Generation of chirp-free picosecond pulses

The frequency spectrum of moderately chirped laser pulses depends upon the portion of the beam which is accepted by the spectrometer. Observation of the development of the chirp in a mode-locked pulse train allows to determine the small incipient chirp of early pulses. A product, bandwidth times pulse duration, of 0.47 ± 0.03 is consistently observed for single pulses switched from a passively mode-locked Nd-glass system.     

Generation of picosecond optical pulses from single heterostructure GaAs diode laser and their emission characteristics

Emission characteristics of a single heterostructure GaAs diode laser are reported using a simple driver circuit. It provides a single picosecond time duration optical pulse, a pulse train or a broad optical pulse depending on the amplitude and time duration of the electrical pump pulse. Results show that relaxation oscillation frequency depends on the amplitude of pumping current pulse as well as on some inherent property of diode laser, which seems to be the level of impurity in lasing medium. Variation of relaxation oscillation frequency with amplitude of current pulse shows only the qualitative agreement with the reported theoretical predictions.     

Generation of rayleigh waves by picosecond laser pulses

In this paper we present the fundamental mechanism which we hold responsible for generation of high frequency Rayleigh waves by picosecond laser pulses on a single crystal surface of Silicon. These Rayleigh waves have been recorded as ripples frozen out on the surface of the crystal upon irradiation with a focused cw mode-locked laser.     

Generation and applications of passively mode-locked picosecond light pulses

A model concerning the generation of picosecond light pulses in solid state lasers is compared with existing experimental observations. The quality of selected single pulses and their favourable properties for investigations with ultrashort light pulses are discussed. Extensive physical applications of picosecond light pulses are reviewed. Emphasis is given to quantitative investigations of non-linear optics and of ultrafast relaxation processes in condensed matter.     

Generation of megawatt peak power picosecond pulses from a divided-pulse fiber amplifier

Control of nonlinearity is a challenge in fiber amplifiers designed to generate pulses of a few picoseconds duration, and as a result, picosecond fiber amplifiers have failed to reach peak power of 1MW. Divided-pulse amplification, combined with the use of circular polarization, allows the generation of 2.2?ps pulses with energy as high as 2.5?μJ and peak power of 1?MW.     

Generation of picosecond pulses in solid-state lasers using new active media

Results are reported of investigations aimed at generating nanosecond radiation pulses in solid-state lasers using new active media having broad gain lines. Passive mode locking is accomplished for the first time in a BeLa:Nd³⁺ laser at a wavelength 1.354 m, and in a YAG:Nd³⁺ laser on a 1.32–m transition. The free lasing and mode-locking regimes were investigated in an alexandrite (BeAl²O₄:Cr³⁺) laser in the 0.72–0.78–m range and in a synchronously pumped laser on F 2- centers in LiF in the 1.12–1.24–m region. The features of nonlinear perception of IR radiation by the eye, using a developed picosecond laser on F₂ ^– centers, are investigated for the first time.Translated from Lazernye Sistemy, pp. 67–86, 1982.     

Generation of picosecond and subpicosecond light pulses with saturable absorbers

Single light pulses, generated by a mode-locked Nd-glass laser, were shortened with saturable absorbers of low initial transmissionT ₀. The pulse duration was reduced from 8 to 2.6 ps after a single pass through a dye cell ofT ₀=10^–7. Light pulses as short as 0.5 ps were observed after five transits through an absorberamplifier system. Detailed calculations of the stationary and the transient situation (with respect to the dye relaxation time) are presented to demonstrate optimum conditions for the pulse shortening.     

Generation and measurement of frequency-tunable picosecond pulses from dye lasers

Experimental techniques for the generation of frequency-tunable picosecond pulses from passively mode-locked dye lasers are reviewed. Direct photoelectric measurements of pulse durations with a streak-camera of time resolution <3 ps are described. Recent studies of the build-up of pulse shortening and of saturable absorber photochemistry are discussed and related to the mode-locking processes in dye lasers.     

Generation of frequency shifted picosecond pulses with low temporal jitter

Transient stimulated Raman scattering is used for the generation of a frequency shifted picosecond light pulse; part of this Raman shifted pulse is subsequently coherently scattered at a material excitation of a second Raman cell. Starting with the second harmonic pulse (t_p = 4 ps) of a mode-locked Nd : glass laser system, both the stimulated and the coherently produced pulses have durations of 2.3 ps at different wavelengths. By the appropriate choice of the Raman medium pulses between 13 000 and 21 000 cm^-1 can be generated. The coherent generation process minimizes the temporal jitter between the two pulses and allows to obtain a high time resolution of better than 0.3 ps in excite and probe experiments.     

Generation of picosecond UV pulses by stimulated anti-Stokes Raman scattering

Picosecond stimulated anti-Stokes Raman scattering of hydrogen gas in the ultraviolet region has been studied, using the second harmonic of a modelocked Nd³⁺: YAG laser as an incident pulse (25 ps, 532 nm, 10 mJ). Good conversion efficiency for higher-order anti-Stokes lines has been realized, yielding 2 μJ (200 kW, 10 ps) output for the 8th one at 192 nm. Some features of transient stimulated Raman scattering have been examined and discussed.     

Generation of picosecond optical phase conjugate pulses using cw mode-locked lasers

Low power picosecond optical phase conjugation has been demonstrated using cw mode-locked argon-ion and dye lasers via 4-wave mixing in ruby. Streak camera and power measurements show that the generated pulses are identical to the input pulses.     

Generation of synchronized femtosecond and picosecond pulses in a dual-wavelength femtosecond Ti:sapphire laser

We obtain synchronized 45-fs and 0.848-ps pulses by achieving cross-mode locking in a double-cavity dual-wavelength femtosecond Ti:sapphire laser. Autocorrelation and cross correlation show that the femtosecond and picosecond pulses are well synchronized, with a timing jitter of 41 fs. Cross-phase modulation dominates the processes of cross-mode locking and synchronization.     

Generation of synchronized femtosecond and picosecond laser pulses in a two-beam-pumped Ti:sapphire laser

<正>Two operating modes,independent self-mode-locking and cross-mode-locking,are presented in a two-beampumped double-cavity dual-wavelength femtosecond Ti:sapphire laser.Synchronization of femtosecond and picosecond laser pulses is achieved by properly adjusting the cavity length matching and distributing the pump laser powers in the two laser cavities,and moreover,a timing jitter of 517 fs between femtosecond and picosecond pulses is obtained,with wavelength tuning ranges around 36 and 22 nm in the femtosecond and picosecond cavities,respectively.     

Generation of tunable picosecond pulses in the ultraviolet region down to 197 nm

Tunable picosecond pulses in the ultraviolet region down to 197 nm with ? 20 kW peak power are generated by the sum frequency mixing of fourth or third harmonic pulses of a mode-locked YAG laser with tunable pulses produced by a LiNbO₃ parametric oscillator pumped by second harmonic pulses of the YAG laser by using a KB5 or KDP crystal.     

Generation of picosecond soliton pulses with tunable repetition rate by modulational instability

Picosecond soliton pulse train has been obtained from a passively mode locked erbium-doped ring fiber laser. The passive mode-locking mechanism that is at play in this laser relies on the modulational instability (MI) theory. By accurately adjusting the polarization setting of the circulating cavity light, the repetition rate can be tuned from 58 to 114 GHz. Theoretical explanations has also been given.     

Generation of picosecond pulses with a large axial interval in the IR and visible spectral regions

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 1, pp. 20–24, January, 1990.     

Interpulse coherence of picosecond pulses

Interferometric studies of trains of picosecond pulses from dye mode-locked Nd: glass lasers have been made. Both autocorrelation and cross correlation measurements of pulses have been recorded. Even for non-minimum width pulses very high fringe contrast ratios have been obtained for both cases indicating considerable similarity between pulses. It is also concluded that the relative phase shift from pulse to pulse is constant.     

Theoretical study of Ni-like Ag 13.9nm TCE x-ray laser driven by two picosecond pulses

The Ni-like Ag 13.9nm x-ray laser has been previously demonstrated that the higher gain near critical surface contributes little to the amplification of the x-ray laser because of severe refraction. In this paper, the transient collision excitation (TCE) Ni-like Ag 13.9nm x-ray laser is simulated, driven by two 3ps short pulse preceded by a 330ps long prepulse, optimization of the peak to peak delay time of the two short pulses is made to get the best results. Simulation indicates that by producing lowly ionized preplasma with smoothly varying electron density, it is possible to decrease electron density gradient in higher density region, and thus higher gains near this region could be utilized, and if the main short pulse is delayed by 900ps, local gains where electron density larger than ～ 4×10²⁰cm^-3 could be utilized.     

Generation and propagation of a picosecond acoustic pulse at a buried interface: time-resolved x-ray diffraction measurements

We report on the propagation of coherent acoustic wave packets in (001) surface oriented Al0.3Ga0.7As/GaAs heterostructure, generated through localized femtosecond photoexcitation of the GaAs. Transient structural changes in both the substrate and film are measured with picosecond time-resolved x-ray diffraction. The data indicate an elastic response consisting of unipolar compression pulses of a few hundred picosecond duration traveling along [001] and [001] directions that are produced by predominately impulsive stress. The transmission and reflection of the strain pulses are in agreement with an acoustic mismatch model of the heterostructure and free-space interfaces.