In a waveform measurement method, first, initial pulsed light is spatially dispersed for respective wavelengths. Next, the initial pulsed light is input to a polarization dependent type SLM in a state where a polarization plane is inclined with respect to a modulation axis direction, and a phase spectrum of a first polarization component of the initial pulsed light along the modulation axis direction is modulated, to cause a time difference between first pulsed light Lp.sub.1 including the first polarization component and second pulsed light Lp.sub.2 including a second polarization component orthogonal to the first polarization component. After combining the wavelength components, an object is irradiated with the pulsed light Lp.sub.1 and the pulsed light Lp.sub.2, and light generated in the object is detected. The above detection operation is performed while changing the time difference, and a temporal waveform of the pulsed light Lp.sub.1 is obtained.

Single-shot transient optical signals are recorded in a time regime of picoseconds to nanosecond. An auxiliary pump beam is crossed through the signal to sample a diagonal slice of space-time, analogous to a rolling shutter. The slice is then imaged onto an ordinary camera, where the recorded spatial trace is a direct representation of the time content of the signal. The pump samples the signal by optically exciting carriers that modify the refractive index in a conventional semiconductor wafer. Through use of birefringent retarders surrounding the wafer, the integrating response of the rapidly excited but persistent carriers is differentiated by probing with two polarization-encoded time-staggered signal replicas that are recombined to interfere destructively.

In a waveform measurement method, first, initial pulsed light is spatially dispersed for respective wavelengths. Next, the initial pulsed light is input to a polarization dependent type SLM in a state where a polarization plane is inclined with respect to a modulation axis direction, and a phase spectrum of a first polarization component of the initial pulsed light along the modulation axis direction is modulated, to cause a time difference between first pulsed light Lp.sub.1 including the first polarization component and second pulsed light Lp.sub.2 including a second polarization component orthogonal to the first polarization component. After combining the wavelength components, an object is irradiated with the pulsed light Lp.sub.1 and the pulsed light Lp.sub.2, and light generated in the object is detected. The above detection operation is performed while changing the time difference, and a temporal waveform of the pulsed light Lp.sub.1 is obtained.

Photonic devices for generating linearly frequency modulated arbitrary microwave signals comprise a laser, and assembly for forming the emitted signal and a photoreceiver the passband of which is in the domain of the microwave frequencies. The forming assembly comprises: a first beam splitter; a first optical channel including a frequency-shifting loop comprising a beam splitter, a first optical amplifier, an optical isolator, a first spectral optical filter and an acousto-optical frequency shifter; a second optical channel including an electro-optical frequency shifter; a second beam splitter; a second optical amplifier; and a second optical filter; the acousto-optical frequency shift, the electro-optical frequency shift and the amplification gain of the first optical amplifier being adjustable.

A light source, including: a pulse generator for providing an initial sequence of light pulses, the pulse generator including an optical source for producing optical pulses; and a modulator in communication with the optical source for increasing or decreasing the selected number of pulses provided by the pulse generator in the selected time period; first and second optical arms, for propagating, respectively, first and second sequences of light pulses, wherein the first optical arm includes a first manipulator configured to generate the first sequence of light pulses from the initial sequence of light pulses, wherein the light source includes a nonlinear optical element arranged to receive the first sequence of light pulses or the second sequence of light pulses, and an optical switch arranged to switch either the first sequence of light pulses or the second sequence of light pulses for reception by the nonlinear optical element.

A second harmonic generator may include a combiner to combine a fundamental optical beam with a residual fundamental optical beam. The second harmonic generator may include a second harmonic crystal, coupled to the combiner, to generate a second harmonic optical beam from the fundamental optical beam and the residual fundamental optical beam. Upon generation of the second harmonic optical beam, the residual fundamental optical beam may exit the second harmonic crystal.

This invention removes the need to provide temperature control for an optical time delay chip, which is usually provided by a thermo-electric-cooler, in order to significantly reduce the power dissipation of the device and allow uncooled operation. Uncooled operation is achieved by monitoring the temperature of the chip, and changing the tuning of each microresonator within the device in order to continue providing the required time delay as the temperature is varied. This invention takes advantage of the fact that microresonators provide a series of resonant wavelengths over a wide wavelength range, so that the closest resonance wavelength below the operating wavelength can always be tuned up to that wavelength. When the device temperature changes, this is accounted for by both the choice of resonance wavelengths and the tuning for each of the microresonators in the device, in order to keep the correct tunable delay.

Beam steering device such as optical phased array (OPA) is a key component in applications of solid-state LIDAR and wireless communication. The traditional single-layer OPA results in a significant energy loss due to the substrate leakage caused by the downward coupling from the grating coupler structure. In the present disclosure, we have investigated a structure based on multi-layers Si.sub.3N.sub.4/SiO.sub.2 platform that can form a 3D OPA to emit the light from the edge of the device with a high efficiency, a 2D converged out-coupling beam will be end-fired to the air. The high efficiency and wide horizontal beam steering are demonstrated numerically, the influence of vertical crosstalk, the delay length, number of waveguide layers, and the fabrication feasibility are also discussed.

A high-speed analog-to-digital converter can produce a digital signal representative of an analog input electrical signal. An optical amplitude modulator can modulate an input optical pulse train using the analog input electrical signal. An optical splitter can split the modulated optical pulse train into a plurality of modulated optical pulse trains. Optical path delays can stagger in time the modulated optical pulse trains to form a plurality of time-staggered modulated optical pulse trains. Demodulators can detect and filter the time-staggered modulated optical pulse trains to form a respective plurality of time-averaged voltages. Analog-to-digital converters can output a respective plurality of digital time series representative of the respective time-averaged voltages. An interleaver can aggregate the plurality of digital time series to form the digital signal, which has a sample rate greater than a repetition rate of the input optical pulse train.

Single-shot transient optical signals are recorded in a time regime of picoseconds to nanosecond. An auxiliary pump beam is crossed through the signal to sample a diagonal slice of space-time, analogous to a rolling shutter. The slice is then imaged onto an ordinary camera, where the recorded spatial trace is a direct representation of the time content of the signal. The pump samples the signal by optically exciting carriers that modify the refractive index in a conventional semiconductor wafer. Through use of birefringent retarders surrounding the wafer, the integrating response of the rapidly excited but persistent carriers is differentiated by probing with two polarization-encoded time-staggered signal replicas that are recombined to interfere destructively.