Trimming of silicon nitride microring resonators with a polysilane top cladding

We demonstrate 23.5 nm shifts of Si/sub 3/N/sub 4/ microring resonances by exposing a polysilane cladding layer to UV light. Our PECVD polysilane cladding is superior to other approaches, because it is insoluble, demonstrates good stability, and exhibits /spl sim/4% index shift.