Tunable optical comb filter combining G-T resonant cavity and birefringence element

Abstract

The invention relates to a tunable optical comb filter combining a G-T resonant cavity and a birefringence element, comprising a beam inputting structure, a polarization light-splitting part, a filtration module and a beam outputting structure, wherein the beam inputting structure comprises input optical fiber and a collimating lens and is used for outputting collimated and focused parallel beams; the polarization light-splitting part comprises a polarization beam splitter and a phase delay element and is used for generating beams in a certain polarization direction; the filtration module comprises the G-T resonant cavity and the birefringence element, and the polarization beams enter the G-T resonant cavity, are reflected back and forth in the G-T resonant cavity, pass through the birefringence element in many times to change an optical length in order to obtain a plurality of different phases of beams injected from the G-T resonant cavity and are output after being reflected by the polarization beam splitter; and the beam outputting structure comprises a focusing lens and output optical fiber and is used for outputting the reflected output beams after being focused. The invention has the characteristics of tunable bandwidths and centre wavelengths, and moreover, an output spectrum has the characteristics of smooth top bandwidths, steep edges and larger out-of-band inhibition ratio.

Description

Technical field: [0001] The invention relates to a tunable bandpass filter applied in an optical communication system, in particular to a tunable optical comb filter combined with a G-T resonant cavity and a birefringent element, that is, a cross-wavelength division multiplexer ( Interleaver). Background technique: [0002] With the rapid development of information technology, dense wavelength division multiplexing technology has become one of the mainstream technologies for developing high-speed and large-capacity all-optical communication networks. Optical band-pass filters are key components in optical communication systems. Correspondingly, a new type of optical passive device optical comb filter has appeared, its function is to decompose the multi-wavelength signal with a frequency interval of v into signals with a frequency interval of 2v according to the odd and even wavelengths, which can effectively increase The number of channels multiplexed on the optical fiber, ...

AI Technical Summary

Problems solved by technology

[0003] CN1315790A describes a filter based on the crystal type to realize the function of odd and even wavelength separation, which uses the difference in the refractive index of o light and e light in a birefringent crystal of a specific length to generate a specific optical path difference, thereby causing a certain phase difference in the beam To achieve comb filtering, and the crystal cascade birefringence polarization interference technology can be used to achieve the spectral transmittance of filter flattened passband and stopband, but the isolation of the transmission spectrum and the flattened passband width are not very good, and It has no tunable characteristics of center wavelength or bandwidth

It has good flatness and isolation at the top of the passband, but in order to obtain a bandpass filter, there are certain restrictions on the setting of structural parameters, and it is difficult to achieve tunable characteristics in the process

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