P. P. Sorokin

Flashlamp‐Pumped Organic‐Dye Lasers

The results of recent theoretical and experimental studies on flashlamp‐pumped organic‐dye lasers are presented. The importance of rapid pumping is considered in detail. Constructional aspects of a suitable flashlamp assembly are given, and lasing characteristics of various organic dyes excited by this lamp are summarized.

Amplification of 350-fsec pulses in XeCl excimer gain modules.

A pair of XeCl gain modules was used to amplify 350-fsec 308-nm pulses to ~10-mJ energies with <1-mJ amplified-stimulated-emission content. Gentle focusing in air of the ~1.5-mJ beam from the first amplifier alone produces ~1000-cm−1 broadening of the pulse spectrum by the mechanism of self-phase modulation.

Tunable coherent ir source based upon four‐wave parametric conversion in alkali metal vapors

A new type of near‐ir source producing a coherent output with a spectrally narrow (∼ 0.1 cm−1) and continuously tunable frequency is described. It utilizes a four‐wave mixing process in alkali metal vapor with input beams provided by two nitrogen‐laser‐pumped dye lasers. Tunable output has so far been observed in the range 2–5.4 μ.

Ruby laser Q-switching elements using phthalocyanine molecules in solution

Following the original suggestion of R. W. Hellwarth, 1 many investigators have succeeded in obtaining coherent light from optically pumped solid state lasers in the form of intense, sharp, single pulses. These pulses are commonly referred to as “giant” pulses, in recognition of the fact that their peak intensity far exceeds that of any of the several pulses (“spikes”) which are normally emitted in several-hundred-microsecond bursts when a laser is pumped beyond threshold. The duration of a giant pulse is usually only a few tens of nanoseconds. In contrast, the duration of each spike in the output of a normally operated laser is several hundred nanoseconds.

FREQUENCY‐LOCKING OF ORGANIC DYE LASERS TO ATOMIC RESONANCE LINES

Locking of the output of a flashlamp‐pumped Rhodamine 6G dye laser to the D lines of sodium vapor was achieved by means of the large Faraday rotation that occurs in the vicinity of the resonance lines. The laser beam was observed to consist spectrally of two sharp components symmetrically disposed on either side of the D1 and D2 lines. The laser doublet splitting varies with magnetic field.

Some theoretical aspects of a proposed double quantum stimulated emission device

A double quantum stimulated emission device is proposed and some operating characteristics and relevant systems of materials are discussed.

160-fsec XeCl excimer amplifier system

An amplifier system based on XeCl gain modules, which, generates bandwidth-limited, 160-fsec, 308-nm, 12-mJ pulses, is described. The UV seed pulses are derived from a colliding-pulse mode-locked laser system.

STIMULATED ELECTRONIC RAMAN SCATTERING

Stimulated electronic Raman scattering in potassium vapor is observed. The primary source was a nitrobenzene Raman‐shifted ruby laser. The secondary beam frequency occurs 58 cm−1 to the high energy side of νp.

Femtosecond transition‐state absorption spectroscopy of Bi atoms produced by photodissociation of gaseous Bi2 molecules

Femtosecond transition‐state absorption spectroscopy has been performed on Bi atoms produced by the 308 nm photodissociation of Bi2 molecules contained in bismuth vapor. The transient spectra obtained are all clearly identifiable as atomic, yet they display striking asymmetries in line shapes and enhancements in intensity that clearly demonstrate that they are spectral signatures of atoms still in the force fields of their receding partners.

Time‐resolved infrared spectral photography: Study of laser‐initiated explosions in HN3

Recent improvements in the technique of time‐resolved infrared spectral photography (TRISP) are described. With this technique CO2 laser‐induced thermal explosions of gas phase HN3/DN3 mixtures were investigated. HCl gas added to the mixtures was utilized to probe the transient temperature of the reaction. An induction period and a phase of rapid energy release were clearly identified and characterized both with respect to temperature and utilization of reactant material.Recent improvements in the technique of time‐resolved infrared spectral photography (TRISP) are described. With this technique CO2 laser‐induced thermal explosions of gas phase HN3/DN3 mixtures were investigated. HCl gas added to the mixtures was utilized to probe the transient temperature of the reaction. An induction period and a phase of rapid energy release were clearly identified and characterized both with respect to temperature and utilization of reactant material.