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The operating principle and features of the oscillating process for a three-wave CO2 laser with acousto-optic Q-switching are described. Optimization of the active-medium composition and its excitation conditions as well as the choice of oscillating lines allow oscillation with an output power up to 5 W per line in a stable multiwave mode to be obtained. An efficient Q-switching method for a three-wave CO2 laser is demonstrated and enables the output radiation to be controlled in both a wide spectral range and a wide range of modulation frequencies. A method for separating signals with different wavelengths by spacing signals in time has been experimentally implemented using an external selective modulator to simplify data acquisition and processing. [ABSTRACT FROM AUTHOR]

The Varshni parameters of the temperature dependence of the bandgap energy in the range 10-313 K and the temperature dependence of the spin-orbit splitting energy have been calculated using experimental data obtained for an InAsSb active layer. Amplified luminescence was observed in the range 10-35 K for LEDs based on InAsSb/InAsSbP heterostructures. The sharp drop in radiation intensity of InAsSb/InAsSbP LEDs at temperatures >32 K was due to extensive growth of the CHCC Auger-recombination process while the CHSH process was the dominant Auger-recombination process at temperatures <35 K. [ABSTRACT FROM AUTHOR]

system of radiative transfer equations is used to calculate the loss coefficient for amplified luminescence fluxes propagating along and transverse to the cavity axis in the active layer of high-power laser diode arrays taking the spreading of charge carriers in the cladding and contact layers of InGaAs/GaAs/AlGaAs heterostructures into account. It is shown that the spreading of charge carriers leads to a significant change in the amplified luminescence flux which can contribute up to 18% to the lasing threshold of these laser diode arrays. The calculated loss coefficients can greatly simplify the determination of the amplified luminescence fluxes in laser diode arrays with an error of less that 16% and can be used to determine how much the amplified luminescence affects the power and dynamic characteristics of diode arrays. [ABSTRACT FROM AUTHOR]

The feasibility of using light-emitting devices, the radiation spectrum of which has maxima at wavelengths of 1.7, 1.9, and 2.2 μm for determining the water concentration in oil and oil products (gasoline, kerosene, diesel fuel) has been demonstrated. It has been found that the measurement error can be lowered if (i) the temperature of the light-emitting diode is maintained accurate to 0.5-1.0°C, (ii) by using a cell through which a permanently stirred analyte is pumped, and (iii) by selecting the repetition rate of radiation pulses from the light-emitting diodes according to the averaging time. A meter of water content in oil and oil products has been developed that is built around IR light-emitting device-photodiode optrons. This device provides water content on-line monitoring accurate to 1.5%. [ABSTRACT FROM AUTHOR]

The development of amplified luminescence fluxes in powerful InGaAs/AlGaAs laser diode arrays (lasing wavelength 940-960 nm) has been studied experimentally and theoretically at pump levels above the threshold value. Flux density values for amplified luminescence propagation along (1.88⋅10 W/m) and across (1.21⋅10 W/m) the laser diode array cavity axis have been evaluated for the threshold pump level at room temperature (293 K). The contribution of the recombination rate induced by the amplified luminescence to the threshold current generation of the laser diode array reaches 7%. It has been shown that the amplified luminescence flux density is increased by 49% as the pump level rises from one to three threshold values. [ABSTRACT FROM AUTHOR]

A system of balance equations is used to calculate the time (t) dependence of the intensity (I) of the output of a Nd:YAG laser rod from the time a pump pulse is applied for different levels of excitation of the rod by arrays of laser diodes (transverse pump configuration). Comparison of the calculations with experimental data shows that an analysis of the I(t) curves can be used to determine the contributions of amplified luminescence and parasitic lasing modes, which do not leave the volume of the active medium, to the overall loss of pump radiation energy. The model approach developed here can be used to evaluate the quality of the active media in diode-pumped solid-state lasers. [ABSTRACT FROM AUTHOR]

We have studied an all solid-state diode-side-pumped laser which lases in the nominally eye-safe spectral range of ~1.5-1.6 μm. The optical configuration of the laser is based on using a potassium gadolinium tungstate crystal doped with neodymium ions, in which lasing occurs at a wavelength of λ = 1.351 μm and stimulated Raman selfconversion occurs to the first Stokes component (λ = 1.538 μm). The maximum output pulse energy was 17 mJ and 7 mJ for repetition frequencies of respectively 1 Hz and 10 Hz. [ABSTRACT FROM AUTHOR]

The spectral characteristics of light emitting diodes based on a InAs/InAsSb/InAsSbP heterostructure, which emit in a wavelength range of 3.5-4.5 µm, are investigated experimentally. It is shown that the temperature shift of the maximum emission wavelength of a light emitting diode in the temperature range 80-313 K is 1.8 nm/K. The temperature dependence of the band gap of the InAsSb active layer is described by the Varshni formula with the characteristic parameters: E = 0.326 eV, a = 2.917 × 10 eV/K, and ß = 168.83 K. The results of our measurements of the concentrations of carbon dioxide (CO) using the studied light emitting diodes show the possibility of the reliable detection of CO in the concentration range 300-100000 ppm. [ABSTRACT FROM AUTHOR]

It has been theoretically ascertained that for defect-free InGaAs and InGaN compounds the uniform distribution of indium atoms is more energetically preferable than the clustering distribution. The presence of gallium and arsenic vacancy in InGaAs and nitrogen vacancy in InGaN facilitates indium atom clustering distribution. It has been shown that the increase in the indium content in InGaAs and InGaN compounds leads to the decrease of the formation energy of gallium, arsenic and nitrogen vacancies. [ABSTRACT FROM AUTHOR]

A model taking into account the up-conversion processes involving the upper laser level and the presence of the unpumped regions within the active element along with the lasing transitions has been developed for the passive Q-switched ytterbium-erbium glass laser which was transversally pumped by the laser diode arrays. The results of the simulation allow determining the working point providing the stable and long-term operation of the laser. The correctness of the proposed optimized model was experimentally proved by means of a comparative investigation of the utmost permissible output lasing characteristics. The maximum output lasing pulse energy up to 16.5 mJ with the pulse duration of 11.5-16.0 ns at the wavelength of 1.535 μm has been achieved with the rectangular active element for the length of 32 mm. [ABSTRACT FROM AUTHOR]