Abstract: A bolometer type infrared detector can restrict temperature drift due to self-heating and has a structure not causing degradation of characteristics by noise. The bolometer type infrared detector has a bolometer thin film serving as infrared ray detecting element, the bolometer thin film being divided into a plurality of rectangular elements, the element being connected in series.

Abstract: A bolometer type infrared detector can restrict temperature drift due to self-heating and has a structure not causing degradation of characteristics by noise. The bolometer type infrared detector has a bolometer thin film serving as infrared ray detecting element, the bolometer thin film being divided into a plurality of rectangular elements, the element being connected in series.

Abstract: An optical semiconductor device comprises a stripe-mesa structure provided on a semi-insulating substrate. The stripe-mesa structure comprises an undoped light absorption layer sandwiched by cladding layers, and by burying layers on both sides. With this structure, the device capacitance is decreased to provide wide bandwidth and ultra-high speed operation properties. This device can be applied to an optical modulator, an integrated type optical modulator, and an optical detector.

Abstract: An optical switch circuit is configured as a matrix array to arbitrarily switch the connections between optical transmission channels. The optical switch circit comprises a plurality of optical splitter coupled to input transmission channels, a plurality of optical switches arranged on the matrix crosspoints, each switch comprising an optoelectronic element and a light modulating element functioning as an electrooptic element, and a plurality of optical combiners coupled to output transmission channels. Thus, a small-sized optical switch circuit suitable for integration is realized. With this circuit, small crosstalk and high speed switching without distortion of broadband signals are expected. Further, this circuit provides a wide adaptability such that light transmitted through multi-mode optical fiber can be switched.