Seminars

2013-05-14

Photonic devices in motion

Asst. Prof. Mo Li, University of Minnesota, Twin Cities - Dept. of Electrical and Computer
Speaker's Website
Asst. Prof. Xiaodong Xu, Dept. of Physics

Even in a simple optics experiment, mirrors, lens and lasers have to be moved around to align and adjust to make the optical system operational. In integrated optical devices, however, every optical component is carved into the semiconductor or glass substrate. Their optical functions can hardly be changed, despite the need to adapt their properties. In this talk, I will present several different approaches to move integrated photonic devices in order to reconfigure their functions, to achieve high precision measurement of minute forces and to couple RF and microwave signals with light. We first demonstrate moving integrated waveguides by using forces generated by light itself. We experimentally prove the theoretical prediction that this new optical force is bipolar – its direction can be tuned to be attractive or repulsive by changing the relative optical phase of coupled lightwaves, resembling the Coulomb force between positive and negative charges. We show the exploitation of optical forces in a variety of interesting optomechanical structures, including photonic crystal, micro-disk optical resonators and cavity optomechanics, and applications in advanced sensing and optical communication. Secondly, we will show that gigahertz surface acoustic waves (SAW) can be excited on the surface of integrated photonic devices build on piezoelectric substrates to interact with light strongly. This leads to a new category of piezo-photonic device with potential applications in RF/microwave photonics. Finally, we will demonstrate processes to transfer photonic devices on to plastic substrates to make them mechanically flexible and tunable.