Повышение мощности и улучшение направленности излучения широкоапертурных гетеролазеров при оптимизации размеров брэгговской решетки

We investigate the dynamics of heterolasers with finite-length planar Bragg structures. Based on the analysis of the dispersion equation describing the eigenwaves propagation in a Bragg structure, we present a physical interpretation of selection of modes with frequencies higher than the stopband. We demonstrate the improvement of stability by using the Bragg structures with transverse dimensions lower than the width of the active area of DFB heterolasers. As a result, the single-mode oscillation regime is sustained over a wider range of pump levels, and, correspondingly, of the output radiation power.

Amplitude modulation of radiation by coupled resonators

In this paper, we describe a method that allows one to realize highly efficient amplitude modulation of radiation at the output of electro-optical laser switches with two coupled resonators, in which electro-optical elements are located both in two split arms and in every arm of a multipath interferometer with combined channels with a control voltage 2 times lower than in existing laser switches. Moreover, the electro-optical elements located in the two split arms of a multipath interferometer with combined channels, with one passage of the light flux through the electro-optical element, must make the opposite controlled changes in the phase difference of the interfering light beams. Therefore, for such electro-optical switches with two coupled resonators the value of the required electric power will be, respectively, 2 times less than that of the existing ones, which significantly expands their operating frequency range. In this case, a laser switch with electrooptical elements located in the two split arms of a multipath interferometer has an asymmetric dependence of the output radiation intensity on the change in the phase difference of the interfering light beams relative to the zero value of the light intensity. A laser switch with electro-optical elements located on all arms of a multipath interferometer with combined channels has a symmetric dependence of the output radiation intensity on the magnitude of the phase difference of the interfering light beams relative to the zero value of the light intensity. In addition, due to the coherent summation of the amplitudes of the interfering light waves, such laser electro-optical shutters also have amplification of radiation with a resonant wavelength.

The modular equipment for training based on the semiconductor lasers

The description is given of the study and research a modular-type training complex for studying the radiation of semiconductor lasers generated in the region of 400 – 950 nm. Structurally, the complex consists of emitter modules (there are 8 of them in the presented set, but in principle their number is not limited by anything), power and control modules, registration modules, and some additional measuring equipment to provide research on the energy, spectral, spatial, polarization and dynamic characteristics of the output radiation. The modular structure provides high variability of the complex and allows you to implement (in the presented version) more than 40 laboratory works, and also allows students to get skills in working with modern equipment and different data processing methods. This complex is focused on educational activities, but on its basis it is possible to carry out research work up to the second stage of higher education. A number of laboratory works based on the use of the complex have been tested at the department of laser physics and spectroscopy of the physics faculty of the Belarusian State University.

The influence various sources of fluctuation on the statistical parameters of the vertical cavity surface emitting lasers output radiation

Based on statistical modeling, a numerical analysis of the effects exerted by different factors (fluctuations of the spontaneous emission intensity, nonequilibrium carrier concentration, injection current density) on the statistical characteristics of radiation at the output of surface emitting semiconductor lasers in the region of polarization instability has been performed. In this region the effect of fluctuations is maximal, offering the possibility for substantiated conclusions about relative effects of the parameters. In a theory of semiconductor lasers it is thought that the intensity fluctuations of spontaneous emission represent the dominant source of fluctuations, whereas all other sources may be neglected. As demonstra ted by the results of conducted statistical modeling, this statement is too rigorous; moreover, such a source is not dominant. Taking into consideration fluctuations of the carrier concentration, which result in fluctuations of the amplification factor, we can derive a complete set of the relationships observed experimentally. This result cannot be associated with features our model because in our theory spontaneous emission is a significant factor. If the influence of spontaneous emission would be the dominant factor, it would affect the simulation results. The obtained data make it possible to doubt the key role of the spontaneous emission intensity fluctuations in the process of statistical characteristics formation for the output radiation and to take into account fluctuations of the nonequilibrium carrier concentration.