Spectral trimming of fano reflectors on silicon and glass substrates

Surface-normal ultra-compact narrowband optical filters and broadband reflectors can all be realized via Fano resonances on patterned single layer silicon nanomembranes (SiNM) layers on SOI. Recently, we reported Fano filters transferred onto glass or flexible polyethylene terephthalate (PET) substrates, employing a low temperature wet-transfer process. Here we report demonstration of broadband reflectors based on Fano resonances, on SOI and on glass substrates, along with the spectral trimming for precise definition of cavity resonances, based on the effective index control of low index oxide layer surrounding patterned SiNM device layer.