6 results about "Sagnac loop" patented technology

The application discloses a kind of intensity modulation polarization encoding quantum key distribution systems based on sagnac ring, including communication end Bob and communication end Alice, the communication end Bob and communication end Alice are connected by optical fiber channel;The laser in the communication end Bob generates optical signal into optical isolator and exports linearly polarized signal parallel to cat eye direction into first polarization maintaining beam splitter;First polarization maintaining beam splitter exports linearly polarized signal parallel to cat eye direction into communication end Alice;Communication end Alice divides the linearly polarized signal parallel to cat eye direction into first linearly polarized signal and second linearly polarized signal with equal intensity and carries out intensity modulation, and finally polarized state signal is output into communication end Bob by the beam combination superposition of third polarization beam splitter after being combined, first single-photon detector to fourth single-photon detector in communication end Bob carries out measurement.The polarization encoding and quantum state modulation of signal are realized by one intensity modulator in the application, and the equipment cost of QKD is reduced.

The application discloses a method and device for generating an optical frequency comb based on Brillouin scattering and an electro-optic modulator, and belongs to the field of photoelectric measurement. The method comprises the following steps: a first laser and a second laser are used to generate pump light and seed light respectively, a multi-wavelength pump light is generated through a cascaded electro-optic modulator, the two lights are injected into a Sagnac loop circuit, an optical frequency comb is output through a fiber forward Brillouin scattering effect and an electro-optic modulator, and a polarization controller is adjusted to optimize the polarization state matching of the pump light and the seed light, so that the Brillouin scattering effect reaches a maximum value. The device is composed of a laser, an electro-optic modulator, a signal generator, an optical amplifier, an optical isolator, an optical coupler, a polarization controller and an optical fiber. The application combines the fiber forward Brillouin scattering effect and the electro-optic modulator, generates an optical frequency comb with wide spectrum and narrow interval, and can accurately control the comb tooth interval of the optical frequency comb through independent adjustment of the signal generator frequency, so that accurate measurement of signals or objects is realized.

The application discloses a nonlinear loop mirror passive mode-locked laser based on pulse chopping technology, which comprises a feedback loop module, a fiber-coupled beam splitter 5 and a Sagnac loop module, wherein the Sagnac loop module comprises an electro-optic modulator 6, a passive optical fiber 7 and a phase biasing device 13; the electro-optic modulator 7 is asymmetrically arranged in the loop and is used for chopping continuous light input from the feedback loop into pulse light and providing a linear phase shift of π; and the phase biasing device generates a linear phase difference to compensate for the deficiency of the accumulated nonlinear phase difference in the fiber loop. The application uses the pulse chopping technology of the electro-optic phase modulator based on the Sagnac loop to chop the continuous light or long pulse light input into the Sagnac loop into picosecond-level pulses, completes the mode-locking process, solves the self-starting problem of the NOLM passive mode-locked laser, can realize the output of ultrashort pulse width laser, reduces the complexity of the system and prolongs the service life of the device.

The application discloses a wavelength-switchable and tunable dual-wavelength single-frequency fiber laser based on birefringence effect, which comprises a partially reflective polarization maintaining fiber grating, a gain fiber, a wavelength division multiplexer, a pump source, a 3dB fiber coupler and an unpumped active fiber; the partially reflective polarization maintaining fiber grating is used as a reflective cavity mirror and simultaneously realizes laser output; the birefringence effect of the fiber is utilized to generate dual-wavelength laser, and wavelength tuning and wavelength switching are realized under the action of longitudinal stress; the 3dB fiber coupler and the unpumped active fiber form a Sagnac loop reflector, which provides feedback for the laser and realizes single longitudinal mode operation as a frequency selection device; the gain fiber absorbs the pump laser injected by the pump source to form particle number inversion and provide gain for the laser. The application utilizes the unpumped active fiber as a saturated absorber for frequency selection and combines the birefringence effect of the partially reflective polarization maintaining fiber grating to realize watt-level dual-wavelength single-frequency laser.

The application discloses a microwave multi-dimensional parameter measurement system and method based on differential frequency-time mapping. In the system, after optical pulses pass through an input end dispersion medium to complete pulse expansion, the optical pulses enter a Sagnac loop. Meanwhile, after a microwave signal to be measured is branched by a radio frequency power divider, the microwave signal to be measured is input into two Mach-Zehnder modulators in the loop to modulate the optical pulses. An adjustable optical delay line is arranged between the first Mach-Zehnder modulator and an optical coupler. The modulated optical pulses output by the loop pass through an output end dispersion medium to realize frequency-time mapping, and map the spectrum information to the time domain. After the optical signal is converted into an electric signal by a photoelectric detector, the electric signal is converted into a digital signal by an analog-to-digital converter and is input into a digital signal processor, so that the time, frequency, amplitude and phase information of the microwave signal to be measured are obtained. The application avoids the problems of narrow bandwidth, high loss and poor adjustability of an electronic delay line, and can simultaneously perform high-precision measurement on the time, frequency, amplitude and phase of a multi-carrier microwave signal.

The invention provides a fiber bragg grating wavelength demodulation device based on double Sagnac rings, and the device comprises a pulse light source which is configured to emit detection pulse light; the fiber bragg grating is configured to reflect a specific light component in the reflected light to generate reflected light corresponding to the specific light component; a first optical fiber coupler configured to split the reflected light into first and second light beams; the first Sagnac ring and the second Sagnac ring are respectively configured to filter the light beams so as to generate first filtered light signals and second filtered light signals, relative wavelength displacement exists between transmission spectrums of the first filtered light signals and the second filtered light signals, and optical path difference exists between output optical paths of the first filtered light signals and the second filtered light signals; a photoelectric detector configured to convert the filtered optical signals to generate analog electrical signals; an analog-to-digital converter configured to convert the analog electrical signal into a digital electrical signal; and the signal processing module is configured to demodulate the Bragg wavelength drift distance of the fiber bragg grating based on the intensity relationship between the two paths of sampling values processed by the first optical fiber coupler in the digital electric signal.