Abstract: A WDM receiver that includes a single, delay interferometer coupled to an N-channel wavelength-demultiplexing filter provides for the simultaneous conversion of a multiplex of N differential-phase-shift-keyed modulated optical signals of different wavelengths into N intensity-modulated optical signal channels. The Nintensity-modulated optical signals may be individually detected by a bank of N photodiode circuits to recover the modulated data stream or used for optical amplification, regeneration, processing, control, or modulation.

Abstract: An optical transmission apparatus employing an FSK scheme is disclosed. The optical transmission apparatus includes a light generator arranged to generate a first tone signal having a first frequency and a second tone signal having a second frequency. The optical transmission apparatus also includes a light modulator including a second modulator for selectively outputting one of the first tone signal and the second tone signal input from the light generator according to input data.

Abstract: A receiving circuit stops a one shot timer from generating an output signal immediately after the output signal is outputted to an external entity until a predetermined stretch time elapses. With this arrangement, the receiving circuit will not generate a new output signal even if (i) noises generated by a voltage fluctuation of the output signal appear on an amplified signal immediately after the output signal is outputted (at the end of the output), and (ii) the value of the amplified signal exceeds a threshold value. Therefore, the receiving circuit can make sure that an unnecessary output signal will not be generated due to the noises.

Abstract: According the invention, a multiplexed light composed of a signal light of a signal wavelength, and a first route control light of a first route control wavelength different from the signal wavelength or a second route control light of a second route control wavelength different from the signal light and the first route control wavelength is incident to a demultiplexer. The demultiplexer demultiplexes the signal light of the signal wavelength, the first route control light, and the second route control light from the multiplexed light. An interferometer optical switch outputs the signal light from first output port according to the first route control light, and outputs the signal light from second output port according to the second route control light.

Abstract: The dispersion monitoring device of the present invention detects a change in dispersion caused in a system by performing the decision process of a received signal using a data flip-flop in which required decision phase and decision threshold are set, averaging the output signal of the data flip-flop using an integration circuit and determining a received waveform, based on a change in a level of an output signal from the integration circuit. In another preferred embodiment, a signal is inputted to a chromatic dispersion change sign monitor. If a chirping parameter is correctly set, residual chromatic dispersion shifts in the negative direction when the peak value of a received signal is large, and it shifts in the positive direction when the peak value of a received signal is small. Using this fact, optimum dispersion compensation is conducted.

Abstract: A laser communications system includes a wide-field sensor, configured to detect a first set of laser communications sources within a first field of view, a narrow-field sensor includes a tracking portion and a control portion configured to receive laser communications from a second set of laser communications sources within a second field of view, wherein the first field of view is larger than the second field of view, and wherein the second set of laser communications sources comprises at least a first source and a second source, and a redirection unit coupled to the narrow-field sensor configured to position the second field of view within the first field of view wherein the first receiving element is positioned in response to the first positioning signal for the first receiving element, and the second receiving element is positioned in response to the first positioning signal for the second receiving element.