9 results about "Laser phase noise" patented technology

According to the coherence-correlation optical time domain reflection detection method and system, a laser signal output by a laser is split into detection light and auxiliary light, and the detection light is injected into a detected optical fiber after being coded and modulated; processing the auxiliary light through an auxiliary light path, and detecting the phase noise of the laser in real time to obtain phase noise information; receiving a reflected signal returned by the detected optical fiber, generating a local reference signal which is homologous with the probe light code, and performing phase adjustment on the local reference signal according to the phase noise information to obtain a phase-compensated local reference signal; and performing sliding window correlation operation on the reflected signal and a local reference signal after phase compensation, realizing optical fiber link reflection characteristic measurement and fault positioning by using a correlation operation result, capturing laser phase noise in real time through an auxiliary optical path, and synchronously completing digital compensation. Related peak broadening and sidelobe lifting caused by phase noise are effectively suppressed, and the signal-to-noise ratio and the dynamic range of long-distance measurement of the system are improved.

The application discloses a laser phase noise measurement method based on delay self-heterodyne and digital demodulation, and relates to the technical field of laser measurement, and comprises the following contents: after being adjusted by a variable optical attenuator, to-be-measured laser is divided into a frequency shift arm and a delay arm, the frequency shift arm is frequency-shifted by an acousto-optic modulator, the delay arm is delayed by a delay optical fiber, and original electric beat frequency signals are obtained by a balanced photoelectric detector after the two arms are coupled; homologous and synchronous quadrature demodulation is carried out on the original electric beat frequency signals, envelope credibility judgment and abnormal sample repair are combined, and a continuous differential phase sequence is obtained; actual optical time delay is determined according to the beat frequency spectrum characteristics and the continuous differential phase sequence, and a differential phase power spectral density is formed; then, transmission relationship conversion is carried out according to the actual optical time delay, bounded spectrum compensation is implemented on a zero point neighborhood and a low credibility frequency point, and an intrinsic phase noise power spectral density is obtained. The application can improve the stability, continuity and result credibility of phase noise measurement under the condition of short delay.

The application discloses a compensation device and method for laser phase noise of an optical frequency domain reflectometer, and relates to the technical field of distributed optical fiber sensing. The compensation device comprises a sweep laser source module, a main interferometer module, an auxiliary interferometer module and a signal processing module. The sweep laser source module is used for outputting a first sweep laser beam and a second sweep laser beam. The main interferometer module receives the first sweep laser beam and generates a first beat frequency signal related to the position of a scattering point of a sensing optical fiber. The auxiliary interferometer module receives the second sweep laser beam and generates a second beat frequency signal related to the position of a weak reflection point of an auxiliary optical fiber. The signal processing module collects the first beat frequency signal and the second beat frequency signal, extracts phase terms of the sensing optical fiber and the auxiliary optical fiber respectively, and realizes phase noise compensation. The compensation method realizes the function of the compensation device, that is, realizes phase noise compensation, analyzes the spectrum of compensation information again, and demodulates strain information along the sensing optical fiber. The application realizes uniform compensation of phase noise, and improves the system measurement distance, spatial resolution and strain accuracy.

The invention discloses a correlation type optical time domain reflection signal processing method and system, and relates to the technical field of optical fiber sensing, and the method comprises the following steps: a transmitting end transmits a dual-polarization quadrature phase shift keying optical signal to an optical fiber; a receiving end obtains a coherent superposition signal of the dual-polarization quadrature phase shift keying optical signal reflected by each scattering point of the optical fiber through coherent detection; respectively calculating respective Jones vector inner products according to the dual-polarization quadrature phase shift keying optical signal and the coherent superposition signal, and performing preset correlation operation according to the Jones vector inner products of the dual-polarization quadrature phase shift keying optical signal and the coherent superposition signal to obtain a composite signal. Natural suppression of laser phase noise, obvious weakening of optical fiber front section common optical path disturbance and stable measurement insensitive to polarization state rotation can be realized.

The invention discloses a laser phase noise elimination method and system for a phi-OTDR (Optical Time Domain Reflectometer), solves the problem of dependence of a phase-sensitive optical time domain reflectometer on a high-cost narrow-linewidth laser in the prior art, and realizes reduction of the influence of the phase noise of the laser in combination with a signal processing algorithm. Therefore, the requirement of the system on the line width of the laser is relaxed, the system cost is greatly reduced, and the compatibility of a sensing system and a communication system is improved; the method comprises the following steps: injecting a composite detection pulse into a to-be-detected optical fiber to obtain backscattered light; performing coherent beat frequency on the backscattered light and the local oscillation light to obtain a synthesized complex amplitude electric signal; processing and synthesizing the complex amplitude electric signal, and separating a scattering signal component corresponding to each sub-pulse through a frequency domain filtering or decoding mode; calculating an instantaneous phase difference between the at least one pair of scattered signal components to obtain a spatial differential phase; wherein the space differential phase eliminates common phase noise introduced by the local oscillation light.

Aspects of the subject disclosure may include, for example, deriving substantially orthogonal optical fields from an output of an optical source, implementing a delay on one of the substantially orthogonal optical fields, resulting in time delayed optical fields, performing coherent detection of the time-delayed optical fields, resolving electrical field signals based on the coherent detection, and causing the electrical field signals to be processed so as to estimate a property of the optical source, wherein estimation of the property facilitates disturbance detection and localization. Other embodiments are disclosed.

The application discloses a time delay interference laser phase noise compensation method and device for optical frequency domain reflection, and comprises the following steps: obtaining a linear sweep signal light based on a signal source; obtaining a first heterodyne signal through a measurement interferometer, and obtaining a second heterodyne signal through a reference interferometer; and processing the first heterodyne signal and the second heterodyne signal by using a time delay interference algorithm, so that direct compensation of laser phase noise is realized; and obtaining a strain signal based on the direct compensation of the laser phase noise. Through compensation of the laser phase noise, high-precision measurement of the strain signal can be realized at a distance far beyond the coherence length of the light source.

This invention provides a single-frequency fiber laser with a wide range of finely adjustable linewidth, comprising a single-frequency fiber laser resonator, a pump source, a wavelength division multiplexer, an integrated fiber isolation coupling device, a monitoring-feedback module, and a phase modulation unit. The wavelength division multiplexer couples the pump light output from the pump source into the single-frequency fiber laser resonator and outputs the generated single-frequency fiber laser. The integrated fiber isolation coupling device splits the single-frequency fiber laser beam and inputs it to the main optical path and the monitoring-feedback module respectively. The monitoring-feedback module acquires the phase fluctuation information of the single-frequency fiber laser in real time and generates a phase modulation signal according to the preset linewidth control requirements. The phase modulation unit compensates for or superimposes the phase fluctuation of the single-frequency fiber laser transmitted on the main optical path according to the phase modulation signal output by the monitoring-feedback module, thereby achieving the effect of suppressing or increasing laser phase noise and realizing the function of finely controlling the linewidth of the fiber laser over a wide range.

The invention discloses a DAS data background noise simulation method and device, electronic equipment and a medium. The method can comprise the following steps: acquiring DAS demodulation equipment parameters; simulating laser phase noise in DAS data; and coherent fading influence in the DAS data is simulated, and finally simulated DAS background noise is output. According to the invention, through effective simulation of the background noise of the DAS data, influence factor analysis of the background noise of the DAS data, parameter optimization of DAS demodulation equipment, background noise removal of the DAS data and the like are guided.