Abstract: A method for extended-pulse sampling includes providing a continuous-time signal comprising a frequency spectrum within a predetermined passband. The continuous time signal is sampled with a plurality of discrete sample pulses having a pulse shape in a time domain that is an impulse response of a filter having the predetermined passband. The plurality of discrete time samples of the continuous-time signal is then provided to an output.

Abstract: A multiple-input multiple output transmit and receive system includes a first antenna that transmits a first signal at a channel frequency that propagates in a first path and that simultaneously receives a pilot signal at the channel frequency with the transmitting the first signal at the channel frequency, where the pilot signal propagates in a second path. A single-channel duplex transmit-receive system is coupled to an output of the first antenna. A processor is coupled to an output of the single-channel duplex transmit-receive system and configured to determine channel state information of the first path at the channel frequency using the received pilot signal.

Abstract: A method of separating a desired signal from an undesired signal includes obtaining a total input signal comprising the desired signal and the undesired signal in a time domain occupying a time duration from time t1 to time t2 of a single symbol in the desired signal. A transform is performed of the total input signal wherein an output of the transform is a time domain signal representing the desired signal.

Abstract: An optical mode converter includes a silicon substrate and a silicon dioxide film deposited on a top surface of the silicon substrate. A lithium niobate waveguide positioned on the silicon dioxide film having a slab and a rib that both taper in a direction of beam propagation through the optical mode converter. A doped silicon dioxide waveguide is positioned on top of the lithium niobate waveguide and has a slab that tapers in the direction of the optical beam propagation through the optical mode converter. The optical mode converter expands an optical mode of the optical beam propagating through the optical mode converter from a first optical mode size to a second optical mode size.

Abstract: A wireless single-frequency-channel, full-duplex, full-time transmit and receive communication node includes an antenna that transmits a transmit signal over a wireless transmit channel and that receives a receive signal over a wireless receive channel. A communications processor includes a first port electrically coupled to the antenna and a second port electrically coupled to a transmit path where the transmit path connects the second port to the first port. A third port of communications processor is electrically coupled to a receive path that connects the first port to the third port. The communications processor is configured to pass the transmit signal in the transmit path to the first port and configured to pass the receive signal in the receive path from the first port to the third port such that the transmit signal and the receive signal occupy a same frequency channel and operate simultaneously in a same time slot.

Abstract: A same-aperture any-frequency simultaneously transmit and receive (STAR) system includes a signal connector having a first port electrically coupled to an antenna, a second port electrically coupled to a transmit signal path, and a third port electrically coupled to receive signal path. The signal connector passes a transmit signal in the transmit signal path to the antenna and a receive signal in the receive signal path. A signal isolator is positioned in the transmit signal path to remove a residual portion of the receive signal from transmit signal path. An output of the signal isolator provides a portion of the transmit signal with the residual portion of the receive signal removed. A signal differencing device having a first input electrically coupled to the output of the signal isolator and a second input electrically coupled to the third port of the signal connector subtracts a portion of the transmit signal in the receive signal path thereby providing a more accurate receive signal.

Abstract: A method and apparatus for efficiently modulating light includes forming a lithium niobate waveguide with a slab region and a ridge region to confine an optical mode traversing the optical modulator under the ridge region. An electro-optic polymer is formed on a top surface of the lithium niobate waveguide with the slab region and the ridge region having dimension sufficient to support an evanescent tail of the optical mode traversing the optical modulator under the ridge region during modulation. Light is applied to an input of the lithium niobate waveguide. A drive voltage is applied to the electro-optic polymer that modulates the light with the evanescent tail so that the mode expands into the electro-optic polymer material a length that provides a desired switching voltage-length product (V?*L).

Abstract: A method of interference suppression with intermodulation distortion mitigation includes processing an RF signal comprising an RF signal of interest and an RF interfering signal to produce a first and second RF drive signal each with a desired RF interference signal power and having a 90 degree relative phase. The first RF drive signal is imposed onto a first optical signal with a modulator to generate a first modulated optical signal so that the modulator has a large-signal behavior that is characterized by a Bessel function of the first kind J1(?), wherein the desired power at a frequency of the interference signal of the first drive signal is chosen to correspond to a zero of the Bessel function of the first kind J1(?).

Abstract: An optical mode converter includes a silicon substrate and a silicon dioxide film deposited on a top surface of the silicon substrate. A lithium niobate waveguide positioned on the silicon dioxide film having a slab and a rib that both taper in a direction of beam propagation through the optical mode converter. A doped silicon dioxide waveguide is positioned on top of the lithium niobate waveguide and has a slab that tapers in the direction of the optical beam propagation through the optical mode converter. The optical mode converter expands an optical mode of the optical beam propagating through the optical mode converter from a first optical mode size to a second optical mode size.

Abstract: A frequency-agnostic wireless radio-frequency front end includes a primary antenna that receives a desired receive signal and interference signals and transmits a desired transmit signal. A diversity antenna receives an internal interference signal and an external interference signal, and a desired receive signal. A receive front end has a first port electrically connected to the diversity antenna and a second port electrically connected to a transmit signal reference source and includes a cancelling circuit that removes the internal interference signal and the external interference signal and provides the desired receive signal to a third port. A transmit-and-receive front end generates the desired transmit signal and includes a connector that passes the desired transmit signal while simultaneously passing the desired receive signal and interference signals to a third port while at least partially blocking the desired transmit signal from propagating to the third port.

Abstract: A bi-directional signal interface includes a first and second port configured to pass transmit RF signals and receive RF signals. A MZI includes a first traveling wave electrode connected to the first bidirectional signal port and a second traveling wave electrode connected to the second bidirectional signal port. A coupler has an input connected to a transmit input port, a first output connected to the first traveling wave electrode, and a second output connected to a second end of the second traveling wave electrode. A laser provides an optical signal to the MZI. An optical filter is coupled to an output of the MZI and preserves the optical carrier and the modulation sideband at the second frequency and rejects the modulation sideband at the first frequency. A detector converts light received from the filter to the receive RF signal and a suppressed level of the transmit RF signal.

Abstract: Techniques are disclosed for magnification compensation and/or beam steering in optical systems. An optical system may include a lens system to receive first radiation associated with an object and direct second radiation associated with an image of the object toward an image plane. The lens system may include a set of lenses, and an actuator system to selectively adjust the set of lenses to adjust a magnification associated with the image symmetrically along a first and a second direction. The lens system may also include a beam steering lens to direct the first radiation to provide the second radiation. In some examples, the lens system may also include a second set of lenses, where the actuator system may also selectively adjust the second set of lenses to adjust the magnification along the first or the second direction. Related methods are also disclosed.

Abstract: Techniques are disclosed for optical distortion reduction in projection systems for scanning projection and/or lithography. A projection system includes an illumination system configured to generate illumination radiation for generating an image of an object to be projected onto an image plane of the projection system. The illumination system includes a field omitting illumination condenser configured to receive the illumination radiation from a radiation source and provide a patterned illumination radiation beam to generate the image of the object, wherein the patterned illumination radiation beam comprises an omitted illumination portion corresponding to a ridge line of a roof prism disposed within an optical path of the projection system.

Abstract: A method of interference suppression with intermodulation distortion mitigation includes processing an RF signal comprising an RF signal of interest and an RF interfering signal to produce a first and second RF drive signal each with a desired RF interference signal power and having a 90 degree relative phase. The first RF drive signal is imposed onto a first optical signal with a modulator to generate a first modulated optical signal so that the modulator has a large-signal behavior that is characterized by a Bessel function of the first kind J1(?), wherein the desired power at a frequency of the interference signal of the first drive signal is chosen to correspond to a zero of the Bessel function of the first kind J1(?).

Abstract: A photonically-sampled electronically-quantized analog-to-digital converter generates an optical signal comprising a series of optical pulses. The optical signal is split into a first and a second optical path. The split optical signal is detected in the first path and then the detected optical signal is converted to a reference digital signal. The split optical signal in the second path is modulated with an input RF signal and a plurality of demultiplexed RF-modulated optically-sampled signals is generated from the modulated optical signal. The plurality of demultiplexed RF-modulated optically-sampled signals is then pulse broadened, detected, and converted to a plurality of sampled-RF digital signals. The reference digital signal and the plurality of sampled-RF digital signals are digital signal processed to generate a digital representation of the input RF signal.

Abstract: A method of full-duplex cellular communications includes receiving a first signal transmitted by a first cellular device at a base station using a cellular uplink frequency in a cellular frequency band. A second signal is transmitted from the base station to the first cellular device using a cellular downlink frequency in the cellular frequency band simultaneously with the receiving the first signal transmitted by the first cellular device. A third signal is transmitted from the base station to a second cellular device using the cellular uplink frequency in the cellular frequency band simultaneously with the receiving the first signal transmitted by the first cellular device and simultaneously with the transmitting the second signal from the base station to the first cellular device.

Abstract: A method of interference suppression with intermodulation distortion mitigation includes processing an RF signal comprising an RF signal of interest and an RF interfering signal to produce a first and second RF drive signal each with a desired RF interference signal power and having a 90 degree relative phase. The first RF drive signal is imposed onto a first optical signal with a modulator to generate a first modulated optical signal so that the modulator has a large-signal behavior that is characterized by a Bessel function of the first kind J1(?), wherein the desired power at a frequency of the interference signal of the first drive signal is chosen to correspond to a zero of the Bessel function of the first kind J1(?).

Abstract: An electromagnetic interface having an impedance with a resistive and a reactive component generates an electromagnetic field in both the reactive near-field region and the radiating far-field. A sensing circuit generates voltage and/or current having at least one of real and imaginary components that are proportional to an electromagnetic field in at least one of the reactive near-field region and the radiating far-field region. An electromagnetic modifier minimizes the electromagnetic field in the reactive near-field region in response to the signal generated at the output of the electromagnetic sensor.

Abstract: A method of interference suppression with intermodulation distortion mitigation includes processing an RF signal comprising an RF signal of interest and an RF interfering signal to produce a first and second RF drive signal each with a desired RF interference signal power and having a 90 degree relative phase. The first RF drive signal is imposed onto a first optical signal with a modulator to generate a first modulated optical signal so that the modulator has a large-signal behavior that is characterized by a Bessel function of the first kind J1(?), wherein the desired power at a frequency of the interference signal of the first drive signal is chosen to correspond to a zero of the Bessel function of the first kind J1(?).

Abstract: A same-aperture any-frequency simultaneously transmit and receive (STAR) system includes a signal connector having a first port electrically coupled to an antenna, a second port electrically coupled to a transmit signal path, and a third port electrically coupled to receive signal path. The signal connector passes a transmit signal in the transmit signal path to the antenna and a receive signal in the receive signal path. A signal isolator is positioned in the transmit signal path to remove a residual portion of the receive signal from transmit signal path. An output of the signal isolator provides a portion of the transmit signal with the residual portion of the receive signal removed. A signal differencing device having a first input electrically coupled to the output of the signal isolator and a second input electrically coupled to the third port of the signal connector subtracts a portion of the transmit signal in the receive signal path thereby providing a more accurate receive signal.