Fig. 2. Reconfigurable spectrometer based on meshes of MZIs and distributed MRRs.

a Schematic of our demonstrated reconfigurable spectrometer based on meshes of switchable MZIs and distributed all-pass MRR filters. The green and red light paths represent two configured optical channels passing through different combinations of MRRs, thus having different spectral responses. b Simulated transmission spectra when different number of MRRs are cascaded, which results in the generation of pseudo-random spectral responses using distributed filters. c Several example channel spectral responses from a 7-stage design. The red solid and dashed lines represent the closest pair of channels that share six of the same MRRs but still feature a significant spectral difference. d The calculated spectral self-correlation function C (Δλ) when the stage number is 7, with a correlation width δλ of 0.59 nm. e The correlation width δλ at different stage numbers. f The absolute value of the averaged cross-correlation between one specific channel and all the other channels