Abstract: An Echelle grating has alternate first (1a) and second (1b) sets of facets (1). The first set of facets (1a) is operative to reflect incident light (4) for diffraction and the second set of facets (1b) extends between adjacent facets of the first set (1a). Only the first set of facets (1a) is metallized to enhance reflection. The second set of facets (1b) is left unmetallized. This configuration reduces polarization dependent loss (PDL).

Abstract: An optical performance monitor for measuring the performance of optical networks has an echelle grating for demultiplexing an input beam into a plurality of wavelengths that are focused onto an array of divided output waveguides. Each divided output waveguide is positioned to receive a corresponding demultiplexed wavelength from the echelle grating or other waveguide multiplexer device. The divided output waveguides laterally separate the corresponding demultiplexed wavelength into a first and second portions. A detector array is positioned to receive the respective portions of the demultiplexed wavelengths and by comparing their relative intensity it is possible to detect any drift in the nominal wavelengths of the channels.

Abstract: An Echelle grating has alternate first (1a) and second (1b) sets of facets (1). The first set of facets (1a) is operative to reflect incident light (4) for diffraction and the second set of facets (1b) extends between adjacent facets of the first set (1a). Only the first set of facets (1a) is metallized to enhance reflection. The second set of facets (1b) is left unmetallized. This configuration reduces polarization dependent loss (PDL).

Abstract: A method is desribed for controlling the pass band of an optical device wherein a phase mask is introduced to modify the shaped of an image produced by the photonic device.

Abstract: The method consists of creating a compensating region within the slab waveguide region, with effective TE and TM mode refractive indices of the compensating region higher than those of the original slab waveguide. Such change in refractive indices is achieved by deposition of an over-layer on the compensating region.

Abstract: Disclosed is an optical double pass equalizer for equalizing a wavelength division multiplexed (WDM) signal. The equalizer comprises a multiplexer/demultiplexer and multiple variable optical attenuators (VOAs) integrated on a single monolithic chip. The WDM signal is demultiplexed into individual wavelength channels by the multiplexer/demultiplexer and each wavelength channel is equalized by a corresponding VOA. The equalized wavelength channels are then multiplexed into an equalized WDM signal by the multiplexer/demultiplexer. This provides several advantages, including a reduction in required assembly and assembly cost, as well as an improved dynamic range in attenuation level or alternatively a reduction in power consumption for a fix attenuation level compared to a single pass VOA unit.

Abstract: A method is disclosed for polarization birefringence compensation in a photonic device with a slab waveguide having a core. A compensator region is formed in the slab waveguide to minimize the wavelength shift between light of different polarizations. A thin capping layer, typically of silicon nitride, having a higher refractive index than the core, is formed on the compensator region to increase the birefringence contrast between the compensator region and the planar waveguide.

Abstract: A method is disclosed for polarization birefringence compensation in a photonic device with a slab waveguide having a core. A compensator region is formed in the slab waveguide to minimize the wavelength shift between light of different polarizations. A thin capping layer, typically of silicon nitride, having a higher refractive index than the core is formed on the compensator region to increase the birefringence contrast between the compensator region and the planar waveguide.

Abstract: An optical performance monitor for measuring the performance of optical networks has an echelle grating for demultiplexing an input beam into a plurality of wavelengths that are focused onto an array of divided output waveguides. Each divided output waveguide is positioned to receive a corresponding demultiplexed wavelength from the echelle grating or other waveguide multiplexer device. The divided output waveguides laterally separate the corresponding demultiplexed wavelength into a first and second portions. A detector array is positioned to receive the respective portions of the demultiplexed wavelengths and by comparing their relative intensity it is possible to detect any drift in the nominal wavelengths of the channels.

Abstract: In a method of bandgap tuning of a quantum well heterostructure wherein ions are implanted in the heterostructure by ion implantation, the ions are implanted so that different regions are implanted in such a way as to create different concentrations of defects. This provides varying bandgap energies to various areas of the heterostructure during a subsequent thermal treatment, which removes residual defects and initiates intermixing in the quantum well region to result in a structure having a selectively shifted bandgap.

Abstract: An active semiconductor device that performs in a substantially polarization independent manner. A quantum well waveguide is intermixed by intermixing atoms across an interface between well and barrier layers. The atoms include at least 2 groups wherein intermixing of one group is at a substantially greater rate than another group. Cations are interdiffused at a greater rate than said anions across interfaces between well and barrier layers. The intermixing must be sufficient to provide strain within layers of the waveguide and sufficient to at least partially degenerate light hole and heavy hole bands of the structure. Preferably intermixing is sufficient to completely degenerate light hole and heavy hold bands to essentially produce a device that is completely polarization independent.

Abstract: A method of selectively tuning the bandedge of a semiconductor heterostructure includes repeatedly forming a disordered region that is spatially separated from a quantum well active region and subsequently annealing the heterostructure each time after the disordered region is formed, so that vacancies/defects in the disordered region diffuse into the quantum well region and enhance interdiffusion at the well-barrier heterojunctions. Repeating, the disordering followed by annealing allows for a greater range in bandgap tuning. The heterostuctures of interest are IH-V material systems, such as AlGaAs/GaAs, where the active region includes structures such as a single quantum well, a multiple quantum well, or a superlattice.