Colloquia & Guest Speakers

Optomechanics with a microscopic membrane in an optical cavity

Dr. Haitan Xu, University of Maryland-College Park

Friday, February 13, 2015
1:30 p.m.–2:30 p.m.

Goergen 109


Suspended microscopic membranes provide new approaches to the study of optomechanics and sensing technologies. In this talk I will present our recent works with a sub-wavelength grating membrane and also a tethered membrane in a Fabry-Perot cavity. The spectral signatures of the system allow more detailed study of the losses than is possible in a simple cavity, and we characterize the reflection, transmission, absorption and scattering losses of the grating membrane. We use this system for highly sensitive and accurate mechanical displacement sensing. We also analytically study and experimentally realize the buckling transition in the "membrane-in-the-middle" system. The optomechanical interaction between the laser and the membrane induces an optical trap, which changes the effective potential of the membrane. Specifically, we find that a harmonic potential, at low power, develops into a double-well potential with increasing optical power, leading to a buckling transition for the membrane-in-the-middle system.


Dr. Haitan Xu is currently a postdoc at the Joint Quantum Institute at University of Maryland-College Park and a guest researcher at the National Institute of Standards and Technology. He received his Ph.D. from University of Maryland, B.Sc and M.Sc. from Zhejiang University. His research fields include optomechanics, silicon photonics, precision measurement, topological physics and quantum computation.