Methods, devices and systems for providing accurate measurements of timing errors using optical techniques are described. An example timing measurement device includes an optical hybrid that receives two optical pulse trains and produces two or more phase shifted optical outputs. The timing measurement device further includes two or more optical filters that receive the outputs of the optical hybrid to produce multiple pulse signals with distinctive frequency bands. The device also includes one or more photodetectors and analog-to-digital converters to receive to produce electrical signals in the digital domain corresponding to the optical outputs of the hybrid. A timing error associated with the optical pulse trains can be determined using the electrical signals in digital domain based on a computed phase difference between a first frequency band signal and a second frequency band signal and a computed frequency difference between the first frequency band signal and the second frequency band.

Example embodiments disclose a tunable optical pair source (TOPS) configured to generate first and second output optical beams having respective first and second frequencies that are phase locked with each other. The TOPS may include a first laser, such as a tunable laser, configured to generate a first laser beam, a radio frequency (RF) oscillator configured to transmit an RF reference signal, a beam splitter in optical communication with the first laser, and an electro-optic modulator configured to modulate the second split beam with the RF reference signal to form a modulated beam having a first sideband comb comprising a plurality of harmonics. Additionally, the TOPS may include an optical filter configured to receive the modulated beam and output a filtered optical beam, and a second laser configured to generate a second laser beam at the second frequency, the second laser being configured to receive the filtered optical beam as a seed.

A common method of down converting a received RF signal mixes the received RF signal with a LO signal to create a beat signal. Exemplary embodiments can address multiple simultaneously received RF signals which beat within receiver electronics at frequencies similar to that of the down converted signals. An RF mixer is disclosed using a photonic circuit arranged to impose the RF signal and the LO signal onto separate optical beams. An arrangement provides a beam carrying the RF signal to a first optical input of a balanced photodiode receiver and another beam carrying the RF and LO signals to a second optical input of the balanced photodiode receiver. Any beat products formed between different RF signals will be cancelled out at the electrical output of the balanced photodiode receiver.

In certain embodiments, an apparatus includes a switch matrix and frequency band isolation circuitry. The switch matrix is configured to receive, at an input port, an electrical signal, which corresponds to a transmission signal received at antennas of an antenna array. The transmission signal corresponds to a transmission spatial sector of the array. The electrical signal includes first and second signal portions in first and second frequency bands, respectively, the electrical signal having been generated from an optical signal that corresponds to the transmission signal. The switch matrix is configured to direct, via an output port and in accordance with a control signal, the electrical signal to a first of multiple signal conversion paths.

An optical filter comprises an array of waveguides fabricated on an optical integrated circuit (PIC). The array comprises individual waveguides, each of which receive light inputs, e.g., individual taps of a multi-tap optical filter used in an interference cancellation circuit. Typically, the output(s) of the individual waveguides are located at an exit (edge) of the PIC. At least one second waveguide in the array is patterned on the PIC in a converged configuration such that the light transiting these waveguides co-propagates and interacts across given portions of the respective waveguides before exiting the waveguide array along a common facet, thereby generating or inhibiting one of intermodulation products, and harmonics. This structural configuration enables the generation of various modes of transmission at the PIC exit, enabling more efficient transfer of the energy, e.g., to an associated photodetector (PD) that provides conversion of the energy to the RF domain.

Devices, methods and systems for generating wideband, high-fidelity arbitrary radio frequency (RF) passband signals are described. A voltage tunable optical filter for arbitrary RF passband signal generation includes a first input configured to receive a broadband optical pulse train, a second input configured to receive a first control voltage representative of an amplitude signal, an electrooptic modulator to receive the broadband optical pulse train and the first control voltage, to modulate the broadband optical pulse train in accordance with the amplitude signal, and to produce two complementary optical outputs that form two arms of an interferometer, an optical delay component to impart an optical path difference into one of the complementary outputs of the electrooptic modulator, and a combiner or a splitter to receive two complementary optical outputs of the electrooptic modulator after impartation of the optical path difference and to produce an output interference pattern of fringes.

A system includes, in part, a multitude of RF receivers, a first optical modulator adapted to modulate an optical signal in accordance with a first data received by a first one of RF receivers to generate a first modulated signal, a second optical modulator adapted to modulate the optical signal in accordance with a second data received by a second RF receiver to generate a second modulated signal, and a first optical fiber adapted to carry the first and second modulated signals. The optical modulator may be a photodiode or a Mach-Zehnder modulator.

A system includes, in part, a first optical modulator adapted to modulate a first optical signal with a first data to generate a first modulated optical signal, a second optical modulator adapted to modulate a second optical signal with a first clock signal to generate a second modulated optical signal, an optical multiplexer adapted to multiplex the first and second optical signals to generate a multiplexed optical signal, and an optical fiber adapted to carry the multiplexed optical signal. The second optical signal has a second wavelength that is different from the first wavelength.

An optical imaging system and method that reconstructs RF sources in k-space by utilizing interference amongst modulated optical beams. In some examples, the system and method may record the interference pattern produced by RF-modulated optical beams conveyed by optical fibers having unequal lengths. The photodetectors record the interference, and computational analysis using known tomography reconstruction methods is performed to reconstruct the RF sources in k-space.

An optical frequency control device includes: a detection circuit to receive first light including a first frequency, receive second light including a second frequency, modulate the first light with a local oscillation signal, and detect a differential beat signal between the frequency of sideband light included in the modulated first light and the second frequency; a light source control circuit to change the second frequency by frequency-dividing the differential beat signal with a first frequency division number, by frequency-dividing a reference signal with a second frequency division number, and by outputting a phase error signal indicating a phase difference between the frequency-divided differential beat signal and the frequency-divided reference signal; and a signal processing unit to set each of the first frequency division number and the second frequency division number according to the set value of a frequency difference between the first frequency and the second frequency.