Regular paper

Design of an efficient terahertz wave source from a GaP waveguide embedded in a silicon slot waveguide

¹ Department of Materials Science, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-11-1021, Sendai 980-8579 Japan
² Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1, Katahira, Aoba-ku, Sendai, 980-8577, Japan

^* k-saito@material.tohoku.ac.jp

Received: 6 March 2015
Revised: 13 April 2015

Abstract

Here, we propose an efficient scheme for terahertz (THz) wave generation on the basis of difference frequency mixing (DFM) using a GaP ridge waveguide embedded in a silicon slot waveguide. Phase matching in the DFM process, between the nonlinear polarisation wave induced by two near-infrared pumps and the generated THz wave in the low-refractive-index slot waveguide, was achieved by utilizing the modal birefringence of the fundamental transverse electric- and transverse magnetic-like modes at telecom wavelengths in the GaP ridge waveguide. The effective cross-sectional area of the THz wave in the waveguide was small, 220 μm2 at 2.26 THz, resulting in a photon conversion efficiency of 5.7 × 10^-2%. The THz output power approached the multi-μW level using the proposed waveguide structure.