Narrowband optical wavelength comb by ARROW-type vertical coupler with thick cavity

A vertical ARROW-coupler filter has been proposed and realised. The ARROWs were deposited on either side of a silicon wafer, which acts as a very thick Fabry-Perot cavity. A wavelength comb like output spectrum with a free spectral range of 3.7 nm and a bandwidth (FWHM) of 0.1 nm was measured.