Oki Electric Industry Co., Ltd.

The Furukawa Electric Co., Ltd.

Oki Electric Industrial Co., Ltd.

Mikiya Suzuki

Shigeru Shikii

Akira Sasaki

Toshio Nakamura

Katsuhiro Ishimura

Yukihiro Ozeki

Shusei Aoki

Sigeru Shikii

An optical amplifying apparatus that amplifies a wavelength-division multiplexed (WDM) optical signal includes an input section, a laser light source, a double-clad optical fiber, a gain equalizer, and a residual pump light attenuating section that attenuates a residual pump light outputted from the double-clad optical fiber. The residual pump light attenuating section is disposed such that the residual pump light of the laser light is incident on the residual pump light attenuating section before being incident on an isolator.

Optical amplifying apparatus and optical transmission system

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.

Wavelength division multiplex transmission system

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. The operating-system optical transmission unit and/or the standby-system optical transmission unit has optical transmission unit internal defect avoidance means which, upon the occurrence of a prescribed number or fewer of wavelength component transmission defects, avoids defects within the optical transmission unit.

Wavelength division multiplex transmission system and communication device

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

Optical fiber amplifier

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. Therefore, by means of passing a Wavelength Division Multiplexing Signal (WDM) through the first and second EDFs, only the portion of the Wavelength Division Multiplexing Signal (WDM) output from the first EDF that corresponds to the signal amplified by the first EDF is absorbed while a Wavelength Division Multiplexing Signal (WDM) passes through the second EDF. Because of this, the gain of the Wavelength Division Multiplexing Signal (WDM) ultimately output from an optical fiber amplifier is flattened.

Optical fiber amplifier and output power flattening method of optical fiber amplifier

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 of the backward-pumping light source to cancel deviation of the amplification of the multiplexed optical signal.

Optical fiber amplifier and a method for controlling the same

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.

Optical component, optical amplifier and method of controlling optical amplifier characteristic

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&lE;P&lE;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. The second optical components are optical components having chromatic dispersion compensation functions, optical components having functions designed to compensate for wavelength dependency output power difference, or optical components demonstrating other required effects. The optical components are DCFs, FBGs, SMFs, optical filters, attenuators, or the like. The second optical components are provided nonselectively or selectively.

Growing community of inventors

Tokyo, Japan

Mikiya Suzuki