Abstract: Disclosed are an optical modulator and control method therefor, the optical modulator includes an input waveguide, an adjustable ring-shaped resonant cavity, a feedback loop waveguide, a first mode converter, and an output waveguide. The input waveguide is configured to receive an initial optical signal, the adjustable ring-shaped resonant cavity is configured to perform resonance and modulation processing on the initial optical signal and output a first optical signal, the feedback loop waveguide is configured to receive and transmit the first optical signal, the first mode converter is configured to perform mode conversion processing on the first optical signal and output a second optical signal to the adjustable ring-shaped resonant cavity, the adjustable ring-shaped resonant cavity is further configured to perform resonance and modulation processing on the second optical signal and output a third optical signal, and the output waveguide configured to receive and output the third optical signal.

Abstract: A distributed fibre sensing system and a vibration detection and positioning method therefor are disclosed. The system comprises: a signal generating module, a light source module, an optical frequency comb generating module, a frequency sweeping and pulse generating module, an optical circulator, a sensing fibre, an interference module, a photoelectric conversion module and a detection and position module. The method comprises: obtaining a plurality of Rayleigh backscattering signals of the sensing fibre; performing a fading elimination processing on the Rayleigh backscattering signals, thereby obtaining a plurality of averaged Rayleigh backscattering signals of non-interference fading and polarization fading; performing a phase processing on the averaged Rayleigh backscattering signals, thereby obtaining phase variance curves; and determining a vibration point according to variances in the phase variance curves, and finally obtaining a position and a vibration waveform of the vibration point.

Abstract: A distributed fibre sensing system and a vibration detection and positioning method therefor are disclosed. The system comprises: a signal generating module, a light source module, an optical frequency comb generating module, a frequency sweeping and pulse generating module, an optical circulator, a sensing fibre, an interference module, a photoelectric conversion module and a detection and position module. The method comprises: obtaining a plurality of Rayleigh backscattering signals of the sensing fibre; performing a fading elimination processing on the Rayleigh backscattering signals, thereby obtaining a plurality of averaged Rayleigh backscattering signals of non-interference fading and polarization fading; performing a phase processing on the averaged Rayleigh backscattering signals, thereby obtaining phase variance curves; and determining a vibration point according to variances in the phase variance curves, and finally obtaining a position and a vibration waveform of the vibration point.

Abstract: Frequency synthesis-based optical frequency domain reflectometry method and system are disclosed. The method is to implement optical frequency reflectometry and comprises: performing an electro-optic modulation and an acousto-optic modulation on a local light to obtain an optical pulse; inputting the optical pulse as a detection pulse optical signal to a test optical fiber; and detecting an obtained Rayleigh backscattered optical signal under coherent detection with the local light, and then performing a photoelectric conversion and a demodulation, wherein: the electro-optic modulation is performed by using a single frequency signal; the acousto-optic modulation is performed by using a pulse signal; and the optical pulse is obtained by simultaneously sweeping multiple frequency components of an optical comb signal which is obtained by the electro-optic modulation.

Abstract: Frequency synthesis-based optical frequency domain reflectometry method and system are disclosed. The method is to implement optical frequency reflectometry and comprises: performing an electro-optic modulation and an acousto-optic modulation on a local light to obtain an optical pulse; inputting the optical pulse as a detection pulse optical signal to a test optical fiber; and detecting an obtained Rayleigh backscattered optical signal under coherent detection with the local light, and then performing a photoelectric conversion and a demodulation, wherein: the electro-optic modulation is performed by using a single frequency signal; the acousto-optic modulation is performed by using a pulse signal; and the optical pulse is obtained by simultaneously sweeping multiple frequency components of an optical comb signal which is obtained by the electro-optic modulation.

Abstract: There are proposed an optical fiber property measuring device and an optical fiber property measuring method which can enhance spatial resolution more than before. In the present invention, in synchronization with frequency modulation applied to x-polarized light, intensity modulation is also applied to the x-polarized light by an intensity modulation means. This makes it possible to increase or decrease the intensity of the x-polarized light at a specific frequency, thereby allowing the effective length of a Brillouin dynamic grating formed by the x-polarized light to be adjusted. As a result, the shape of the reflection spectrum obtained when y-polarized light is reflecting by the Brillouin dynamic grating can also be adjusted optimally, which leads to enhancement of spatial resolution with the y-polarized light.

Abstract: There are proposed an optical fiber property measuring device and an optical fiber property measuring method which can enhance spatial resolution more than before. In the present invention, in synchronization with frequency modulation applied to x-polarized light, intensity modulation is also applied to the x-polarized light by an intensity modulation means. This makes it possible to increase or decrease the intensity of the x-polarized light at a specific frequency, thereby allowing the effective length of a Brillouin dynamic grating formed by the x-polarized light to be adjusted. As a result, the shape of the reflection spectrum obtained when y-polarized light is reflecting by the Brillouin dynamic grating can also be adjusted optimally, which leads to enhancement of spatial resolution with the y-polarized light.

Abstract: A measurement precision is improved and a measurement range is extended by efficiently suppressing a noise level of integrated unnecessary components from non-correlation positions. Measuring means 33 detects the Brillouin gain of a probe light output from a measurement-target optical fiber FUT while sweeping a frequency difference between the pump light and the probe light, and measures the distribution of strains of the measurement-target optical fiber FUT. An optical intensity modulator 4 performs intensity modulation on output light in synchronization with frequency modulation performed on a light source 1. Accordingly, the spectrum distribution with respect to the frequency of light from the light source 1 can be adjusted arbitrarily, and a noise spectrum shape generated at a position other than a correlation peak position and spreading over a frequency axis can be adjusted, and the peak frequency of a Lorentz spectrum generated at the correlation peak position can be measured precisely.

Abstract: A measurement precision is improved and a measurement range is extended by efficiently suppressing a noise level of integrated unnecessary components from non-correlation positions. Measuring means 33 detects the Brillouin gain of a probe light output from a measurement-target optical fiber FUT while sweeping a frequency difference between the pump light and the probe light, and measures the distribution of strains of the measurement-target optical fiber FUT. An optical intensity modulator 4 performs intensity modulation on output light in synchronization with frequency modulation performed on a light source 1. Accordingly, the spectrum distribution with respect to the frequency of light from the light source 1 can be adjusted arbitrarily, and a noise spectrum shape generated at a position other than a correlation peak position and spreading over a frequency axis can be adjusted, and the peak frequency of a Lorentz spectrum generated at the correlation peak position can be measured precisely.