Abstract: A client signal received at an ingress interface is adapted to a higher-rate transport signal. Clock frequency acceleration is achieved by an M/N-multiplying PLL where the magnitude of M and N can be restricted without causing the rate of the resulting transport signal rate to deviate unacceptably from a nominal transport signal rate. Each frame of the transport signal has a payload section with a fixed number of transport payload bytes, each of which is either a dummy byte or a client byte. The number of client bytes per transport frame is within one byte of the number of client bytes actually received at the ingress interface during the duration of the frame. The designation of each frame as a low-fill frame or a high-fill frame is automatically regulated by checking the fill level of a memory element and is redundantly encoded by the ingress interface and transmitted to an egress interface as part of the frame.

Abstract: An optical apparatus for transfer of full-duplex data signals over an optical waveguide comprises electro-optic transducers, coupled to the optical waveguide at opposite ends thereof. The electro-optic transducers are responsive, in a first mode, to drive signal pulses to produce transmit optical signal pulses for transmission along the optical waveguide and responsive, in a second mode, to receive optical signal pulses detected by the electro-optic transducer means to produce detected signal pulses. Drivers, coupled to the electro-optic transducers, generate pairs of the drive signal pulses in response to each transmit bit of the data signals. Receivers, also coupled to the electro-optic transducers, generate receive bits of the data signals in response to at least one of each pair of the detected signal pulses.

Abstract: In methods and apparatus for controlling the D.C. bias point of a nonlinear device, asymmetric envelope modulation is applied to an input signal, and the nonlinear device is driven by the asymmetric envelope-modulated signal and a D.C. bias signal. A nonlinear characteristic of the device is monitored at the modulation frequency, and the D.C. bias signal is controlled in response to the monitored characteristic so as to reduce the monitored characteristic at the modulation frequency. The methods and apparatus are particularly useful for controlling the D.C. bias point of semiconductor diode lasers, in which case the monitored characteristic can be the light output of the laser or the voltage across the laser.

Abstract: A monolithically integrated structure comprises a laser diode, a photodetector diode and a reference diode which are monolithically integrated on a common substrate. The photodetector diode is optically coupled to the laser diode. The reference diode is substantially identical to the photodetector diode and optically decoupled from the laser diode. When substantially equal reverse biases are applied to the photodetector diode and the reference diode, the reference diode conducts a leakage current which can be used to substantially cancel the leakage current of the photodetector diode. The monolithically integrated structure may also include a modulator diode which is monolithically integrated on the common substrate and optically coupled to the laser diode. The monolithically integrated structure is useful in optical communications systems.

Abstract: An optical connector comprises two optical connector bodies, each carrying an optical element such as an optical fiber, a lens, an optical source or an optical detector. Each optical connector body has a guide formation extending in a direction transverse to the optical axis of its respective optical element and a stop means extending in a direction transverse to its respective guide formation. Sliding engagement of the guide formations guides relative movement of the connector bodies in a direction transverse to the optical axes to bring the stop means into engagement and the optical axes into alignment. The optical connector is particularly suited to optical interconnection of circuit boards slidably mounted in card guides.

Abstract: An optical connector comprises two optical connector bodies, each carrying an optical element such as an optical fiber, a lens, an optical source or an optical detector. Each optical connector body has a guide formation extending in a direction transverse to the optical axis of its respective optical element and a stop means extending in a direction transverse to its respective guide formation. Sliding engagement of the guide formations guides relative movement of the connector bodies in a direction transverse to the optical axes to bring the stop means into engagement and the optical axes into alignment. The optical connector is particularly suited to optical interconnection of circuit boards slidably mounted in card guides.