Electro‐Thermally Driven Vanadium Dioxide Based Guided Wave THz Modulator

Abstract To meet the growing demand for integrated, broadband, on‐chip, external THz modulation, a CMOS‐compatible THz modulator operating in the 0.5–0.6 THz frequency range is proposed. To the best of the author's knowledge, this is the first report of a volatile phase change material (PCM) vanadium dioxide () based, electro‐thermally driven on‐chip THz modulator designed using the SOI dielectric waveguide platform. For an active length and thickness of 1000 µm and 150 nm of the , respectively, the modulator achieves a modulation depth of more than 90 with an insertion loss of less than 1 dB. Two micro‐fin heater configurations, one enabling direct heating and the other being graphene assisted, are used for the electro‐thermally driven phase transformation of . The response time (sum of the rise and fall time) of the modulator for the direct and graphene assisted micro‐fin heaters are 2.45 and 0.79 ms, respectively, which is the highest modulation speed achieved to date using the electro‐thermal excitation of for its THz modulation application. Additionally, a taper coupler is designed and investigated. It exhibits an average coupling loss of 0.19 dB per coupling section and an average propagation loss of 0.24 dB cm −1 .