Abstract: An optical channel monitor, includes: a wavelength demultiplexer that demultiplexes input signal light; photodetectors that are arranged on a demultiplexed side of the wavelength demultiplexer, and receive light in a wavelength band wider than a wavelength band of the signal light; and a calculator that calculates a light level of signal light of each wavelength by means of linear compensation on the basis of a received light level of light in the wavelength band of the signal light and a received light level of light of a wavelength outside the wavelength band of the signal light at the photodetectors.

Abstract: A wavelength division multiplexing filter according to the present invention is a wavelength division multiplexing filter having a variable filter shape. The wavelength division multiplexing filter has a resolution equal to 2N times (N being an integer, where N?1) a reference frequency interval and has frequency arrangement of center frequencies of frequency slots corresponding to the 2N-times resolution be offset by half a cycle with respect to the frequency arrangement of standard wavelength grids having a frequency interval equal to ½N of the reference frequency interval.

Abstract: A light channel monitor includes an optical separating section configured to separate a wavelength multiplexed optical signal into optical signals for channels and monitors configured to measure intensities of the optical signals for the channels. A processing section is configured to correct the measured intensities of the optical signals based on a wavelength transmission characteristic of the optical separating section to calculate the wavelength multiplexed optical signal before the separation.

Abstract: The present invention is to provide an optical feedback control unit for determining an optical output by a feedback control, an optical communication system, a feedback control method, and a recording medium for recording a program. According to the present invention, even when used in the system to which a plurality of nodes are connected, the unstable system may become stable by the proper feedback control without being affected by the optical level change according to the polarized variation or the loss variation.

Abstract: A wavelength division multiplexing filter according to the present invention is a wavelength division multiplexing filter having a variable filter shape. The wavelength division multiplexing filter has a resolution equal to 2N times (N being an integer, where N?1) a reference frequency interval and has frequency arrangement of center frequencies of frequency slots corresponding to the 2N-times resolution be offset by half a cycle with respect to the frequency arrangement of standard wavelength grids having a frequency interval equal to 1/2? of the reference frequency interval.

Abstract: A method of collecting data from an optical channel monitor for monitoring the power of a wavelength-division multiplexed light signal at each wavelength is disclosed. The total light power is analog-to-digital converted by an A/D converter. The data of the total light power which has been analog-to-digital converted is compared with a reference light power by a comparator for each conversion, and when the difference between the total light power and the reference light power exceeds a predetermined threshold, a power fluctuation flag is turned ON. After the comparison, the above process of the analog-to-digital conversion and the comparison is iterated until the optical channel monitor completes the data collection for each wavelength. Thereafter, the processor determines whether the power fluctuation flag is ON or not. When the power fluctuation flag is ON, the processor discards the currently collected data and maintains the data which were collected immediately before.

Abstract: Methods and systems for controlling power fluctuations in a network including a plurality of nodes are disclosed. A node in the network may be configured to modify power levels in accordance with either an active state or an inactive state. The node may transition to an inactive state in response to a power change that exceeds a power change threshold. The role of the node in controlling the power fluctuation in the network is reduced in the inactive state.

Abstract: The present invention is to provide an optical feedback control unit for determining an optical output by a feedback control, an optical communication system, a feedback control method, and a recording medium for recording a program. According to the present invention, even when used in the system to which a plurality of nodes are connected, the unstable system may become stable by the proper feedback control without being affected by the optical level change according to the polarized variation or the loss variation.

Abstract: The present invention achieves highly reliable optical-fiber loss adjustment at low cost, with easy work. An optical fiber is inserted from an optical fiber insertion opening into a space between an internal wall and a plurality of optical-fiber support members and, due to its self-resilience, comes in contact with the support members on its outer side. Since the radius of curvature of the fiber is sufficiently small, a loss can be adjusted with the number of turns of the fiber. The support members have a cylindrical shape and therefore come in point contact with the fiber, which can prevent microbending. Moreover, the interval (angle) between adjacent ones of the support members and the radius thereof are set such that the fiber can be led into and out of an optical-fiber adjustor, with no stress imposed.

Abstract: The present invention achieves highly reliable optical-fiber loss adjustment at low cost, with easy work. An optical fiber is inserted from an optical fiber insertion opening into a space between an internal wall and a plurality of optical-fiber support members and, due to its self-resilience, comes in contact with the support members on its outer side. Since the radius of curvature of the fiber is sufficiently small, a loss can be adjusted with the number of turns of the fiber. The support members have a cylindrical shape and therefore come in point contact with the fiber, which can prevent microbending. Moreover, the interval (angle) between adjacent ones of the support members and the radius thereof are set such that the fiber can be led into and out of an optical-fiber adjustor, with no stress imposed.

Abstract: An optical add/drop device, an optical add/drop system, and method thereof is provided herein. The optical add/drop system may include, a first variable coupler which splits input light to through light and dropped light, a wavelength blocker which attenuates an intensity of each channel of the through light, a second variable coupler which couples the through light from the wavelength blocker and added light, and a dropped light detector which measures an intensity of the dropped light. Further, the system may include an added light detector which measures an intensity of the added light, a through light detector which measures an intensity of the each channel of the through light from the wavelength blocker, and a controller which controls the first variable coupler, controls the wavelength, and controls the second variable coupler.

Abstract: The output monitor/control device is provided with: Mach-Zehnder circuit 104 that receives a light beam, branches the light beam into two light beams having a phase difference of 180°, and transmits each of the light beams, exhibiting a periodic optical transmittance-optical frequency characteristic a period of a frequency interval corresponding to a predetermined free spectral range; first and second photodiodes that each receive one of two light beams supplied from the Mach-Zehnder circuit; calculation circuit 108 that calculates a predefined discrimination formula for evaluating wavelength change of the light beam based on output currents of the photodiodes; and wavelength control circuit 111 that detects change in wavelength based on the calculation results by the calculation circuit and adjusts the wavelength to a set value.

Abstract: A heating element device has a laminate of a plurality of heating element plates, each of the heating element plates having an insulator and a resistor, which is capable of generating heat upon the supply of electric power, provided on the insulator. The plurality of heating element plates are each independently controllable with respect to energization. The heating element device also has a temperature detection plate having an insulator and a resistor, capable of undergoing a change in resistance value upon a change in temperature, provided on the insulator.

Abstract: A heating element device has a laminate of a plurality of heating element plates, each of the heating element plates having an insulator and a resistor, which is capable of generating heat upon the supply of electric power, provided on the insulator. The plurality of heating element plates are each independently controllable with respect to energization. The heating element device also has a temperature detection plate having an insulator and a resistor, capable of undergoing a change in resistance value upon a change in temperature, provided on the insulator.

Abstract: A temperature controller 51 is disclosed, which comprises a temperature control element 53 disposed on the bottom of a case 52, a light-waveguide element 11 and a metal plate 55 intervening between the elements 53 and 11. The metal groove 55 has a groove, in which a temperature sensor 36 is buried together with a highly heat conductive material. The detected temperature output of the temperature sensor 36 is inputted to a temperature control circuit 58 for controlling the temperature of the temperature control element 53. The temperature sensor 36 inclusive of its lead lines are buried in the metal plate 55 such as to cover a long distance. Thus, the temperature control is less subject to the influence of the ambient temperature and can thus be made with high accuracy.

Abstract: A laser oscillation wavelength monitoring device, which can obtain a changing direction and a changing amount of an oscillation wavelength without any relation with a polarization state of an incident light, whose manufacturing is made to be easy, is provided.

Abstract: A heater includes (a) at least one heat generator which converts electric power to heat, (b) at least one substrate on which the heat generator is formed, and (c) at least one lead through which electric power is applied to the heat generator and which supports the substrate. For instance, the substrate has two opposite sides from each of which the lead extends, and the lead is comprised of a first portion outwardly extending from a side of the substrate, a second portion downwardly extending from an end of the first portion, and a third portion extending outwardly from an end of the second portion.

Abstract: The output monitor/control device is provided with: Mach-Zehnder circuit 104 that receives a light beam, branches the light beam into two light beams having a phase difference of 180°, and transmits each of the light beams, exhibiting a periodic optical transmittance-optical frequency characteristic a period of a frequency interval corresponding to a predetermined free spectral range; first and second photodiodes that each receive one of two light beams supplied from the Mach-Zehnder circuit; calculation circuit 108 that calculates a predefined discrimination formula for evaluating wavelength change of the light beam based on output currents of the photodiodes; and wavelength control circuit 111 that detects change in wavelength based on the calculation results by the calculation circuit and adjusts the wavelength to a set value.

Abstract: A temperature controller 51 is disclosed, which comprises a temperature control element 53 disposed on the bottom of a case 52, a light-waveguide element 11 and a metal plate 55 intervening between the elements 53 and 11. The metal groove 55 has a groove, in which a temperature sensor 36 is buried together with a highly heat conductive material. The detected temperature output of the temperature sensor 36 is inputted to a temperature control circuit 58 for controlling the temperature of the temperature control element 53. The temperature sensor 36 inclusive of its lead lines are buried in the metal plate 55 such as to cover a long distance. Thus, the temperature control is less subject to the influence of the ambient temperature and can thus be made with high accuracy.

Abstract: An optical device of the invention having a first doubly refracting crystal plate of parallel plate type whose crystal optical axis is inclined in relation to the optical axis of an incident light, a second doubly refracting crystal plate of parallel plate type which is equal to the first doubly refracting crystal plate of parallel plate type in inclination of the crystal optical axis inclined in relation to the optical axis and in plate thickness, and a Faraday rotator which is disposed between the first and the second doubly refracting crystal plate of parallel plate type and. turns by 90 degrees an incident linear polarized light which is in the optical axis direction of the incident light and has wavelength of the incident light. The invention can provide a polarization-independent optical isolator which is small-sized and capable of selecting a direction of the input/output optical fiber at will.