Miniature narrow-band filter for multistage filtering

Abstract

The invention discloses a miniature narrow-band filter for multistage filtering, comprising an input collimator, a first-stage filter, an FP (Fabry-Perot) cavity and an output collimator, wherein theinput collimator is used for performing beam expansion on an input optical signal and then transmitting the optical signal into the first-stage filter through a free space; the first-stage filter is used for performing first-stage filtering on the optical signal transmitted by the input collimator and then transmitting the optical signal into the FP cavity through the free space; the FP cavity isused for performing narrow-band filtering on the optical signal filtered by the first-stage filter and then transmitting the optical signal to the output collimator through the free space; and the output collimator is used for receiving the optical signal which is transmitted by the FP cavity after being subjected to narrow-band filtering, and performing coupling and output on the optical signal.According to the miniature narrow-band filter of the invention, the first-stage filter is combined with the FP cavity, so that an application bottleneck of evenly spaced comb-shaped waveforms of an FPcavity filter can be solved, and narrow-band filtering in a large spectral range can be achieved; at the same time, control on a working temperature is achieved based on a thermistor and a semiconductor cooler TEC, thereby improving reliability of the filter.

Description

technical field

[0001] The invention relates to the field of optical filtering, in particular to a miniature narrow-band filter for multi-stage filtering. Background technique

[0002] Fabry-Perot cavity (Fabry-Perot, FP) filter is one of the important devices in the fields of modern optical fiber communication and optical fiber sensing. The FP cavity is generally composed of a glass plate coated with a high-reflection film on the inner surface and an anti-reflective film on the outer surface. When the wavelength of the incident light wave is an integer multiple of the cavity length, the light wave can form a stable oscillation, and multiple beams will be generated between the output light waves. Interference, and finally output comb waveforms with equal intervals. Compared with other filters based on atomic filters, coherent filters, and grating filters, FP cavity filters can realize the advantages of wide working filter section, tunable center wavelength, narrow filter li...

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