N. B. Zvonkov

Difference mode generation in injection lasers

The nonlinear generation of a difference mode in an injection laser is considered. A new design based on the InGaP/GaAs/InGaAs heterostructure is suggested in order to generate two laser modes with a wavelength of about 1 µm and a difference mode at a wavelength of about 10 µm. In lasers with a 100-µm-wide waveguide, the power output of the difference mode can be as high as ∼10 mW at ∼10 W in the short-wavelength modes.

Toward far- and mid-IR intraband lasers based on hot carrier intervalley/real-space transfer in multiple quantum well systems

Discussion of ways to achieve mid and far IR intraband lasing just by lateral electric field carrier (electron or hole) heating in multiple quantum well (MQW) structures is given. It is argued that the Gunn diodes are low frequency indirect transition lasers based on hot electron population inversion arising under electron intervalley transfer. In the MQW structures direct optical transitions exist while hot carrier population inversion can be achieved due to inter-valley/real space transfer. The two MQW structures are considered in this work: GaAs/AlAs and GaAs/InGaAs systems. In the first the hot electron (Gamma) -X intervalley/real space transfer from GaAs layers to AlAs layers provides population inversion while in the second the inversion can arise due to interlevel/interlayer transfer. Evaluations via the Monte-Carlo simulation of the hot electron phenomena in some of the structures are given and observation of the hot carrier phenomena of the type (including far and mid IR emission and absorption) are presented. Consideration of the appropriate laser design which provides also a way to cope with the low frequency (Gunn type) current oscillations is given.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

New designs and recent experiments on intracavity nonlinear wave mixing in semiconductor lasers

We present theoretical and experimental results on intracavity nonlinear wave mixing in newly-designed two- and multi-wavelength heterolasers. The intracavity nonlinear mixing has been already demonstrated in our works using quantum cascade lasers as well as butt-joint lasers. These experiments clearly show prospects of the intracavity nonlinear mixing in semiconductor injection lasers. We focus on the most promising schemes of nonlinear-mixing lasers (NML), which may be used for the sum-, double- and difference-frequency generation in a wide infrared range. The NMLs can be implemented both in the interband lasers (diode-type lasers) and intersubband lasers (quantum cascade lasers).

Two-wavelength butt-joint diode lasers for the difference- and sum-frequency generation

Summary form only given. The new design of the nonlinear mixing heterolasers, Butt-Joint Laser, where two butt-joined laser diodes are optically coupled but injection pumped separately, are presented. Two diode lasers operate at slightly different frequencies in the near-IR range and are mounted top side down on a mutual heat sink with their facets touched or separated by a few micron distance in such a way that their waveguides are aligned in the transverse direction. This robust design guarantees stable CW room-temperature two-wavelength generation and provides an efficient nonlinear optical mixing. The latter results in the difference-frequency (terahertz) as well as the sum-frequency and second-harmonic radiation in the standard edge-emitting geometry. The surface-emitting schemes of the Butt-Joint Lasers are also proposed.

Particularities of the photoluminescence spectra of Cr4+:Ca2GeO4 single crystal films

It was found that the room-temperature photoluminescence (PL) spectra of Cr4+:Ca2GeO4 single crystal films grown by magnetron sputtering on Ca2GeO4 bulk single crystal substrates exhibit a sharp emission band in the region of ∼1.17 μm with satellites at ∼1.21 and 1.27 μm. Particularities of the PL spectra are interpreted within the framework of a model based on the interaction between electrons of the Cr4+ center and the oscillations excited in the film.

Luminescence of Cr{sup 4+}:Ca{sub 2}GeO{sub 4} films in the near infrared region

The Cr4+:Ca2GeO4 films are produced on fused silica substrates by the method of RF magnetron sputtering. Both initial films and those annealed in air at temperatures below 700 °C are amorphous. The films annealed at temperatures from 500 to 700 °C exhibit luminescence in the wavelength range from 1200 to 1400 nm upon laser excitation at 980 nm, which suggests that they contain tetravalent chromium ions.

GaAsSb/GaAs quantum well growth by MOCVD hydride epitaxy with laser sputtering of antimony

A new method of obtaining quantum-size GaAs1−xSbx (x⩽0.45) layers is proposed. The method consists in laser vaporization of solid metallic antimony near the substrate directly in the reactor. The antimony concentration is set by the antimony sputtering time with the arsine flux shut off. The polarization of the photoluminescence of the obtained layers indicates the formation of quantum wires. The heterostructures obtained are used to fabricate laser diodes.