Abstract: An object of the invention is to clear up factors in deterioration due to optical reflection and to provide an optical transmission apparatus and an optical transmission system in which a superior optical transmission characteristic can be obtained for analog signals even if a reflection phenomenon occurs in an optical transmission line. There are provided a frequency converter (3) for converting the frequency band of a to-be-transmitted electric signal into a predetermined frequency band higher that this frequency band, and a semiconductor laser (4) serving as an electro-optic converter for performing electro-optic conversion upon the frequency-converted electric signal.

Abstract: An object of the present invention is to provide an optical transmitter that can suppress degradation of distortion characteristic and RIN characteristic caused by relaxation oscillation at high temperature by controlling average driving current of a light emitting element so that the average optical output power of the light emitting element is increased as the temperature increases like a case where the environmental temperature around the light emitting element increases.

Abstract: Up and down signal levels in a wireless base station and a forward base station can be automatically adjusted into predetermined levels respectively with a simple configuration. In an interface portion 12, a pilot signal P of a predetermined level is generated by a pilot signal generator 120, and multiplexed with a down transmission signal 111 from a wireless base station 11 by a multiplexer 121. The multiplexed signal is amplified with a constant gain by a down signal amplifier 122, then converted into a down optical signal by an electro-optic converter 123, wavelength-multiplexed by an optical multi/demultiplexer 124, sent out to an optical fiber 15, and transmitted to a forward base station 13. In the forward base station 13, the down optical signal wavelength-demultiplexed by an optical multi/demultiplexer 124 is converted into a down electric signal by an opto-electric converter 125, and the pilot signal P is demultiplexed by a demultiplexer 133.

Abstract: To provide a signal transmission system which can increase the number of slave stations being coupled with a simple configuration, A master station 10 communicates with a plurality of slave stations 20 each having an antenna 25. The slave station 20 includes a frequency converter 26 for converting a signal of a radio frequency band received through the antenna into an intermediate frequency band signal, and an E/O converter 27 for converting an electrical signal into an optical signal. The master station 10 includes O/E converters 14a to 14c for converting signals received from the slave stations 20 into electrical signals, respectively, a synthesizer 17 for synthesizing the signals thus converted into the electrical signals and a frequency converter 18 for converting the synthesized signal into a radio frequency band signal.

Abstract: A small-sized optical transceiver module, wherein any stress attributable to the differences in coefficient of thermal expansion between a transmission section optical system, a receiving section optical system, and the components which integrate and fix them and the like is not applied therebetween, and which is not influenced by any stress at the time of attachment/detachment of the optical connector is disclosed.

Abstract: The present invention discloses an optical transmitting/receiving module designed in small size and produced at low cost without the need to use an optical waveguide, which requires complicated process and larger area, and the invention also discloses a method for manufacturing such an optical transmitting/receiving module. According to the present invention, a V-groove running in linear direction and a vertical groove (a groove having vertical side surfaces) crossing obliquely said V-groove at the end of the V-groove, an optical fiber core is arranged to the end of the V-groove, a wavelength selective filter is arranged in the vertical groove, and a light emitting element and a light receiving element are arranged respectively in transmitting direction and reflecting direction of the wavelength selective filter.

Abstract: The invention provides a bidirectional optical module which can enable bidirectional utilization of one optical fiber transmission channel with low-cost, and an optical transmission device using it. This optical module comprises a light receiver, wherein a photo acceptance unit is optically coupled with a light output part obtained by cutting an optical fiber in the middle thereof aslant an optical fiber core, and inserting a filter/half mirror between obtained cross sections of the core; and a light transmitter, wherein a light emitting device is optically coupled with one end of the optical fiber. The light receiver is set to have a receptacle structure having a ferrule in which the other end of the optical fiber is inserted from inside, and which can physically contact with an optical connector.

Abstract: The present invention provides a one-core bidirectional optical transmitting/receiving module for wavelength multiplexing, which does not require optical waveguide fabricated with high precision and which has superb high frequency characteristics and has very low optical and electrical crosstalks and available at low cost. At the middle of an optical fiber 1 buried in a glass substrate 3, a light irradiating portion is provided, which has a wavelength selection filter 2 placed obliquely to the optical fiber. The light irradiating portion is fixed immediately above a backside entrance type photodetection element 4 mounted on a ceramic substrate 6 by flip-clip bonding, and only optical signals with specific wavelength are received. An optical fiber extra portion 7 between a photodetection unit and a light emitting unit has sufficient length, and an end of the optical fiber is optically coupled with the light emitting element.

Abstract: The present invention discloses an optical transmitting/receiving module designed in small size and produced at low cost without the need to use an optical waveguide, which requires complicated process and larger area, and the invention also discloses a method for manufacturing such an optical transmitting/receiving module. According to the present invention, a V-groove running in linear direction and a vertical groove (a groove having vertical side surfaces) crossing obliquely said V-groove at the end of the V-groove, an optical fiber core is arranged to the end of the V-groove, a wavelength selective filter is arranged in the vertical groove, and a light emitting element and a light receiving element are arranged respectively in transmitting direction and reflecting direction of the wavelength selective filter.