Acousto-optic lens with very fast focus scanning

We propose and experimentally demonstrate an acousto-optic cylindrical lens with a very fast (400-kHz) focal scanning. The lens is realized by use of two adjacent acousto-optic scanners with counterpropagating acoustic waves that have the same frequency modulation but a pi phase difference. This scheme completely suppresses the lateral scan but adds the linear chirp of the two waves and thus functions as a fast focal-scan lens. We also demonstrate the use of this scanning lens in a very fast confocal profilometer.     

Yb-Bi pulsed fiber lasers

A new type of pulsed fiber laser is suggested and developed - Yb-Bi lasers. In such lasers the Yb fiber laser is Q-switched by use of a saturable absorber, a Bi-doped fiber placed in its own resonator, and pulsed lasing is obtained in both fiber lasers. Continous-wave diode-clad pumping of the Yb-Bi lasers at a 975 nm wavelength with power up to 16.5 W results in pulsed laser action in a spectral diapason of 1050-1200 nm with a maximum pulse energy of up to 100 microJ, an average power up to 7.5 W, and a repetition rate up to 100 kHz.     

Threshold conditions for pulsed gamma ray lasers

We examine the threshold conditions for both lasing and superradiance in a pulsed γ-ray laser. We find that both threshold conditions are much more restrictive than the Schalow-Townes condition for lasing in a steady-state laser.     

High-pressure pulsed CO2 lasers

This paper presents a large body of data allowing one to determine the energy, time, and spectral characteristics of high-pressure pulsed CO₂ lasers over wide ranges of parameters. Institute of High-Current Electronics, Siberian Division of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 19–28, April, 2000.     

A double-prism beam expander for pulsed dye lasers

The design of a pulsed dye laser cavity incorporating a double-prism beam expander is described and operating characteristics compared with those of single-prism systems. Narrow spectral linewidths (δλ = 0.008 Å) are achieved at relatively high efficiency (> 10%) for coumarin 500 dye solutions. Background superfluorescence in the output is low and the cavity is free from external coupling effects.     

A new simple model for high-power pulsed gas lasers

An analysis of a modified electrode geometry for pulsed gas-laser excitation circuits, generating shorter excitation pulses than those normally obtained, is reported. Results from an atmospheric N₂ laser obtained with this electrode geometry are compared with others available in the literature.Paper partially presented at the XIII Intern. Quantum Electronics Conf., Los Angeles, CA, USA (1984)     

Spectral purity of pulsed dye lasers

High-spectral purity of pulsed dye lasers is required by many experiments. Unfortunately, the dye laser output is usually accompanied by a spectrally broadband background of spontaneous emission (ASE). We have carried out detailed studies of the ASE background using a dye laser operating with an oscillator, pre- and main amplifier.Dedicated to Prof. Dr. Herbert Welling on the occasion of his 60th birthday     

Research into pulsed power-driven recombination lasers

Time-resolved measurements of XUV emissions from recombining Ne and Al plasmas are reported. The DNA/PITHON pulsed-power generator was used to produce hot, dense aluminum and neon plasmas in a Z-pinch configuration. The Al Xl, 4f-3d and 4 d-3p lines at 154.4 and 150.4 Å were observed to be anomalously bright compared to the Al Xl, 4d-2p line. This anomaly, which might be suggestive of recombination lasing, may also be explained by opacity, whereby the optically thick 4→2 lines are reduced in apparent intensity with respect to the 4→3 lines. The Ne X 4-3 line was observed to be spatially localized on axis where emissions from the Ne X 3-2 line were sharply reduced in intensity. On axis, the anomalous brightness of the Ne X 4-3 line suggests a strong inversion     

Strongly coupled intracavity frequency-doubled pulsed lasers

Simple expressions for the peak power, pulse energy, and pulse length of strongly coupled intracavity frequency-doubled lasers are presented. For nonlinear coupling values that correspond to many common systems, these expressions agree well with the results of numerical integration of the rate equations. In contrast with weak nonlinear or linear coupling, pulsed lasers with strong nonlinear coupling only deplete the population inversion down to the threshold level.     

Improved absorption spectroscopy with pulsed lasers

A simple formalism is given to allow for intensity correction and background suppression in absorption spectroscopy with pulsed lasers. By experimental examples the online application with a microcomputer is demonstrated, and the computer is also used for analyzing the correlation between signal and reference channels. The optimization of the correlation and the intensity correction yields a gain of a factor of about 30 in the signal-tonoise ratio of the recorded spectra compared to conventional absorption experiments. Spectral lines were observed, which would not be detectable by fluorescence technique.     

High-power high-pressure pulsed CO2 lasers

The results of investigations and development of high-pressureCO ₂ lasers are considered. It is shown that the high-pressure active medium allows radiation pulses to be formed with smooth tuning of frequency and duration over wide ranges. Data on small-size wide-apertureCO ₂ lasers with an output pulse energy up to 5 kJ are presented. Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 74–77, August, 1999.     

Transient behaviour of pulsed dye lasers

Some aspects of the transient behaviour of pulsed dye lasers are investigated both theoretically and experimentally. Relaxation oscillations induced in the output from a dye cell by an external reflector have been observed and explained, using a rate equation approximation to the physical situation in the dye cell. These oscillations are shown to play an important part in the generation of short laser pulses from long cavity dye lasers. Finally, it is proposed that 10 ps pulses can be obtained from conventional dye lasers pumped by 100 ps pulses from a high-pressure nitrogen laser.     

Resonator insensitive investigation to thermal lens for end-pumped lasers

Optical pumping of solid-state lasers induces a thermal lens effect in the laser crystal; this thermal effect determines the beam properties. In this paper, the focal length of the thermal lens is calculated, and resonator parameter (g_1 g_2) is obtained, which is insensitive to thermal distortions when the product of the resonator parameters (g_1, g_2) equals 1/2. By using our calculated results, we get the fundamental transverse mode laser output with optic－optic conversion of 48.6%, and slope efficiency of 56.3%.     

Low cost Pockels cell driver for pulsed solid state lasers

The paper describes a low cost Pockels cell driver for Q-switching flash lamp pumped pulsed solid state lasers. The driver consists of a high voltage pulsed power supply variable from 0 to 5 kV using a standard step up transformer. The pulse width and pulse repetition rate are varied using standard TTL circuits from 50 μs to 2 ms and 1 ppm to 50 Hz, respectively. The pulsed high voltage along with a high voltage switch consisting of a stack of bipolar transistors is used to drive a Pockels cell. The Q-switched pulsed duration measured in Ruby and Nd-YAG lasers are 35 and 15 ns, respectively. The Pockels cell driver performance is consistent for more than 5×10⁷ shots.     

A simple heterodyne frequency offset locking system for pulsed lasers

As a new approach the heterodyne frequency offset locking system which is applicable to a broad range of pulsed lasers is described. A 100 MHz wide-band and all-digital frequency discriminating technique is presented and an offset locking loop in which the frequency discriminator works accordingly is designed. The result of the experiment on offset locking between a CW CO₂ laser and an electro-optically Q-switched CO₂ laser with an optical pulse width 300 ns and its repetition rate 20 kHz showed that the beat frequency stability was kept within ±2 MHz.