A photonic synthesizer includes a multifrequency optical source to produce a signal of interest from a pair of lasers, which may be self-injection locked chip lasers. The signal is referenced to a high frequency clock using a photonic mixer/divider based on an electro-optical modulator and a relatively slow photodiode. The electro-optical modulator produces optical harmonics from the beams from the pair of lasers, where one harmonic from the first laser beam and one harmonic from the second laser beam beat on the photodiode. A phase locked control signal is generated for controlling the output frequency of one or both of the two lasers. The output signal of the photonic synthesizer is generated using a relatively fast photodiode based on a difference in frequencies of the pair of lasers. The output signal may be a millimeter wave-band signal. The photonic synthesizer can be formed as a photonic integrated circuit (PIC).

The present application relates to radio detection and ranging (radar) systems and, in particular, to a radar system having a photonics-based signal generator. Such a radar system comprises a stepped-frequency optical signal generator, an optical-to-electrical converter, and a transmitter. The stepped-frequency optical signal generator is configured for converting an optical signal into a stepped-frequency optical signal. The optical-to-electrical converter for converting the stepped-frequency optical signal into a stepped-frequency electrical signal. The transmitter for transmitting a microwave signal based on the stepped-frequency electrical signal.

A sensing system. In some embodiments, the system includes a first imaging radio frequency receiver, a second imaging radio frequency receiver, a first optical beam combiner, a first imaging optical receiver, a second optical beam combiner, and an optical detector array. The first optical beam combiner may be configured to combine optical signals of the imaging radio frequency receivers. The second optical beam combiner may be configured to combine the optical signals of the imaging radio frequency receivers, and the optical signal of the first imaging optical receiver.

An optoelectronic emitter with a phased array antenna on a photonic chip includes a power splitter, an array of phase shifters and elementary emitters, and an integrated control device. The integrated control device includes an interferometric focusing lens, the entrance and exit faces of which are curved and define a free propagation region with a homogeneous refractive index. Input waveguides are connected to the entrance face orthogonal thereto and have an effective index for the guided modes adapted such that the optical paths of the input waveguides are identical to each other.

The application provides an optical network apparatus and an optical module. The optical network apparatus is configured to: convert, by a processing chip, the received N electrical signals from a board interface chip into a first electrical signal and a second electrical signal; and send the above two electrical signals to a first optical transmission component and a second optical transmission component, respectively; convert, by the first optical transmission component, the first electrical signal into a first optical signal; and convert, by the second optical transmission component, the second electrical signal into a second optical signal. The N to-be-sent electrical signals are combined, and only two optical transmission components are connected to the processing chip. Therefore, the processing chip does not need to be connected to four optical transmission components, fewer optical transmission components are required, and costs are reduced.

Embodiments of the present invention comprise a signal processing method and apparatus for use in a satellite payload in which an input RF signal received at a receiver antenna is modulated by using a single optical carrier at the input of an optical modulator. The optical domain signal is processed and is subsequently combined with a single unmodulated optical LO tone to provide an output RF signal for radiation by a transmitter antenna or for further digital processing by an on-board processor. This results in a clean generation of the frequency-converted RF signal at the output of the opto-electrical conversion stage.

An RF transmitter comprising an optical source configured to generate a pair of optical lines separated by an RF carrier frequency. The transmitter may comprise a graphene photodetector having at least two electrical contacts; a transmit antenna coupled to a first of the electrical contacts; and an electrical data signal input connected to a second of the electrical contacts. The graphene photodetector is illuminated by the optical source; it may comprise a graphene photo-thermal effect (PTE) photodetector or a bolometric photodetector. A corresponding receiver is also described.

In a general aspect, a communication system comprises a first station and a second station. The first station includes a photonic crystal maser, a laser subsystem, and a tracking subsystem. A photonic crystal structure of the photonic crystal maser is formed of dielectric material and has an array of cavities and an elongated slot. The elongated slot is disposed in a defect region of the array of cavities. The photonic crystal maser also includes a vapor disposed in the elongated slot and operable to emit a target RF electromagnetic radiation in response to receiving an optical signal. The array of cavities and the elongated slot define a waveguide configured to form the target RF electromagnetic radiation, when emitted, into a beam. The second station includes a receiver configured to couple to the beam of target RF electromagnetic radiation.

A distributed antenna system comprises a first access unit and a remote unit, wherein the first access unit and the remote unit are coupled via an analog optical fiber, and the first access unit comprises: a first port configured to receive a first downlink analog radio frequency signal; a first analog-to-digital conversion unit configured to perform analog-to-digital conversion on the first downlink analog radio frequency signal to generate a first downlink digital signal; a first digital processing unit configured to perform digital signal processing on the first downlink digital signal to generate a second downlink digital signal; a first digital-to-analog conversion unit configured to perform digital-to-analog conversion on the second downlink digital signal to generate a second downlink analog radio frequency signal; and an analog optical module configured to perform electro-optical conversion on the second downlink analog radio frequency signal to generate a first downlink analog optical signal.

A method of RF signal processing comprises receiving an incoming RF signal at each of a plurality of antenna elements that are arranged in a first pattern. The received RF signals from each of the plurality of antenna elements are modulated onto an optical carrier to generate a plurality of modulated signals that each have at least one sideband. The modulated signals are directed along a corresponding plurality of optical channels with outputs arranged in a second pattern corresponding to the first pattern. A composite optical signal is formed using light emanating from the outputs of the plurality of optical channels. Non-spatial information contained in at least one of the received RF signals is extracted from the composite signal.