Showing papers on "Regenerative amplification published in 2003"

High-conversion-efficiency optical parametric chirped-pulse amplification system using spatiotemporally shaped pump pulses.

Abstract: High-conversion-efficiency, high-stability optical parametric chirped-pulse amplification is demonstrated with a spatiotemporally shaped pump laser system. Broadband 5-mJ pulses are produced at a 5-Hz repetition rate with a pump-to-signal conversion efficiency of 29% and energy stability better than 2% rms. To our knowledge this is the highest conversion efficiency and stability achieved in an optical parametric chirped-pulse amplification system.

30-mJ, diode-pumped, chirped-pulse Yb:YLF regenerative amplifier

Abstract: A diode-pumped chirped-pulse regenerative amplifier with a cooled Yb:YLF crystal has been developed. The output pulse energy is 30 mJ at 20-Hz repetition rate. A high effective extraction efficiency of 68% is obtained, which is attributed to reduced saturation fluence at low temperature and to a high effective pulse energy fluence during regenerative amplification. After pulse compression by use of a parallel grating pair, 18-mJ pulse energy and 795-fs pulse duration are obtained.

High-power and high-contrast optical parametric chirped pulse amplification in beta-BaB2O4 crystal.

Abstract: We have developed a high-power laser system based on optical parametric chirped-pulse amplification in a β‐BaB2O4 crystal. The system provides gain of 108, a conversion efficiency of ∼23%, an output energy of ∼65 mJ, and good amplified beam quality. The prepulse ratio has been measured to be 1.5×10-8 or less. The spectral width was as broad as 16.5 nm centered at 1053 nm.

Design of a highly stable, high-conversion-efficiency, optical parametric chirped-pulse amplification system with good beam quality.

Abstract: An optical parametric chirped-pulse amplifier (OPCPA) design that provides 40% pump-to-signal conversion efficiency and over-500-mJ signal energy at 1054 nm for front-end injection into a Nd:glass amplifier chain is presented. This OPCPA system is currently being built as the prototype front end for the OMEGA EP (extended performance) laser system at the University of Rochester’s Laboratory for Laser Energetics. Using a three-dimensional spatial and temporal numerical model, several design considerations necessary to achieve high conversion efficiency, good output stability, and good beam quality are discussed. The dependence of OPCPA output on the pump beam’s spatiotemporal shape and the relative size of seed and pump beams is described. This includes the effects of pump intensity modulation and pump-signal walk-off. The trade-off among efficiency, stability, and low output beam intensity modulation is discussed.

Picosecond-pulse amplification with an external passive optical cavity.

Abstract: We experimentally demonstrate the amplification of picosecond pulses at high repetition rates through the coherent addition of successive pulses of a mode-locked pulse train in a high-finesse optical cavity equipped with cavity dumping. Amplification greater than 30 times is obtained at a repetition rate of 253 kHz, boosting the 5.3-nJ pulses from a commercial mode-locked picosecond Ti:sapphire laser to pulse energies of more than 150 nJ.

Optical Parametric Chirped-Pulse Amplification in Periodically-Poled KTiOPO4 at 1053 nm

Abstract: Generation of high peak power [1] and high focal intensity from Nd:glass short-pulse lasers is receiving much attention, particularly in large laser facilities where fast ignition [2] may be used for high-gain inertial confinement fusion. Optical parametric chirped pulse amplification (OPCPA) [3] has been recently studied as an alternative techology for the front end of a short-pulse Nd:glass laser. This is the result of superior characteristics of OPCPA when it is used for broadband amplification at wavelengths near 1 µm. It offers increased bandwidth over amplification in Nd:glass, while its gain is several orders of magnitude higher than that of Ti:sapphire at 1 µm, eliminating the need for regenerative amplification. Additionally, OPCPA exhibits high prepulse contrast as a result of cavityless amplification, which is of great importance for high-fidelity target experiments. Other favorable characteristics of OPCPA include high peak power scalability through large-aperture potassium dihydrogen phosphate (KDP) crystals [4] and potential high average power scalability due to negligible thermal deposition.

Amplified spontaneous emission in a Ti: Sapphire regenerative amplifier

Abstract: Amplified spontaneous emission power and contrast ratio in a linear miltipass Ti:sapphire regenerative amplifier with a wavelength centered at 1054 nm are calculated and measured. It is shown that the passive losses of a seed pulse and the losses in coupling to the regenerative amplifier cavity mode degrade the intensity contrast ratio to 10(-6)-10(-7). The advantage of an optical parametric chirped pulse amplifier with respect to the contrast ratio is discussed.

Numerical analysis of optical parametric chirped pulse amplification with time delay.

Abstract: A new scheme for efficient optical parametric chirped pulse amplification is proposed by introducing a time delay between long pump and short seed pulses. Numerical results show that high conversion efficiency from the pump to seed and high gain can be achieved simultaneously, and the amplified seed pulse is stable and not sensitive to timing jitter.

High-power Colquiriite lasers with high slope efficiencies pumped by broad-area laser diodes

Abstract: Efficient high-power operation of Cr:LiSAF, Cr:LiSGAF, and Cr:LiCAF lasers pumped by broad-area laser diodes is demonstrated. A maximum slope efficiency of 51 % and output power of 0.55 W was reached at 1.2 W of absorbed pump power, which is the highest output power to date with broad-area laser diode pumping. With the laser design used the onset of thermal quenching in Cr:LiSAF due to high temperatures was pushed to higher pump powers and good mode matching was achieved.

Directly diode-pumped Yb3+:SrY4(SiO4)3O regenerative amplifier.

Abstract: We report a regenerative amplifier based on an Yb-doped apatite crystal: Yb3+: SrY4(SiO4) 3O (Yb:SYS). We obtained 420-fs pulses at a central wavelength of 1066 nm with an energy of 100μJ at 300 Hz after compression. To the best of our knowledge, this system is the first regenerative amplifier based on an Yb:SYS crystal and provides duration among the shortest ones generated by a directly diode-pumped regenerative amplifier.

Nd:glass diode-pumped regenerative amplifier, multimillijoule short-pulse chirped-pulse-amplifier laser.

Abstract: We have built a diode-pumped Nd:glass regenerative amplifier that is able to produce energies up to 20 mJ within a 470-fs pulse duration at a 1-Hz repetition rate. We obtained this amplifier by using specific intracavity components such as a phase mirror and a birefringent filter to generate a large spatial mode and a large spectral width.

Micromachining of Cr Thin Film and Glass Using an Ultrashort Pulsed Laser

Abstract: Materials processing by ultrashort pulsed laser is actively being applied to micromachining technology due to its advantages with regard to non-thermal machining. In this study, materials processing with ultrashort pulses was studied by using the high repetition rate of a 800 nm Ti:sapphire regenerative amplifier. This revealed that the highly precise micromachining of metallic thin film and bulk glass with a minimal heat affected zone (HAZ) could be obtained by using near damage threshold energy. Grooves with diffraction limited sub-micrometer width were obtained with widths of 620 nm on Cr thin film and 800 nm on a soda-lime glass substrate. The machined patterns were investigated through SEM images. We also phenomenologically examined the influence of variations of parameters and proposed the optimal process conditions for microfabrication.

Femtosecond all-solid-state laser for refractive surgery

Abstract: Refractive surgery in the pursuit of perfect vision (e.g. 20/10) requires firstly an exact measurement of abberations induced by the eye and then a sophisticated surgical approach. A recent extension of wavefront measurement techniques and adaptive optics to ophthalmology has quantitatively characterized the quality of the human eye. The next milestone towards perfect vision is developing a more efficient and precise laser scalpel and evaluating minimal-invasive laser surgery strategies. Femtosecond all-solid-state MOPA lasers based on passive modelocking and chirped pulse amplification are excellent candidates for eye surgery due to their stability, ultra-high intensity and compact tabletop size. Furthermore, taking into account the peak emission in the near IR and diffraction limited focusing abilities, surgical laser systems performing precise intrastromal incisions for corneal flap resection and intrastromal corneal reshaping promise significant improvement over today's Photorefractive Keratectomy (PRK) and Laser Assisted In Situ Keratomileusis (LASIK) techniques which utilize UV excimer lasers. Through dispersion control and optimized regenerative amplification, a compact femtosecond all-solid-state laser with pulsed energy well above LIOB threshold and kHz repetition rate is constructed. After applying a pulse sequence to the eye, the modified corneal morphology is investigated by high resolution microscopy (Multi Photon/SHG Confocal Microscope).

Diode-pumped 100-fs lasers based on a new apatite-structure crystal: Yb 3+ :SrY 4 (SiO 4 ) 3 O

Abstract: We demonstrated, for the first time, sub-100-fs lasers based on an Yb-doped apatite crystal: Yb3+:SrY4(SiO4)3O, also called Yb:SYS Pulses as short as 94-fs have been obtained at 1070 nm with an average power of 110 mW We also developed a regenerative amplifier based on this crystal, and obtained 100μJ, 420-fs pulses following compression

High repetition rate, high energy femtosecond fiber cpa system

Abstract: 300-fs pulses with microjoule pulse energy at repetition rates in the range of 1 to 75 MHz are generated using a diode-pumped ytterbium-doped double-clad fiber based chirped pulse amplification system. At the highest repetition rate average output powers up to 60 W are achieved.

Cascaded-optical parametric amplification for extreme contrast enhancement

Abstract: We demonstrate for the first time a straightforward technique for complete prepulse elimination in chirped pulse amplification systems, using two cascaded optical parametric amplifiers.

Mapping the Complex Dynamics of a Semiconductor Laser Subject to Optical Injection

Abstract: Single‐mode semiconductor lasers can exhibit stable, bi‐stable, periodic, quasi‐periodic, and chaotic output characteristics when subjected to monochromatic, near‐resonant external optical injection. Experimental measurements of the spectral characteristics of a semiconductor laser under external optical injection identify the various nonlinear output characteristics. Single‐mode operation is maintained in all cases. Optical spectra of the laser are augmented by power spectra and spectra of the regenerative amplification of a weak optical probe. The output characteristics are mapped as a function of the strength of the optical injection and the detuning between the injection frequency and the frequency of the unperturbed laser. A comparison of the observed features with the predictions of a rate‐equation model shows quantitative agreement over a wide range of injection characteristics [1]. All key model parameters can be determined experimentally. The agreement permits identification of specific routes to chaos and sudden chaotic transitions that are observed in the spectra. This demonstrates the power of dynamical systems modeling for the quantitative prediction of nonlinear dynamics and chaos of semiconductor lasers.

A new beam break up integral measurement: experimental demonstration at few tens of joule level on Alise (200 J) laser facility

Abstract: We experimentally demonstrate the B-integral measurement using the so-called "temporal diffraction" technique. It is obtained by manipulating strongly chirped femtosecond pulses in the spectral domain and taking advantage of spectral-time coupling generated by nonlinear effect.

Regenerative amplification of laser diode pulses with variable pulse duration from ps to ns range

Abstract: A laser diode seeded Nd:YAG regenerative amplifier is demonstrated. The pulse duration of the laser diode is variable from 150 ps to 3 ns. Pulse energies of 0.5 mJ at kHz repetition rate are measured.

Multi−photon imaging using a Ti:sapphire regenerative amplifier

Abstract: It is shown that two-photon fluorescence images can be obtained almost throughout the entire grey-matter layers of the mouse neocortex by using optically amplified femtosecond pulses. The maximum imaging depth is not limited by the available excitation power but instead by the generation of out-of focus fluorescence.

Femtosecond Cr: forsterite regenerative amplifier operating at 5-10 kHz

Abstract: Chirped pulse amplification in Cr: forsterite at 1.25µm produced 0.86W (0.75W) of average power, or 465mW (400mW) after compression, at 5kHz (10kHz) with pulse durations of 135fs (shortest) and 150fs (typical).