Investigation of Non-Linear Optical Behavior of Semiconductors for Optical Switching. Volume 1

摘要

Studies were conducted on semiconductor doped filter glasses which have been observed to exhibit third order optical non-linearity. This NLO behavior switches on and off in sub-picosecond times. However, the switching time, the NLO coefficient and the operating temperature are affected by the microstructure of the precipitated CdS and CdSe semiconductors. Studies were conducted to examine the crystal microstructures developed in these filter glasses and to correlate them with the optical properties of the semiconductors. There appears to be a potential for an increase in NLO coefficient by a factor of 10 to 1000 with the development of a suitable microstructure. Results and implications of the studies are presented. Studies on thin films of semiconducting CdS showed that microstructure can be controlled by suitable sputtering conditions. Strong exciton transitions were observed and have a high potential for NLO behavior. Composite thin films of CdS semiconducting crystals confined in a glass matrix were formed by co-evaporation. Studies of the phase separation behavior of fluoride glasses were continued in the system: CdF2, LiF, AlF3, PbF2. Two levels of phase separation were observed, consisting of a large microstructure of isolated spheres 3-10 micrometers in diameter, and a very small interconnected microstructure resulting from secondary phase separation.