Multi-freedom-degree spectral filter capable of compensating chromatic dispersion of polarization mode

Abstract

The invention provides a multi-freedom-degree spectral filter capable of compensating chromatic dispersion of a polarization mode. The filter comprises a first optical fiber collimator, a thin-film polarizer, a phase type liquid crystal, a second optical fiber collimator, an additional polarization maintaining fiber, a polarization maintaining optical fiber with an optical axis rotating and an optical fiber analyzer. The thin-film polarizer is rotated and the voltage of the phase type liquid crystal and the length of the additional polarization maintaining fiber are adjusted, thereby realizing decoupling adjustment on the modulation depth, the peak wavelength and the free spectral range of the filter. The multi-freedom-degree spectral filter has height controllability. The multi-freedom-degree spectral filter can be used for compensating an amplitude and frequency modulation effect caused by chromatic dispersion of a fiber polarization mode when wide-spectrum light in a high-power laser system is transmitted in a polarization-maintaining device and a polarization-maintaining fiber. When the multi-freedom-degree spectral filter is in use, according to a time-domain waveform monitored by an oscilloscope, a controller is controlled based on a computer feedback to adjust a parameter of a compensation unit, thereby realizing automatic real-time compensation of chromatic dispersion of a polarization mode.

Description

technical field

[0001] The invention relates to the field of spectral filter devices, in particular to a multi-degree-of-freedom spectral filter capable of compensating polarization mode dispersion. Background technique

[0002] In the field of lasers, especially in the field of high-power lasers, in order to control the generation of nonlinear effects and achieve smoothing of the focal spot, it is necessary to use a phase modulator to broaden the spectrum of the single-frequency laser. However, the polarization-maintaining device in the laser system and the polarization-mode dispersion (including differential group delay and low polarization extinction ratio) in the polarization-maintaining fiber will produce a polarization filtering effect, so that different spectral components in the broadened spectrum The non-uniform transmission, when reaching the output, causes the frequency-modulated part of the laser to convert to amplitude modulation, a phenomenon known as the ampli...

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