Retroreflection by Cavity-Resonator-Integrated Guided-Mode Resonance Mirror

A cavity-resonator-integrated guided-mode resonance mirror (CRIGM) consists of a grating coupler integrated in a waveguide resonator constructed of a pair of distributed Bragg reflectors on a high-reflection substrate. A narrowband retroreflection for an oblique incidence was predicted theoretically. A CRIGM with 20-μm aperture is designed and fabricated for the incidence angle of about 9° and the operation wavelength of 1540 nm. A narrowband retroreflection of <; 1-nm bandwidth is demonstrated experimentally.