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U Keller - One of the best experts on this subject based on the ideXlab platform.

  • dilute nitride absorbers in passive devices for mode locking of Solid State Lasers
    Journal of Crystal Growth, 2005
    Co-Authors: S Schon, S C Zeller, Rachel Grange, A Rutz, V Liverini, M Haiml, U Keller
    Abstract:

    Abstract We report on the growth, material and nonlinear optical properties of GaInNAs quantum wells (QWs) used in semiconductor saturable absorber mirrors (SESAMs) for passive mode locking of Solid-State Lasers in the telecommunication wavelength range from 1.3 to 1.55 μm. The antiresonant SESAMs were grown by molecular beam epitaxy with a nitrogen concentration of 1.6% and 2.6%, respectively. They were subject to rapid thermal annealing to fine-tune the absorption wavelength by blueshifting the photoluminescence wavelength. The appearance of QW intermixing upon thermal annealing was studied by X-ray rocking curve measurements. The thermal annealing procedure was proved not to alter the GaInNAs SESAM by QW intermixing for temperatures up to 800 °C. Optical characterization was applied to investigate the nonlinear SESAM properties. Degenerate pump-probe experiments revealed similar recovery times for both SESAMs in the tens of picoseconds range. We demonstrated stable self-starting passive cw mode locking with sub-10 ps pulses at 1314 and 1534 nm.

  • pulse energy dynamics of passively mode locked Solid State Lasers above the q switching threshold
    Journal of The Optical Society of America B-optical Physics, 2004
    Co-Authors: Adrian Schlatter, S C Zeller, Rachel Grange, Rudiger Paschotta, U Keller
    Abstract:

    We have investigated the dynamical behavior of various passively mode-locked Solid-State Lasers by measuring how a modulation of the pump power affects the output power. We show theoretically and experimentally how the damping of the relaxation oscillations is reduced and finally becomes zero when the pump power is reduced so that the threshold for Q-switched mode locking is approached. For the first time to our knowledge, this method provides important information on the stability of mode locking above the Q-switched mode-locking threshold. It is applicable to Lasers that are mode locked with slow-saturable absorbers. The results helped to explain the cause of unexpectedly low Q-switching thresholds in two cases. Also we obtain some useful spectroscopic information.

  • pulse energy dynamics of passively mode locked Solid State Lasers above the q switching threshold
    Advanced Solid-State Photonics (TOPS) (2004) paper 41, 2004
    Co-Authors: Adrian Schlatter, S C Zeller, Rachel Grange, Rudiger Paschotta, U Keller
    Abstract:

    We have investigated the dynamical behavior of various passively mode-locked Solid-State Lasers by measuring how a modulation of the pump power affects the output power. We show theoretically and experimentally how the damping of the relaxation oscillations is reduced and finally becomes zero when the pump power is reduced so that the threshold for Q-switched mode locking is approached. For the first time to our knowledge, this method provides important information on the stability of mode locking above the Q-switched mode-locking threshold. It is applicable to Lasers that are mode locked with slow-saturable absorbers. The results helped to explain the cause of unexpectedly low Q-switching thresholds in two cases. Also we obtain some useful spectroscopic information. © 2004 Optical Society of America OCIS codes: 140.3580, 140.4050, 140.3540.

  • ultrafast Solid State Lasers
    Conference on Lasers and Electro-Optics, 2000
    Co-Authors: U Keller
    Abstract:

    Today's ultrafast all-Solid-State Lasers continue to demonstrate unsurpassed performances in terms of pulse duration, pulse repetition rates, average power and wavelength range. Optical pulses in the 5-femtosecond range are produced by a variety of methods. Although different in technical detail, each method relies on the same three key components: spectral broadening due to the nonlinear optical Kerr effect, dispersion control, and ultrabroadband amplification. The shortest pulses generated to date all rely on chirped mirrors for dispersion compensation. A major limitation in chirped mirror design arises due to interference between light reflected at different penetration depths inside the minor structure. This results in residual oscillations in the group delay dispersion (GDD) which ultimately limits pulse shortening Unfortunately, there is always a trade-off-between GDD-oscillations and reflection bandwidth. The double-chirped mirror technique (DCM) reduced GDD oscillations and resulted in the sub-6-fs pulses. Novel DCM designs result in a sufficiently large reflection bandwidth that could, in principle, support 4-fs pulses. The technique of Kerr lens mode-locking, successful with Ti:sapphire, has not performed so well in directly diode-pumped Lasers. Semiconductor saturable absorber mirrors (SESAMs) were a breakthrough resulting in the first demonstration of self-starting and stable passive mode locking of diode-pumped Solid-State Lasers with an intracavity saturable absorber. The design freedom of SESAMs has allowed us systematically to investigate the stability regime of passive cw mode-locking with an improved understanding and modeling of Q-switching instabilities. Simple design guidelines allowed us to push the frontiers of ultrafast Solid-State Lasers.

  • Semiconductor saturable absorber mirrors (SESAM's) for femtosecond to nanosecond pulse generation in Solid-State Lasers
    IEEE Journal of Selected Topics in Quantum Electronics, 1996
    Co-Authors: U Keller, D Kopf, K.j. Weingarten, F.x. Kartner, B. Braun, I.d. Jung, R. Fluck, C. Honninger, N. Matuschek
    Abstract:

    Intracavity semiconductor saturable absorber mirrors (SESAM's) offer unique and exciting possibilities for passively pulsed Solid-State laser systems, extending from Q-switched pulses in the nanosecond and picosecond regime to mode-locked pulses from 10's of picoseconds to sub-10 fs. This paper reviews the design requirements of SESAM's for stable pulse generation in both the mode-locked and Q-switched regime. The combination of device structure and material parameters for SESAM's provide sufficient design freedom to choose key parameters such as recovery time, saturation intensity, and saturation fluence, in a compact structure with low insertion loss. We have been able to demonstrate, for example, passive modelocking (with no Q-switching) using an intracavity saturable absorber in Solid-State Lasers with long upper State lifetimes (e.g., 1-/spl mu/m neodymium transitions), Kerr lens modelocking assisted with pulsewidths as short as 6.5 fs from a Ti:sapphire laser-the shortest pulses ever produced directly out of a laser without any external pulse compression, and passive Q-switching with pulses as short as 56 ps-the shortest pulses ever produced directly from a Q-switched Solid-State laser. Diode-pumping of such Lasers is leading to practical, real-world ultrafast sources, and we will review results on diode-pumped Cr:LiSAF, Nd:glass, Yb:YAG, Nd:YAG, Nd:YLF, Nd:LSB, and Nd:YVO/sub 4/.

Patrick Georges - One of the best experts on this subject based on the ideXlab platform.

  • Light-emitting diode pumped luminescent concentrators: a new opportunity for low-cost Solid-State Lasers
    Optica, 2016
    Co-Authors: Adrien Barbet, Sebastien Forget, Sebastien Chenais, Amandine Paul, Thomas Gallinelli, François Balembois, Jean-philippe Blanchot, Frédéric Druon, Patrick Georges
    Abstract:

    High-power light-emitting diodes (LEDs) today are twice as powerful as four years ago while meantime their price has been divided by 4 making them promising sources for laser pumping. However, their irradiance still falls short by one order of magnitude of what is needed to efficiently pump Solid-State Lasers. We demonstrate that an LED-pumped Ce:YAG luminescent concentrator (LC) can increase the irradiance of blue LEDs by a factor of 10, with an optical efficiency of 25%, making them much more suitable to pump Solid-State Lasers. In our demonstration , we used 100 Hz pulsed LEDs emitting 190 W∕cm 2 at 430 nm to illuminate a Ce:YAG LC, leading to an output irra-diance of 1830 W∕cm 2. The LC is used to pump a Nd:YVO 4 laser producing 360 μJ at 1064 nm, corresponding to an optical efficiency of 2.2% with respect to the LC. LED-pumped lumi-nescent concentrators pave the way for high-power, low-cost, Solid-State Lasers.

  • On thermal effects in Solid State Lasers: the case of ytterbium-doped materials
    Progress in Quantum Electronics, 2006
    Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick Georges
    Abstract:

    A review of theoretical and experimental studies of thermal effects in Solid-State Lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of Solid-State laser. Our aim here is not to make a list of the techniques that have been used to minimize thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a State-of-the-art of the tools at the disposal of the laser scientist to measure thermal effects. After a presentation of some general properties of Yb-doped materials, we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally. This is the first step before studying the complex problem of thermal lensing (part III). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of thermal lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Part IV will be devoted to a State-of-the-art of experimental techniques used to measure thermal lensing. Eventually, in part V, we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.

  • On thermal effects in Solid State Lasers: the case of ytterbium-doped materials
    Progress in Quantum Electronics, 2006
    Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick Georges
    Abstract:

    Abstract A review of theoretical and experimental studies of thermal effects in Solid-State Lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of Solid-State laser. Our aim here is not to make a list of the techniques that have been used to minimize thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a State-of-the-art of the tools at the disposal of the laser scientist to measure thermal effects. After a presentation of some general properties of Yb-doped materials ( Section 1 ), we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally ( Section 2 ). This is the first step before studying the complex problem of thermal lensing ( Section 3 ). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of thermal lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Section 4 will be devoted to a State-of-the-art of experimental techniques used to measure thermal lensing. Eventually, in Section 5 , we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.

D C Hanna - One of the best experts on this subject based on the ideXlab platform.

  • simple method for reducing the depolarization loss resulting from thermally induced birefringence in Solid State Lasers
    Optics Letters, 1999
    Co-Authors: W. Andrew Clarkson, N S Felgate, D C Hanna
    Abstract:

    A simple technique for reducing the loss that is due to depolarization resulting from thermally induced stress birefringence in Solid-State Lasers is reported. The technique uses a single intracavity quarter-wave plate with its fast or slow axis aligned parallel to the preferred plane of polarization, defined by an intracavity polarizer. This technique has been applied to a diode-bar-pumped Nd:YAG laser operating at 946??nm, resulting in a measured reduction in depolarization loss from ?1.7% to ?0.0006% and yielding a diffraction-limited, TEM00, linearly polarized output power of 2.9??W for an incident pump power of 14.3??W.

  • simple method for reducing the depolarization loss resulting from thermally induced birefringence in Solid State Lasers
    Optics Letters, 1999
    Co-Authors: W A Clarkson, N S Felgate, D C Hanna
    Abstract:

    A simple technique for reducing the loss that is due to depolarization resulting from thermally induced stress birefringence in Solid-State Lasers is reported. The technique uses a single intracavity quarter-wave plate with its fast or slow axis aligned parallel to the preferred plane of polarization, defined by an intracavity polarizer. This technique has been applied to a diode-bar-pumped Nd:YAG laser operating at 946 nm, resulting in a measured reduction in depolarization loss from approximately 1.7% to approximately 0.0006% and yielding a diffraction-limited, TEM(00) , linearly polarized output power of 2.9 W for an incident pump power of 14.3 W.

P F Moulto - One of the best experts on this subject based on the ideXlab platform.

  • tunable Solid State Lasers
    Proceedings of the IEEE, 1992
    Co-Authors: P F Moulto
    Abstract:

    Reviews the basic physics of tunable Solid-State Lasers and discusses the characteristics of the most significant established and emerging systems. Particular emphasis is placed on trivalent transition metals; alexandrite, other Cr-doped systems, and Ti: sapphire are also discussed. Other systems, rare earth and forsterite, are considered. >

Sebastien Chenais - One of the best experts on this subject based on the ideXlab platform.

  • Light-emitting diode pumped luminescent concentrators: a new opportunity for low-cost Solid-State Lasers
    Optica, 2016
    Co-Authors: Adrien Barbet, Sebastien Forget, Sebastien Chenais, Amandine Paul, Thomas Gallinelli, François Balembois, Jean-philippe Blanchot, Frédéric Druon, Patrick Georges
    Abstract:

    High-power light-emitting diodes (LEDs) today are twice as powerful as four years ago while meantime their price has been divided by 4 making them promising sources for laser pumping. However, their irradiance still falls short by one order of magnitude of what is needed to efficiently pump Solid-State Lasers. We demonstrate that an LED-pumped Ce:YAG luminescent concentrator (LC) can increase the irradiance of blue LEDs by a factor of 10, with an optical efficiency of 25%, making them much more suitable to pump Solid-State Lasers. In our demonstration , we used 100 Hz pulsed LEDs emitting 190 W∕cm 2 at 430 nm to illuminate a Ce:YAG LC, leading to an output irra-diance of 1830 W∕cm 2. The LC is used to pump a Nd:YVO 4 laser producing 360 μJ at 1064 nm, corresponding to an optical efficiency of 2.2% with respect to the LC. LED-pumped lumi-nescent concentrators pave the way for high-power, low-cost, Solid-State Lasers.

  • organic Solid State Lasers
    2013
    Co-Authors: Sebastien Forget, Sebastien Chenais
    Abstract:

    Fundamentals of laser physics.- Organic materials for Solid-State Lasers.- Organic Lasers resonators.- Prospects for electrical pumping.- Organic Lasers at the nanoscale.- Applications of organic Solid-State Lasers.

  • On thermal effects in Solid State Lasers: the case of ytterbium-doped materials
    Progress in Quantum Electronics, 2006
    Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick Georges
    Abstract:

    A review of theoretical and experimental studies of thermal effects in Solid-State Lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of Solid-State laser. Our aim here is not to make a list of the techniques that have been used to minimize thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a State-of-the-art of the tools at the disposal of the laser scientist to measure thermal effects. After a presentation of some general properties of Yb-doped materials, we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally. This is the first step before studying the complex problem of thermal lensing (part III). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of thermal lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Part IV will be devoted to a State-of-the-art of experimental techniques used to measure thermal lensing. Eventually, in part V, we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.

  • On thermal effects in Solid State Lasers: the case of ytterbium-doped materials
    Progress in Quantum Electronics, 2006
    Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick Georges
    Abstract:

    Abstract A review of theoretical and experimental studies of thermal effects in Solid-State Lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of Solid-State laser. Our aim here is not to make a list of the techniques that have been used to minimize thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a State-of-the-art of the tools at the disposal of the laser scientist to measure thermal effects. After a presentation of some general properties of Yb-doped materials ( Section 1 ), we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally ( Section 2 ). This is the first step before studying the complex problem of thermal lensing ( Section 3 ). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of thermal lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Section 4 will be devoted to a State-of-the-art of experimental techniques used to measure thermal lensing. Eventually, in Section 5 , we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.