Abstract: A semiconductor modulator is disclosed which exhibits a negative alpha parameter at low operating bias. The device includes at least two barrier layers with a quantum well layer therebetween. An additional layer is formed adjacent to the quantum well layer, the additional layer having a bulk bandgap energy greater than the quantum well layer so as to form a stepped well between the barrier layers.

Abstract: The invention, in accordance with one aspect, is an optical assembly including a substrate, a light emitting device mounted over a major surface of the substrate and having a back face, at least one channel formed in the substrate near the back face of the light emitting device, and at least one photodetector optically coupled to the light emitted from the back face. The channel includes at least one surface adapted to receive a portion of the back face light and reflect it away from the photodetector so that the photodetector receives primarily direct light from the back face.

Abstract: The invention is an optical apparatus and method of fabrication wherein an optical device such as a semiconductor laser includes a grating and a waveguide optically coupled to the grating. At least a portion of the waveguide coupled to the grating has a width which varies along the length of the waveguide in such a manner as to broaden the spectral line width of light output from the device. The width can be varied according to linear, sinusoidal or saw-tooth functions. A broadened line width permits pumping of a Raman amplifier at a high power without inducing any significant Brillouin Scattering.