Abstract: A semiconductor pump laser comprises a ridge waveguide electro-optical structure, which converts a ridge injection current into light and an integrated wavelength selective facet reflector. This reflector controls the longitudinal modal operation of the pump laser. Specifically, the reflector comprises a first reflective structure for reflecting light to return through the ridge waveguide electro-optical structure. A second reflective structure provides wavelength-selective reflectivity when operating in combination with the first reflective structure. In other words, the phase of light reflected from the first and second reflective structures is such that the net reflectivity of the facet is wavelength selective, or favors certain wavelengths over other wavelengths.

Abstract: A phase modulator circuit and method for generating an output signal having individually positionable edges is described. The phase modulator includes a programmable pulse generator, such as an interval counter, a delay, or a ring oscillator for producing the output signal, and a control value source, such as a memory, for delivering a sequence of control values to the generator. The control values determine the time between successive output pulses. A programmable interval counter includes a free running counter, the output of which is compared to a control value, preferably stored as a modulo data value, to generate an output pulse. A first programmable delay circuit includes a ring oscillator having plural delay lines for fine control of edge positioning. To fully synchronize the delay circuit to a coarse control interval counter, the clock input to the interval counter can be provided by the ring oscillator.