Design of Mid-Infrared Electro-Optic Modulators Based on Aluminum Nitride Waveguides

We propose and theoretically evaluate the performance of aluminum nitride (AlN) waveguides as mid-infrared (mid-IR) electrooptic (EO) modulators. The device configurations considered include a strip waveguide modulator and a horizontal slot waveguide modulator. The device dimensions were optimized by finite element analysis of the mode field and electric fields in order to calculate the modulation efficiency and the loss. By applying 15 V on the modulator, a maximum effective waveguide index change of over 2 × 10
^-5
is obtained using the slot waveguide structure. The modulator has a reasonable loss of ~2 dB/cm at 2.5 μm wavelength with oxide cladding absorption taken into account. The modulation efficiency of the slot waveguide is found to be twice of the normal strip waveguide. The results also indicate that EO effect in AlN works well over a wide range of wavelengths in mid-IR.