Abstract: STM traffic, e.g. voice and video telephony (VT), as well as packet mode (e.g. ATM) traffic, e.g. broadcast digital video, interactive television, and data, are transmitted via a multiple access broadband fiber/coaxial cable network. Customer premises equipment (CPE) at stations, and a bandwidth controller, which may be at a head end or central office, with which all stations communicate, work together to adapt to the changing demands of the traffic mix, and efficiently allocate bandwidth to a variety of bursty and isochronous traffic sources. The bandwidth allocation defines two types of time slots, STM and ATM, and divides each frame into two corresponding STM and ATM regions. The boundary between the regions can be changed dynamically. A contention access signaling channel is provided in the STM region, for call control and set-up requests.

Abstract: A Sagnac gate-based self-routing optical signal switching node demultiplexes each channel of data bits of an N channel multiplexed optical data signal to one of a plurality of output terminals in accordance with the routing bit(s) of each data channel received in the N channel multiplexed optical data signal. In one embodiment, each data channel includes multiple routing bits enabling greater demultiplexer selectivity.

Abstract: An optical regenerator includes a clock recovery circuit which recovers an optical clock signal from a received deteriorated optical data signal. The recovered optical clock signal is used to generate a new optical clock signal. The new optical clock signal and the received deteriorated optical data signal are applied as an input signal and control signal, respectively, to a Sagnac switch which encodes the new optical clock signal with the encoded information of the deteriorated optical data signal thereby regenerating a clean optical data signal.

Abstract: An optical crossbar exchange arrangement is implemented using a modified Sagnac switch. During the absence of a control signal, two separately numbered inputs are coupled to the same numbered outputs of the Sagnac switch (i.e., input1 to output1, etc.). During the presence of a control signal each of the two numbered inputs are switched and are coupled to a different numbered output (e.g., input1 to output2, etc.).

Abstract: An optical linear feedback shift register arrangement includes an optical encoding means implemented using a modified Sagnac switch. The encoding means encodes a received optical clock signal with a value derived from an exclusive-or of a first and second delayed version of an encoded signal received, respectively, at a first and second control ports. The resulting encoded clock signal, appearing at an output port, is then coupled through a first delay means to said first control port and coupled through a second delay means to said second control port. In another arrangement, an optical communication system utilizes the above-described linear feedback shift register to encode a data signal at a transmitter location and uses an identical linear feedback shift register at the receiver location to decode the encoded data signal.

Abstract: An all-optical circulating shift register encodes a received optical clock signal with a value derived from an encoded optical signal received at a control port thereof. A data input to the shift register is used to modify an encoded optical signal. The resulting encoded clock signal, appearing at an output port, is coupled back to the control port. The shift register uses the encoded clock signal at the control port to encode a subsequently-received clock signal. In one embodiment, the optical shift register is implemented using a Sagnac switch having a feedback path coupled between an output port and a control port of the Sagnac switch.

Abstract: Transmission capabilities of optical fibers are enhanced with all-optical means for removing noise from signal pulses and for creating clean output pulses with specified characteristics. This is accomplished with a nonlinear interferometer that is designed to operate on an amplified optical signal in the manner of a threshold device. More specifically, the nonlinear interferometer is designed to have a relatively level region in its input/output transfer function in the neighborhood of the low input signal and in the neighborhood of the high input signal. Depending on the input signal characteristics, it is sometimes beneficial to design the interfereometer so that the nominal high level of the input signal falls approximately in the middle of its corresponding flat region. In another embodiment, a bandpass filter is included at the output of the interferometer to remove the excess bandwidth that is created by the preceding amplifiers and the interferometer itself.

Abstract: An optical switch employs a modified sagnac arrangement that includes a sagnac loop and a coupler for injecting a signal into the loop and developing thereby two signals that travel along the loop in opposite directions. The coupler has at least one signal port that is accessible from outside the switch. In addition, a coupler is included to inject a pump signal into the loop to travel through the loop only in one direction. The loop is made of, or comprises, a material that has a controllable propagation speed. More particularly, the propagation speed in the material is a function of, for example, the intensity of the pump signal. The switch action is attained when the applied signals are in the form of pulses with pulse widths and relative positions are controlled to achieve a particular interaction. The switch action is observed by sending a pulse down a sagnac loop and observing its return.