37results about How to "Suppress intensity noise" patented technology

The invention discloses a digital closed loop optical fiber gyroscope with a double-interferometer system. The digital closed loop optical fiber gyroscope comprises a light source driver, a light source, a third beam splitter, a first angular speed sensing module, a second angular speed sensing module, an optical fiber ring and a logic circuit, wherein light emitted by the light source is divided into two beams of incident light after passing through the third beam splitter, and the two beams of incident light respectively enter the first angular speed sensing module and the second angular speed sensing module; the two modules uses the same optical fiber ring, so that two different interferometers are formed in the polarization maintaining optical fiber ring and respectively output signals; the logic circuit receives the signals and performs differential calculation to obtain speed information sensed by the interferometers. The digital closed loop optical fiber gyroscope disclosed by the invention controls a polarization state through a polarization beam splitting / combing device through the same polarization maintaining optical fiber ring, so that the two interferometers in different polarization states are formed in the optical fiber ring; the two polarization states are separated, so that the light-based double-polarization double-interferometer system is implemented, and the precision of the digital closed loop optical fiber gyroscope can be obviously improved, and the intensity noise of the light source is suppressed.

The invention provides a continuously tunable single-frequency Ti sapphire laser device. The continuously tunable single-frequency Ti sapphire laser device comprises a pump source (3), a Ti sapphire crystal (2), a laser resonant cavity, an isolator, a double-refraction filter (4), an etalon (5) and piezoelectric ceramic (14), wherein a nonlinear crystal (1) is inserted between a third flat concave mirror (11) and a fourth flat concave mirror (12) forming the laser resonant cavity, the nonlinear crystal (1) is an optical crystal machined to be provided with two unparallel light through surfaces or an optical crystal placed in a light path at a Brewster angle; moreover, the nonlinear crystal (1) is used for realizing generation of second harmonics of the base-frequency light of the laser device in a mode of critical phase matching or noncritical phase matching. According to the continuously tunable single-frequency Ti sapphire laser device provided by the invention, the nonlinear loss stressed by the main oscillation mode of the base-frequency light is one half of a non-oscillation mode, thus the oscillation starting of the non-oscillation mode of the base-frequency light is effectively suppressed, and the laser device realizes continuously tunable property for the frequency in a valid gain bandwidth. The laser device is compact in structure and convenient to operate.

The invention belongs to the technical field of all-fiber-optic current transformers, and in particular relates to a high-precision and high-reliability all-fiber-optic current transformer. By adopting the redundant design method of the active optical device, the output optical power of the light source unit is more stable, and the stability of the average wavelength of the light source is improved. By adding a depolarization head in the optical path system, the stability and measurement accuracy of the optical path system are improved. Through the digital signal processing unit, the correlation of the output light of the two output ports of the second single-mode coupler is used to convert the two beams of light into electrical signals and send them to the signal processing unit, and the digital circuit subtraction method is used to suppress the noise of the light source intensity and improve The signal-to-noise ratio is improved, and the measurement accuracy of the system is improved. Through the automatic compensation technology of the ratio temperature error of the all-fiber current transformer, the Verdet constant of the low birefringence fiber and the ratio error caused by the wave plate phase delay with the temperature change are mutually compensated, thereby improving the full temperature measurement accuracy of the system.

The invention relates to a method and device for improving the signal to noise ratio of a laser micro-vibration sensing system. The light emitted by a laser is divided into two light beams by an optical fiber coupler, the weak light beam is directly converted into an electrical signal through a third photoelectric detector, and the strong light beam is emitted through an optical fiber collimator to serve as a light source of an interferometer. The light emitted by the optical fiber collimator is divided into reflected light and transmission light through a first polarizing beam splitting device, the reflected light serves as reference light, and the transmission light serves as signal light. The reference light and the signal light are input to a first photoelectric detector and a second photoelectric detector respectively through a second wave plate and a second polarizing beam splitting device. The output of the second photoelectric detector is subtracted from the output of the first photoelectric detector, then the difference is divided by the output of the third photoelectric detector, two orthogonal signals are obtained by frequency mixing and filtering on the result, A / D conversion is carried out on the two orthogonal signals, and a carrier wave demodulation algorithm is generated through a phase position so that demodulation can be achieved. The signal to noise ratio can be improved by 5dB to 10dB, and the measurement capability of weak vibration signals is enhanced.

The invention discloses a broadband single-frequency fiber laser intensity noise suppression device for achieving a nearly schottky noise limit. The broadband single-frequency fiber laser intensity noise suppression device comprises a single-frequency fiber laser resonator, a wavelength division multiplexer, a single-mode semiconductor pump light source, an optical fiber isolator, a polarization controller, a laser saturated amplification device, an optical fiber filter module, an optical fiber coupler, a photoelectric detector and a feedback control system. According to the broadband single-frequency fiber laser intensity noise suppression device disclosed by the invention, the broadband intensity noise of output laser can be reduced through the laser saturated amplification device; feedback control is carried out on the laser saturated amplification device, so that the intensity noise of the output laser can be further reduced; the frequency range of intensity noise suppression can be further expanded; and finally, the effects of keeping the intensity noise of a single-frequency laser within a broadband and simultaneously reducing the intensity noise close to schottky noise limit are achieved. The broadband single-frequency fiber laser intensity noise suppression device for achieving the nearly schottky noise limit has a broad application prospect and great application value in the fields of ultra-high precision and ultra-long distance laser ranging, optical fiber sensing, atomic and molecular spectroscopy and the like.

The invention discloses an attosecond precision timing detection device and method based on a linear optical effect. The method is as follows: introducing a radio frequency offset frequency into an optical pulse signal of input light, and introducing a to-be-measured optical pulse signal into the optical pulse signal with the introduced radio frequency offset frequency. Timing error; the original optical pulse signal and the optical pulse signal introduced with timing error are coupled to each other; the optical pulse signal output after coupling is converted into an electrical signal, which is expressed as an electrical pulse sequence in the time domain, and the electrical pulse sequence includes the radio frequency offset. Shift the frequency signal, extract the RF offset frequency signal through a band-pass filter; extract the envelope signal of the RF offset frequency signal, the envelope signal contains the timing information to be measured; record the envelope signal under different delays in real time The voltage value can obtain the relationship curve between the timing information introduced by the timing device to be measured and the final output voltage of the detection device of the present invention, thereby completing the process of timing calibration.