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Vol. 18 (2015 year), No. 4

Vlasov A. B., Vlasova S. V., Alloyarov K. B., Muhalev V. A.
The method of controlling the properties of rubber insulation of cables

The method of controlling the properties of rubber insulation of cables allowing evaluation of the technical condition of the insulation during aging has been developed. The method is based on measuring the hardness of the insulation during operation

(in Russian, стр.10, fig. 14, tables. 1, ref 4, Adobe PDF, Adobe PDF 0 Kb)

Vol. 19 (2016 year), No. 4, DOI: 10.21443/1560-9278-2016-4

Vlasova S. V., Petrov V. V., Shapochkin P. Yu.
The use of semiconductor laser diodes at low temperatures

The theoretical analysis and experimental research of possibility of using commercially available semiconductor laser diodes at low temperatures (down to the temperature of 50 K) has been performed in the paper. The relevance of this work is caused by the need to develop sensors for remote measurement of low temperatures on the basis of semiconductor laser emitters. To implement the idea some analysis of wavelength emitted by the semiconductor laser diode as a function of medium temperature has been made. Physical causes that determine this relationship have been discussed. It has been shown that the temperature coefficient of change of the band gap width is a key factor in determining the dependence of the wave length of the laser radiation from the medium temperature. The calculation of numerical values of the temperature coefficient of change of the band gap width for the studied semiconductor laser diodes has been performed. Comparison of the experimental results with the published data has been performed. The temperature coefficient of change of the band gap width for some diode brands has been determined experimentally. It has been shown that in the temperature range 130 ? 150 K there is a sharp change in the parameter being analyzed. It has been commented that further studies are needed in this direction to explain possible reasons for the observed effect. To determine the effect of temperature on the nature of the semiconductor laser diode emission spectrum the emission spectra at several temperatures have been measured. It has been shown that at a certain temperature the semiconductor laser diode can be operated in a single mode. It has been noted that the value of the temperature coefficient of change of the band gap width is maintained irrespective of the laser operation mode (single mode, multimode, spontaneous emission mode). The results of the research are relevant for analysis of the work of laser emitters at low operating temperatures.

(in English, стр.7, fig. 1, tables. 1, ref 8, Adobe PDF, Adobe PDF 0 Kb)

Vol. 20 (2017 year), No. 4, DOI: 10.21443/1560-9278-2017-20-4

Vlasova S. V., Vlasov A. B., Shapochkin P. Yu.
Features of laser diodes' radiation in different temperature intervals

In the literature there is practically no information on the change in the characteristics of the emission spectrum of industrial semiconductor laser diodes in a wide range of temperatures, including cryogenic temperatures. Nevertheless, this information is decisive when choosing specific laser diodes for industrial devices. An experimental study of features of the emission spectra of laser semiconductor diodes in the temperature range 50–300 K has been conducted. The material used in the laser diodes' manufacture is a compound based on the solid quaternary AlGaInP solution. The radiation spectrum has been investigated using a monochromator MDR-23 with a CCD detector installed. The study has proved that the temperature of the laser diode operation determines the nature of the radiation spectrum, in particular the predominance of stimulated or induced radiation has taken place, the range of wavelengths of radiation changes as well. It is believed that in the temperature range from 50 to 300 K in the volume of the laser diode material some processes are realized, as a result of which the value of the forbidden band width changes, it decreases by approximately 4.2–4.5 % from the value corresponding to the temperature of 50 K. The calculation of the value of the temperature coefficient of the change in the forbidden band width has shown that in the temperature range from 50 to 300 K the meaning of ? varies in absolute value by 2–3 times. A new experimental method for determining ionization energies of exciton levels has been proposed. It is of practical use for monitoring the electro-physical parameters of semiconductor materials used in the manufacture of industrial semiconductor lasers. The advantage of the proposed method is the ability to obtain qualitative and quantitative information about the exciton spectrum of the laser diode material directly in the region of the p–n-junction where the laser radiation is formed.

(in English, стр.8, fig. 3, tables. 2, ref 6, Adobe PDF, Adobe PDF 0 Kb)