Abstract: Apparatus including: a substrate layer having a substantially planar top surface; an optically conductive peak located and elongated on, and spanning a first thickness measured in a direction generally away from, the top surface; the optically conductive peak having first and second lateral walls each including distal and proximal lateral wall portions, the proximal lateral wall portions intersecting the top surface; and first and second sidewall layers located on the distal lateral wall portions, the sidewall layers not intersecting the top surface and spanning a second thickness that is less than the first thickness measured in the same direction.

Abstract: An apparatus and method for use in an adaptive optical equalizer including, in one embodiment an optical equalizer having an input and output coupled to receive an incoming optical signal and configured to generate an output optical signal by phase modulation and/or amplitude modulation of the receive optical signal in response to electronic control signals. A photodiode is configured to receive the output optical signal and generate an representative current signal. A control signal generator is configured to generate the electronic control signals in accordance with predetermined criteria and in response to the representative current signal from the photodiode. An interferometer is connected to receive the incoming and output optical signal from the optical equalizer, the differential amplifier is configured to receive electronic versions of outputs from the interferometer for generating a difference signal and supplying the difference signal to the control signal generator.

Abstract: A method for fabricating a bipolar transistor includes forming a vertical sequence of semiconductor layers, forming an implant mask on the last formed semiconductor layer, and implanting dopant ions into a portion of one or more of the semiconductor layers. The sequence of semiconductor layers includes a collector layer, a base layer that is in contact with the collector layer, and an emitter layer that is in contact with the base layer. The implanting uses a process in which the implant mask stops dopant ions from penetrating into a portion of the sequence of layers.

Abstract: An optical data transmission system and a method of communicating data. In one embodiment, the transmission system is part of an optical data communication system that includes: (1) an optical pulse transmitter configured to generate amplitude-modulated optical pulses at a fixed repetition rate, (2) an optical filter coupled to an output of the optical pulse transmitter, having a transmission notch at the fixed repetition rate and configured to filter the optical pulses and (3) an optical detector coupled to an output of the optical filter and configured to produce an output electrical signal representative of intensities of the optical pulses provided by the optical filter.

Abstract: An optical integrated circuit comprises a semiconductor body, a semiconductor optical waveguide located on the body, and a bipolar phototransistor located on and optically coupled to the waveguide. In a preferred embodiment, the base region of the transistor is configured to absorb radiation propagating in the waveguide, but the emitter and collector regions are both configured not to absorb the propagating radiation. In a further preferred embodiment, the waveguide is configured to guide the radiation along a propagation axis therein, and the transistor makes an elongated footprint along the waveguide, the footprint being elongated along the direction of the propagation axis. In another preferred embodiment, the footprint is at least three times longer along the propagation axis than along a direction perpendicular thereto.

Abstract: Apparatus including: a substrate layer having a substantially planar top surface; an optically conductive peak located and elongated on, and spanning a first thickness measured in a direction generally away from, the top surface; the optically conductive peak having first and second lateral walls each including distal and proximal lateral wall portions, the proximal lateral wall portions intersecting the top surface; and first and second sidewall layers located on the distal lateral wall portions, the sidewall layers not intersecting the top surface and spanning a second thickness that is less than the first thickness measured in the same direction.

Abstract: A method is provided for identifying a contaminant in a gaseous space. The method includes: generating a broadband optical waveform; shaping the optical waveform to match an expected waveform for a known contaminant; and transmitting the shaped optical waveform towards an unknown contaminant. Upon receiving a reflected optical waveform from the unknown contaminant, determining whether the unknown contaminant correlates to the known contaminant based on the reflected waveform.

Abstract: An optical digital-to-analog (D/A) converter and a method of optically converting digital data into analog form. In one embodiment, the optical D/A converter includes: (1) a splitter configured to receive and split an input coherent optical carrier into a plurality of mutually coherent optical carriers, (2) a switching stage coupled to the splitter and including a corresponding plurality of selector switches configured to pass or interrupt selected ones of the plurality of coherent optical carriers responsive to pattern bits, (3) an amplitude and phase offset stage coupled to the switching stage and including a corresponding plurality of amplitude and phase offset units configured to offset amplitudes or phases of passed ones of the plurality of mutually coherent optical carriers responsive to offset signals and (4) a combiner coupled to the amplitude and phase offset stage and configured to recombine the mutually coherent optical carriers to yield an optical output signal.

Abstract: A method for determining symbols PSK modulated on an optical carrier includes interfering a first polarization component of the modulated optical carrier and a reference optical carrier in a first optical mixer and interfering the first polarization component of the modulated optical carrier and the reference with a different relative phase in a second optical mixer. The method also includes sampling the interfered carriers from the first optical mixer to produce first digital sampled values and sampling the interfered carriers from the second optical mixer to produce second digital sampled values. The first and second digital sampled values of a sampling period form a first complex sampling value thereof. The method also includes offsetting a phase of a complex signal value corresponding to each first complex sampling value to correct for a phase error caused by a frequency offset between the modulated and reference optical carriers.

Abstract: A signal receiver, such as an RF-matched filter receiver, includes an optical source (e.g. a mode-locked laser) providing an optical signal, and a first optical modulator to modulate the optical signal with a received RF signal and provide a modulated optical signal. A second optical modulator modulates the modulated optical signal with a reference signal and provides a twice modulated optical signal. The modulators may be Mach-Zehnder Modulators (MZM) and/or Indium Phosphide (InP) modulators. An optical detector receives the twice modulated optical signal and provides a detected signal, and a processing unit receives the detected signal and extracts or measures cross-correlation between the received RF signal and the reference signal.

Abstract: A method for transmitting digital data includes splitting a coherent optical carrier having a subcarrier into mutually coherent optical carriers, producing corresponding sequences of phase shifts in each of the mutually coherent optical carriers, and then, interfering the mutually coherent optical carriers. The interfering produces an output optical carrier whose subcarrier has modulated inphase and quadrature components with a corresponding sequence of pairs of values. The pairs of values of the modulated inphase and quadrature phase components produced by the interfering correspond to a sequence of coordinate pairs for the signal points the 4-PSK 2D, 16-QAM 2D, or 16-PSK 2D constellation.

Abstract: Apparatus including: a substrate layer having a substantially planar top surface; an optically conductive peak located and elongated on, and spanning a first thickness measured in a direction generally away from, the top surface; the optically conductive peak having first and second lateral walls each including distal and proximal lateral wall portions, the proximal lateral wall portions intersecting the top surface; and first and second sidewall layers located on the distal lateral wall portions, the sidewall layers not intersecting the top surface and spanning a second thickness that is less than the first thickness measured in the same direction.

Abstract: The present invention provides an optical beamforming RF transmitter. In one embodiment, the optical beamforming RF transmitter includes an optical WDM splitter having an input and a plurality of outputs. The optical beamforming RF transmitter also includes an array of antennas, where each antenna has an optical input configured to drive the corresponding antenna, and an array of optical modulators, such that each modulator has an output connected to a corresponding one of the antennas and an input connected to one of the outputs of the optical WDM splitter. The optical beamforming RF transmitter further includes a mode-locked laser having an output optically coupled to the input of the optical WDM splitter.

Abstract: An optical digital-to-analog (D/A) converter and a method of optically converting digital data into analog form. In one embodiment, the optical D/A converter includes: (1) a splitter configured to receive and split an input coherent optical carrier into a plurality of mutually coherent optical carriers, (2) a switching stage coupled to the splitter and including a corresponding plurality of selector switches configured to pass or interrupt selected ones of the plurality of coherent optical carriers responsive to pattern bits, (3) an amplitude and phase offset stage coupled to the switching stage and including a corresponding plurality of amplitude and phase offset units configured to offset amplitudes or phases of passed ones of the plurality of mutually coherent optical carriers responsive to offset signals and (4) a combiner coupled to the amplitude and phase offset stage and configured to recombine the mutually coherent optical carriers to yield an optical output signal.

Abstract: An optical heterodyne receiver and a method of extracting data from a phase-modulated input optical signal. In one embodiment, the optical heterodyne receiver includes: (1) a photonic quadrature demodulator having first and second optical inputs and first and second electrical outputs and configured to generate at the first and second electrical outputs an in-phase signal and a quadrature-phase signal, respectively, in response to receiving a modulated optical signal at the first optical input and a reference optical oscillator signal at the second optical input, (2) a passive radio frequency single sideband demodulator coupled to the photonic quadrature demodulator and configured to extract at least one sideband of the in-phase signal or the quadrature-phase signal and (3) at least one analog-to-digital converter coupled to the passive radio frequency single sideband demodulator and configured to receive and sample the at least one sideband.

Abstract: Apparatus comprising: a first compound semiconductor composition layer doped to have a first charge carrier polarity; a second compound semiconductor composition layer doped to have a second charge carrier polarity and located on the first layer; a third compound semiconductor composition layer doped to have the first charge carrier polarity and located on the second layer; a base electrode on the second layer; and a spacer ring interposed between and defining a charge carrier access path distance between the base electrode and the third layer, the path distance being within a range of between about 200 ? and about 1000 ?. Techniques for making apparatus. Apparatus is useful as a heterobipolar transistor, particularly for high frequency applications.

Abstract: A receiver for coherent detection of a PSK modulated optical carrier includes an optical detector, digital-to-analog converters, and a digital module. The optical detector is configured to mix the modulated optical carrier with two phase components of a reference optical carrier and to produce analog output signals representative of optical signals produced by said mixing. The digital-to-analog converters are connected to receive the analog output signals and to produce digital signals from the received analog output signals. The digital module is connected to receive the digital signals and to perform one of compensating the received digital signals for a conjugate phase misalignment between the mixed components, extracting phase of the received digital signals, and estimating a frequency offset between the two carriers from the received digital signals.

Abstract: Microelectronic apparatus having protection against high frequency crosstalk radiation, comprising: a planar insulating substrate; an active semiconductor electronic device located over a first region of the insulating substrate; and a doped semiconductor located in a second region of the insulating substrate substantially surrounding the first region. Apparatus further comprising a dissipative conductor overlaying and adjacent to the doped semiconductor. Apparatus additionally comprising metallic test probe contacts making electrical connections with the active semiconductor electronic device. Application of the apparatus to dissipate crosstalk radiation having a center frequency within a range between about 1 gigahertz and about 1,000 gigahertz. Methods for making the apparatus.

Abstract: An optical integrated circuit comprises a semiconductor body, a semiconductor optical waveguide located on the body, and a bipolar phototransistor located on and optically coupled to the waveguide. In a preferred embodiment, the base region of the transistor is configured to absorb radiation propagating in the waveguide, but the emitter and collector regions are both configured not to absorb the propagating radiation. In a further preferred embodiment, the waveguide is configured to guide the radiation along a propagation axis therein, and the transistor makes an elongated footprint along the waveguide, the footprint being elongated along the direction of the propagation axis. In another preferred embodiment, the footprint is at least three times longer along the propagation axis than along a direction perpendicular thereto.

Abstract: A driver, e.g., for use with electro-optic (E/O) modulators. The driver is configured to generate a driving signal based on an electronic NRZ input data signal and an input clock signal. The driver converts the NRZ input data signal to an RZ format and produces an amplified RZ signal that can be applied to an E/O modulator. The amplification gain of the driver is adjustable to enable interfacing with different modulators. In one embodiment of the invention, the driving signal is generated based on a comparison between the NRZ input data signal and an offset clock signal generated from the input clock signal. The width of pulses in the driving signal, e.g., corresponding to logical “ones,” may be tuned by, e.g., changing the DC offset of the clock signal. The driver may be implemented as an ASIC configured to operate at the data rate of, e.g., 10 GBit/s.