Reconfigurable Tunable Optical Filters Based On A 16×16 Switch Matrix

A tunable optical filter is the key component in the optical communication systems and optical signal processing systems.Reconfigurable optical filters with tailorable performances are highly demanded for multi-purpose adaptive signal processing applications.We demonstrate reconfigurable tunable optical filters based on a 16×16 Benes switch chip.The basic unit of the optical filter is a dual-ring assisted Mach-Zehnder interferometer?DR-MZI?.TiN microheaters are integrated in both ring resonators for resonance control,allowing for continuous tuning of the filter center wavelength and the bandwidth.In this thesis,the transmission matrix model is used to simulate and analyze the performance of the filters.By thermally tuning the resonance of the MRR and selecting the optical path through the seven DR-MZI units,the original optical switch chip can be reconfigured as a 2^nd to 14^th-order optical bandpass filter.Moreover,by adjusting the“bar-state”DR-MZI,the bandwidth of each order filter can be tuned between 0.19 nm?23.75 GHz?and 1.06 nm?132.5 GHz?,while ensuring that the in-band ripple is less than 1 dB.For the 10^th-and 12^th-order filters,the filter roll-off factor and shaping factor can reach 231.9 dB/nm and 0.63,respectively.For the 8^th-and 10^th-order filters,the out-of-band rejection ratio?OBRR?of the filter can be greater than 30 dB.In the experiment,the filter center wavelength tuning range can exceed half of the free spectral range,and the passband shape of the filter keeps almost unchanged.We note that the approach introduced in this paper can be generalized to schemes that use an N×N switch matrix for multiple parallel optical filters and wavelength-selective devices,opening a way towards the realization of software-defined photonic functionality in a general photonic integrated circuit.