Abstract: A colorimetric sensor including: a substrate; and a periodic array of nanostructures provided to the substrate, wherein the periodic array of nanostructures is configured to provide a change in color based on a medium being within a predetermined distance of the colorimetric sensor. The periodic array of nanostructures may be configured (width, height, spacing) to provide optical wave-guide properties or surface Plasmon resonance in order to effect a distinct change in color based on the medium being sensed. In some cases, the colorimetric may include a reflective surface to reflect light from the sensor. Further, the reflective surface may be metallic.

Abstract: Semiconductor devices having various combinations of curved waveguides and mode transformers are described. According to some exemplary embodiments, the mode transformer itself can be fabricated as all or part of the curved waveguide. For these exemplary embodiments it can be beneficial to use mode transformers whose active regions are relatively small to minimize losses associated with the introduced curvature, e.g., mode transformers that employ resonantly coupled waveguides and a tapered active waveguide in the mode transformation region. According to other exemplary embodiments, the mode transformer can be disposed along a straight portion of the waveguide, e.g., between the curved portion of the waveguide and the back facet. The present invention also provides flexibility in manufacturing by permitting different types of devices to be generated from a wafer depending upon where the devices are cleaved.

Abstract: A semiconductor optical amplifier (SOA) with efficient current injection is described. Injection current density is controlled to be higher in some areas and lower in others to provide, e.g., improved saturation power and/or noise figure. Controlled injection current can be accomplished by varying the resistivity of the current injection electrode. This, in turn, can be accomplished by patterning openings in the dielectric layer above the current injection metallization in a manner which varies the series resistance along the length of the device.

Abstract: A semiconductor optical amplifier (SOA) has an overall gain that is substantially polarization independent, i.e., less than 1 dB difference between transverse electric (TE) and transverse magnetic (TM) gain. The SOA includes gain and polarization rotation functions integrated onto a single substrate. According to one exemplary embodiment, a passive polarization rotation section is disposed between two active gain sections.

Abstract: A semiconductor optical amplifier (SOA) has an overall gain that is substantially polarization independent, i.e., less than 1 dB difference between transverse electric (TE) and transverse magnetic (TM) gain. The SOA includes a residual cladding layer having different thicknesses over different portions of the gain section. Over a first portion of the gain section, the residual cladding layer is thinner than over a second portion of the gain section. This results in the first portion providing more gain to optical energy having a TE polarization state than optical energy having a TM polarization state. In the second portion of the gain section, however, more gain is provided to optical energy having a TM polarization state than energy having a TE polarization state. The resulting gain differences can be designed to offset one another so that the output has a gain that is substantially polarization independent.

Abstract: Semiconductor devices having various combinations of curved waveguides and mode transformers are described. According to some exemplary embodiments, the mode transformer itself can be fabricated as all or part of the curved waveguide. For these exemplary embodiments it can be beneficial to use mode transformers whose active regions are relatively small to minimize losses associated with the introduced curvature, e.g., mode transformers that employ resonantly coupled waveguides and a tapered active waveguide in the mode transformation region. According to other exemplary embodiments, the mode transformer can be disposed along a straight portion of the waveguide, e.g., between the curved portion of the waveguide and the back facet. The present invention also provides flexibility in manufacturing by permitting different types of devices to be generated from a wafer depending upon where the devices are cleaved.

Abstract: An optical device is provided comprising a gain section adapted to emit radiation at a radiation wavelength, a coupling section adjacent to the gain section for transitioning radiation between an active waveguide and a passive waveguide, and a passive section adjacent to the coupling section supporting a single-lobed optical mode in the passive waveguide at the radiation wavelength. The passive waveguide has an index of refraction and dimension such that the confinement of the radiation within the active waveguide in the gain section is reduced.

Abstract: An optical device is provided comprising a gain section adapted to emit radiation at a radiation wavelength, a coupling section adjacent to the gain section for transitioning radiation between an active waveguide and a passive waveguide, and a passive section adjacent to the coupling section supporting a single-lobed optical mode in the passive waveguide at the radiation wavelength. The passive waveguide has an index of refraction and dimension such that the confinement of the radiation within the active waveguide in the gain section is reduced.