Abstract: Providing a common broadcast channel in a WDM (wavelength division multiplexed) system is accomplished by applying a pulsed light source to a dispersive delay line, and also applying the light source to each of M delay lines, such that the Mth delay line has a delay of (M-1) time slots, where M is a nonnegative integer representing the number of time slots to be provided for the broadcast channel. The dispersive delay line spreads the spectrum of the pulsed light source across the desired bandwidth of the WDM system to provide a wide-spectrum signal, and this wide-spectrum signal may then be modulated to provide a plurality of WDM channels. The M delay lines provide delayed pulses that may be modulated to provide a common broadcast channel for reception on a plurality of WDM receivers.

Abstract: Misfit strain-induced piezoelectric fields are achieved from a new class of asymmetric quantum well devices which employ a simplified strained layer semiconductor structure. In the simplified structure, at least a single intrinsic lattice-mismatched narrow bandgap layer is included in a wider bandgap p-i-n structure so that the field resulting from biaxial stress is opposed to the electric field in the diode. According to the structure chosen, the biaxial stress may be either biaxial tension or biaxial compression. In reverse bias operation, the p-i-n diode produces a characteristic "blue shift" of the quantum well absorption peaks. As a result of the induced fields and the "blue shift" property of the devices, devices exhibit good on-off contrast with relatively low applied power and exhibit reduced tolerances on the operating wavelength of incident light.