High-power high-brightness multimode edge emitting pumps have been developed. Comprehensive development efforts have resulted in 3 mm-long cavity diodes with far-field divergence reduced down to 26 degrees. Output in excess of 20W CW from 90 mu m-wide aperture single emitter was demonstrated for the first time. Peak power was reached at 25A CW driving current and was limited by power supply. Peak CW power efficiency was as high as 67%. Two coolerless package types designed to operate up to 10W output and up to 20W output are reported. About 95% fiber coupling efficiency into NA < 0. 12 was demonstrated in the entire range of driving currents for both types of pumps. For packages of the later design efficiency over 50% is maintained up to 16W CW ex-fiber output. Diode junction overheat above heatsink temperature is less than 20 degrees C up to similar to 18W ex-fiber output.

ZnCdSe/ZnSe quantum wells of different thicknesses are grown by molecular-beam epitaxy on ZnSe(001) substrates. The latter are cut from ZnSe ingots obtained by gas transport in hydrogen. The substrate surface is prepared by colloid-chemical polishing followed by annealing in atomic hydrogen and deposition of a protective selenium film. The surface topography is monitored during epitaxial growth by reflection high-energy electron diffraction (RHEED). The surface microrelief of the samples is examined by atomic force microscopy, and the cathodoluminescence of the quantum-well structures is studied at 40 and 300 K. The relatively low microroughness of the surface, the high-contrast elongated reflections in the diffraction pattern, and the dependence of the spectral position of the quantum-well luminescence line on the well width attest to the high structural quality of the structures grown. (C) 1997 American Institute of Physics.

The thermal stability and luminescence properties of ZnCdSe/ZnSe quantum-well structures grown by molecular-beam epitaxy are investigated. A comparative analysis is made of the photoluminescence spectra of the structures before and after annealing. In the sample spectra after annealing (at 500 °C) a decrease in the intensity of the exciton luminescence line by more than two orders of magnitude, accompanied by an increase in the intensity of the deep levels, is observed. As a result of annealing at a lower temperature (about 400 °C), a narrowing of the exciton luminescence, accompanied by a shift of the maximum toward longer wavelengths, was detected.

Cathodoluminescence (CL), photoreflection (PR), phototransmission (PT) of single and multiquantum wells (MQWs) and strain layer ZnCdSeZnSe superlattices (SLs) grown by molecular beam epitaxy (MBE) were studied. An increase of the Stokes shift with the number of quantum wells (QWs) and the appearance of new lines in CL and PT spectra were observed. Room temperature (RT) vertical-cavity surface-emitting laser (VCSEL) operation was achieved by using the SL structures. Output power up to 2.2 W in single longitudinal mode with λ = 493 nm was obtained. Cut facet laser wavelength of the same SL structure was 502 nm.

The use of a broad-bandgap II-VI semiconductors and their ternary and quaternary alloys for vertical-cavity surface-emitting laser (VCSEL) fabrication open a new additional possibilities for their design and applications. In particular, one of the promising using is the realization of a large screen color high definition TV (HDTV) laser projection systems, and flat panel color displays [1,2]. One of the main advantages of the II-VI VCSEL's, in this case, is the possibility of the full color HDTV laser screen creation based only on this materials. The bulk II-VI compounds were used recently for the first successful demonstration of the laser cathode ray tube (LCRT) and color laser TV system [3]. However, one of the limitations of this scheme was the sufficiently high E-beam current threshold, in particular, for the room-temperature operation.

Theoretical and experimental studies of vibrational modes in the (Zn, Cd)Se/ZnSe quantum wells and ZnSe films are presented. The space distribution of electric field accompanying the quasi-transverse vibrations and hence the intensity of corresponding Raman line depends considerably on the thickness of the layers. The quasi-longitudinal vibration and its Raman intensity are insensitive to the thickness. These quasi-transverse and quasi-longitudinal modes give the main contribution to the Raman spectra of the (Zn, Cd)Se/ZnSe quantum wells.

A superlattice with strained ZnCdSe/ZnSe layers was grown by the method of molecular beam epitaxy. This superlattice was used as the active layer in the screen of a laser cathode-ray tube. The room-temperature output power was 1.6 W in the form of one longitudinal mode at the 484 nm wavelength. The earlier results obtained at electron energies below 50 keV were improved.

Alternating ferroelectric domains were created in LiNbO3, LiTaO3and KTP by various methods.

Since its invention by Bierlein and coworkers, application of the waveguides in a KTP (KTiOPO 4 ) crystal for the SHG in the blue-green spectral range is very promising [1,2].

One of the ways in the development of the compact blue-green lasers is frequency doubling of near-IR semiconductor laser in nonlinear crystal, in particular, using quasi-phase matching (QPM) in waveguides. QPM was realized by the periodic domain inversion in the several ferroelectric crystals, such as LiNbO LiTaO3 and KTP [1-3]. Various domain inversion techniques were proposed to get efficient SHG in the waveguide geometry, but basically for LiNbO3 and LiTaO3 crystals. Only one method based on the Ba2+ + Rb+ ion exchange through the periodical mask was applied for KTP [3].

Much interest has been attracted recently to the problem of design compact blue-green light sources. Most the activity is concentrated around the frequency doubling of semiconductor lasers with the wavelengths of 0.8-0.9 μm. On the other hand rare-earth doped fiber lasers are an interesting alternative to diode lasers due to their tunability, high quality output beam etc [1]. Such lasers are compatible with channel KTP-waveguides [2] which are very promising for the nonlinear frequency conversion from the near-IR to green and blue. The phase-matched type II interaction or quasi- phase-matched type I interaction can be used depending on the fundamental wavelength [3].

KTP crystals, characterised by superior properties, are used widely in nonlinear optics, in particular for second harmonic generation. Also, owing to easy fabrication technology of low loss optical waveguides (~1dB/cm), the KTP crystals are used for the fabrication of integrated optical elements [1]. The important advantage of waveguides in KTP (for example, in comparison with that in the more widely used Ti:LiNbO3) is the high optical damage resistance, up to 0.9W more light power in visible range [2].

A fiber amplifier containing a waveguide activated with Er3+ ions was used for the first time to reduce the losses and thus improve the resolving power of a fiber Michelson interferometer. An interferometer with a path difference between the arms amounting to 5 km was constructed and the losses in this interferometer were fully compensated by the use of such an amplifier.