Tri-port depolarizing tunable optical filter based on TFF

Abstract

The three-port polarizing offset tunable optical filter based on TFF comprises a set or more tunable filter unit with one composed of optical ring connected to the multi channel optical signal input end, a thin film filter, the polarized beam divider A & B on the same light path on the back and forth of the thin film filter plate, featuring in the polarized beam divider A dividing input signal light dividing into P and S parallel lights, with P having half wave plate C rotating P into P-S, two parallel S lights reaching thin film filter plate whose normal line slants on the two parallel S light paths, half wave plate D rotating S into S-P, polarized beam divider B synthesizing P and S into ordinary light signal to output, reflective mirror E paralleling laid with thin film filter plate with reflective mirror F setting behind reflective mirror E with F vertically set with two parallel light paths. It is simple in structure, easy for realization, being able to eliminate polarized relative consumption and polarized light dividing.

Description

technical field [0001] The invention relates to a three-port tunable optical filter capable of eliminating polarization-related loss and polarization separation. Specifically, it relates to a three-port tunable optical filter based on thin-film interference filtering (TFF) technology. The three-port tunable optical filter can be widely used in the reconfigurable optical path multiplexer / demultiplexer ROADM, one of the key components in the dense wavelength division multiplexing system; it can also be used in the optical performance monitor OPM In order to simplify the photoelectric conversion and monitoring equipment; it can also be combined with a broadband light source to form a tunable light source; in addition, it can also be used in many aspects such as sensor networks. Background technique [0002] At present, there are many technologies that can be used for tunable optical filters, mainly including F-P cavity type, acousto-optic tunable filter type and fiber Bragg gr...

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Problems solved by technology

[0012] However, there is still a problem with this solution. Although the filter after designing and optimizing the film system aligns the central wavelengths of the two polarized lights when it is incident at a large angle, so that the polarization-dependent loss is relatively low.

However, as the tuning angle increases, due to the change of the bandwidth of the two polarizations, the transmitted light will inevitably appear polarization separation, as shown in Figure 8(2)

This separation of polarized light will affect the filtering performance of the device to a certain extent, which limits the further expansion of the tuning range.

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