Mid-infrared optical modulator based on D-shaped PCF

Recently, photonic crystal fibers (PCFs) have become of compelling interest due to their diverse applications, especially in the mid-infrared (mid-IR) wavelength regime. In this work, an optical mid-IR modulator based on D-shaped PCF with germanium-antimony-tellurium (GST) as a phase-changing material (PCM) is presented and analyzed. Because of the phase transition of the GST material between amorphous (dielectric-like) and crystalline (metal-like) states, the modulation process can be attained. The optical losses of the fundamental TE mode supported by the PCF core in amorphous (ON) and crystalline (OFF) states are investigated. The results reveal that the suggested modulator has an ultra-high extinction ratio (ER) that approaches 206 dB, while the insertion loss (IL) is less than 9.8 × 10
⁻⁶
dB throughout the studied wavelength range of 3 – 5.8 μm with a device length (L
D
) of 0.5 mm.