Reconfigurable optical all-pass filter

Abstract

The invention discloses a reconfigurable optical all-pass filter. The reconfigurable optical all-pass filter comprises three optical couplers, N+2 optical phase shifters and N micro-rings, wherein the output end of the first optical coupler, the input end of the second optical coupler and the first optical phase shifter form an MZI1 structure, and the output end of the second optical coupler, the input end of the third optical coupler, the second optical phase shifter, the third optical phase shifter and the first micro-ring form an MZI2 structure. The interference characteristic of a Mach-Zehnder interferometer and the resonance characteristic of a micro-ring are utilized, a signal is input into a chip and is divided into two paths through an MZI1 structure to be input into an MZI2 structure, one path of signal is filtered by the micro-ring, and the other path of signal passes through the phase shifters and a waveguide, the two paths of signals are interfered by the third optical coupler, are processed by the plurality of cascaded all-pass micro-rings, and are finally output from the second coupling grating. By changing the amplitude ratio and the phase difference of the two paths of signals and adjusting the coupling coefficient of the micro-ring, flat amplitude-frequency response is realized, so that the all-pass filter is realized.

Description

technical field [0001] The invention belongs to the technical field of optical filters and microwave photons, and more specifically relates to a reconfigurable optical all-pass filter. Background technique [0002] The all-pass filter is a special filter that keeps the amplitude constant within a certain frequency range and only changes the phase information. It can also be called an all-pass network (phase filter). The traditional filter achieves signal filtering through the change of its own amplitude-frequency response, while the all-pass filter changes the phase information of the signal through its own phase-frequency response characteristics, and has no effect on the signal amplitude except for a fixed insertion loss. In electricity, this characteristic is often used to eliminate unwanted phase effects in the system and introduce delays to specific signals; in the field of optics, it can be used to construct optical delay lines by designing the phase response of all-pa...

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Problems solved by technology

But in reality, the loss of the waveguide cannot be ignored, so the amplitude response of the microring resonator is no longer a straight line constant at 1, but a concave curve

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