Abstract: A wave division multiplexing system in which low frequency intensity modulation of the optical channels is avoided in order to reduce or substantially prevent inter-channel cross-talk of low frequency telemetry signals by phase modulating the low frequency telemetry signal so as to recover the transmitted signal at the receiver. The system includes multiple transmitters and receivers. Each transmitter includes an optical source, such as a laser, a radio frequency generator having a low frequency telemetry signal impressed thereon, and an optical phase modulator. The phase modulated low frequency telemetry signal generated by each transmitter is combined using a multiplexer before being amplified and transmitted through a single optical fiber. A demultiplexer receives the transmitted signal and separates it into respective optical channels based on the particular frequency of each transmitter. Respective signals for each optical channel are transmitted to an associated receiver.

Abstract: A non-mechanical electrically adjustable delay device which does not suffer from interruptions in impedance inherent in multiple-tap delay lines. The wide band electrical delay line is capable of delaying a wide band of signals without significant distortion, e.g., up into the microwave range, and allows continuous transmission of a signal between the input port and the output port. The exemplary wide band electrical delay line comprises two transmission lines, preferably parallel to one another, and having different propagation velocities. A plurality of electrical cross connect circuits are connected between the two transmission lines. The electrical cross connect circuits are spaced along the lengths of the two transmission lines, e.g., preferably to form evenly spaced distances therebetween. The total delay through the wide band electrical delay line is adjusted by selectively activating an appropriate one of the plurality of cross connect circuits between the two transmission lines.

Abstract: A hybrid tunable Bragg laser including a double heterostructure gain section, a Bragg reflector section optically coupled to said gain section, and an optical extension constructed to yield a plurality of longitudinal modes. Preferably, the optical section has a predetermined length and effective reflectivity adapted to yield the plurality of longitudinal modes.

Abstract: An apparatus and method which utilize polarization diversity detection to compensate for polarization-mode dispersion (PMD) introduced in an optical signal propagating over a medium such as optical fiber. A received optical signal is separated into first and second polarization components by a polarization beam splitter (PBS). A control signal corresponding to a phase difference between the polarization components is used to drive at least one polarization controller located in the optical signal path before the PBS, such that the two polarization components are aligned with the PSPs of the received optical signal. The control signal may also be used to adjust a variable delay element such that phases of the two polarization components are aligned before the components are combined to provide a PMD-compensated output signal.