A Coarse Wavelength Division Multiplexing Filter

Abstract

The present application discloses a coarse wavelength division multiplexing filter, comprising a first waveguide arm for transmitting a first mode light wave and a second waveguide arm for transmitting a second mode light wave, the first waveguide arm and the second waveguide arm An MZI filter structure is formed, wherein the first waveguide arm includes a first phase compensation area and a first mode athermal area, the second waveguide arm includes a second phase compensation area and a second mode athermal area; the first mode athermal The lengths of the zone and the second mode athermal zone meet the preset athermal requirements; the first phase compensation zone and the second phase compensation zone keep the relative phase shift of the first waveguide arm and the second waveguide arm constant, and compensate the first The difference in length between the mode athermal zone and the second mode athermal zone. In this application, by setting the mode athermal region and the phase compensation region on the two waveguide arms respectively, an athermal filter structure with equal length of the two arms is realized, and there is no need to use curved waveguides or negative refractive index materials, and no waveguide or mode conversion.

Description

technical field [0001] The present application relates to but not limited to the technical field of silicon-based photonic integrated chips, and in particular relates to a Coarse Wavelength Division Multiplexing (CWDM) filter. Background technique [0002] As a wave division and multiplexing device, a filter has an important application in a wavelength division multiplexing (Wavelength Division Multiplexing, WDM) communication system. The development of off-chip filters is relatively mature, but silicon photonics-based filters are still in the stage of exploration and development. At present, the main technical paths of silicon-based filters are: microring resonator, arrayed waveguide grating (ArrayedWaveguide Grating, AWG), cascaded Mach Zehnder Interferometer (MZI) and concave grating, etc. Realize the requirements of the communication system for the flat-top effect of the filter passband. However, silicon material has a large thermo-optic coefficient, and the refractive...

AI Technical Summary

Problems solved by technology

In this kind of scheme, the first thing to face is the problem of polarization conversion. It is necessary to convert the polarization state of the input and output light, and a cascaded polarization splitter converter (Polarization Splitter Rotator, PSR) is required, which will bring about insertion loss and device size. increase

In addition, the thermo-optic coefficients of the Transverse Magnetic (TM) mode and the Transverse Electric (TE) mode only have a large difference in thick silicon, and in thin silicon, their thermo-optic coefficients have a small difference. Suitable for athermal design of filter

TE 1 mode is often chosen for an athermal design in thin silicon, but due to the TE 1 The characteristics of the mode itself, it still needs waveguide and mode conversion in the trace to complete the athermal design, which increases the size of the device and reduces the athermal characteristics of the filter

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