V. I. Kozlovsky

3.77-5.05-μm tunable solid-state lasers based on Fe/sup 2+/-doped ZnSe crystals operating at low and room temperatures

Spectroscopic properties and lasing of Fe:ZnSe and co-doped Fe:Cr:ZnSe crystals in the mid-infrared spectral range were studied at room and low temperatures. Using a free-running Er:YAG laser as a pump source, the output energy of the thermoelectrically cooled Fe:ZnSe laser was 142 mJ with 30% slope efficiency at T=220 K. Passive Q-switched oscillation of Er:YAG laser with Fe:ZnSe crystal was demonstrated and used as a pump source for a Fe:ZnSe laser system. Room-temperature (RT) gain-switched lasing of Fe:ZnSe was achieved in microchip and selective cavity configurations using Q-switched Er:YAG and Raman-shifted Nd:YAG lasers as pump sources. The microchip laser threshold of 100 mJ/cm2 was demonstrated using a Fe:ZnSe crystal without any reflection coatings. A slope efficiency of 13%, oscillation threshold of 1.3 mJ, and tunable oscillation of Fe:ZnSe laser systems over 3.95-5.05 mum spectral range were realized at RT

Vapour growth and doping of ZnSe single crystals

The results of seeded vapour-phase free growth of ZnSe single crystals in both the and directions are presented and discussed. Optimum growth conditions were found to be essentially different for these two directions. The doping by In and Al from both vapour phase during the growth process at T = 1180-1240°C and liquid phase by means of annealing in liquid Zn with In or Al additions at T = 900-950°C was performed. To characterize grown crystals, selective chemical etching. X-ray diffraction rocking curve, cathodoluminescence study, atomic-emission analysis, specific resistance and Hall effect measurements were carried out.

Full color TV projector based on A2B6 electron-beam pumped semiconductor lasers

The description of full color TV projector is given. Three primary colors (red, 620 nm; green, 540 nm; blue, 455 nm) are obtained by means of A2B6 e-beam pumped semiconductor lasers. The laser element size is 5 cm. For laser pumping and laser beam controlling, cathode-ray tubes are used. Maximum light output in white is 3000–5000 lm (9–15 W). A full color picture is obtained on a 5 m viewing screen (12 m2). The size of the laser element is 5 cm. High resolution (up to 2000 pixels per line) gives a possibility to use such a projector in HDTV. The main characteristics of the basic elements are given. It is supposed to begin the development of TV projector with a light output to 104 lm.

Seeded vapour-phase free growth of ZnSe single crystals in the 〈1 0 0〉 direction

Abstract Seeded vapour-phase free growth of ZnSe single crystals at T g = 1100–1250°C in 〈1 0 0〉 direction was studied. The 〈1 0 0〉 growth process was found to be more sensitive to the temperature profile in a furnace than the 〈1 1 1〉 direction. The problem that seed attachment to a support pedestal is followed by a generation of high dislocation density was solved by use of a reverse temperature gradient along the axis of the furnace between the seed and the pedestal and by optical monitoring of the attachment process during the growth. Seeds with dislocation density of 10 4 –10 5 cm −2 and 2–4 cm 2 area selected from single crystals grown in 〈1 1 1〉 direction were used for the first growth processes in 〈1 0 0〉 direction. To increase the diameter of the grown crystals, a tangential growth regime was developed. Twin free ZnSe single crystals of 51 mm diameter and of 15 mm height were grown in helium. The average dislocation density was about 10 4 cm −2 and the full-width at half-maximum (FWHM) of the X-ray rocking curve was as small as 16 arcsec.

Band alignment in ZnCdTe/ZnTe and ZnCdSe/ZnSe SQW structures grown on GaAs(100) by MBE

Molecular-beam-epitaxy-grown ZnTe/CdZnTe/ZnTe and ZnSe/ZnCdSe/ZnSe strained single-quantum-well structures with non-doping layers were investigated by cathodoluminescence (CL) and deep-level transient spectroscopy (DLTS). The activation energies for deep levels in ZnTe and ZnSe buffer layers grown on GaAs were determined by the DLTS spectra. Moreover, an additional DLTS peak that depends on the quantum well (QW) parameters and correlates with the QW emission line position in the CL spectra was observed. This peak is interpreted as an emission of electrons from a ground level in the QW. Obtained DLTS and CL results were used for the estimation of the conduction band offset parameter QC.

Vapour phase and liquid phase doping of ZnSe by group III elements

Abstract A vapour phase doping of ZnSe single crystals by In impurity during a growth process at T = 1180°C was developed. A liquid phase doping was performed by means of annealing of crystal wafers in liquid Zn with an addition of In or Al at T = 900°C. Atomic-emission analysis, cathodoluminescence study, specific resistance and Hall measurements were carried out. The concentration of the In and Al impurities in ZnSe single crystals were in a range from 10 17 to 10 19 cm −3 . High n-type conductivity in the ZnSe single crystals doped by In or Al impurities was achieved: the specific resistance was as low as 0.05 Ω cm for the Al liquid phase doping and about 1 Ω cm for the In vapour phase doping followed by annealing in the liquid Zn : In.

Hexagonal ZnCdS epilayers and CdSSe/ZnCdS QW structures on CdS(0001) and ZnCdS(0001) substrates grown by MOVPE

Abstract Optimization of growth conditions allows us to grow mirror-like hexagonal ZnCdS layers and CdSSe/ZnCdS quantum well (QW) structures on CdS(0001) and ZnCdS(0001) substrates by MOVPE. ZnCdS epilayers with high cathodoluminescence (CL) intensity at room temperature (RT) have also been obtained. An intense QW emission line has been observed in CdS/ZnCdS QW structures. With increasing excitation intensity the line shifted to shorter wavelength, which is a manifestation of an internal piezoelectric effect. An additional short-wavelength line appears in low-temperature CL spectra of CdSSe/ZnCdS QW structures due to localization of charge carriers by nonuniformity of alloy composition or QW thickness.

InGaAs/GaAs Multiple-Quantum-Well Semiconductor Disk Laser Pumped With Electron Beam

We report an electron-beam-pumped vertical-external-cavity surface-emitting laser [or semiconductor disk laser (SDL)] on the basis of InGaAs/GaAs multiple-quantum-well structure grown monolithically by molecular-beam epitaxy together with high-reflective AlGaAs/GaAs distributed Bragg reflector. The auxiliary mirror of the optical cavity is spherical with 20- or 30-mm radius of curvature and a transparency of 1.5%. The SDL is operated in a pulse mode at the room temperature and in a continuous wave (CW) mode at the temperature of liquid nitrogen. A pulse peak power of 9 W is achieved at wavelength of λ = 1035 nm under pumping by electrons with energy of 42 keV. The full-width at half-maximum pulse duration is 150-320 ns. Maximum laser efficiency of about 15% is achieved at the electron energy of 22-23 keV. The full-beam divergence is below 10 mrad. At the CW mode, we obtained 23 mW of average output power near the wavelength λ = 1026 nm.

2.94 μm Er:YAG Q-switched laser with Fe2+: ZnSe passive shutter

A passive Q-switching of 2.94-μm Er:YAG laser has been demonstrated using Fe2+:ZnSe single crystal saturable absorber. A giant pulse width ofabout 35 ns and output energy up to 30 mJ in fundamental mode were obtained.

Electron Beam Pumped VCSEL Light Source For Projection Display

An electron beam pumped vertical cavity laser, or an “eVCSEL”, has been developed as a low-cost light source for LCOS and DLP based consumer television. 1000 lumens directed towards the spatial light modulator requires a total power of 144 watts for lasers in the three primary colors. This power surplus allows for high screen brightness for rear projection televisions of diagonals greater than 50 inches and eliminates the need for high gain screens with the benefit of larger viewing angles. Because of the high saturation of laser light, a color gamut approaching that of the human visual system is possible, creating superior image reproduction.