All-optical control of optical modes in subwavelength-scaled photonic waveguides based on nonlinear optoacoustic effects

Abstract

Light scattering in subwavelength-scaled photonic waveguides provides a unique mechanism to facilitate reconfigurable all-optical control. This thesis presents theoretical and experimental investigation of various nonlinear optical phenomena involving optoacoustic interactions, which offer intriguing optical manipulation techniques. Firstly, the extreme polarization-selective nonlinear interactions between two tones of optical signals are investigated in high aspect-ratio photonics waveguides. This polarization-selectiveness could be exploited for all-optical polarization control in a vast range of waveguide systems. Secondly, the genuinely all-optical vortex mode generation has been thoroughly investigated in subwavelength-hole photonic waveguides, where the optical excitation of acoustic vortex modes can take place, providing a unprecedented means for optical vortex mode conversion without the need of preparation of an initial vortex seed. Based on the full-vectorial analytical theory for all types of nonlinearities, the detailed assessment of the feasibility has been examined. Finally, gigahertz passive mode-locking stabilized by acoustic resonances has been experimentally demonstrated in an erbium-doped fiber laser by use of a high-quality silica microfiber. The pulse trains have been elucidated by dissipative four-wave mixing mode-locking by the optoacoustic interactions with the aid of the coupled nonlinear Schrödinger equations. Our proposed schemes could be applicable to various kinds of integrated waveguide systems for the next-generation ultrahigh-bandwidth optical communication and advanced signal processing.