Optically Excited Vanadium Dioxide Switches with dc–330 GHz Bandwidth and Sub-Microsecond Switching Time

In this work, we demonstrate the first vanadium dioxide (VO2) phase change material (PCM) RF single-pole, single-throw switches with >300 GHz bandwidth using optical excitation. PCM switches often rely on integrated microheaters to excite the phase transition, which introduces parasitic shunt capacitance degrading performance at the mmWave band. A 785 nm fiber-coupled laser was focused onto the device under test using a lens tower. A minimum of 37 mW optical power excited the phase transition. On-wafer measurements from dc to 330 GHz over four bands indicate an average of 0.8 dB insertion loss across the entire band with >13.7 dB isolation and >15 dB return loss. Furthermore, we demonstrate a turn-on time as fast as 248 ns (10–90%) and a turn-off time of 283 ns (90–10%). Our optically excited switches exhibit a competitive RONCOFF of 15.5 fs with wider bandwidths and faster transition times compared to microheater-based switches.