Abstract: The present invention has an object to provide a control method and a control apparatus for a variable wavelength optical filter, which can reliably and stably control drive conditions of the variable wavelength optical filter, independent of the number of wavelengths to be selectively separated in collective.

Abstract: The present invention aims at providing a control method and a control apparatus for controlling variable selected wavelengths at respective stages with high accuracy and reliability, to obtain desired wavelength characteristics, in a multi-staged band rejection type optical wavelength variable filter.

Abstract: The present invention aims at providing a connecting method of optical devices capable of suppressing a periodic wavelength dependence loss and the like, due to the inter-polarization-mode interference caused when connecting a plurality of optical devices by using an optical path having a polarization-preserving characteristic, and an optical apparatus applied with the connecting method. To this end, the connecting method according to the present invention, is to connect a plurality of optical devices to one another by using an optical path of polarization-preserving type having optical characteristics in which a light is propagated along two different polarization axes for substantially equal distances.

Abstract: The present invention aims at providing a connecting method capable of suppressing an influence of stray light for a plurality of optical function devices formed on the same substrate, and an optical apparatus applied with the control method. To this end, in the connecting method of optical function devices according to the present invention, the plurality of optical function devices formed on the same substrate are cascade connected so that both ends of an optical path passing through the plurality of optical function devices are positioned on the same end face of the substrate. According to such a connecting method, it becomes possible to effectively suppress a leakage of stray light from an optical input side to an optical output side.

Abstract: The present invention aims at providing a control method and a control apparatus for controlling the operation setting of an optical device with high accuracy, so as to reliably obtain characteristics according to a desired relationship to be set corresponding to a signal light, immediately after the control start.

Abstract: The present invention aims at providing an optical wavelength filter of band rejection type capable of reliably and stably blocking a light of a desired wavelength from passing through. To this end, the optical wavelength filter of the present invention comprises a plurality of optical filter sections each blocking the light corresponding to the selected wavelength from passing through, the respective optical filter sections being cascade connected to be in a multi-staged structure, wherein the selected wavelengths in the optical filter sections are deviated from one another, to form a blocking band having a wavelength band corresponding to a deviation amount.

Abstract: In the control method for the optical filter according to the present invention, WDM signal light obtained by wavelength division multiplexing a plurality of optical signals having different wavelengths is supplied to an optical filter to obtain output WDM signal light including a part of the plurality of optical signals. The output WDM signal light is converted into an electrical signal per wavelength channel of the output WDM signal light. Then, the optical filter is controlled according to the electrical signal so that the characteristic of the optical filter becomes stable.

Abstract: The present invention relates to a control method and device for an optical filter, and a primary object of the present invention is to achieve accurate tracking control of the optical filter. Disclosed herein is a control method for an optical filter including first and second optical filter units cascaded, each having an input and first and second outputs. The first output of the first optical filter unit is connected to the input of the second optical filter unit. First light output from the second output of the first optical filter unit is converted into a first electrical signal having a level corresponding to the power of the first light, and second light output from the second output of the second optical filter unit is converted into a second electrical signal having a level corresponding to the power of the second light. A control signal is generated according to the first and second electrical signals. Then, the first and second optical filter units are controlled according to the control signal.

Abstract: The present invention aims at providing a control method and a control apparatus for controlling variable selected wavelengths at respective stages with high accuracy and reliability, to obtain desired wavelength characteristics, in a multi-staged band rejection type optical wavelength variable filter.

Abstract: In an OADM system, an OADM device includes an AOTF. The AOTF can select an optional wavelength by changing the frequency of an RF signal to be applied. An optical signal having a specified wavelength can be dropped from a wavelength-multiplexed optical signal input from an input terminal, or a wavelength-multiplexed optical signal input from an add port can be multiplexed with a through optical signal. However, considering the increase in coherent cross talk, the AOTF should be exclusively used for dropping in an actual device configuration. Otherwise, a drop optical signal is branched by an optical coupler with the wavelength selected by a tributary station. Thus, the wavelength selected by the tributary station can be extracted by the AOTF from the through optical signal.

Abstract: M wavelength separating sections receive multiplexed optical signals each having N kinds of wavelengths different. Each of the multiplexed optical signals are separated into N optical signals. M relays conduct optical reproduction and relay to convert each of the N optical signals into electric signals and then produce optical signals modulated with desired optical wavelengths. A refill section mutually refills M sets of the reproduced and relayed optical signals. A focusing section focuses the M sets of optical signals refilled in the refill section. A light source supplies input lights having desired wavelengths, which lights are modulated in the relays. The light source includes N light sources outputting N kinds of optical wavelengths. A multiplexer/brancher multiplexes the lights from the N light sources to produce a multiplexed light and branches the multiplexed light into M×N distributed lights. M wavelength filters distribuitively receive N distributed lights of the M×N distributed lights.

Abstract: In an OADM system, an OADM device includes an AOTF. The AOTF can select an optional wavelength by changing the frequency of an RF signal to be applied. An optical signal having a specified wavelength can be dropped from a wavelength-multiplexed optical signal input from an input terminal, or a wavelength-multiplexed optical signal input from an add port can be multiplexed with a through optical signal. However, considering the increase in coherent cross talk, the AOTF should be exclusively used for dropping in an actual device configuration. Otherwise, a drop optical signal is branched by an optical coupler with the wavelength selected by a tributary station. Thus, the wavelength selected by the tributary station can be extracted by the AOTF from the through optical signal.

Abstract: An optical transmission system in which a wavelength-division-multplexed (WDM) optical signal including a plurality of optical signals having different wavelengths is demultiplexed into first optical signals and second optical signals. The second optical signals have wavelengths longer than wavelengths of the first optical signals. A first dispersion compensator compensates dispersion of the first optical signals. A second dispersion compensator compensates dispersion of the second optical signals. The dispersion compensated first and second optical signals are then multiplexed together.

Abstract: Disclosed herein is a light source device and a wavelength control device therefor. The light source device includes a plurality of laser diodes, a temperature sensor provided in the vicinity of the plurality of laser diodes, a control loop for controlling the temperatures of the plurality of laser diodes according to an output from the temperature sensor to thereby control the oscillation wavelengths of the plurality of laser diodes, and a unit for compensating temperature control conditions for the laser diodes other than a reference laser diode selected from the plurality of laser diodes, according to a change in temperature control condition for the reference laser diode. By the compensation of the temperature control conditions, the oscillation wavelength of each laser diode can be easily stabilized to each wavelength channel of WDM.

Abstract: An optical transmission system in which a wavelength-division-multiplexed (WDM) optical signal including a plurality of optical signals having different wavelengths is demultiplexed into first optical signals and second optical signals. The second optical signals have wavelengths longer than wavelengths of the first optical signals. A first dispersion compensator compensates dispersion of the first optical signals. A second dispersion compensator compensates dispersion of the second optical signals. The dispersion compensated first and second optical signals are then multiplied together.

Abstract: An optical transmitting device which combines a plurality of signal lights, each having a different, corresponding, frequency, into a wavelength division multiplexed signal light. The frequencies are spaced apart from each other in a manner with eliminates the effects of four-wave mixing (FWM). More specifically, the difference in frequencies of any pair-combination of the signal lights is different from the difference in frequencies between any other pair-combination of the signal lights. Moreover, the plurality of signal lights include n signal lights having respectively corresponding frequencies f1 through fn arranged in order from f1 to fn along a frequency spectrum, where frequencies f1 through fn−1 have respectively corresponding integer spacing coefficients m1 through mn−1, and frequencies fi and fi+1 are separated by mi·&Dgr;fS−F, where i=1 to (n−1) and &Dgr;fS−F is a unit of spacing between frequencies.

Abstract: The present invention relates to an optical cross connect unit comprising M wavelength separating sections for receiving multiplexed optical signals each having N kinds of wavelengths different from each other through M optical fibers, respectively, and for wavelength-separating each of the multiplexed optical signals into N optical signals, M optical reproduction relay sections each for conducting an optical reproduction and relay in a manner of making a conversion of each of the N optical signals, wavelength-separated in each of the wavelength separating sections, into an electric signal and then modulating it with a desired optical wavelength, a refill section for mutually refilling M sets of optical signals optically reproduced and relayed in the optical reproduction relay sections, a focusing section for focusing the M sets of optical signals refilled in the refill section, and a light source unit for supplying input lights having desired wavelengths to be modulated in the M optical reproduction relay se

Abstract: In an OADM system, an OADM device includes an AOTF. The AOTF can select an optional wavelength by changing the frequency of an RF signal to be applied. An optical signal having a specified wavelength can be dropped from a wavelength-multiplexed optical signal input from an input terminal, or a wavelength-multiplexed optical signal input from an add port can be multiplexed with a through optical signal. However, considering the increase in coherent cross talk, the AOTF should be exclusively used for dropping in an actual device configuration. Otherwise, a drop optical signal is branched by an optical coupler with the wavelength selected by a tributary station. Thus, the wavelength selected by the tributary station can be extracted by the AOTF from the through optical signal.

Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength &lgr;0 of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.

Abstract: The invention provides an optical wavelength multiplex transmission method wherein a band in the proximity of a zero dispersion wavelength of an optical fiber is used and optical signals are disposed at efficient channel spacings taking an influence of the band, the wavelength dispersion and the four wave mixing into consideration to realize an optical communication system of an increased capacity which is not influenced by crosstalk by FWM. When optical signals of a plurality of channels having different wavelengths are to be multiplexed and transmitted using an optical fiber, a four wave mixing suppressing guard band of a predetermined bandwidth including the zero-dispersion wavelength &lgr;0 of the optical fiber is set, and signal light waves of the plurality of channels to be multiplexed are arranged on one of the shorter wavelength side and the longer wavelength side outside the guard band.