% (strength) and ∼130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (∼30% and ∼40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ∼1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process.

  10. Ac-conductivity and dielectric response of new zinc-phosphate glass/metal composites

    Science.gov (United States)

    Maaroufi, A.; Oabi, O.; Lucas, B.

    2016-07-01

    The ac-conductivity and dielectric response of new composites based on zinc-phosphate glass with composition 45 mol%ZnO-55 mol%P2O5, filled with metallic powder of nickel (ZP/Ni) were investigated by impedance spectroscopy in the frequency range from 100 Hz to 1 MHz at room temperature. A high percolating jump of seven times has been observed in the conductivity behavior from low volume fraction of filler to the higher fractions, indicating an insulator - semiconductor phase transition. The measured conductivity at higher filler volume fraction is about 10-1 S/cm and is frequency independent, while, the obtained conductivity for low filler volume fraction is around 10-8 S/cm and is frequency dependent. Moreover, the elaborated composites are characterized by high dielectric constants in the range of 105 for conductive composites at low frequencies (100 Hz). In addition, the distribution of the relaxation processes was also evaluated. The Debye, Cole-Cole, Davidson-Cole and Havriliak-Negami models in electric modulus formalism were used to model the observed relaxation phenomena in ZP/Ni composites. The observed relaxation phenomena are fairly simulated by Davidson-Cole model, and an account of the interpretation of results is given.

  11. Bone Tissue Engineering by Using Calcium Phosphate Glass Scaffolds and the Avidin-Biotin Binding System.

    Science.gov (United States)

    Kim, Min-Chul; Hong, Min-Ho; Lee, Byung-Hyun; Choi, Heon-Jin; Ko, Yeong-Mu; Lee, Yong-Keun

    2015-12-01

    Highly porous and interconnected scaffolds were fabricated using calcium phosphate glass (CPG) for bone tissue engineering. An avidin-biotin binding system was used to improve osteoblast-like cell adhesion to the scaffold. The scaffolds had open macro- and micro-scale pores, and continuous struts without cracks or defects. Scaffolds prepared using a mixture (amorphous and crystalline CPG) were stronger than amorphous group and crystalline group. Cell adhesion assays showed that more cells adhered, with increasing cell seeding efficiency to the avidin-adsorbed scaffolds, and that cell attachment to the highly porous scaffolds significantly differed between avidin-adsorbed scaffolds and other scaffolds. Proliferation was also significantly higher for avidin-adsorbed scaffolds. Osteoblastic differentiation of MG-63 cells was observed at 3 days, and MG-63 cells in direct contact with avidin-adsorbed scaffolds were positive for type I collagen, osteopontin, and alkaline phosphatase gene expression. Osteocalcin expression was observed in the avidin-adsorbed scaffolds at 7 days, indicating that cell differentiation in avidin-adsorbed scaffolds occurred faster than the other scaffolds. Thus, these CPG scaffolds have excellent biological properties suitable for use in bone tissue engineering.

  12. Antibacterial activity evaluation of bioactive glass and biphasic calcium phosphate nanopowders mixtures

    Science.gov (United States)

    Nazemi, Zahra; Mehdikhani-Nahrkhalaji, Mehdi; Haghbin-Nazarpak, Masoumeh; Staji, Hamid; Kalani, Mohammad Mehdi

    2016-12-01

    The aim of this work was to evaluate the antibacterial activity of bioactive glass (BG) and biphasic calcium phosphate (BCP) nanopowders mixtures for the first time. 37S BG and BCP (50% HA-50% β-TCP) nanopowders were prepared via sol-gel technique. Characterization techniques such as X-ray diffraction, scanning electron microscopy, transition electron microscopy, and X-ray fluorescent. The antibacterial activity was studied using Escherichia coli and Salmonella typhi as gram-negative, and Staphylococcus aureus as gram-positive bacteria. The antibacterial effect of BG, BCP nanopowders, and their mixtures was evaluated at different concentrations. The 37S BG nanopowders showed minimum bactericidal concentration at 25 mg/ml. At broth concentrations below 300 mg/ml, BCP showed no antibacterial activity. BCP and BG nanopowders mixture (M2) with 60/40 ratio of BCP/BG showed noticeable antibacterial effect. It was concluded that BCP and 37S BG nanopowders mixture could be used as a good candidate for dental and orthopedic applications.

  13. Laser Diode Pumped 1.54μm Er:Yb:Phosphate Glass Continuous Wave Compact Laser

    Institute of Scientific and Technical Information of China (English)

    孟凡臻; 宋峰; 张潮波; 丁欣; 商美茹; 张光寅

    2003-01-01

    We report a cw Er3+ :Yb3+ co-doped phosphate glass laser pumped by a laser diode. The maximum output power of 78.3mW and a slope efficiency of 15.25% were achieved. The laser spectral region was from 1532nm to 1535nm, with the peak laser wavelength at 1534nm. The laser modes and time stability were also measured.The thermal effect had little influence on the output in our experiment.

  14. Synthesis of Ag doped calcium phosphate particles and their antibacterial effect as additives in dental glass ionomer cements

    OpenAIRE

    2016-01-01

    Developing dental restorations with enhanced antibacterial properties has been a constant quest for materials scientists. The aim of this study was to synthesize silver doped calcium phosphate particles and use them to improve antibacterial properties of conventional glass ionomer cement. The Ag doped monetite (Ag-DCPA) and hydroxyapatite (Ag-HA) were synthesized by precipitation method and characterized using X-ray diffraction, scanning electron microscope and X-ray fluorescence spectroscopy...

  15. Diode-end-pumped passively mode-locked Nd:GAGG laser at 1.3 μm with SESAM Diode-end-pumped passively mode-locked Nd:GAGG laser

    Science.gov (United States)

    Li, Y. B.; Jia, Z. T.; Yang, Y.; Fu, X. W.; Yuan, D. S.; Zhi, Y. C.; Dong, C. M.; Zhang, B. T.; He, J. L.; Tao, X. T.

    2012-08-01

    The performance of a passively mode-locked Nd:Gd3AlxGa5-xO12 (Nd:GAGG) laser at 1332 nm was experimentally investigated by using a semiconductor saturable absorber mirror (SESAM) for the first time. At the absorbed pump power of 6.7 W, the average output power was obtained to be 293 mW with the pulse duration of 6.3 ps and the repetition rate of 32.2 MHz. The corresponding single pulse energy and the peak power were determined to be 4.55 nJ and 722 W, respectively.

  16. Novel resorbable glass-ceramic scaffolds for hard tissue engineering: from the parent phosphate glass to its bone-like macroporous derivatives.

    Science.gov (United States)

    Bretcanu, Oana; Baino, Francesco; Verné, Enrica; Vitale-Brovarone, Chiara

    2014-05-01

    One of the major challenges of hard tissue engineering research focuses on the development of scaffolds that can match the mechanical properties of the host bone and resorb at the same rate as the bone is repaired. The aim of this work was the synthesis and characterization of a resorbable phosphate glass, as well as its application for the fabrication of three dimensional (3-D) scaffolds for bone regeneration. The glass microstructure and behaviour upon heating were analysed by X-ray diffraction, differential scanning calorimetry and hot stage microscopy. The glass solubility was investigated according to relevant ISO standards using distilled water, simulated body fluid (SBF) and Tris-HCl as testing media. The glass underwent progressive dissolution over time in all three media but the formation of a hydroxyapatite-like layer was also observed on the samples soaked in SBF and Tris-HCl, which demonstrated the bioactivity of the material. The glass powder was used to fabricate 3-D macroporous bone-like glass-ceramic scaffolds by adopting polyethylene particles as pore formers: during thermal treatment, the polymer additive was removed and the sintering of glass particles was allowed. The obtained scaffolds exhibited high porosity (87 vol.%) and compressive strength around 1.5 MPa. After soaking for 4 months in SBF, the scaffolds mass loss was 76 wt.% and the pH of the solution did not exceed the 7.55 value, thereby remaining in a physiological range. The produced scaffolds, being resorbable, bioactive, architecturally similar to trabecular bone and exhibiting interesting mechanical properties, can be proposed as promising candidates for bone repair applications.

  17. Comparison of ion exchange and cw CO2 laser treatment of Nd-doped phosphate laser glass

    Science.gov (United States)

    Hui, Gong; Chengfu, Li

    1996-05-01

    In recent years, the effect of laser pre-irradiation and ion exchange on glasses surface were widely carried out to stabilize their damage thresholds. But comparison of ion exchange and CW CO2 laser treatment is never studied, this paper is devoted to the investigation of this question. Nd-doped phosphate laser glasses were heated with CW CO2 laser radiation and were strengthened by ion exchange. Laser damage thresholds of the surface were measured with 1064 nm 10 ns pulses focused to small spots irradiation. Both ion exchange treatment and CW CO2 laser treatment result in residual compress stress occurred at surface, peak-to- volley and microcracks decreased in surface appearance, and damage thresholds of surfaces increased by a factor of over 2. Polariscope, reflected optical microscope and atomic force microscope are used for stress, damage morphologies and surface topography analysis on glass surface. It is shown that laser condition mechanism is consistent with ion exchange treatment mechanism.

  18. Iron Phosphate Glass for Vitrifying Hanford AZ102 LAW in Joule Heated and Cold Crucible Induction Melters - 12240

    Energy Technology Data Exchange (ETDEWEB)

    Day, Delbert E.; Brow, Richard K.; Ray, Chandra S.; Reis, Signo T. [Missouri University of Science and Technology, 1870 Miner Circle, Rolla, MO 65409 (United States); Kim, Cheol-Woon [MO-SCI Corporation, 4040 HyPoint North, Rolla, MO 65401 (United States); Vienna, John D.; Sevigny, Gary [Pacific North West National Laboratory, Battelle Blvd., Richland, WA 99352 (United States); Peeler, David; Johnson, Fabienne C.; Hansen, Eric K. [Savannah River National Laboratory, Savannah River Site, 999-W, Aiken, SC 29803 (United States); Soelberg, Nick [Idaho National Laboratory, 2525 Fremont Avenue, Idaho Falls, ID 83415 (United States); Pegg, Ian L.; Gan, Hao [Catholic University of America, 620 Michigan Avenue, N.E., Washington, DC 20064 (United States)

    2012-07-01

    An iron phosphate composition for vitrifying a high sulfate (∼17 wt%) and high alkali (∼80 wt%) Hanford low activity waste (LAW), known as AZ-102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ-102 which corresponded to a total alkali and sulfate (represented as SO{sub 3}) content of 21 and 4.4 wt%, respectively. A slurry (7 M Na{sup +}) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090 deg. C for 10 days in a small JHM at PNNL and for 70 hours in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their canister centerline cooled (CCC) counterparts met the requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT) responses in the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract. These glass waste forms retained up to 77 % of the SO{sub 3} (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium (used as a surrogate for Tc) all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition was melted continuously in a slurry fed JHM and in the US, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste. The following conclusions are drawn from the results of the present work. (1) An iron phosphate composition, designated as MS26AZ102F-2, containing 26 wt% of the simulated high sulfate (17 wt%), high alkali (80 wt%) Hanford AZ-102 LAW meets all the criteria for processing in a JHM and CCIM. This

  19. Development of beta-tricalcium phosphate/sol-gel derived bioactive glass composites: physical, mechanical, and in vitro biological evaluations.

    Science.gov (United States)

    Hesaraki, Saeed; Safari, Mojgan; Shokrgozar, Mohammad Ali

    2009-10-01

    In this study, composites of beta-tricalcium phosphate (beta-TCP) and sol gel derived bioactive glass (10, 25, and 40 wt %) based on the SiO(2)-CaO-MgO-P(2)O(5) system were prepared and sintered at 1000-1200 degrees C. The mechanical properties were investigated by measuring bending strength, Vickers hardness and fracture toughness. Structural properties were evaluated by XRD and SEM analysis, and the biological properties were studied by soaking the samples in simulated body fluid (SBF) and in contact with osteoblastic cell for viability assay. When the samples were sintered at 1200 degrees C, the mechanical strength increased, up to 34%, by increasing the amount of bioactive glass phase. In contrast, it decreased when the samples were sintered at 1000 and 1100 degrees C. The results showed that the strength could be improved up to 56% when more firing period was used. Incorporation of the bioactive glass phase into beta-TCP increased the microhardness but did not significantly change the fracture toughness. Phase analysis revealed that beta-TCP or magnesium-substituted beta-TCP was the main crystalline phase of the composites beside some calcium silicate crystallized in the bioactive glass phase. Plenty precipitation of calcium phosphate layer onto the surfaces of the beta-TCP/bioactive glass composites soaked in SBF indicated superior bioactivity of these materials compared to pure beta-TCP without any precipitation. The ability of beta-TCP/bioactive glass composites to support the growth of human osteoblastic cells was considerably better than that of pure beta-TCP. These results may be used to indicate which compositions and processing conditions can provide appropriate materials for hard tissue regeneration.

  20. Modeling and Direct Electric-Field Measurements of Passively Mode-Locked Quantum-Dot Lasers (Postprint)

    Science.gov (United States)

    2010-07-01

    H. Li, K. J. Malloy, and L. F. Lester, “Extremely low room-temperature threshold current density diode lasers using InAs dots in In0 .15Ga0 .85As...Fuchs, K. J. Malloy, and L. F. Lester, “Gain and linewidth enhancement factor in InAs quantum-dot laser diodes ,” IEEE Photon. Tech. Lett., vol. 11, no...device physics, and fabrication and characterization of semiconduc- tor quantum-dot light emitters that include mode- locked laser and superluminescent