The results of the influence of point defects (vacancy with interstitial atom) on the GaN/AlN heterointerface is presented. It was ascertained that presence of Al atom vacancy in the heterointerface leads to the contacting layer atoms rearrangement. The presence of N atom vacancy does not influence on the contacting Ga and Al layers intermixing.
Physical and fabrication peculiarities which provide the high output energy and beam quality for the diode pumped erbium glass and Nd:YAG lasers are considered. Developed design approach allow to make passively Q-switched erbium glass eye-safe portable laser sources with output energy 8 − 12 mJ (output pulse duration is less than 25 ns, pulse repetition rate up to 5 Hz) and beam quality M2 less than 1.3. To reach these values the erbium laser pump unit parameters were optimized also. Namely, for the powerful laser diode arrays the optimal near-field fill-factor, output mirror reflectivity and heterostructure properties were determined. Construction of advanced diode and solid–state lasers as well as the optical properties of the active element and the pump unit make possible the lasing within a rather wide temperature interval (e.g. from minus forty till plus sixty Celsius degree) without application of water–based chillers. The transversally pumped Nd:YAG laser output beam uniformity was investigated depending on the active element (AE) pump conditions. In particular, to enhance the pump uniformity within AE volume, a special layer which practically doesn’t absorb the pump radiation but effectively scatters the pump and lasing beams, was used. Application of such layer results in amplified spontaneous emission suppression and improvement of the laser output beam uniformity. The carried out investigations allow us to fabricate the solid-state Nd:YAG lasers (1064 nm) with the output energy up to 420 mJ at the pulse repetition rate up to 30 Hz and the output energy up to 100 mJ at the pulse repetition rate of of 100 Hz. Also the laser sources with following characteristics: 35 mJ, 30 Hz (266 nm); 60 mJ, 30 Hz (355 nm); 100 mJ, 30 Hz (532 nm) were manufactured on the base of the developed Nd:YAG quantrons.
Power, special and temporal characteristics of high–performance advanced LD–pumped solid–state laser systems
emitting in the spectral ranges of 1064, 1535 and 1570 (fundamental modes) as well as 266, 355 and 532 nm (fourth,
third and second harmonics) are discussed. The ways for further improvement of those laser systems are proposed. In
addition, the problem of optimization of the pump unit based on the powerful laser diode arrays (LDAs) is analyzed. The effect of the LDA internal optical loss on the amplified spontaneous emission flux value developed within the LDA
active layer is considered in detail.
New methods for precise control of main parameters of LD-pumped solid-state lasers assigned for spectroscopic
applications have been developed. Tunable lasing in wide range has been achieved. Active elements on the base of
crystals (Nd3+:YAG, Nd3+:YVO4) and glasses (Er,Yb doped boro-silico-phosphate glass) were used. The active crystals with uniform and non-uniform distribution of the activator ions were studied. Output beams with high quality and
polarization degree have been realized.
Lanthanum beryllate, new efficient solid-state laser material for laser diode pumping has been investigated. Slope efficiency comparison for BEL:Nd and YAG:Nd under the same cavity conditions was carried out. Two wavelength lasing regime for fundamental mode and tunable four wavelength lasing regime for intracavity doubled mode were observed.
Influence of light feedback in laser diode end-pumped Nd3+:KGd(WO4) laser with intracavity doubling as well as wavelength temperature variations of the pump source on stability of solid-state laser output power and efficiency have been investigated. Threshold and slope efficiency were measured under different output coupler transparencies and pumping beam waist sizes. Maximum output power of 130 mW for fundamental mode and 25 mW for SHG was obtained.
Disordered crystal with Ca-gallogermanate structure are one of the most appropriate laser materials for compact systems with different special lasing regimes. Output power dependence on laser diode pump power and pumping wavelength temperature tuning of Nd:La3Ga5.5Nb0.5O14 laser, one of a large group of Ca-gallogermanates, under laser diode pump are presented in this research. Maximum output power of 68 mW under 250 mW pump power was reached. Slope efficiency was 41 percent.
We built three monolithic lasers pumped longitudinally by laser diodes. All lasers had the same dimensions and worked in CW mode. The lasers were based on neodymium doped crystals. They appeared to have quite good power stability. Comparison of the parameters of built lasers is presented in this work.
This work presents the parameter comparison of diode pumped solid state lasers worked in longitudinally pump configuration in cw operation. We built three monolithic lasers based on neodymium doped crystals (Nd:YAG, Nd:KGW and Nd:BLGO). They appeared to have quite good power stability and high quality quasi-TEM00 mode beams.
The second harmonic generation (SHG) of laser diodes is an attractive way of obtaining short- wavelength, coherent light in the blue spectral range. Conversion into second harmonic can be performed directly in non-linear crystal. The second harmonic generation from 1 watt, 980 nm diode laser in non-linear crystal LiIO3 was obtained. Description of experiments and results is presented.
Conventional methods of solid state laser pumping use the broad spectrum output obtained from flashlamps and it leads to an inefficient system requiring cooling. The use of diode lasers as pump sources offers a potentially huge increase in overall efficiency coupled with the compactness and reliability usually associated with solid state devices. Spectral analysis of the absorption pumping bands for four neodymium doped laser materials was measured. The spectrum of emission radiation of the thermally tunable diode laser was matched for these materials.
The effect of nonradiative Auger and Shockley-Hall-Read recombinations and nonlinear gain on an InGaAsP/InP (A.=1.3 μm) and AlGaAs/GaAs laser transient process and threshold parameters has been studied on the basis of numerical solving the rate equations of an injection laser. N onradiative recombination increases the delay time of an output switching on and decreases the damping rate of output relaxation oscillations significantly.
Keywords: injection lasers, transient processes, output dynamics, Auger recombination, Shocley-Hall-Read recombination, threshold parameters
Holographic interferometric technique for measurement of laser diode crystal thermoelastic deformations is presented. Using this technique allows us to estimate thermoelastic stresses in laser crystal, active layer temperature and dynamics of heat transfer from laser crystal to heatsink.
The laser diode device (LDD) leasing in near infrared region (IR), synchronized with the cardiac pulse, is designed for laser therapy. The special pulse sensor was used for monitoring of the cardiac action. The unique future of this device allows to synchronize the laser action with the cardiac rhythm. This laser is a result of Polish-Belarussian cooperation. It was used in the clinics for treatment of 88 patients suffering from high blood pressure. The positive clinical effects were seen in 86% of cases. The further studies are continued.
The special laser diode device (LDD) leasing in the near infrared region (IR) with two wavelengths: (lambda) 1 equals 850 nm and (lambda) 2 equals 1000 nm, designed for laser therapy, is presented. This device is characterized by a unique feature, namely a separate built-in illuminator, operating in 670 nm. The special construction of LDD and the illuminator enables the user to visualize exactly the surface irradiated by IR radiation. The exposure time and the output of laser power are also controlled and can be displayed on the LED monitor at the front panel. This new device, described here, is compact, low cost, and user friendly.
Interferometric measurements of wavefront phase distributions for laser diodes applied in optical disk memory units were carried out. The influence of laser diode wavefront astigmatism on the focused light spot dimensions was investigated.