The real-time information processing and manipulation of electromagnetic waves using nonlinear Qptical techniques has resulted in a myriad of new applications in diverse fields such as quantum electronics, image processing, optical computing, adaptive optics, and nonlinear spectroscopy. In this paper, we review and explore the field, provide a historical perspective, analyze several of the nonlinear interactions useful for the generation of phase-conjugate replicas, and conclude with a brief survey of potential applications and suitable nonlinear media.

Nonlinear Optical Phase Conjugation

A review of laser-induced photoionization of polyatomic molecules and the application of this process in mass-spectrometry is presented. Combination of laser selective photoionization and mass spectral analysis of fragments as a promising tool for the detection of trace amounts of complex molecules is considered particularly.

Laser multiphoton and multistep photoionization of molecules and mass spectrometry

A review is given of experimental data on exciplex lasers. An analysis is made of the optical characteristics of lasing transitions, experimental conditions for achieving laser action, mechanisms of formation of the active level populations, character of nonequilibrium of the active medium, and proposed new active media. Detailed tables are presented with data on optical transitions, exciplex quenching rates, and characteristic parameters of the media and pump sources of existing lasers.

https://iopscience.iop.org/article/10.1070/QE1980v010n04ABEH010101/pdf

Active media of exciplex lasers (review)

Strong laser action on the 342‐nm band of I2 has been obtained by transverse pumping I2/SF6 mixtures at 193 nm with an ArF laser. The highest output energy obtained was 230 mJ at an intrinsic energy conversion efficiency of approximately 30% equivalent to a photon efficiency of greater than 50%.

Efficient laser action on the 342‐nm band of molecular iodine using ArF laser pumping

The I2 D’(2g)-A’(2u) transition has been excited by collisionally induced optical double resonance. This system has been rotationally analysed for more than 50 vibrational levels of the A’(2u) state. The long range behaviour of the A’ state has been studied. The dissociation energy of this state has been determined to be Dc = 2 505.7 ± 1.9 cm-1. The D’ state has been identifed with the 03B1 state of King et al. (Chem. Phys. 56 (1981) 145). The energies of the D’ and A’ states have been determined relative to X 1~g+(03BD = 0, J = 0) to be T0 = 40 331.6 ± 1.6 cm-1 and To = 9 988.7 ± 1.6 cm-1, respectively. The mechanism of this double resonance is discussed. Efficient collisional transfer to the D’ state is observed and helps to shed some light on the operation of the optically pumped I2 D’-A’ laser. J. Physique 43 (1982) 1639-1651 NOVEMBRE 1982, :

Collisionally induced optical double resonance in I2 : rotational analysis of the D'(2g) - A'(2u) laser transition

Green luminescence and stimulated emission in the form of ~2 μsec pulses were observed as a result of photodissociation of HgBr2 vapor with radiation from an open high-current discharge. The rates of quenching of the luminescence by various buffer gases were determined.

Stimulated emission at λ = 502 nm as a result of prolonged optical pumping of HgBr2 vapor

Results are presented of observations of the fluorescence of iodine vapor, subjected to cw optical pumping, as a function of the temperature and pressure of the SF6, N2, Ar, Xe, He, and Kr buffer gases. It is shown that an increase of the fluorescence in the 340 nm band with rising buffer gas pressure is accompanied by a decrease in the iodine fluorescence in the 250–330 nm band. The efficiency of the action of the buffer gas depends on its molecular weight and on the wavelength of the exciting light. The intensity depends on the buffer gas used. An estimate is made of the rate of quenching of the fluorescence by iodine molecules in the ground state kqτ =(3.0±0.30)×10−18 cm3. For Xe, kqτ = (1.2±0.6)×10−18 cm3. It is shown that the fluorescence quantum efficiency η does not depend on the mixture temperature up to 425 °C. The value of η for optical pumping (λ = 190 nm) of a mixture of iodine vapor and 5 atm SF6 is η = 0.04±0.02 and for a mixture with 1.5 atm Ar, is η = 0.05±0.02.

https://iopscience.iop.org/article/10.1070/QE1978v008n02ABEH008488/pdf

Investigation of the fluorescence of molecular iodine in the 340 nm band

Lasing in the 485-520 nm range was observed for the first time in vapors of coumarin 153 (C153), 7-diethylamino-3(2'-benzoxazolyl)-coumarin, C7, and C6 mixed with buffer gases. The pressure was about 35 atm and the vapors were excited with the third harmonic of a neodymium laser (355 nm).

Coumarins in the gaseous phase. I. Stimulated emission of coumarin vapors in the range 485–520 nm

A bleaching-wave laser (utilizing an ether solution of coumarin 6 and 1,4-diphenylbutadiene) was pumped by a flashlamp-type source utilizing magnetoplasma compressors. When the bleaching wave propagated in the solution at a velocity of ~ 1 km/s, cw lasing was obtained for 30–40 μs with an output energy of 1.2 J in the 517 ± 5 nm range. Estimates were made of the threshold pump intensity and of the internal losses in the bleaching-wave laser. It was found that, compared with a laser without a bleaching wave (utilizing an ethyl solution of coumarin 6), a bleaching wave improved greatly (under the same excitation conditions) the output energy and the directionality of the radiation.

Bleaching-wave laser excited by radiation from magnetoplasma compressors

Results are given of observations of intense multistep photoionization of POPOP, paraterphenyl, and naphthalene molecules pumped by a pulsed continuous-spectrum light source. Investigations were made of the dependence of the photocurrent on the temperature of the cell containing a substance and on the intensity and spectral composition of the pump radiation. Estimates were made of the position of the triplet level of the paraterphenyl and naphthalene molecules in the gaseous phase. Results are presented of a study of the ionization of excited singlet states of the paraterphenyl molecule by λ =266 nm laser radiation.

Yu Yu Stoĭlov

Papers

Stimulated emission at λ = 502 nm as a result of prolonged optical pumping of HgBr2 vapor

Investigation of the fluorescence of molecular iodine in the 340 nm band

Coumarins in the gaseous phase. I. Stimulated emission of coumarin vapors in the range 485–520 nm

Bleaching-wave laser excited by radiation from magnetoplasma compressors

Multistep photoionization of dye vapors