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The application of optical fibers to the transmission of solar radiation is discussed. Attenuations of the extraterrestrial solar radiation spectrum in optical fiber materials, fused‐silica and soda‐lime‐silicate glass, are calculated based on intrinsic attenuation mechanisms. It is shown that fused‐silica‐core optical fibers transmit solar radiation effectively over distances of about 40 m. Possible areas of application of optical fibers to the solar energy utilization systems are suggested.

Several specimens of Al2O3‐added high‐silica‐content glass of various additive concentration which were prepared with a chemical vapor deposition (CVD) process are studied by Raman spectroscopy. The Raman spectrum of the glass is found to be close to that of fused silica, and the Raman band characteristic to the nonbridging oxygens was not observed in this glass. A quadratic behavior of the refractive index change as a function of the additive concentration is observed in this glass and is explained with a detailed ionic polarizability concept on the basis of the Raman spectroscopy. The effect of the refractive index fluctuation in this glass on the optical attenuation is also discussed.

A versatile Raman‐spectrometric method for a prompt and reliable isotopic analysis is described. It makes real‐time analysis possible if needed. The Raman spectrometric method is applied to the analysis of deuterium in a mixture of D2O and H2O liquid. The Raman‐spectrometric determination is found to agree closely with the volumetric one. Sensitivity of Raman spectrometry is confirmed well under 1 mol%.

For the evaluation of optical fiber material by Raman spectrometry, the Raman spectra of B2O3‐doped high‐silica‐content glass and four TiO2‐doped high‐silica‐content glasses are studied extensively making reference to that of pure fused silica. Extra Raman bands at about 935 cm−1 are found commonly in the high‐silica‐content glasses and assigned to the motion of the nonbridging oxygen. The theory of Raman spectrometry of high‐silica‐content glasses is developed and it is verified experimentally with TiO2‐doped high‐silica‐content glass.

Characteristics of high‐energy/power amplifiers including large‐signal gain, extraction efficiency, and pulse deformation are analyzed in terms of material and operating parameters. A figure of merit for large‐signal amplifier material is defined, which is inversely proportional to the stimulated‐emission cross section. A method for detailed pulse tailoring in nonlinear amplifiers is developed. It is found that a high stored‐energy density, which is obtainable with a small stimulated‐emission cross section, is very important for achieving high gain and tolerable pulse deformation. The high stored‐energy density is also found to be effective for suppressing laser beam degradation due to nonlinear refractive‐index effects.

The generation of self‐sustained pulsations in degraded (GaAl)As double‐heterostructure diode lasers is explained by invoking microscale absorption centers possessing a large cross section. The microscale degradation centers are found to affect the laser characteristics at a concentration level as low as 1014–1015 cm−3.

In order to offer an effective method to measure a characteristic such as the light attenuation in an optical waveguide without breaking or contacting the sample, regular light scattering signals have been separated from the irregular ones by rejecting the Rayleigh component.

The acceptance angle of a fiber is increased remarkably by forming the fiber end spherically. It was demonstrated with light coupling into a fused‐silica‐core glass fiber from a mesa‐stripe‐geometry GaAs diode laser. The coupling efficiency increased in this way is observed to be 5.2 times as high as that of a previous method. The proper design of a fiber in this manner will lead to a light coupling efficiency higher than 90%.

The degradation of cw double‐heterostructure semiconductor lasers is analyzed. It is clearly shown that the recoverable initial degradation mode of long‐life AlxGa1−xAs‐GaAs lasers is caused by a reduction of minority‐carrier lifetime, the effect of which is readily distinguished from other possible processes such as increased cavity loss or minority‐carrier leakage.

Fluorescence owing to organic impurities in a Raman spectroscopic sample is quenched by the photochemical reaction, which improves the Raman spectroscopy. The quenching technique is demonstrated in the Raman spectroscopy of liquid methanol.

A new type of glass fiber is discussed. The core of the fiber is pure fused silica, and the cladding is a high‐silica‐content glass. This type of glass fiber has potentially the lowest attenuation of light propagation. A light attenuation of approximately 20 dB/km was measured at a 632.8‐nm wavelength in the preliminary work.