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An investigation was made of the current-voltage characteristics of injection lasers with isoperiodic PbSnSeTe layers and of double-heterostructure lasers with a controlled carrier-density profile, based on lead selenide. The investigation was carried out in the temperature range 20–80 K. The methods used in the fabrication of lasers and in measurements under pulsed conditions are described. It is shown that at 20 K the tunnel component of the current becomes important. An increase in temperature increases the role of the thermal current and already at 80 K the diffusion component becomes the dominant one. The tunnel component of the threshold current at 80 K is ~0.25.

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.

A laser spectrometer for the investigation of a nonequilibrium molecular plasma was constructed. Diode lasers with a record width of a continuous frequency tuning range (10 cm−1 ) were used in this spectrometer. The spectrometer response time (10 nsec) made it possible to use liquid nitrogen to cool the diode lasers so that the resolution was at least 10−3 cm−1 when the tuning rate was ~105 cm−1/sec. An investigation was made of the distribution of the vibrational and rotational energies between the internal degrees of freedom of the CO2 molecules and the gas temperature in a glow discharge was determined.

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.

An analysis is made of the factors which influence the threshold current in PbSe/Pb1–xSnxSe injection heterolasers. These factors include the waveguide structure, electron confinement, inhomogeneity of the distribution of the gain across the thickness, nonradiative recombination at the heterojunctions and in the bulk, and temperature. The conditions are identified under which anomalies can be expected in the temperature dependence of the threshold current because of the influence of free carriers on the refractive index. The results agree with the experimental values of the threshold current density for a surface recombination velocity of ~2×105 cm/sec and an internal quantum efficiency of ≤0.1.

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 diode laser was used in a high-resolution study of the ..nu../sub 2/+..nu../sub 4/ band absorption spectrum of the CF/sub 4/ gas. Vibrational--rotational spectra of the pumping and lasing transitions in a CF/sub 4/ laser were analyzed theoretically and its tuning characteristics were determined.

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 investigation was made of the photoluminescence emitted from epitaxial films of Pb1–xSnxSe1–yTey solid solutions (0 ≤ x 0.47, 0 ≤ y 0.65), grown by the method of liquid epitaxy on n-type PbSe substrates. Next, n-Pb1–xSnxSe1–yTey/n-PbSe heterostructures, with the Pb1–xSnxSe1–yTey active layer (0.015 ≤ x ≤ 0.092, 0.0006 ≤ y ≤ 0.026), were matched in respect of the lattice constant to the substrate (Δa/a =10−1–10−3%) and used as optically excited heterolasers. The spectral and threshold characteristics were determined as a function of the thickness of the active layer d, temperature, and resonator length. Variation of the composition of the active layer altered the emission wavelength within the range 8–12.5 μ at 77°K. Electron and optical confinement effects were observed when the thickness d was reduced. For the optimal thickness dopt≈/cm2 at 77°K. The loss factor (5.5 cm−1), gain (0.11 cm/W), and carrier density (2×1017 cm−3) in the active layer were determined.

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.

A study was made of the influence of hydrostatic pressures up to 1.8 kbar on the emission spectra of a cw PbSe injection laser at temperatures of 4.2 and 20.3 °K. The quasicontinuous tuning range was 8.2–9.2 μ (1090–1220 cm−1). The measured rates of continuous change of the mode frequency with the current and pressure reached +0.01±0.003 cm−1/mA and -0.026±0.001 cm−1/bar. The continuous pressure-tuning range was ~1.7 cm−1. At 20.3 °K the laser emitted a single mode of about 25 μW power. The pressure-tunable PbSe laser was used in the determination of the transmission spectra of Ge standards with a resolution of 10−2 cm−1.

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.