Abstract: An inventive accelerometer includes a proof mass and a pair of vibrating sensors. An excitation-and-detection circuit drives one sensor at resonant frequencies f1 and F1, with f1?F1; a second excitation-and-detection circuit drives the other sensor at resonant frequencies f2 and F2, with f2?F2. The vibrational modes driven at the frequencies f1 and f2 are the same for each sensor; the vibrational modes driven at the frequencies F1 and F2 are the same for each sensor. Compressive or tensile loads oppositely applied by the proof mass to the vibrating sensors cause a difference frequency ?F=F1?F2 to vary monotonically with acceleration of the apparatus along a sensing axis, from which a measurement of acceleration can be generated.

Abstract: An inventive accelerometer includes a proof mass, vibrating sensors, and an excitation-and-detection circuit. The vibrating sensors are substantially identical, and each exhibits corresponding fundamental and higher-order vibrational modes characterized by corresponding fundamental and higher-order resonant mode frequencies. The excitation-and-detection circuit drives each corresponding vibrating sensor at one of its resonant mode frequencies f1 or f2; the vibrational modes driven at the frequencies f1 and f2 are the same for each sensor. Compressive or tensile loads oppositely applied by the proof mass to the vibrating sensors cause a difference frequency ?f=f1?f2 to vary monotonically with acceleration of the apparatus along the sensing axis. The excitation-and-detection circuit includes at least one low-pass filter with a low-pass cut-off frequency fLP that is less than ?f.

Abstract: An inventive accelerometer includes a proof mass and a pair of vibrating sensors. Excitation-and-detection circuits drive vibrational modes of one sensor at resonant frequencies f1, F1, and F?1, and drive those same vibrational modes of the other sensor at resonant frequencies f2, F2, and F?2. Compressive or tensile loads oppositely applied by the proof mass to the vibrating sensors cause difference frequencies ?f=f1?f2, ?F=F1?F2, and ?F?=F?1?F?2 to vary monotonically with acceleration of the apparatus along a sensing axis. A measurement of acceleration can be generated based at least in part on a linear or nonlinear function of one or more or all of f1, f2, F1, F2, F?1, or F?2, and can be generated using a trained neural network.

Abstract: A semiconductor device comprises a device substrate and a metal film, with first and second non-recessed areal regions separated by a recessed areal region. The metal film covers contiguously the recessed and non-recessed areal regions and transition surfaces joining them. A first transition surface includes metallized portions over which (i) the first transition surface is not parallel to the other transition surface, (ii) the first transition surface is inclined relative to the device substrate, and (iii) the metal film on the first transition surface is contiguous with adjacent metal film portions on the recessed and non-recessed areal regions. A portion of an optoelectronic device surface running parallel to an optical waveguide of the device can be left exposed by a metal film on the device. Light propagating transversely out of the waveguide through the exposed portion can be detected, measured, or imaged for non-destructive device characterization or testing.

Abstract: A semiconductor laser source includes a partial-grating DFB laser with two laser electrodes, one over the grating and the other between the grating and one end of the laser. Constant laser currents flow into the waveguide through the electrodes (typically different from each other) and produce laser output. A wavelength discriminator, an optical detector, and a wavelength-control circuit act as a wavelength-control feedback mechanism to generate a wavelength control current that flows through one laser electrode or the other, or through both electrodes with opposite polarities. Phase noise on the laser output can be reduced at modulation frequencies exceeding several hundred kHz up to one or several tens of MHz or more. The laser-wavelength can be swept while exhibiting reduced phase noise.

Abstract: A control circuit coupled to a light source and an optical modulator receives an electrical modulating signal with alternating active and idle temporal segments; the active temporal segments encode corresponding information. A portion of a source optical signal produced by the light source is transmitted by the modulator as the output optical signal. During idle temporal segments, the light source produces a non-zero source idle power level, and the modulator transmits at a constant idle transmission level. During active temporal segments, the light source produces a source average active power level, the modulator transmits at an average active transmission level that is higher than the idle transmission level, and the output optical signal is modulated in accordance with the electrical modulating signal, so that each active temporal segment of the output optical signal encodes the information of the corresponding active temporal segment of the electrical modulating signal.

Abstract: A modulated semiconductor laser source includes a waveguide on a semiconductor substrate; first and second reflectors; a laser electrode; an optical modulator; and a laser-electrode electrical circuit. The reflectors and a resonator segment of the waveguide define a laser resonator with laser output transmitted through the second reflector. The laser electrode is positioned over the resonator segment and a laser current flows through the laser electrode into the resonator segment to produce optical gain. The modulator receives and modulates the laser output, in response to a primary modulation signal, to produce a modulated output optical signal. The laser-electrode circuit is coupled to the laser electrode and derives from the primary modulation signal a laser-electrode secondary modulation current, optimized to reduce chirp in the modulated output signal, that flows through the laser electrode into or out of the resonator segment in addition to the laser current.

Abstract: A method of making an optical modulator by determining the material composition of the quantum well region in the waveguide portion of the modulator so that the modulator is transparent at a gain peak wavelength that is greater than the predetermined wavelength by a predetermined amount, and fabricating the modulator with the determined material composition.

Abstract: A semiconductor device comprising a substrate; a monolithic gain region disposed on the substrate and operable to produce optical gain in response to current injection, including a first electrode over a first portion of the gain region having a first length L1, with a first current I1 being applied; and a second electrode over a second portion of the gain region having a second length L2, with a second current I2 being applied; wherein I1/L1 is greater than I2/L2.

Abstract: An optical modulator including an information-containing radio frequency signal input; a semiconductor device having an optical input optically for receiving the coherent light beam, and a electrode connected to said radio frequency signal input and having a modulated bias potential so that current is generated in the second semiconductor device and extracted therefrom, while the coherent light beam is optically modulated by the signal changing the carrier density in the semiconductor device.

Abstract: A semiconductor device comprising a substrate; a monolithic gain region disposed on the substrate and operable to produce optical gain in response to current injection, including a first electrode over a first portion of the gain region having a first length L1, with a first current I1 being applied; and a second electrode over a second portion of the gain region having a second length L2, with a second current I2 being applied; wherein I1/L1 is greater than I2/L2.

Abstract: A hybrid silicon/III-V compound semiconductor laser device comprising a silicon substrate including a channel configured for silicide line formation as a function of current through the channel; so that the temperature of the laser device is adjusted to a predetermined level.

Abstract: A semiconductor device or an integrated circuit formed on a substrate with shunt disposed on the substrate in parallel with the device or circuit and designed to form a closed circuit or discharge path when the device is subjected to an electrostatic discharge pulse.

Abstract: A method of fabricating waveguide on a semiconductor substrate including an optical input at a first end region for receiving a continuous wave coherent light beam having a predetermined first beam profile, and a second end region opposite the first end region active layer for transferring the light beam with a predetermined second beam profile, including forming a sequence of layers including a bottom cladding layer, an active layer, and a top cladding layer on a semiconductor substrate; providing an appropriately configured mask over the region where a waveguide is to be formed; etching the semiconductor substrate down to the active layer thereby forming a partial waveguide structure; and re-growing the top cladding layer and the contact layer to the uniformly planar level of the top surface of the partial waveguide structure.

Abstract: An optical fiber data communications network in which an electro-optical transceiver couples a plurality of serial electrical data buses over a single bidirectional optical fiber link, and includes a controller that functions by oversampling the digital electrical signal on each of such buses, multiplexes them, and converts the signal into a high speed optical signal for transmission over an optical fiber.

Abstract: An optical modulator including an information-containing radio frequency signal input; a semiconductor device having an optical input optically for receiving the coherent light beam, and a electrode connected to said radio frequency signal input and having a modulated bias potential so that current is generated in the second semiconductor device and extracted therefrom, while the coherent light beam is optically modulated by the signal changing the carrier density in the semiconductor device.

Abstract: A tunable laser configured in a small package subassembly including a gain chip positioned in the interior space between first and second tunable filter subassemblies. The tunable laser is packaged in either a rectangular or cylindrical housing, with an electrical input interface positioned at one end of the housing.

Abstract: A tunable laser transmitter configured in a small package subassembly coupled to a printed circuit board. The tunable laser transmitter includes a housing with a volume formed by exterior walls. An electrical input interface is positioned at the first end of the housing. A first and a second optical output interface is positioned at the second end of the housing, the first output being configured to transmit a modulated optical beam, and the second output configured to transmit a cw beam to the local oscillator of an external receiver.

Abstract: An apparatus for analyzing, identifying or imaging an target including first and second laser beams coupled to a pair of photoconductive switches to produce CW signals in one or more bands in a range of frequencies greater than 100 GHz focused on and transmitted through or reflected from the target; and a detector for acquiring spectral information from signals received from the target and using a multi-spectral heterodyne process to generate an electrical signal representative of some characteristics of the target. The lasers are tuned to different frequencies and a frequency shifter in the path of one laser beam allows the terahertz beam to be finely adjusted in one or more selected frequency bands.

Abstract: A method of fabricating a semiconductor laser device by forming a semiconductor structure at least part of which is in the form of a mesa structure having a flat top. The steps include depositing a passivation layer over the mesa structure, forming a contact opening in the passivation layer on the flat top of the mesa structure; and depositing a metal contact portion, with the deposited metal contact portion contacting the semiconductor structure via the contact opening. The contact opening formed through the passivation layer has a smaller area than the flat top of the mesa structure to allow for wider tolerances in alignment accuracy. The metal contact portion comprises a platinum layer between one or more gold layers to provide an effective barrier against Au diffusion into the semiconductor material.