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A method for measuring the line width Γ of the emission spectrum of a TEA CO2 laser is described and the results of such measurements are given. The experimental value Γ = 0.013 ± 0.002 cm − 1 is compared with the results of a simple modeling calculation. A good agreement is obtained between the measured and calculated results.

The current status of the lead salt diode lasers developed at Lebedev Physical Institute is described. Diffused lasers, LPE lattice-matched PbSnSeTe lasers, PbSSe diode lasers with controlled carrier concentration, and PbS/PbSSes/PbSnSe heterostructure lasers with a quantum-well active region are discussed. The lasers have improved performance due to their superior electrical and optical confinement.

Long delays of stimulated emission from homojunction lead chalcogenide lasers are shown to be due to the appearance of a thermoelastic waveguide because of inhomogeneous heat release, low thermal diffusivity, and high strain sensitivity.

The Zeeman effect in the infrared absorption spectrum of a molecule without an electronic magnetic moment was observed using a linear spectroscopic technique with a tunable diode laser. In the magnetic field B = 500 kG weak splittings of the asR(4, 1) and asR(4, 0) lines in the v 2 -band of NH 3 were recorded. The values of the Zeeman splittings in these cases were −1×10 -2 cm -1 . The picture of the Zeeman splittings observed is shown to be connected with the difference between the g -factors for the excited (υ 2 = 1) and the ground (υ 2 = 0) vibrational states of the NH 3 molecule. This difference is about (-10)-(15)% of the g -factor for the lower vibrational level of the transition.

An intracavity spectroscopy method makes use of pulsed PbSnSe lasers with external resonators. The sensitivity (signal amplitude) is increased by a factor exceeding 102. A simple theoretical model is proposed for the description of the behavior of a tunable diode laser with an external resonator when frequency-selective losses are introduced into the resonator.

The absorption spectra of 14NH3 and 15NH3 molecules from 930 cm-1 to 1220 cm-1 have been obtained with CW and pulsed Pb1–xSnxSe diode lasers. The laser emission frequency has been tuned by varying crystal composition, diode temperature, hydrostatic pressure, or injection current. The registration of the absorption spectra with CW PbSe laser continuously tuned by varying hydrostatic pressure has been accomplished. The possibility of gas isotope abundancies measurements by diode lasers is considered.

An investigation of time dependences of the spectral and spatial distributions of the radiation emitted by pulsed homojunction wide-contact PbS1–xSex lasers revealed excitation of autowaves (self-oscillatory waves) of the free carrier density at two similar frequencies (≲ 107 Hz). These autowaves resulted in simultaneous emission of laser radiation of two types, associated with modulation of the refractive index and of the optical gain. The width of the channels was governed by the thickness of the laser diode wafer, but was independent of the resonator width. The transverse (along with p-n junction plane) intermode spacing was governed by the amplitude and spatial period (channel width) of the autowaves. A study was made of the influence of the conditions of operation ofthe laser diodes on the autowave parameters. A strong scatter of the threshold current density in a batch of 30 injection lasers with a constant resonator length, formed freshly by four-sided cleaving from a single wafer, was attributed to changes in lateral optical confinement as a result of a change in the resonator width, which was a consequence of interference between the autowaves in the resonator induced by the lateral faces of the crystal.

A study was made of the use of middle-infrared pulsed laser diodes in investigations of the width and profile of absorption lines of molecular gases. Broadening of the absorption lines of CF2Cl2 and SF6 located in the region of 930 cm-1 was studied by correlation processing of the laser diode spectra. The coefficient representing the broadening of the CF2Cl2 lines in air depended on the buffer gas pressure and it increased from 5.7 to 12.9 MHz/Torr when this pressure was increased from 0 to 100 Torr. The broadening coefficient of the 32SF6 lines by helium was independent of the He pressure in the range 5-100 Torr and amounted to 6 MHz/Torr. The self-broadening coefficients of NH3 and CF2Cl2 were found to be 28.5 and 31.2 MHz/Torr.

A prototype device was made for measuring the concentration of carbon monoxide in the atmosphere with the aid of pulsed injection lasers. It is suitable for operation under urban and field conditions, and has a sensitivity of 0.01 ppm. A description is given of the characteristics of the device and of the results of using it continuously for long periods.

An analysis is made of the possibility of using multicomponent solutions of IV-VI compounds in laser heterostructures free of lattice mismatch and associated defects and stresses. Characteristics of a PbSe--PbSnTeSe at lambda=10 ..mu.., are estimated. The relative jump in the refractive index needed for optical confinement is estimated to be 8%.

High-resolution spectra of the ν3 band of 192OsO4 gas were obtained using diode lasers. Eighty seven of the observed absorption lines were identified. The values of four scalar and two tensor spectroscopic constants were determined more accurately and two new constants, a scalar and a tensor, were also obtained. This set of constants can be used to calculate the spectrum of 192OsO4 up to J = 50 with an error not exceeding 10−3 cm−1.

An investigation was made of the characteristics of lasing of semiconductor (lead chalcogenide) active elements pumped longitudinally by an electron beam. The dependences of the threshold current and of the lasing efficiency on the temperature of an active element and on the electron energy were determined.

The first picosecond optical parametric oscillator based on an LiNbO3 crystal was built. It amplified tunable (near 4 μ) radiation from a semiconductor injection laser.

Stimulated emission from an external-cavity diode laser was obtained for the first time in the region of the 10 μ wavelength and high-resolution spectra were recorded under intracavity absorption conditions.

An investigation was made of fluctuations of the output frequency of a pulsed diode laser emitting at ~ 10μ. An analysis of signals transmitted by a Fabry–Perot interferometer made it possible to determine the frequency dispersion Δνl ≈ 2.5 MHz for a normal distribution law and also the correlation time of frequency fluctuations, which was 0.2 μsec.