Abstract: A photonic integrated chip is configured as a transmitter-receiver chip. The photonic integrated chip includes a light emitter, a light detector, a multi-mode interference coupler, and a mode-filed adapter. The light emitted by the light emitter is guided to a core layer formed below the multi-mode interference coupler, and further to the mode-filed adapter for transmission of light to an optical fiber coupled with the photonic integrated chip. Similarly, light received by the mode-filed adapter from the optical fiber propagates to the core layer, and is guided by the multi-mode interference coupler into the light detector. The photonic integrated chip is utilized to realize a single-unit transmitter-receiver module for a fiber optic gyroscope circuit based on monolithic integration of photonics components via wafer fabrication on a substrate. The photonic integrated chip has a low fabrication cost, low size, and is robust.

Abstract: A mode field adapter (MFA) is disclosed. The MFA is tapered and includes a passive core region and an active core region separated by a distance. Further, the passive core region includes first and second passive layers that are separated by another distance. The MFA is configured to receive an optical signal from a first waveguide, and alter, for transmission to a second waveguide, an optical mode of the optical signal. The optical mode is altered based on the distance between the first and second passive layers, the distance between the active and passive core regions, and the tapering of the MFA. The optical mode is altered such that an optical loss associated with the optical signal traversing from the first waveguide to the second waveguide by way of the MFA is within a tolerance limit.

Abstract: A laser module includes a gain chip, temperature sensors, a case, and a thermoelectric cooler (TEC). The gain chip emits a laser beam. One of the temperature sensors measures a first temperature of the gain chip and is encompassed by the gain chip. The other temperature sensor is adhered to the case and measures a second temperature. The TEC tunes the laser beam emitted by the gain chip to a desired wavelength by varying the first temperature of the gain chip through a set of third temperatures for various values of the second temperature. The set of third temperatures is selected from various values of the first temperature such that the laser beam emitted at the set of third temperatures is mode-hop free.

Abstract: An optoelectronic device includes a semiconductor die that includes a substrate layer, a laser diode, first and second conducting pads, a cathode pad, an anode pad, and a passivation layer. The laser diode and the conducting pads are formed on the substrate layer. The formation of the conducting pads directly on the substrate layer offers an increased area for heat dissipation. The cathode pad is formed on the first conducting pad whereas the anode pad is formed above the second conducting pad. The passivation layer is formed above the laser diode. The attachment of the semiconductor die to a submount of the optoelectronic device occurs by way of the cathode pad and the anode pad. After the attachment, a free space is created directly between the passivation layer and the submount to reduce the impact of solder bonding stress on the laser diode.

Abstract: A photonic integrated chip is configured as a transmitter-receiver chip. The photonic integrated chip includes a light emitter, a light detector, a multi-mode interference coupler, and a mode-filed adapter. The light emitted by the light emitter is guided to a core layer formed below the multi-mode interference coupler, and further to the mode-filed adapter for transmission of light to an optical fiber coupled with the photonic integrated chip. Similarly, light received by the mode-filed adapter from the optical fiber propagates to the core layer, and is guided by the multi-mode interference coupler into the light detector. The photonic integrated chip is utilized to realize a single-unit transmitter-receiver module for a fiber optic gyroscope circuit based on monolithic integration of photonics components via wafer fabrication on a substrate. The photonic integrated chip has a low fabrication cost, low size, and is robust.

Abstract: A super luminescent light emitting diode includes an active waveguide that is grown using selective area epitaxy, a resistance array, and a contact pad. The active waveguide has a varying bandgap due to a width of the mask that is used for growing the active waveguide. The active waveguide is injected with varying current at each longitudinal section of the active waveguide due to varying resistance associated with the resistance array at each longitudinal section. The varying current is injected by the contact pad. The contact pad is a single continuous electrode. The varying bandgap and varying current at each longitudinal section of the active waveguide enable emission of optical light by each section of the active waveguide such that a combination of all the emitted light leads to emission of a super-broadband continuous spectrum and tailorable spectrum profile of the optical light.

Abstract: A superluminescent light emitting diode (SLED) includes an active layer that includes a set of mixed strain quantum wells. The set of mixed strain quantum wells includes a set of compressive strained quantum wells and a set of tensile strained quantum wells. A potential difference applied across the SLED causes movement of electron carriers and hole carriers towards the active layer. Radiative recombination of electron and hole pairs in the set of compressive strained quantum wells enables emission of laterally polarized light and radiative recombination of electron and hole pairs in the set of tensile strained quantum wells enables emission of vertically polarized light. A combination of the laterally polarized light and vertically polarized light results in the emission of incoherent light from the SLED.

Abstract: A photonic integrated circuit (PIC) includes various mode field adapters (MFAs), a waveguide, and various contact pads. All the MFAs are on a same facet of the PIC. One MFA of the PIC outputs a first optical signal that is an amplified version of a second optical signal. The waveguide is divided into two waveguide arms and a bend portion to join the two waveguide arms. The waveguide extends between the MFAs such that the second optical signal propagates through the waveguide. Further, each waveguide arm is formed between the contact pads. The second optical signal propagating through the waveguide is amplified based on a current that is injected in the PIC by way of the contact pads.

Abstract: A wafer-level semiconductor die attachment method includes placing a semiconductor die of a plurality of semiconductor dies at an initial placement position to overlap a sub-mount pad on a sub-mount of a pre-singulated wafer. A die pad of the semiconductor die comes in contact with a solder layer deposited over the sub-mount pad. The semiconductor die and the sub-mount include a plurality of die and sub-mount mating features, respectively. The solder layer is heated locally to temporarily hold the semiconductor die at the initial placement position. The pre-singulated wafer is reflowed, when each semiconductor die is temporarily held at the corresponding initial placement position. During reflow, each semiconductor die slides from the initial placement position and a contact is established between the corresponding plurality of die and sub-mount mating features. Thereby, each semiconductor die is permanently attached to the corresponding sub-mount.

Abstract: A method for manufacturing an optoelectronic assembly includes attaching an optical die, a first lens, a second lens, and an optical fiber to a sub-mount. The sub-mount includes a plurality of passive alignment features which aid in the passive alignment of the optical die, the first lens, and the optical fiber for attachment. The second lens is actively aligned between the first lens and the optical fiber, based on a coupling efficiency with which an optical signal emitted by the optical die is coupled into the optical fiber through the first and second lenses. The active alignment of the second lens includes calibration of at least one of a position and a degree of tilt of the second lens.

Abstract: A device for optical space switching in optical networks. The optical device comprises a broad area optical waveguide section having a number of electrodes extending over at least a portion of the length of the broad area optical waveguide section. The application of an electrical signal to an electrode causes a local change in effective refractive index of the broad area optical waveguide section, thereby causing light preferentially to propagate along a predetermined path in dependence on the configuration of the electrode. In particular the broad area waveguide device is implemented in indium phosphide (InP). Also described is a method for waveguiding in the optical device.

Abstract: The present invention relates to a semiconductor optical tap comprising: a multimode interferometer (MMI) (6); an input waveguide (1) coupled to the MMI; a first output waveguide (2) coupled to the MMI; and a second output waveguide (3) coupled to the MMI. The first and second output waveguides (2,3) overlap (d) such that unequal portions of light are coupled from the MMI into the first and second output waveguides (2,3). The input waveguide (1) and the first and second output waveguides (2,3) may have a rib structure. They may also be adiabatically tapered waveguides. The first and second output waveguides (2,3) may have different starting widths.

Abstract: In the present invention, a semiconductor device is formed which includes an MIM capacitor located on the upper surface of a heterostructure from which the emitter, base and collector sections of a nearby HBT are defined. In this way the capacitor and HBT share a substantially common structure, with the base and emitter electrodes of the HBT fashioned from the same metal layers as the upper and lower capacitor plates, respectively. Furthermore, as the insulator region of the capacitor is formed prior to definition of the HBT structure, the dielectric material used can be deposited by means of a plasma enhanced process, without damaging the HBT structure.

Abstract: The present invention relates to a semiconductor photodetector. The photodetector is a waveguide photodetector, which comprises: a waveguide (1,2,3) having a III-V ridge structure including an active layer (1); a semiconductor layer (4) deposited on top of the ridge structure; and, metal detector electrodes (not shown) on the surface of the higher refractive index semiconductor layer (4). The semiconductor layer (4) has a higher refractive index than the waveguide structure (1,2,3). The ridge structure is configured to widen along the length of the waveguide (1,2,3) such that light passing through the active layer (1) of the waveguide couples more efficiently up into the higher refractive index semiconductor layer (4).

Abstract: We propose a technique for fabricating stacked photonic lightwave circuits (PLCs), with both high and low refractive index steps, comprising the use of etched PECVD dielectric layers for the light guiding structures and which are surrounded and separated by an interlayer PLC cladding (IPC) comprising a non-conformal layer of sol-gel, whose composition, refractive index and thickness can be tailored to the requirements of the device.

Abstract: Disclosed is a strain relief interface for connecting a packaged optical device and an optical fibre. The optical fibre passes through a snout bore extending from a side wall of the package. The interface comprises two moulded jackets. The first moulded jacket surrounds, and is affixed to, a sheathed section of optical fibre from which a fibre jacket has been removed. A first end of the first moulded jacket is affixed to a fibre jacket that encases an adjacent section of optical fibre. A second end of the first moulded jacket is affixed to the snout bore and to a ferrule located within the snout bore. The second moulded jacket surrounds, and is affixed to, the first moulded jacket, a portion of the fibre jacket and the snout bore. Also disclosed is a method for fabricating a strain relief interface.

Abstract: The layer structure of a DC-PBH laser diode consists of an n-InP substrate (51), an n-InP buffer layer (52), an undoped-InGaAsP active layer (53), a p-Inp cladding layer (54), a p-InP current blocking layer (55), an n-InP current blocking layer (56), a p-InP cladding layer (57), and a p-InGaAsP contact layer (58). An additional layer of Fe-doped InP layer (55a) creates an acceptor level (Fe3+/Fe2+) near mid-band gap. The iron impurities are deep level traps, and will make the capacitance C2 less dependent of the impurity concentration of layer (56) which is normally doped with a concentration larger than 1×1018 cm−3 to lower the leakage current from p-InP blocking layer (57) to p-InP blocking layer (55) that does not contribute to light emission. The capacitance C2 and hence the overall capacitance Cp-n-p-n will be reduced with this Fe doped InP layer (55a) and consequently the displacement current through the current blocking structure during high speed operation will be lowered.

Abstract: There is provided a semiconductor laser comprising a gain section and an adjacent Bragg section, wherein output laser light is emitted via a facet at an interface between air and the gain section, the Bragg section comprising a distributed reflecting structure having a length substantially greater than required to ensure single longitudinal mode operation of the laser in which the side-mode suppression ratio (SMSR) is 35 dB or more, thereby in use substantially suppressing optical feedback from a facet at an interface between the Bragg section and air, and wherein an interface between the Bragg section and the gain section is quantum well intermixed, thereby rendering the interface substantially anti-reflecting at the wavelength of the laser.

Abstract: A wavelength locked tunable laser source comprising a tunable laser source, an optical reference source characterized by a frequency spectrum with two combs of discrete components of different spacing, an optical mixing device and feedback control circuitry. An optical output of the laser source is heterodyned with an output of the optical reference source at the optical mixing device to produce an electrical signal in dependence on a difference beat frequency of the two optical outputs, the feedback control circuitry being operative to process the electrical signal to provide a feedback signal which is used to tune the wavelength of the laser source so as to minimize the beat frequency and thereby substantially lock the wavelength of the laser source to a wavelength in the spectrum of the optical reference source. The use of an optical reference source with a spectrum comprising two frequency combs provides a mechanism for determining the absolute frequency to which the laser has been locked.

Abstract: The present invention relates to a semiconductor photodetector. The photodetector is a waveguide photodetector, which comprises: a waveguide (1,2,3) having a III-V ridge structure including an active layer (1); a semiconductor layer (4) deposited on top of the ridge structure; and, metal detector electrodes (not shown) on the surface of the higher refractive index semiconductor layer (4). The semiconductor layer (4) has a higher refractive index than the waveguide structure (1,2,3). The ridge structure is configured to widen along the length of the waveguide (1,2,3) such that light passing through the active layer (1) of the waveguide couples more efficiently up into the higher refractive index semiconductor layer (4).