Phys.org  March 11, 2024
Researchers in Japan constructed a tunable Fabry–Perot interferometer (FPI) by controlling the effective refractive index of pitch-variable subwavelength gratings (PV-SWGs) that were incorporated into an FP cavity. The period of the PV-SWG could be varied to change the effective refractive index and shift the optical resonant frequency of the FPI. Compared with conventional methods that tune the optical resonance by adding fillers or deforming the cavity, the  FPI obtained a higher transmission and quality factor (Q-factor) for the transmittance peak, and its resonant frequency could be shifted by simply stretching the PV-SWG. According to the researchers as the effective refractive index and the working frequency could be tailored by altering the geometry design of the PV-SWG, the FPI holds significance for the development of THz communications and for applications at different wave bands… read more. TECHNICAL ARTICLEÂ
Schematic concept of the developed tunable filter… Credit: Optics Letters Vol. 49, Issue 4, pp. 951-954 (2024) Â Â Â Â