Horn-Shaped Metal-Clad Modulator Coupled to InP Waveguide

We propose a compact horn-shaped metal-clad cavity modulator integrated on an InP waveguide, operating in 1.5-μm wavelength range. Through 3D finite difference time-domain simulation, we show that the Q factor of the resonant transmission dip can be enhanced drastically from 152 to 408 by introducing a horn-shaped SiO
₂
insulation layer to the cavity with an optimized slope angle. As a result, efficient modulation with the extinction ratio of 3.2 dB and insertion loss of 1.5 dB is obtained in a 2.3-μm-long modulator under a refractive index change of Δn=0.01.