Lidar observations of the upper atmosphere have been made at Syowa Station, Antarctica by the Japanese Antarctic Research Expedition (JARE) for 3 years since 1983. This work has been performed as part of the Middle Atmosphere Program (MAP). The mesospheric sodium layer and the stratospheric aerozol in the polar region have been studied by lidar measurements. This paper describes mainly the outline of the study on the sodium layer observed by lidars, and reports the results and some problems obtained in Antarctica.

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An optoelectronic integrated circuit (OEIC) is a circuit incorporating both optoelectronic and electronic devices on a single semiconductor substrate. They have great advantages in improving the speed and noise characteristics of optoelectronic devices through the elimination of parasitic reactances, implementing multifunction and multi-channel signal processing capabilities and also realizing high reliability and low cost. This paper describes basic technologies for OEIC fabrication, present status of the technology of Ga As-based OEICs operating at the wavelength near 0.8μm, their applications and future prospects.
A variety of processing techniques for planar integrated structures as well as new optoelectronic devices suitable for integration, which include planar, low-capacitance metal-semiconductor-metal (MSM) photodiodes and low-threshold quantum well lasers, have been developed and applied to the fabrication of OEIC transmitters and receivers that can operate at a bitrate of 2 Gbps. Also four-channel arrays of these OEICs have been fabricated. Applicability of these OEICs to high-speed optical links and advanced optical components including 4×4 optical switches has been demonstrated and also the possibility of optical interconnections using OEICs in the future is suggested. Further technological requirements include the simplification of integrated structure for transmitters and the development of fabrication technique for In P-based OEICs usable at long wavelengths. A new integrable quantum well laser structure and a simple Ga In As PIN/FET receiver have been proposed.

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Plasma-assisted chemical vapor deposition (CVD) is used to deposit solid films for microelectronic applications. Laser spectroscopic methods should facilitate improved understanding of physical and chemical processes ocurring in CVD which, in turn, should lead to the process control and the novel deposition methods. In this paper, laser diagnostic techniques appropriate to spatially-resolved concentration measurements of the species which are the key to CVD process will be reviewed. The review will mainly encompass the Raman spectroscopy and the laser-induced fluorescence spectroscopy. The specific examples of the investigation of CVD process using these techniques are also described.

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A 20 k W fast-axial-flow CO₂ laser has been realized by using high-frequency turboblowers developed especially for laser operation. Each of the two high-frequency turboblowers utilized in the equipment has a revolution of 8, 800 rpm, a gas flow rate of 8.4 m³/s, and an adiabatic head of 4, 000 kg-m/kg. The equipment has six discharge-tubes connected optically in series, and each is 134 mm in diameter, and 1, 000 mm in length. Thelaser output power of 20 k W is extracted from an unstable resonator. The output beam through a zinc-selenidewindow has a diameter of 90 mm.

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A gas flow type waveguide CO₂ laser has been made of Pyrex glass. The output power, frequency tunability and relative change in refractive index of the amplifying medium have been measured as a function of inlet pressure and discharge current. The small signal gain and saturation intensity are determined by fitting a theoretical equation to output power curves measured as a function of the frequency for two gas-mixingra tios.

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