Optical gradient force for all-optical control in photonic circuits

• Main Author: Xu, Kaijun.
• Other Authors: Liu Aiqun
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
• Online Access: http://hdl.handle.net/10356/46714
• Institution: Nanyang Technological University

In this project, we apply the optical gradient force in a slot-waveguide structure for all-optical control of a mechanically variable waveguide structure. The optical gradient force is ideal for realising all-optical control since it offers immense design flexibility, low power operation and direct tenability through the optical pump power. The slot-waveguide also has great flexibility for design variation and optimisation despite its simple and compact structure. The relationship between the slot-waveguide dimensions and the generated optical force, waveguide mechanical displacement and slot-waveguide delay is investigated and the design is optimised for high performance and ease of fabrication. When used as a nano-optomechanical actuator, the designed slot-waveguide produces a force of 1 pN/μm/mW, which is on the same order as the force produced by existing electrostatic comb drives. However, the optical actuator has additional advantages such as avoiding the problem of side-instability and immunity to electromagnetic interference and mechanical shock. We also simulate the performance of the designed slot-waveguide as a tunable optical delay line and find that the slot-waveguide can produce a refractive index change comparable to that of an optical fiber based delay line. However, the slot-waveguide delay line is optically controlled, compact and requires lower pump power, enabling its use in integrated optical signal processing components. An experimental demonstration of the nano-optomechanical actuator is presented as proof of concept, showing that the theoretical analysis is valid and setting the direction for future exploration of the optical gradient force.