A radiation source for emitting terahertz radiation (6) is specified, comprising at least two laser light sources emitting laser radiation (11, 12) of different frequencies, and a photomixer (5) comprising a photoconductive semiconductor material (51) and an antenna structure (52), the photomixer (5) being configured to emit the laser radiation (11, 12) of the laser light sources (1, 2) and emitting terahertz radiation (6) with at least one beat frequency of the laser light sources, and wherein the at least two laser light sources are surface-emitting semiconductor lasers (1, 2) which are arranged in a one-dimensional or two-dimensional array on a common carrier (10).

Devices, methods for analog-to-digital converters (ADCs) that perform high-dynamic range measurements based on optical techniques are disclosed. In one example aspect, an optical encoder includes a polarization rotator configured to receive a train of optical pulses, and an electro-optic (EO) modulator coupled to an output of the polarization rotator. The EO modulator is configured to receive a radio frequency (RF) signal and to produce a phase modulated signal in accordance with the RF signal. The optical encoder also includes a polarizing beam splitter coupled to the output of the EO modulator; and an optical hybrid configured to receive two optical signals from the polarizing beam splitter and to produce four optical outputs that are each phase shifted with respect to one another.

An optoelectronic component for generating and radiating an electromagnetic signal exhibiting a frequency lying between 30 GHz and 10 THz referred to as a microwave frequency, comprises: a planar guide configured to confine and propagate freely in a plane XY a first and a second optical wave exhibiting an optical frequency difference, referred to as a heterodyne beat, equal to the microwave frequency, a system for injecting the optical waves into the planar guide, a photo-mixer coupled to the planar guide to generate, on the basis of the first optical wave and of the second optical wave, a signal exhibiting the microwave frequency, the photo-mixer having an elongated shape exhibiting along an axis Y a large dimension greater than or equal to half the wavelength of the signal, the injection system configured so that the optical waves overlap in the planar guide and are coupled with the photo-mixer over a length along the axis Y at least equal to half the wavelength of the signal, the photo-mixer thus being able to radiate the signal.

A digital signal processing, DSP, unit (10) for use in a coherent optical receiver for an optical communications network. The DSP unit comprises an adaptive equaliser (12) and a processing block (22). The equaliser (12) comprises input ports for receiving electrical signals, each corresponding to a different state of polarization of an optical signal received by the coherent optical receiver,and output ports,each connected to a processing branch (14). A processing branch comprises a symbol sequence estimator, SSE, (16) and a carrier phase estimator, CPE, (18) comprising an input for receiving signal taped from an output of the processing branch. An output of the CPE is connected to a phase adjuster (20) interconnecting the respective output port of the equaliser and the SSE. The processing block (22) is connected to an output of the CPE,an output of the processing branch and at least one of the output of the phase adjuster and the outputs of the equalizer.

A tunable laser system includes a laser diode producing a light beam having a plurality of frequencies in a visible portion of a light spectrum. A collimating lens arranged in front of the laser diode produces a collimated light beam from the light beam produced by the laser diode. A partial reflector arranged in a path of the collimated laser beam reflects a first portion of the collimated light beam and passes a second portion of the collimated light beam as an output light beam. The first portion of the collimated light beam enters the laser diode and mixes with the plurality of frequencies of the light beam produced by the laser diode so that the laser diode produces a self-injection-locked light beam including at least two frequencies having a frequency difference in a terahertz frequency range. A translational stage adjusts a distance between the laser diode and the partial reflector. The laser diode or the partial reflector is mounted on the translational stage. The at least two frequencies of the self-injection-locked light beam are based on the distance between the laser diode and the partial reflector.

A transceiver based on at least one optical source is provided to facilitate wireless communication in a wearable display device, where the wearable display device is embedded with one or more planar antennas. The transceiver operates in terahertz and may be coupled to two different antennas, one for transmission and the other for reception.

This invention disclosed a system and method for characteristics measurement of electromagnetic signals. The measurement system comprises a multi-repetition-rate pulsed light source, a frequency mixer for electrical signal and optical signal, and a data acquisition and processing device. The measurement system accurately determines the characteristic information of the signal to be measured, such as frequency, phase, intensity, and their variations, by measuring the low frequency mixed signal generated by the multi-repetition-rate pulsed light source and the signal to be measured in the frequency mixer. This system has the advantages of simple structure, high measurement accuracy, low cost and large measurable frequency range. The system can be applied to the measurement of various electromagnetic signals, covering the spectral range from microwave, millimeter wave, to terahertz and even light wave.

A system may include an optical phased array, a photodiode array, and a radiofrequency (RF) antenna element array. The optical phased array may be configured to: receive a laser signal from a signal laser; and output an optical beam. Each photodiode may be configured to: receive at least a portion of the optical beam and at least a portion of an optical plane wave beam, wherein the optical plane wave beam is formed based at least on a local oscillator (LO) laser that outputs a laser beam having a different wavelength from the signal laser; and output an electronic signal based on the at least the portion of the optical beam and the at least a portion of the optical plane wave beam. The RF antenna element array may be configured to output an RF beam based on received electronic signals from the photodiode array.

Devices, methods for analog-to-digital converters (ADCs) that perform high-dynamic range measurements based on optical techniques are disclosed. In one example aspect, an optical encoder includes a polarization rotator configured to receive a train of optical pulses, and an electro-optic (EO) modulator coupled to an output of the polarization rotator. The EO modulator is configured to receive a radio frequency (RF) signal and to produce a phase modulated signal in accordance with the RF signal. The optical encoder also includes a polarizing beam splitter coupled to the output of the EO modulator; and an optical hybrid configured to receive two optical signals from the polarizing beam splitter and to produce four optical outputs that are each phase shifted with respect to one another.

A terahertz-wave generation method of generating a terahertz wave in a direction satisfying a non-collinear phase-matching condition by making pump light incident on a nonlinear optical crystal capable of generating a terahertz wave by optical parametric effect, makes the pump light incident on the nonlinear optical crystal so that a peak excited power density is equal to or greater than a predetermined terahertz-wave lasing threshold and equal to or less than a predetermined laser damage threshold, and an average excited power density, is equal to or less than a predetermined photorefractive effect occurrence threshold, the pump light having a pulse width of 10 ps or more, the pulse width of 1 ns or less, and a repetition frequency of 1 kHz or more.