LAUSR

A dual-slot silicon electro-optic modulator based on indium tin oxide is proposed with high modulation efficiency, low loss, and broadband operation leveraging the epsilon-near-zero (ENZ) effect. The design is verified by numerical simulation with Lumerical Solutions. The active modulation region consists of two slots for enhancing the overlap between the optical mode and the ENZ region to improve the performance of the electro-absorption modulator. By combining the confinement of the dual-slot waveguide and the ENZ effect, we can obtain a high modulation efficiency of 1.44 dB/$\mu$m at the wavelength of 1.55 $\mu$m. The modulator with a modulation region length of only 10 $\mu$m demonstrates a low insertion loss and a high extinction ratio, with the corresponding values of 0.37 and 14.4 dB, respectively. Through the optimized design, the efficient coupling can be achieved between the silicon waveguide and the dual-slot waveguide with the coupling loss of only 0.12 dB. Moreover, the modulator can operate in a wide spectrum, covering the S-, C-, and L-band. The dual-slot electro-optic modulator thus provides various merits including high modulation efficiency, ultracompact footprint, broad optical bandwidth, and complementary metal–oxide–semiconductor compatibility.