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.

A hyperspectral radiometer may comprise one or more antennas, a electro-optical modulator modulating the received RF signal onto an optical carrier to generate a modulated signal having at least one sideband; a filter filtering the modulated signal to pass the sideband to a photodetector; and a photodetector producing an electrical signal from which information of the RF signal can be extracted. In some examples, the optical sideband may be spatially dispersed to provide a plurality of spatially separate optical components to the photodetector, where the spatially separate optical components having different frequencies and correspond to different frequencies of the received RF signal. In some examples, the passed sideband may be mixed with an optical beam having a frequency offset from the optical carrier to form a combined beam having at least one optical signal component having a beat frequency from which information of the RF signal can be extracted.

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 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 J.sub.1(), 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 J.sub.1(). The second RF drive signal is imposed onto a second optical signal with a modulator to generate a second modulated optical signal so that the modulator has a large-signal behavior that is characterized by a Bessel function of the first kind J.sub.1(), wherein the desired power at a frequency of the interference signal of the second drive signal is chosen to correspond to another zero of the Bessel function of the first kind J1(). The first and second modulated optical signal are combined with an optical power ratio that is selected to suppress third-order intermodulation distortion products in an electrical signal generated by detecting the optically combined first and second modulated optical signals.

An electronic device may include wireless circuitry that conveys radio-frequency signals at frequencies greater than or equal to 100 GHz using first and second optical local oscillator (LO) signals generated by clocking circuitry. The clocking circuitry may include a first laser that generates the first optical LO signal and a second laser that generates the second optical LO signal. First and second self-injection locking loop paths may be coupled around the first and second lasers respectively. The first loop path may include a first mixer, an optical reference, and a second mixer. The second loop path may include a photodiode, the first mixer, and the optical reference. The photodiode may provide a radio-frequency signal to the mixers. The optical reference may include an optical delay line or resonator and may reduce phase noise of optical signals used to self-injection lock the first and second lasers.

An optical communication system includes N optical modules at the local end. Each optical module includes a first optical interface and a second optical interface. A first optical interface of a first optical module in each of the N optical modules at the local end is connected to a peer end through a common optical fiber. A second optical interface of an i.sup.th optical module in the N optical modules at the local end is connected to a first optical interface of an (i+1)th optical module in the N optical modules at the local end, and i=1, 2, . . . , N1.

An apparatus and method is provided to correlate radiation beams, such as RF beams, optical beams, and/or acoustic beams. A plurality of sensors are distributed according to a first pattern and disposed adjacent to a first interference region. The plurality of sensors may capture incoming radiation and convert the incoming radiation to a plurality of signals. A plurality of radiating elements are distributed according to a second pattern that differs from the first pattern and are disposed adjacent to a second interference region. A plurality of channels are connected between the sensors and the radiating elements, each channel connecting a corresponding sensor to receive a corresponding signal. Each of the radiating elements is in communication with a corresponding one of the plurality of channels to provide an outgoing radiation corresponding to the signal received by the channel. The second pattern has a relationship to the first pattern such that first and second beams of incoming radiation in the first interference region captured by the plurality of sensors are respectively mapped to corresponding first and second beams of outgoing radiation emitted by the plurality of radiating elements into the second interference region.

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.

An optical imaging system and method that reconstructs RF sources in k-space by utilizing interference amongst modulated optical beams. The system and method involves recording with photodetectors 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.

A novel device, system and method is disclosed for transmitting audio from a wireless audio device to wireless headphones and/or speakers (or combination thereof) via a combination of digital and analog, one and/or two way, radio frequency and infrared wireless technologies for the purposes of providing entertainment for one or more listeners using the headphones or speakers with internal or external battery or power supply and one or more integrated power connections for the wireless audio device or other devices.