Polarization independent silicon on calcium fluoride-based MIR optical modulator

Efficient mid-infrared (MIR) optical modulator is reported and numerically analyzed for both the transverse electric (TE) and transverse magnetic (TM) polarized modes. The proposed design is based on the silicon-on-calcium-fluoride platform with vanadium dioxide (VO 2 ) as a phase changing material. Due to the attractive property of its phase transition between dielectric (ON) and metallic (OFF) states under the effect of an applied electric field, VO 2 is utilized to enable the modulation process. At an operating wavelength of 3.5 μm, the reported modulator realizes an extinction ratio (ER) of 10.9 dB/μm with an insertion loss (IL) of 0.24 dB/μm for the TE polarized mode. However, for the TM polarized mode, an ER, and IL of 9.5 dB/μm, and 0.19 dB/μm, respectively are achieved. Additionally, the suggested design has a good fabrication tolerance of ± 10% where the ER is better than 10.4 dB/μm and 8.6 dB/μm for the TE and TM polarized modes with IL less than 0.26 dB/ μm. Therefore, the suggested modulator can play a pivotal role in different MIR applications including imaging, sensing, security, and communications.