Laser Institute of Shandong Academy of Science

Laser Institute of Shandong Academy of Sciences

Bing Cao

Jiasheng Ni

Chen Wang

Chang Li

Ying Shang

Sheng Huang

Chang Wang

Wenan Zhao

Yingying Wang

Xiaohui Liu

Yanbin Wu

Wen'an Zhao

Yang Liu

Long Ma

Jian Yang

Zhiqiang Song

Qian Guo

Lei Lv

Shuai Qu

Weitao Wang

The application relates to a distributed acoustic sensing voice message recognition system and method. The system includes a sensing optical fiber, configured to receive a voice message and convert the voice message into a voice signal; a laser emission unit, configured to emit a laser signal with a narrow linewidth and with spontaneous emission noise being eliminated; a circulator, configured to transmit the laser signal to the sensing optical fiber to monitor the voice signal, and receive a backward Rayleigh scattering signal from the sensing optical fiber; a collection unit, configured to collect the backward Rayleigh scattering signal emitted by the circulator; and a convolutional recurrent network unit, configured to perform complex field mapping on the backward Rayleigh scattering signal collected by the collection unit, to reconstruct the voice signal.

Distributed acoustic sensing voice message recognition system and method

The present application provides a multi-wavelength laser for synchronously monitoring the temperature and pressure of an ocean. A pulse controller is used to convert a broadband laser outputted by a broadband laser source into a broadband pulsed light, and then a phase shifted fiber bragg grating unit is used to demodulate a plurality of pulsed light with different wavelengths from the broadband pulsed light. The pulsed light outputted by the laser is emitted into a sensing fiber in seawater via a wavelength division multiplexer, scattered light is returned to a control demodulation module via the wavelength division multiplexer, the control demodulation module demodulates the scattered light, so that the dynamic pressure is parsed according to a phase change of a light signal, and the seawater temperature is parsed according to a wavelength change of the light signal.

Multi-wavelength laser for synchronously monitoring temperature and pressure of ocean

An EHz ultrafast modulated pulse scanning laser and a distributed fiber sensing system. A plurality of phase-shift gratings are engraved on a doped fiber, the phase-shift gratings having different central window wavelengths and a wavelength interval between the adjacent central window wavelengths being a preset fixed value. When a pump light emitted by a pump laser source is coupled by a wavelength division multiplexer and enters the doped fiber, a single-mode narrow-linewidth laser light having multiple wavelengths with a wavelength interval being a preset fixed value can be generated, by using the phase-shift gratings graved on the doped fiber. The ultrafast modulation is completed by using a time-domain control method based on an EOM. An internally frequency converted pulse light formed by splicing pulse lights whose frequencies linearly increase is obtained, thus forming the EHz ultrafast modulation of a distributed feedback fiber laser. In this way, a coherence length of an output laser light is increased while a frequency of the laser light is remained.

EHz ultrafast modulated pulse scanning laser and distributed fiber sensing system

The present application discloses a fiber distributed acoustic sensing system, including a forward pump source, a wavelength division multiplexer, an active phase-shifted grating array, a backward pump source, and a data demodulation and processing device. The active phase-shifted grating array includes several active phase-shifted gratings engraved on a same fiber, each active phase-shifted grating having a same excitation light wavelength. The active phase-shifted grating array is configured to receive a forward pump pulse and a backward pump light pulse incident from the backward pump source, so that a forward excitation light and a backward excitation light are generated in each active phase-shifted grating, and two adjacent active phase-shifted gratings are enabled to generate excitation light self interference within a same pulse duration. The data demodulation and processing device is configured to perform interference detection on a fiber phase between two adjacent active phase-shifted gratings to detect an acoustic signal acted on the fiber. According to the system in the present application, the passive reflected light interference is replaced with active excitation light interference, thus the excitation light signal has great strength and high stability, and environmental adaptability is high.

Fiber distributed acoustic sensing system

A high-performance distributed fiber sensing system based on EHz ultrafast pulse scanning. During testing of a disturbance signal, an internally frequency converted pulse light emitted by an EHz ultrafast pulse scanning laser enters a sensing fiber after passing through a circulator, and a backward Rayleigh scattering signal transmitted by the sensing fiber enters an unbalanced Michelson interferometer after passing through a coupler. By designing an arm length difference between two interference arms, interferences sequentially occur for the backward Rayleigh scattering light at a position where lengths of two adjacent arms differ. A signal received after passing through the unbalanced Michelson interferometer includes a phase difference signal caused by an external disturbance signal in the sensing fiber. Finally, variations of the phase difference signal over time are demodulated by using a phase demodulation unit, so that a dynamic measurement of the disturbance signal in the sensing fiber may be performed.

High-performance distributed fiber sensing system based on EHz ultrafast pulse scanning

The present invention provides an event positioning method, device and application in a distributed fiber vibration monitoring system. When a location at which an event occurs in a sensing fiber is to be positioned, an interference field signal having a maximum optical power is obtained by comparing optical powers of respective interference field signals corresponding to backward Rayleigh scattering lights that are generated when a pulse light is transmitted in the sensing fiber. Subsequently, a sensing location of the interference field signal having the maximum optical power is calculated. Finally, the location at which the event occurs in the sensing fiber is determined, according to the sensing location and a location distribution pattern of the event. According to the positioning method provided in the present invention, by screening the interference field signals and then calculating the event location, the spatial resolution is not determined merely by the pulse width of the optical signal. Therefore, the location positioning of the event can be more accurate, thereby improving an accuracy of the spatial resolution.

Event positioning method, device and application in distributed fiber vibration monitoring system

An optical fiber distributed monitoring system and method is provided. The system includes a laser device, an acousto-optic modulator, a phase matching interferometer, a photoelectric detector and a phase demodulation module. After entering the phase matching interferometer, the Rayleigh backscattering light containing parameter information output from the sensing optical fiber enters the two arms of the phase matching interferometer respectively, and the light of the two arms of the phase matching interferometer is phase-modulated by the first modulation wave and the second modulation wave, respectively and then interfere with each other to generate interference light. The photoelectric detector converts a light signal into an electric signal, and the phase demodulation module processes the electric signal based on the Hilbert algorithm to obtain the parameter change of the environment under test.

Optical fiber distributed monitoring system and method

Provided is a fiber optic acoustic wave detection system, pertaining to the fiber optic sensing technical field. The system comprises a power output apparatus, a backward Rayleigh scattering principle-based first distributed sensing apparatus, a backward weak optical fiber grating reflection principle-based second distributed sensing apparatus, and a third distributed sensing apparatus. The first distributed sensing apparatus and the second distributed sensing apparatus are connected with the power output apparatus, respectively. The first distributed sensing apparatus and the second distributed sensing apparatus are connected with the third distributed sensing apparatus, respectively. Compared with conventional approaches, the signal contrast and sensitivity of the detection system are greatly improved by combining the backward Rayleigh scattered signal in the first distributed sensing apparatus with the backward weak optical fiber grating reflected signal in the second distributed sensing apparatus, and the detection system detection bandwidth is significantly widened by the third distributed sensing apparatus.

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Jinan, China

Bing Cao