An optical signal detection system includes: a nonlinear converter that nonlinearly converts a plurality of first optical signals into a plurality of second optical signals, and also a third optical signal into a fourth optical signal; a spectrometer that obtains each of a plurality of first spectral data items from a different one of the plurality of second optical signals, and also a third spectral data item from the fourth optical signal; and a detection device that detects the third optical signal and outputs a detection result. The detection device includes: an analyzer that performs sparse principal component analysis on the plurality of first spectral data items to generate a plurality of second spectral data items; and a detector that compares the third spectral data item with each of the plurality of second spectral data items, and detects the third optical signal based on the result of the comparison.

The invention relates to devices and methods of characterising a single unknown pulse signal. They create multiple replica of the original that may be more reliably measured, by dividing the signal through nodes and using different signal pathways that may apply a temporal delay. The device and methods have multiple fields of application, most notably with the internal confinement fusion industry.

The invention relates to devices and methods of characterising a single unknown pulse signal. They create multiple replica of the original that may be more reliably measured, by dividing the signal through nodes and using different signal pathways that may apply a temporal delay. The device and methods have multiple fields of application, most notably with the internal confinement fusion industry.

A system for determining an absolute carrier-envelope phase (CEP) of ultrashort laser pulses includes a laser system for generating a laser beam including ultrashort optical pulses of a duration of less than 10 fs, an ultrabroadband quarter-wave plate configured to polarize the laser beam, and a gas jet emitting a continuous jet stream into the laser beam. The system includes focusing optics to adjust a focal spot of the laser beam to the gas jet, and a detector arrangement including a beam block and a microchannel plate (MCP) imaging detector, wherein the laser beam is directed to the detector arrangement. The method involves using angular streaking to determine the absolute CEP of both elliptically and linearly polarized light.

A system for determining an absolute carrier-envelope phase (CEP) of ultrashort laser pulses includes a laser system for generating a laser beam including ultrashort optical pulses of a duration of less than 10 fs, an ultrabroadband quarter-wave plate configured to polarize the laser beam, and a gas jet emitting a continuous jet stream into the laser beam. The system includes focusing optics to adjust a focal spot of the laser beam to the gas jet, and a detector arrangement including a beam block and a microchannel plate (MCP) imaging detector, wherein the laser beam is directed to the detector arrangement. The method involves using angular streaking to determine the absolute CEP of both elliptically and linearly polarized light.

The method comprises A method includes steps for creating at least two replicas of an input pulse to be characterised, varying the relative amplitude of the two replicas within a range, creating a nonlinear signal at each case of said amplitude variation, measuring the spectra of the nonlinear signals and recovering the spectral amplitude and phase of the input pulse with a proper algorithm. The system includes a replicator for creating at least two replicas of the input pulse and varying their relative amplitude within a range of relative amplitudes, a nonlinear medium, which obtains a nonlinear signal for each relative amplitude, and an analyzer, associated to the nonlinear signal for measuring and characterising spectrally each nonlinear signal.

The method comprises A method includes steps for creating at least two replicas of an input pulse to be characterised, varying the relative amplitude of the two replicas within a range, creating a nonlinear signal at each case of said amplitude variation, measuring the spectra of the nonlinear signals and recovering the spectral amplitude and phase of the input pulse with a proper algorithm. The system includes a replicator for creating at least two replicas of the input pulse and varying their relative amplitude within a range of relative amplitudes, a nonlinear medium, which obtains a nonlinear signal for each relative amplitude, and an analyzer, associated to the nonlinear signal for measuring and characterising spectrally each nonlinear signal.

Methods and devices are described for performing an all-phase measurement of an ultra-fast laser pulse having a spectral range of greater than one octave. The ultra-fast laser pulse may be split into a first beam comprising a fundamental light with a wavelength λ.sub.0 and a second beam comprising a light with a wavelength 2λ.sub.0. The light with the wavelength 2λ.sub.0 may be frequency doubled to a light with a wavelength λ.sub.0 to generate an interference with the fundamental light. Fourier transform may be performed on an interference spectrum of the interference, and a relative envelope delay (RED) between the fundamental light and the frequency doubled light and a carrier envelope phase (CEP) may be acquired based on a result of the Fourier transform.

Methods and devices are described for performing an all-phase measurement of an ultra-fast laser pulse having a spectral range of greater than one octave. The ultra-fast laser pulse may be split into a first beam comprising a fundamental light with a wavelength λ.sub.0 and a second beam comprising a light with a wavelength 2λ.sub.0. The light with the wavelength 2λ.sub.0 may be frequency doubled to a light with a wavelength λ.sub.0 to generate an interference with the fundamental light. Fourier transform may be performed on an interference spectrum of the interference, and a relative envelope delay (RED) between the fundamental light and the frequency doubled light and a carrier envelope phase (CEP) may be acquired based on a result of the Fourier transform.

The process and device for diagnosing the quality of compression of an ultrashort pulse, consist of performing an approximation of the Strehl ratio by: —a first step allowing the measurement of spatio-spectral images of the ultrashort light pulse brief initial (Ii) using one or more parallel imaging spectrometers; —a second step allowing an interaction of said pulse with a nonlinear optical material (DMNL), the aforementioned interaction generating, by a nonlinear optical mechanism of an n order, a secondary pulse (Is) of intensity proportional to the temporal intensity aforementioned ultrashort light pulse (Ii) raised to the power of n; —a third step allowing the measurement of the spatio-spectral image or images of the secondary pulse (Is); —the processing of the images thus obtained will be translated into an expression of the ratio of the maximum intensity obtained by that which could be obtained for the pulse without phase distortion.