Combination electro-optical and thermo-optical phase tuner in aluminum nitride

A large band gap, high refractive index, and a non-zero electro-optic coefficient distinguish aluminum nitride as a wave-guiding material, particularly for photonic integrated circuits in the visible to ultraviolet wavelength range. However, the electro-optic coefficient is modest, typically requiring over 100 V to switch a Mach–Zehnder style modulator ( V π L π >200 Vcm). This paper demonstrates the combined use of thermo-optic and electro-optic tuning, using the same electrodes simultaneously for both types of tuning. This combination tuner achieves the tuning bandwidth of a purely electro-optic approach with the tuning range of a purely thermo-optic approach while adding no additional nanofabrication steps. The only additional complexity is in the off-chip control electronics. To demonstrate the benefit of a combination tuner approach, we present two sample applications of its use with an aluminum nitride micro-ring modulator: data transfer through electro-optic modulation and stabilizing the transmission intensity against environmental perturbations.