Abstract: An optical amplifying apparatus that amplifies an optical signal, including an input section whereto the optical signal is inputted, a laser light source that generates laser light, the laser light source including an uncooled semiconductor laser device, an optical fiber that amplifies the optical signal by a stimulated emission based on the laser light from the laser light source, an output section that outputs the optical signal amplified by the optical fiber, and a passive optical component disposed between the optical fiber and the output section. The laser light source is thermally coupled to the optical fiber and/or the passive optical component via a thermally conductive medium. An oscillating wavelength of the laser light source is varied by increasing a temperature of the laser light source with heat generated by the optical fiber and/or the passive optical component.

Abstract: There is provided a wavelength division multiplex transmission system with satisfactory transmission characteristics and extensive functions for avoidance of defects. Transmission signals to be transmitted by an optical transmission device are distributed among a plurality of wavelength components, converted into WDM signals, and sent to a WDM transmission network, and WDM signals from the WDM transmission network are restored to the transmission signals by an optical receiving device. This system includes a wavelength component-specific route setting device which sets routes for transmission on the WDM transmission network for each wavelength component.

Abstract: A wavelength division multiplex transmission system with substantial functions for avoidance of defects is provided. The system comprises an optical transmission device and an optical receiving device. The optical transmission device comprises an operating-system optical transmission unit and a standby-system optical transmission unit, and distributes transmission signals to be transmitted among a plurality of wavelength components, converts the signals into WDM signals, and transmits the WDM signals to a WDM transmission network. The optical receiving device comprises an operating-system optical receiving unit and a standby-system optical receiving unit, and restores WDM signals from the WDM transmission network into transmission signals.

Abstract: An optical module 1 comprises an inlet side optical fiber, an optical filter optically connected to the inlet side optical fiber, and an outlet side optical fiber optically connected to the optical filter, wherein, the optical filter comprises a gain-slope compensation optical filter to flatten a gain slope (dG/d?, where G:gain, ?:wavelength)of a gain of an optical amplifier connected to the inlet side optical fiber or the outlet side optical fiber. An optical amplifying module comprises an optical amplifier with the above-mentioned optical module 1. An optical transmission system comprises the optical module 1, an optical amplifier and an optical branching means, wherein FDM (Frequency Division Multiplexing) signal is branched and transmitted.

Abstract: An EDFA 1 is comprised of a pre-amp 2 and a post-amp 3, which are connected in series, a photocoupler 4, a long wave pass filter (LWPF) 5 and an LWPF controller 6. The photocoupler 4 is connected to an input-stage of the EDFA 1 and enters the light signal in the LWPF controller 6. The LWPF 5 is located between the pre-amp 2 and the post-amp 3, and its cutoff wavelength is adjustable. A short-wavelength-part of the light signal which is amplified by the pre-amp 2, is cut off by the LWPF 5. The LWPF controller 6 detects an input signal power of the input light signal and adjusts the cutoff wavelength of the LWPF 5 based on the detected input signal power. Gain of light signals which are output from the post-amp 3, are equalized ranging the extensive input signal power and covering wide signal-wavelength bands.

Abstract: Optical fiber amplifiers with a simple composition than can accurately flatten optical output power in a fixed range are provided. Main optical amplifiers and first gain equalizers connected to these amplifiers are disposed between input port and output port. The main optical amplifiers comprise first EDFs which function as first amplification optical fibers, pumping light sources for providing pumping to drive the first EDFs using amplification characteristics, and second isolators. It is preferable for the second isolators to be isolators that can eliminate optical pumping power. The first gain equalizers are comprised by second absorption EDF. This second EDF operates such that the gain of the optical signal decreases in a non-pumping state or in a slight pumping state. The amplification characteristics used by the first EDF to amplify the optical signal power are opposite to the absorption characteristics used by the second EDF to absorb the optical signal power.

Abstract: A wavelength division multiplex transmission system with substantial functions for avoidance of defects is provided. The system comprises an optical transmission device and an optical receiving device. The optical transmission device comprises an operating-system optical transmission unit and a standby-system optical transmission unit, and distributes transmission signals to be transmitted among a plurality of wavelength components, converts the signals into WDM signals, and transmits the WDM signals to a WDM transmission network. The optical receiving device comprises an operating-system optical receiving unit and a standby-system optical receiving unit, and restores WDM signals from the WDM transmission network into transmission signals.

Abstract: There is provided a wavelength division multiplex transmission system with satisfactory transmission characteristics and extensive functions for avoidance of defects. Transmission signals to be transmitted by an optical transmission device are distributed among a plurality of wavelength components, converted into WDM signals, and sent to a WDM transmission network, and WDM signals from the WDM transmission network are restored to the transmission signals by an optical receiving device. This system includes a wavelength component-specific route setting device which sets routes for transmission on the WDM transmission network for each wavelength component.

Abstract: According to the present invention, an optical fiber amplifier is provided, including: an erbium-doped fiber to which a multiplexed optical signal into which a plurality of optical signals in a long-wavelength band are multiplexed is supplied and which performs amplification in the long-wavelength band; a forward-pumping light source for supplying forward-pumping light to the erbium-doped optical fiber; a backward-pumping light source for supplying backward-pumping light to the erbium-doped optical fiber, the backward-pumping light source having an output power variable based on a control signal; an input-power detector for detecting an input power of the multiplexed optical signal input to the erbium-doped fiber; a temperature detector for detecting a temperature of the erbium-doped fiber; and a control circuit for outputting the control signal based on the input power detected by the input-power detector and the temperature detected by the temperature detector, the control signal changing the output power o

Abstract: An optical amplifier that can easily cope with alteration of characteristics and whereby a prescribed characteristic can be obtained in a stable fashion. In an optical amplifier, a plurality of optical components including optical amplification media that amplify input signal light are cascade-connected. There are provided (1) a temperature adjustment member capable of changing the temperature of one or a plurality of optical components in accordance with a temperature control signal that is input, and (2) a characteristic control device that supplies in respect of the temperature adjustment member a control signal that controls a prescribed optical characteristic having temperature dependence in one or a plurality of optical components that are the subject of adjustment by the temperature adjustment member, being a prescribed optical characteristic that is demanded for the optical amplifier.

Abstract: There is provided an optical amplifier for reducing the optical output power difference and/or obtaining high output power across a wide wavelength band. The optical amplifier comprises a plurality of optical amplifier units connected in two or more stages. At least one of the optical amplifier units comprises a first optical component of a single input and N outputs that has an optical-demultiplexing function, and P units of optical amplification means for the individual amplification of light that is output from P (where 1≦P≦N) output terminals selected from the N (integer) output terminals of the first optical component. Second optical components are provided to the input side of the first optical component or between the output side of the first optical component and the input side of the optical amplification means.