Abstract: A photodetector comprises a semiconductor substrate with entrance and reflecting faces formed at the substrate upper surface. The reflecting face forms an acute angle with the substrate surface and is positioned so that an optical beam transmitted through the entrance face into the substrate is internally reflected from the reflecting face toward the substrate upper surface. A photodetector active region is formed on the substrate upper surface and is positioned so that the reflected optical beam impinges on the active region. The photodetector may be mounted on a second substrate for receiving an optical beam from a planar waveguide formed on the second substrate or an optical fiber mounted in a groove on the second substrate.

Abstract: An optical apparatus comprises an optical device fabricated on a substrate, an external-transfer optical waveguide fabricated on the substrate and/or on the optical device, and a transmission optical waveguide. The optical device and/or the external-transfer waveguide are adapted for and positioned for transfer of optical power therebetween (end-transfer or transverse-transfer). The external-transfer waveguide and/or the transmission waveguide are adapted for transverse-transfer of optical power therebetween (mode-interference-coupled or adiabatic). The transmission waveguide is initially provided as a component mechanically separate from the substrate, device, and external-transfer waveguide. Assembly of the transmission waveguide with the substrate, device, and/or external-transfer waveguide results in relative positioning of the external-transfer waveguide and the transmission waveguide for enabling transverse-transfer of optical power therebetween.

Abstract: An optical apparatus comprises a semiconductor optical device waveguide formed on a semiconductor substrate, and an integrated end-coupled waveguide formed on the semiconductor substrate. The integrated waveguide may comprise materials differing from those of the device waveguide and the substrate. Spatially selective material processing may be employed for first forming the optical device waveguide on the substrate, and for subsequently depositing and forming the integrated end-coupled waveguide on the substrate. Spatially selective material processing enables accurate spatial mode matching and transverse alignment of the waveguides, and multiple device waveguides and corresponding integrated end-coupled waveguides may be fabricated concurrently on a common substrate on a wafer scale.

Abstract: A method for micro-hermetic packaging of an optical device comprises: forming a micro-hermetic cavity on a substrate; providing a transmission optical waveguide transferring optical power between the interior and the exterior of the micro-hermetic cavity; fabricating or mounting at least one optical device within the micro-hermetic cavity; enabling optical power transfer between the optical device and the transmission optical waveguide; and sealing the optical device within the micro-hermetic cavity. The micro-hermetic cavity may be fabricated of a size comparable to the optical device, and many such cavities may be simultaneously fabricated on a single substrate using wafer-scale processing. The transmission optical waveguide, electrical feed-throughs, and/or other monitoring/controlling components may be provided with the micro-hermetic cavity on the same substrate, or as a separate component and/or on a separate substrate.

Abstract: Formation of a substantially flat upper cladding surface over a waveguide core facilitates transverse-coupling between assembled waveguides, and/or provides mechanical alignment and/or support. An embedding medium may be employed for securing optical assemblies and protecting optical surfaces thereof. Structural elements fabricated with a low-profile core may be employed for providing mechanical alignment and/or support, aiding in the encapsulation process, and so forth.

Abstract: A fiber-optic-taper loop probe includes first and second fiber segments, first and second tapering segments, and a center taper segment. In a preferred embodiment, first and second fiber segments are about 125 ?m in diameter, and the center taper segment has a substantially constant diameter of about 2-5 ?m. The fiber-optic taper forms a loop, the center taper segment remaining substantially straight and opposite the crossing point of the loop. The loop is secured to a support structure to maintain its shape and facilitate positioning relative to an optical component to be tested. The fiber segments may be connected to an optical characterization system including one or more light sources, lasers, detectors, spectrometers, etc. The geometry of the loop enables transverse-optical-coupling of the loop probe with an optical component without undesirable contact between other portions of the loop probe and other portions of the optical component and/or substrate.

Abstract: A multi-layer laterally-confined dispersion-engineered optical waveguide may include one multi-layer reflector stack for guiding an optical mode along a surface thereof, or may include two multi-layer reflector stacks with a core therebetween for guiding an optical mode along the core. Dispersive properties of such multi-layer waveguides enable modal-index-matching between low-index optical fibers and/or waveguides and high-index integrated optical components and efficient transfer of optical signal power therebetween. Integrated optical devices incorporating such multi-layer waveguides may therefore exhibit low (<3 dB) insertion losses. Incorporation of an active layer (electro-optic, electro-absorptive, non-linear-optical) into such waveguides enables active control of optical loss and/or modal index with relatively low-voltage/low-intensity control signals. Integrated optical devices incorporating such waveguides may therefore exhibit relatively low drive signal requirements.

Abstract: A packaged fiber-coupled optical device comprises an alignment housing with a fiber retainer, optical fiber segment(s), and optical component(s) (on substrate(s) with fiber groove(s)). Upon assembly the protruding end(s) of the fiber segment(s) is/are positioned against the fiber retainer, and the fiber groove(s) is/are aligned with the protruding end(s) of the fiber segment(s). The fiber retainer urges the protruding end(s) of the fiber segment(s) into the fiber groove(s). The fiber groove(s) position the protruding end(s) of the optical fiber(s) seated therein for optical coupling with optical component(s). The alignment housing and/or a fiber subassembly may be configured for engaging a mating fiber-optic connector.

Abstract: A grating-stabilized semiconductor laser comprises a semiconductor laser gain medium, an integrated low-index waveguide, and a waveguide grating segment providing optical feedback for laser oscillation. The laser may be adapted for multi-mode or single-mode operation. A multiple-mode laser may oscillate with reduced power and/or wavelength fluctuations associated with longitudinal mode wavelength shifts, relative to Fabry-Perot lasers lacking gratings. A single-mode laser may include a compensator, wavelength reference, and detector for generating an error signal, and a feedback mechanism for controlling the compensator for maintaining the laser wavelength locked to the reference. The laser may include means for altering, enhancing, tuning, and/or stabilizing the waveguide grating reflectivity spectral profile. The laser may be adapted for optical transverse-coupling to another waveguide.

Abstract: An optical signal may be received into orthogonal linearly polarized modes of a transmission optical waveguide, the transmission waveguide including first and second transverse-coupling segments thereof. Optical signal polarized along one polarization direction may be substantially completely transferred from the transmission waveguide into a first transverse-coupled waveguide, the first transverse-coupled waveguide being optically transverse-coupled to the first transverse-coupling segment of the transmission waveguide. Optical signal polarized along the other polarization direction may be substantially completely transferred from the transmission waveguide into a second transverse-coupled waveguide, the second transverse-coupled waveguide being optically transverse-coupled to the second transverse-coupling segment of the transmission waveguide. The optical signals carried by the first and second transverse-coupled waveguides may be combined into a single waveguide.

Abstract: An alignment device includes an alignment member with one or more waveguide-alignment grooves, resonator alignment grooves, and/or an alignment groove for a second optical element such as a modulator. The various alignment grooves reliably establish and stably maintain evanescent optical coupling between the optical elements positioned therein. A method for assembling a resonant optical power control device may include: fabricating an alignment member with the alignment grooves; positioning and securing the optical elements in corresponding alignment grooves for optical coupling therebetween. Alignment grooves in the substrate and/or in one or more of the optical elements are fabricated at proper depths and positions and preferably with mating grooves and/or flanges to enable optical coupling without extensive active alignment procedures.

Abstract: A fiber-ring optical resonator comprises a transverse segment of an optical fiber differing from adjacent segments in at least one physical property (e.g., diameter, density, refractive index, chemical composition, etc) so that it may support a resonant circumferential optical mode and enable evanescent optical coupling between the circumferential mode and an optical mode of a second optical element. The resonator may be fabricated with alignment structure(s) for enabling passive alignment of the second optical element for evanescent coupling, and/or with structure for suppressing undesired modes and/or resonances. A fiber-ring resonator may form a portion of a resonant optical filter or modulator. A plurality of optically-coupled fiber-ring resonators (formed on one or more fibers) may provide tailored spectral properties.

Abstract: A method for cylindrical processing of an optical medium, including optical fiber and optical materials of substantially cylindrical form. The method of the preferred embodiments includes the steps of rotating an optical medium about a longitudinal relative rotation axis thereof relative to a processing tool; spatially selectively applying the processing tool to a portion of a surface of the optical medium in operative cooperation with relative rotation of the optical medium and the processing tool, thereby producing a patterned (i.e., spatially selective) structural alteration of the optical medium, the pattern including altered, differentially-altered and unaltered portions of the optical medium. Specialized techniques for spatially selectively generating the structural alteration may include masking/etching, masking/deposition, machining or patterning with lasers or beams, combinations thereof, and/or functional equivalents thereof.

Abstract: Optical components may be aligned for transverse-optical coupling by: fabricating a first optical component on a substrate; fabricating an alignment member on the substrate suitably positioned relative to the first optical component; and assembling a second optical component onto the alignment member, thereby establishing transverse optical coupling between the optical components. The substrate may preferably be substantially planar. The alignment member may mechanically engage the second optical component so as to accurately establish and stably maintain transverse optical coupling. The first optical component and the alignment member may preferably be fabricated on the substrate using precision spatially selective materials processing techniques. Transverse optical coupling between two optical components may be stably maintained by substantially embedding transverse-coupled portions of the components in a substantially solid substantially transparent low-index medium.

Abstract: A resonant optical filter includes first and second transmission waveguides and a resonator (including one or more evanescently coupled resonator segments). The resonator supports at least one circumferential resonant mode and is evanescently coupled to the waveguides. An optical signal entering the filter through a waveguide and substantially resonant with the resonator is transferred to the other waveguide, while an optical signal entering the filter and substantially non-resonant with the resonator remains in the same waveguide. Multiple resonator segments may be formed on a common resonator fiber and positioned for enabling coupling between them, resulting in a tailored frequency filter function. The resonators may include alignment structure(s) (flanges, grooves, etc) for enabling passive positioning and/or supporting first and second transmission waveguides, such as optical fiber tapers.

Abstract: A recessed area formed on a substrate surface is filled with heat sink material to form a heat sink. The heat sink material has thermal conductivity greater than that of the substrate. The heat sink may have a substantially flat surface substantially flush with the substrate surface. The substrate may further include: a planar optical waveguide formed thereon positioned for optical coupling with an optical device mounted on the substrate in thermal contact with the heat sink; and/or an electrical contact layer formed thereon positioned for establishing electrical continuity with an optical device mounted on the substrate in thermal contact with the heat sink. The electrical contact may also provide thermal contact between the device and heat sink. The substrate may further include a low-index optical buffer layer formed on its surface. Materials for the substrate, buffer layer, and heat sink may include silicon, silica, and diamond, respectively.

Abstract: A multi-layer laterally-confined dispersion-engineered optical waveguide may include one multi-layer reflector stack for guiding an optical mode along a surface thereof, or may include two multi-layer reflector stacks with a core therebetween for guiding an optical mode along the core. Dispersive properties of such multi-layer waveguides enable modal-index-matching between low-index optical fibers and/or waveguides and high-index integrated optical components and efficient transfer of optical signal power therebetween. Integrated optical devices incorporating such multi-layer waveguides may therefore exhibit low (<3 dB) insertion losses. Incorporation of an active layer (electro-optic, electro-absorptive, non-linear-optical) into such waveguides enables active control of optical loss and/or modal index with relatively low-voltage/low-intensity control signals. Integrated optical devices incorporating such waveguides may therefore exhibit relatively low drive signal requirements.