Reconfigurable bandpass optical filters based on subwavelength grating waveguides with a Ge2Sb2Te5 cavity

We demonstrate a reconfigurable optical bandpass filter based on subwavelength grating (SWG) waveguide operating in the Bragg reflection regime and integrated with a cavity of the phase-change material Ge2Sb2Te5 (GST). Partial crystallization of GST provides us with an efficient tool to modify the effective optical properties of the GST governed by the effective medium theory. Consequently, the resonance wavelength as well as the transmission peak can be tuned in the designed filters. Numerical simulations indicate that the presented SWG waveguide with a single GST cavity offers up to 8.8 nm redshift while the transmission amplitude can be modulated from 0.544 to 0.007. The presented Fabry-Perot structure can also be used as a nonvolatile optical switch with a high extinction ratio of about 24 dB at the wavelength of 1548.3 nm. (C) 2021 Optical Society of America

Automated summary

This study demonstrates a reconfigurable optical bandpass filter based on subwavelength grating waveguide and a cavity of phase-change material GST, allowing for tuning of resonance wavelength and transmission peak by modifying the partial crystallization of GST. Numerical simulations show that the structure can achieve an 8.8 nm wavelength redshift and modulation of transmission amplitude.