Nanostructured al SWG Reflectors on thin LP-Si3N4 Membranes as (TiO2/SiO2)³ Bragg Reflector Alternative for Vis Fabry-Pérot Interferometers

This contribution presents a Fabry-Pérot Interferometer (FPI) for the visible spectral range from 555 nm to 585 nm. Two approaches for the FPI reflectors are investigated: a (TiO
₂
/PE-SiO
₂
)
³
Bragg reflector consisting of 55 nm TiO
₂
and 97 nm PE-SiO
₂
layers on 210 nm thin LP-Si
₃
N
₄
membranes as well as a 50 nm thin Al subwavelength grating (SWG) reflector with 140 nm structure dimension and 200 nm structure pitch on 150 nm thin LP-Si
₃
N
₄
membranes. Reflectance is up to 97 % realizing an FPI with peak transmittance up to 40 %, a full width half maximum (FWHM) bandwidth of 1.8 nm and a free spectral range (FSR) of 30 nm.