Active Tunable Filters Based on GeSbTe Phase-Change Materials and Surface Plasmon Resonance

Tunable mid-wave infrared (MWIR) filters are highly desirable in a wide variety of imaging and sensing applications, as the MWIR contains numerous invaluable spectral signatures. Here, we demonstrate a solid-state, actively tunable, narrowband MWIR transmission filter based on a plasmonic nanohole array (PNA) design integrated with the phase change material GeSbTe (GST-PCM). Through finite-difference time domain simulations and experimental results, we show narrowband (~100nm), high efficiency (~90%) transmission filtering, tunable across the entire MWIR spectrum (3~5?m). The active tunability of the GST/PNA filter has been demonstrated by 532nm nanosecond (ns) single laser pulse irradiation for the phase transformation and the device shows consistent behavior across a number of phase change cycles.