Abstract: A wavelength division multiplexer utilizes an optical source in the form of at least two separate laser array components, each laser array component including a group of laser diodes operating at wavelengths that are spaced by a multiple of the pre-defined channel spacing of the multiplexer. This optical source thus generates a plurality of non-sequential optical signals that need to be re-ordered at some point along the signal path so that all of the signals are multiplexed onto a single output signal path. The multiplexer utilizes an arrayed waveguide grating (AWG) to combine the various optical signals, with a specialized apparatus for re-ordering the non-sequential wavelengths of the propagating plurality of N optical signals disposed either at the input or output of the AWG.

Abstract: The specification describes an optical integrated circuit for a wavelength division demultiplexer. The demultiplexer comprises an AWG filter comprising a waveguide grating array between multimoded coupler regions. Crosstalk in the optical signals from the demultiplexer is reduced by integrating a second AWG filter on each output waveguide. In an alternative embodiment the second filter is a generalized Mach-Zehnder (M-Z) interferometer filter employing multimode interference filter (MMI) coupler regions connected by a waveguide array.

Abstract: An optical filter, such as a wavelength-division multiplexer, demultiplexer, or optical router, in which several single-mode waveguides are coupled to the sides of an optical interaction region containing a wavelength dispersive element that collects light from one or more input waveguides inputting light to the interaction region and disperses it according to wavelength to one or more output waveguides outputting wavelength-separated light. According to the invention, a multi-moded waveguide is interposed between one or more of the single-moded waveguides and the optical interaction region. It has a predetermined length to create at one end a multiply peaked image of a singly peaked profile presented to it at the other end, thus being a multi-mode interference (MMI) filter that presents a flatter filter profile at the interface between the MMI and the optical interaction region and affords reduced filter sensitivity to wavelength drift of an optical signal.

Abstract: A birefringence-free semiconductor waveguide comprising on a substrate a plurality of layers some of which are in tensile strain with respect to the substrate and others of which are in compressive strain. Birefringent-free behavior with respect to a guided light signal traveling in the waveguiding structure and possessing a photon energy lower than the bandgap of the constituent waveguide layers is obtained when birefringence introduced into the individual layers of the waveguiding structure by the strain is sufficient to compensate for the intrinsic geometric modal birefringence of the waveguiding structure that exists in the case where all layers are not strained.