Abstract: An optical transmission system is provided, which permits high-precision optical transmission of a signal even if the signal has a high accurate timing, an indefinite period, and a DC component. The transmitting side is provided with a rise edge detecting circuit 1 for detecting the rise edge of a transmitting signal waveform, a transmitting pulse generating circuit 2 for generating a transmitting pulse signal (b) constituted by a pair of opposite-polarity pulses inverting their polarities at the detected timing, and a light intensity modulation circuit 3 for generating a light intensity modulated signal (c) based on the pulse signal (b). The receiving side is provided with an AC-coupled receiving circuit 4 for receiving the light intensity modulated signal (c) and extracting therefrom only an AC component, and a discrimination circuit 5 for discriminating the rise timing from the received signal.

Abstract: A method and apparatus is provided for dispersion mapping that yields improved transmission performance for optical transmission systems by providing a more optimal balance between the reduction of both accumulated chromatic dispersion and nonlinear mixing. In particular, the chromatic dispersion is arranged on both a short length scale (within one amplification period) and a long length scale so that the average dispersion returns to zero. The dispersion management within one fiber span is arranged so that the magnitude of the dispersion is large in the section of the fiber span in which the optical power is large and is small in the section of the fiber span in which the optical power is small. This arrangement reduces both the amount of nonlinear mixing and the accumulated chromatic dispersion within the given fiber span.

Abstract: Loss of optical signal is detected in a synchronous communications system by detecting features of a monitor signal occurring at a detection frequency corresponding to the frame rate. Since the frame rate is substantially less than the bit rate, monitoring and detection can be performed at a lower bandwidth than the bit rate. An auto-correlation circuit utilises delays which are an integral multiple of the frame rate and produces a detection value which is compared with a threshold value. Alternatively, detection may be based on a power measurement of a band pass filtered monitor signal by setting the lower bandwidth limit above zero frequency and normalizing the measurement of power relative to an average power measurement. A loss of signal may then be detected by a change in power measurement relative to a threshold and can be used for asynchronous systems as well as synchronous systems.

Abstract: An optical address decoder, and an associated method for routing optical data packets. One embodiment of the decoder includes a plurality of waveguides, and semireflective elements that define, within each waveguide, a resonant cavity, each resonant cavity being of a different length. Addresses are encoded as equal spacings of sequences of optical pulses. An address to be decoded is directed simultaneously to all waveguides. Resonance is set up only in the waveguide whose resonant cavity matches the optical pulse spacing of the address. Another embodiment of the decoder includes a plurality of waveguides of different lengths, with the length difference between adjacent waveguides corresponding to a certain propagation time interval. Each waveguide terminates in an optoelectronic detector. Addresses are encoded as patterns of bits spaced according to this propagation time interval, with optical pulses representing "1" bits. An address to be decoded is directed, bit by bit, simultaneously to all waveguides.

Abstract: This invention disclosure describes the application of a polarization insensitive acoustically-tuned optical filter used in a multichannel WDM system to equalize variations in the power level of the WDM channels. The invention also describes a simple means for providing a low frequency control system which enables the equalizer to determine the signal levels of N optical carriers prior to equalizing the signals.