Wavelength-tunable deep-ultraviolet thin-film filter: design and experimental demonstration

A deep-ultraviolet (DUV) narrowband tunable filter with a central wavelength of 225.0 nm is designed, fabricated, and demonstrated experimentally. The simulation results showed a transmittance of about 42.1% at 225.0 nm and a full width at half-maximum (FWHM) of ∼1.2nm. The experimental results for normal incidence light revealed a corresponding central wavelength of 225.0 nm, a transmittance of 27.7%, and a FWHM of 1.9 nm. By changing the incident angle, the central wavelength can be tuned from 225.0 to 224.5 nm. This DUV narrowband tunable filter has been shown to demonstrate good performance and has broad applicability.