Abstract: An optical transmission device obtains driving control data corresponding to a temperature detected by a temperature detection circuit (112) from memory means (173), controls a driving current to be supplied to a laser diode (100) based on the driving control data, and measures a driving current to be actually supplied to the laser diode whose emission power is held constant by an automatic optical output control circuit (115, 113). Further, when the difference between the measured driving current and a driving current determined by the driving control data corresponding to the detected temperature at that time exceeds an allowable range, the optical transmission device updates the driving control data related to the corresponding temperature, on the memory means so that the difference between the driving currents is defined as each of increases in bias current and modulating current.

Abstract: An optical transmission device obtains driving control data corresponding to a temperature detected by a temperature detection circuit (112) from memory means (173), controls a driving current to be supplied to a laser diode (100) based on the driving control data, and measures a driving current to be actually supplied to the laser diode whose emission power is held constant by an automatic optical output control circuit (115, 113). Further, when the difference between the measured driving current and a driving current determined by the driving control data corresponding to the detected temperature at that time exceeds an allowable range, the optical transmission device updates the driving control data.

Abstract: A parallel optical switching apparatus wherein at least one m-channel light emission element array and one n-channel light receiving element array are optically connected via an m.times.n optical conversion element array and the optical conversion element array has an optical amplification function by inductive discharge of input light for each element and performs optical arithmetic or optical conversion in parallel for input light from the light emission element array by the amplification and modulation function.

Abstract: In a polarization dependency type optical isolator comprising wedgelike polarizing prisms 3 and 5 and a Faraday rotator 4, the mode field diameters of an input side fiber 1 and an output side fiber 7 are the same as that of a transmission fiber and an erbium-doped fiber to be connected to them. The shape and other features of each lens are controlled so that the spot size of a parallel ray which is converted from an incident ray by an input side lens 2 is equal to the spot size of a parallel ray which is converted by an output side lens 6 when a reference beam is irradiated from the fiber 7. In a rare-earth-doped fiber optical amplifier using an optical isolator which is configured in a manner similar to this, the connecting portion of the fiber and the optical isolator can be spliced by fusion without increasing the insertion loss of the optical isolator in the forward direction and the connection loss due to a difference in the mode field diameter is reduced.

Abstract: In a photoelectric device, particularly, a photoelectric device for optical communication, an optical fiber is fixed at two fixing points so that the extremity of the optical fiber is disposed opposite to the light emitting surface of a laser diode chip and the optical fiber extends in a nonlinear shape, for example, in a moderate curve, between the two fixing points. Even though holding members fixedly holding the optical fiber at the two fixing points and a base member supporting the holding members are formed of a metal or metals having a coefficient of thermal expansion far greater than that of the optical fiber, and even if the distance between the two fixing points is varied due to the thermal expansion or contraction of the holding members and the base member, the optical fiber is obliged only to change the shape of extension.

Abstract: In a photoelectric device, particularly, a photoelectric device for optical communication, an optical fiber is fixed at two fixing points so that the extremity of the optical fiber is disposed opposite to the light emitting surface of a laser diode chip and the optical fiber extends in a nonlinear shape, for example, in a moderate curve, between the two fixing points. Even though holding members fixedly holding the optical fiber at the two fixing points and a base member supporting the holding members are formed of a metal or metals having a coefficient of thermal expansion far greater than that of the optical fiber, and even if the distance between the two fixing points is varied due to the thermal expansion or contraction of the holding members and the base member, the optical fiber is obliged only to change the shape of extension.

Abstract: In a photoelectric device, particularly, a photoelectric device for optical communication, an optical fiber is fixed at two fixing points so that the extremity of the optical fiber is disposed opposite to the light emitting surface of a laser diode chip and the optical fiber extends in a nonlinear shape, for example, in a moderate curve, between the two fixing points. Even though holding members fixedly holding the optical fiber at the two fixing points and a base member supporting the holding members are formed of a metal or metals having a coefficient of thermal expansion far greater than that of the optical fiber, and even if the distance between the two fixing points is varied due to the thermal expansion or contraction of the holding members and the base member, the optical fiber is obliged only to change the shape of extension.

Abstract: This invention relates to a semiconductor laser of a buried-hetero structure. In this semiconductor laser, the side surfaces of an active layer are in contact with a plane having a stable state of interface. As a result, the threshold current value of this semiconductor laser is low, and a stable operation can be obtained without causing any kink (projection) in the current-optical output characteristics. An optical communication system using this semiconductor layer has a low operating current, and can maintain high coupling efficiency with an optical fiber without the occurrence of noise, so that optical communication having high reliability is possible.

Abstract: This invention relates to a semiconductor laser of a buried-hetero structure. In this semiconductor laser, the side surfaces of an active layer are in contact with a plane having a stable state of interface. As a result, the threshold current value of this semiconductor laser is low, and a stable operation can be obtained without causing any kink (projection ) in the current-optical output characteristics. An optical communication system using this semiconductor layer has a low operating current, and can maintain high coupling efficiency with an optical fiber without the occurrence of noise, so that optical communication having high reliability is possible.