Beijing Information Science & Technology University

Other

Bejing Information Science & Technology University

Fei Luo

Wei He

Mingli Dong

Lianqing Zhu

Xiaoping Lou

Yinmin Zhang

Feng Liu

Hong Li

Wei Zhuang

Tung Feng Yeh

Fan Zhang

Yudong Jia

Kuo Meng

Xiaochen Meng

Zhehai Zhou

A fiber grating demodulation system for enhancing spectral resolution by finely adjusting a linear array detector, includes a laser pump source, a wavelength division multiplexer, a fiber Bragg grating, a diaphragm, a slit, a collimating mirror, a light splitting grating, an imaging focus mirror, a linear array detector. The laser pump source, the wavelength division multiplexer, and the fiber Bragg grating are connected in sequence, the wavelength division multiplexer is connected to the diaphragm. Light emitted from the laser pump source is multiplexed by the wavelength division multiplexer and then enters the fiber Bragg grating, and a reflection spectrum of the fiber Bragg grating enters the slit of the fiber grating demodulation system as injected light. After passing through the slit, the injected light is reflected by the collimating mirror, the light splitting grating, the imaging focus mirror in sequence, and is finally converged to the linear array detector.

Fiber grating demodulation system for enhancing spectral resolution by finely shifting linear array detector

A fiber grating demodulation system for enhancing spectral resolution by finely adjusting a slit, includes a laser pump source, a wavelength division multiplexer, a fiber Bragg grating, a diaphragm, a slit, a collimating mirror, a light splitting grating, an imaging focus mirror, and a linear array detector. The laser pump source, the wavelength division multiplexer, the fiber Bragg grating are connected in sequence, and the wavelength division multiplexer is connected to the diaphragm. Light emitted from the laser pump source is multiplexed by the wavelength division multiplexer and then enters the fiber Bragg grating, a reflection spectrum of the fiber Bragg grating enters the slit of the fiber grating demodulation system as injected light. After passing through the slit, the injected light is reflected by the collimating mirror, the light splitting grating, and the imaging focus mirror in sequence, and is finally converged to the linear array detector.

Fiber grating demodulation system for enhancing spectral resolution by finely shifting slit

Application of non-uniform strain to discrete segments of a fiber grating mechanically changes the structure type of the associated device, e.g., the refractive index perturbation profile of the fiber grating is changed from uniform to phase shifted superstructured, or from chirped to superstructured. The strain may be applied with one or more deformable corrugated slides which are bonded to the fiber grating between the discrete segments. The applied strain changes the local period of fiber grating. Complex changes may be achieved via variations of corrugated slide dimensions. An LPFG may be provided with bare fiber by applying periodically longitudinal axial strain to fiber at multiple discrete segments on the fiber.

Tunable superstructure fiber grating device

A fiber grating demodulation system for enhancing spectral resolution by finely adjusting a light splitting grating, includes a laser pump source, a wavelength division multiplexer, a fiber Bragg grating, a diaphragm, a slit, a collimating mirror, a light splitting grating, an imaging focus mirror, and a linear array detector. The laser pump source, the wavelength division multiplexer, the fiber Bragg grating are connected in sequence, the wavelength division multiplexer is connected to the diaphragm. Light emitted from the laser pump source is multiplexed by the wavelength division multiplexer and then enters the fiber Bragg grating, a reflection spectrum of the fiber Bragg grating enters the slit of the fiber grating demodulation system as injected light. After passing through the slit, the injected light is reflected by the collimating mirror, the light splitting grating, and the imaging focus mirror in sequence, and is finally converged to the linear array detector.

Fiber grating demodulation system for enhancing spectral resolution by finely rotating light splitting grating

A fiber grating demodulation system for enhancing spectral resolution of a detector array, includes a laser pump source, a wavelength division multiplexer, a fiber Bragg grating, a diaphragm, a slit, a collimating mirror, a light splitting grating, an imaging focus mirror, and a linear array detector. The laser pump source, the wavelength division multiplexer, and the fiber Bragg grating are connected in sequence, and the wavelength division multiplexer is connected to the diaphragm. Light emitted from the laser pump source is multiplexed by the wavelength division multiplexer and then enters the fiber Bragg grating. A reflection spectrum of the fiber Bragg grating enters the slit of the fiber grating demodulation system as injected light. After passing through the slit, the injected light is reflected by the collimating mirror. The light splitting grating, and the imaging focus mirror in sequence, and is finally converged to the linear array detector.

Fiber grating demodulation system for enhancing spectral resolution of detector array

A fiber grating demodulation system for enhancing spectral resolution by finely adjusting an imaging focus mirror, includes a laser pump source, a wavelength division multiplexer, a fiber Bragg grating, a diaphragm, a slit, a collimating mirror, a light splitting grating, an imaging focus mirror, a linear array detector. The laser pump source, the wavelength division multiplexer, the fiber Bragg grating are connected in sequence, the wavelength division multiplexer is connected to the diaphragm. Light emitted from the laser pump source is multiplexed by the wavelength division multiplexer and then enters the fiber Bragg grating, a reflection spectrum of the fiber Bragg grating enters the slit of the fiber grating demodulation system as injected light. After passing through the slit, the injected light is reflected by the collimating mirror, the light splitting grating, and the imaging focus mirror in sequence, and is finally converged to the linear array detector.

Fiber grating demodulation system for enhancing spectral resolution by finely rotating imaging focus mirror

A fiber grating demodulation system for enhancing spectral resolution by finely adjusting a collimating mirror, includes a laser pump source, a wavelength division multiplexer, a fiber Bragg grating, a diaphragm, a slit, a collimating mirror, a light splitting grating, an imaging focus mirror, a linear array detector. The laser pump source, the wavelength division multiplexer, and the fiber Bragg grating are connected in sequence, the wavelength division multiplexer is connected to the diaphragm Light emitted from the laser pump source is multiplexed by the wavelength division multiplexer and then enters the fiber Bragg grating, a reflection spectrum of the fiber Bragg grating enters the slit of the fiber grating demodulation system as injected light. After passing through the slit, the injected light is reflected by the collimating mirror, the light splitting grating, and the imaging focus mirror in sequence, and is finally converged to the linear array detector.

Fiber grating demodulation system for enhancing spectral resolution by finely adjusting a collimating mirror

A Q-switched all-fiber laser utilizes a long period fiber grating (LPFG) modulator. The LPFG modulator is characterized by optical spectral characteristics that are controlled by application of stress via an actuator. In particular, the actuator applies stress to selected sections of the LPFG in order to modulate a light signal at a specified wavelength. Further, a controller is utilized to control the application of stress in the time domain, and thereby switch the Q-factor of the fiber laser cavity. In addition to the LPFG, the laser cavity comprises a pair of fiber Bragg gratings (FBGs) and a fiber gain medium.

Q-switched all-fiber laser

A Q-switched all-fiber laser has a long period fiber grating (LPFG) switch with optical spectral characteristics that are controlled by application of stress. An actuator applies stress to selected sections of the LPFG in order to switch a fiber laser cavity at a specified wavelength. A controller controls the application of stress in the time domain, thereby switching the Q-factor of the fiber laser cavity.

A gas detection system with an inner ring cavity fiber laser using saturated absorption optical fiber is provided. The system comprising a ring fiber laser consisted of a pump source, a wavelength division multiplexer, a first active optical fiber, a first coupler, a fiber Bragg grating and a second coupler connected successively; an optical isolator coupled between said first active optical fiber and said first coupler; a second active grating connected between said fiber Bragg grating and said first coupler; a detection gas chamber connected between said first coupler and said second coupler; a first photoelectric detector for detecting the laser intensity outputted from said ring fiber laser to generate a first light intensity signal; a second photoelectric detector for receiving the intensity measuring beam passing through the detection gas chamber to generate a second light intensity signal; and a feedback control unit.

Gas detection system using intracavity fiber laser with loop cavity having saturated absorption fiber

A method for measuring the strain of material using a short cavity fiber laser, includes steps of: a) arranging the short cavity fiber laser, which laser comprises sequentially coupled laser diode pumping source, a wavelength division multiplexer, a fiber bragg grating, an active fiber and a loop mirror; b) fixing the short cavity fiber laser on the material whose strain will be measured, and matching the stretching direction of the fiber of the short cavity fiber laser with the direction of the strain produced by the material to be measured; c) measuring the drift amount of longitudinal mode output by the short cavity fiber laser; and d) calculating and obtaining the strain of the material to be measured.

Method for measuring the strain of material using short cavity fiber laser

The present invention provides a fiber laser gas detection system using active feedback compensation by a reference cavity, said system comprising: an optical fiber laser consists of a laser diode pump source, a wavelength division multiplexer, an active optical fiber and a fiber Bragg grating connected successively; an optical isolator coupled with said wavelength division multiplexer for blocking a reverse light transmission in said active fiber; a coupler connected with said optical isolator for dividing the laser light after being isolated by the optical isolator into a reference beam, a detecting beam and an intensity measuring beam according a certain ration power. The gas detection system according to the present invention can take advantages of the unique superiority of compact structure and narrow linewidth of the laser output of the fiber laser, and achieve a gas detection method with high sensitive and high precision by feedback controlling.

Gas detection system using fiber laser with active feedback compensation by reference cavity

A fiber laser gas detection system with a double wavelength combination using reference cavity compensation is provided. The system comprises an optical fiber laser respectively emitting beams having a first and second wavelengths, which consists of a laser diode pump source, a first wavelength division multiplexer, an active optical fiber, a first fiber bragg grating and a second fiber bragg grating connected successively; an optical isolator; a coupler for dividing the beams according to power ratio, the divided beams is introduced into a reference gas chamber and a detecting gas chamber respectively; a second wavelength division multiplexer connecting the reference room and a third wavelength division multiplexer connecting the detecting gas chamber; a first, a second, a third and a fourth photoelectric detector; a feedback control unit, receiving the first to fourth light intensity signals and adjusting the fiber laser using the comparison results as a feedback signal.

Gas detection system using a fiber laser with double-wavelength combination having reference-cavity compensation function

A gas detection system using a semiconductor laser with a reference gas cavity compensation is provided, said system comprising a first light source emitting a first beam of a first wavelength as a detection beam; a second light source emitting a second beam of a second wavelength, which is different from the first wavelength, as a reference beam; a first wavelength division multiplexer connected with said first light source and said second light source; a broadband coupler connected with said first wavelength division multiplexer; a reference gas chamber, which is introduced with reference gas of the same composition as that of the gas to be detected and of a known concentration; a detection gas chamber, which is introduced with the gas to be detected.

Gas detection system using semiconductor laser with feedback compensation by gas reference cavity

A method for measuring magnetic induction intensity of a magnetic field using a short cavity fiber laser, includes the steps of: a) arranging the short cavity fiber laser, where the short cavity laser has sequentially coupled laser diode pumping source, a wavelength division multiplexer, a fiber Bragg grating, an active optical fiber and a loop mirror; b) fixing the short cavity fiber laser on a magnetostrictive material; c) disposing the short cavity fiber laser and the magnetostrictive material in the magnetic field to be measured, and matching the stretching direction of the magnetostrictive material with the direction of the magnetic field to be measured; d) measuring the drift amount of longitudinal mode output by the short cavity fiber laser; and e) calculating the magnetic induction intensity of the magnetic field to be measured.

Growing community of inventors

Winchester, MA, United States of America

Fei Luo