Tunable three-ring cascade filter

Abstract

The invention discloses a tunable three-ring cascade filter. The tunable three-ring cascade filter comprises an input waveguide (10) which is the input waveguide of a first-level micro-ring resonant cavity filter (20), the first-level micro-ring resonant cavity filter (20) which is coupled with the input waveguide in the same plane, a second-level micro-ring resonant filter (21) which is coupled with the first-level micro-ring resonant cavity filter in the same plane, a third-level micro-ring resonant cavity filter (22) which is coupled with the second-level micro-ring resonant cavity filter in the same plane, a single-mode output waveguide (11) which is the output waveguide of the third-level micro-ring resonant cavity filter (22), and a heater (30) which is used for heating the first-level micro-ring resonant cavity filter, the second-level micro-ring resonant cavity filter and the third-level micro-ring resonant cavity filter, wherein the radius of the third-level micro-ring resonance cavity filter (22) is equal to the radius of the first-level micro-ring resonant filter.

Description

technical field [0001] The invention relates to the field of integrated optics, in particular to a thermo-optic tunable three-ring cascaded filter with low crosstalk and a large free spectral range. Background technique [0002] In modern optical network technology, a reconfigurable optical add / drop wavelength division multiplexer (ROADM) can flexibly allocate capacity and reconstruct a dense wavelength division multiplexing (DWDM) network, and is a key device for automatic switching of optical networks. Although the FFP filter has been commercialized and can be used to realize low-speed optical network applications, its application is limited because its tuning range is smaller than the EDFA band. Liquid crystal filter has similar performance to FFP, although it has a wider tunable range and faster tuning speed, but it has not been commercially available on a large scale. Due to the reliability problems of MEMS filters, MEMS devices cannot be industrialized in the end. FB...

AI Technical Summary

Problems solved by technology

Due to the reliability problems of MEMS filters, MEMS devices cannot be industrialized in the end

FBG filters do not have the problem of alignment with optical fibers, and have been commercially available. However, the tuning range of FBG is very small and cannot meet the requirements of wide-range wavelength tuning.

Acousto-optic tunable filters have also been commercially available to achieve multi-wavelength frequency selection, but there are problems such as large bandwidth, high side lobes, and frequency shift.

Active tunable filters have great potential for ultra-high speed and narrow bandwidth, but their requirements for temperature and current stability are still a problem

In 2008, Joonoh Park et al. from Kwangwoon University in South Korea reported a thermal-optic photonics based on a polymer Ploymer waveguide coupled microring on IEEE Photonics Technology Letters, VOL.20, NO.12, 2008, pp.988-990. Tunable filter, the specific structure is a single waveguide coupling double microring structure, and the two microrings are also in a coupling state, its disadvantage is that the filtering spectrum is a multi-peak envelope structure, and the filtering spectrum with high side mode suppression ratio cannot be realized type

Although the single microring resonator filter based on SOI photonic wire waveguide has the advantages of small size and narrow passband bandwidth, its disadvantage is that it needs a large heating current to obtain relatively large wavelength tuning.

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