Colloquium 09-10-01

 

3:30 p.m. in Room 307 of the Optical Sciences Meinel Building

Speaker:

Marko Loncar

Harvard University School of Engineering and Applied Sciences

Title:

Optical Nanostructures for Advanced Communication Systems

 

Host:

Masud Mansuripur

 

Abstract:

Wavelength-scale optical resonators can enable on-chip manipulation of photons, and will be important building blocks for optical- and quantum-communication systems. We recently demonstrated photonic crystal nanobeam cavity1,2 , fabricated in silicon, that supports modes with quality factor Q~106. Furthermore, by taking advantage of mechanical degrees of freedom of two coupled-nanobeam cavities3, we demonstrated reconfigurable optical filters4 that could be dynamically and reversibly tuned. In our structure, that combines NEMS with nanophotonics, an external bias voltage controls the separation (<100nm) between the nanobeams via the electrostatic force, which in turn has a strong effect on the resonant wavelength of the structure.  We demonstrate tunable filters with a tuning range of ~10nm, using less than 6V of external bias and negligible steady-state power consumption4.

Bright single-photon source based on diamond nanowire5, that we recently discovered, is another example of novel functionalities enabled by nanostructuring. Nitrogen vacancy (NV) color center in diamond has emerged as promising quantum emitter that combines the key advantages of isolated atomic systems with solid-state integration. In order to further improve the efficiency of NV-based quantum-emitters, it is important to enhance the collection efficiency of emitted photons.  We achieved this using nanowire-antenna approach, and demonstrated an order of magnitude larger collection efficiency over devices based on bulk diamond crystals.

 

1P. B. Deotare, M. W. McCutcheon, I. W. Frank, M. Khan, and M. Lončar, APL, 94, 121106 (2009)