10 μm detection system with 40 picosecond resolution

A 10 μm detection system with a temporal resolution of ? 40 psec has been used to investigate the output of a multi-atmosphere CO₂ laser. Mode-locking, by means of p-type germanium, has permitted the observation of pulses as short as ? 75 psec.     

Picosecond x-ray chronoscopy

An X-ray/VUV streak camera with a time resolution of ≈20 psec is described. X-ray pulses, from a laser plasma, down to 22 psec half width, separated by 42 psec, are clearly resolved. Photoelectron time-dispersion effects and the absolute sensitivity of the camera are discussed.     

Direct measurement of pulse broadening in the second harmonic of mode-locked Nd: glass laser

Direct measurement of pulse broadening in the second harmonic of a mode-locked Nd: glass laser has been made using a high-speed streak camera. Recorded pulsewidths varied from 3.8 psec to greater than 15 psec.     

Pulse propagation through multimode fibres

To evaluate their communication potential, measurements have been made on multimode glass fibres. Detector limited pulses of 180 psec risetime from a Ga-As laser were transmitted through various lengths of fibre. After a 120 m length the risetime was still not greater than 450 psec. Measurements with a mode locked He-Ne laser, done on shorter lengths of fibre, agreed with the above results.     

Picosecond pulses from mode-locked dye lasers

Picosecond pulses have been generated in laser pumped (15 psec) and flashlamp pumped (6 psec) mode-locked dye lasers. Two-photon fluorescence and streak camera measurements are described.     

Polymethine IR laser dyes for passive mode-locking of ruby lasers

Several polymethine IR laser dyes, in addition to the well known DDI and cryptocyanine, are found to be suitable for mode-locking of ruby lasers. While with DDI pulses as short as 12 psec are obtained these new mode-lockers generate pulses in the 40 to 100 psec range, presumably due to their longer recovery time of the ground-state absorption.     

Direct linear measurement of ultrashort light pulses with a picosecond streak camera

The durations of ultra-short (4–7 psec) laser pulses have been directly measured with an image tube streak camera designed for time resolution in the picosecond region. The camera was calibrated with simultaneously recorded two photon fluorescence pulse profiles and it is shown that a time resolution limit of ≈1 psec should be possible with this system.     

Suppression of the spectral narrowing effect in lasers mode-locked by saturable absorbers

A gain profile with a very flat top is produced by incorporating a Fabry-Pérot interferometer in the cavity of a mode-locked Nd-glass laser. With proper adjustment of the interferometer parameters, the spectral narrowing effect is significantly reduced, and bandwidth-limited pulses as short as 1.5 psec have been observed.     

Time resolved spectroscopy of picosecond laser pulses with the aid of optical Kerr effect photography

An extension of the transverse gating, focal plane, optical Kerr effect photographic technique has permitted the direct observation of a frequency sweep within single ≈ 10 psec duration 0.53 μ wavelength pulses derived from a mode-locked Nd: glass laser.     

Suppression of fast-ions from a laser-produced plasma

Fast-ion emission occurs when a target is irradiated with single 25 psec pulses from a Nd: YAG/glass laser but is suppressed when the same target is irradiated with a mode-locked pulse train at the same intensity. Possible explanations for this effect are given.     

The effect of saturable absorber lifetime in picosecond pulse generation. II. The cresyl-violet laser

Picosecond pulse generation in a pulsed cresyl-violet laser, mode-locked by four saturable absorbers (DTDCI, DDCI, DCI, and DCI'), of different relaxation times, has been directly studied. In contrast to the ruby laser case, the ultimate pulse duration is largely independent of the absorber lifetime. Pulses of ? 4 psec duration are obtained from a cw Rhodamine B dye laser mode-locked with cresyl-violet.     

Observation du “hole burning” dans une solution de cryptocyanine dans le methanol

A hole-burning effect is observed spectroscopically in a solution of cryptocyanine in methanol, when excited by a mode-locked ruby laser. The hole width is about 5 Å. A transverse relaxation time of 5 psec is deduced and its significance is discussed.     

High power,subnanosecond pulse from a tea nitrogen laser with travelling wave excitation

A segmented flat-plate Blumlein circuit has been used to excite a travelling wave of inversion in pure nitrogen at atmospheric pressure in a 50 cm long discharge channel. UV laser emission in the forward direction was typically 200 times more intense than in the opposite direction. Laser pulse duration as determined by streak photography was 400 psec, whereas peak power was about 1 MW.     

Picosecond study of color center translocation in LiTaO3

By the use of dual-beam picosecond absorption spectroscopy technique, we observed color center dislocation in LiTaO₃ single crystal. The time constant for the translocation was found to be 100 ± 40 psec, and independent of excitation laser power.     

System for nanosecond and picosecond laser synchronization using high-voltage semiconductor switches

Results are presented on the development and investigation of a system for the synchronization of the emission of a nanosecond laser, used for plasma heating, with the emission of a diagnostic picosecond laser. The system is based on the use of the fast-semiconductor-switch technology, and ensures a temporal synchronization instability not higher than 100 psec.Laser-Plansma Laboratory and Special Design Office. Lebedev Physics Institutes, Academy of Sciences of the USSR. Translated from Preprint No. 85 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow, 1988.     

强场下的Li-like氖复合机制X光激光的数值模拟

论述了隧道电离和阈上电离加热过程。并把此二过程加到一个non-LTE平均原子模型,用此模型来研究强场下光致电离类锂氖复合机制X射线激光。计算结果表明,当驱动激光脉冲为100fs、波长为0.248μm、功率密度为2×10¹⁷Wcm^-2,氖气的密度为10^-3gcm^-3时,类锂氖精细结构跃迁3d_5/2→2p_3/2(λ=98Å)的最大增益系数约为100cm^-1,其维持时间约为1.5ps。     

A Far Infrared Super Radiant FEL

The basic physics, results of 3–D simulations, and relevant parameters for the design of a far infrared FEL, which operates in the SASE superradiant short bunch regime, are presented. It is shown that a quite interesting device can be easily developed, with rather new features, producing coherent laser pulses with ∼10 psec duration and around 7 MW peak power.     

Picosecond optical sampling oscilloscope

Single picosecond laser pulses are displayed on a real-time oscilloscope by a multi-channel sampling technique of picosecond resolution. An ultrafast optical gate simultaneously cuts out N samples from the laser pulse. The N samples are centered at 3.9 psec intervals from the leading to the lagging edge of the pulse; they are directed to a photo-multiplier of 3 nsec response, via N fibers cut to propagation delays of 15 nsec, 25 nsec,…, (10 N + 5) nsec. The samples appear sequentially on a 0.8 nsec risetime oscilloscope and their envelope represents a display of the laser pulse.     

Mode-locked He-Ne laser pulse compression and expansion

By means of an electro-optic internal modulator it is possible to obtain from a laser He-Ne recurring pulses whose duration (about 500 psec) is the inverse of the Ne amplifying spectral bandwidth. The optical frequency of these pulses, passing through an external modulator is translated or linearly modulated. The duration of the linear frequency modulated pulses, whose spectrum is widely broadened, is then reduced by travels into a dispersive interferometric structure (optical dispersive delay line). A pulse compression ratio at least equal to 3 has been obtained.     

Results of 2D numerical simulations of subnanosecond iodine laser interaction with an al foil target

This report presents the results of a theoretical study and 2D numerical simulations of the interaction of subnanosecond iodine laser pulses with an Al-foil target. The target and laser parameters correspond to the experimental conditions of the “PERUN” iodine laser facility (IP, Prague: pulse energy <50 J, ∼300 psec, focal spot d ∼100 μm; target: Al foil of thickness 30 μm). The simulations were made by using the two-dimensional Lagrange code “ATLANT” (FIAN-IMM, Moscow). We varied the diameter of the focal spot and studied the dependence of the plasma parameters (temperature, x-ray yield, etc.) on the laser flux density and the diameter of focal spots. The numerical results were compared with experimental data. Published as Preprint No. 38 of the Lebedev Physics Institute (FIAN), Moscow, 1993.