Cornell University - Visit www.cornell.edu Kirby Research Group at Cornell: Microfluidics and Nanofluidics : - Home College of Engineering - visit www.engr.cornell.edu Cornell University - Visit www.cornell.edu
Cornell University, College of Engineering Search Cornell
News Contact Info Login
Chemical Synthesis and Nonlinear Optics in Microchannels
Funding: Center for Nanoscale Systems
Quantum and nonlinear optical properties offer many exciting opportunities for technological breakthroughs. One of these is in data storage, in which nonlinear optical techniques have the potential to store information using single photons. In many cases, the underlying optical process for realizing these schemes has been electromagnetically induced transparency (EIT), a nonlinear optical technique by which a material is made transparent to radiation of one frequency by using laser light at a different frequency to generate a coherent superposition of states. This concept has been expanded to schemes that allow two extremely weak fields--which, in principle, can consist of single photon pulses--to strongly interact. Practical implementation of these proposals in which a single photon can switch another photon could lead to the realization of critical components (e.g., quantum phase gates) for quantum information applications.

Photonic band-gap fibers (PBGFs) offer unmatched ability to both (a) tightly confine light into a small region (e.g., 10 microns) and (b) allow this light to propagate for long pathlengths (say, meters). However, these fibers (until recently) could not be used to induce atom-light interactions because of the chemical incompatibilities of atomic vapors with the silica material from which PBGFs are constructed.

Our group currently collaborates with Alex Gaeta's group to create devices with novel nonlinear and quantum optical properties. We have performed liquid-phase microfluidic chemical synthesis inside photonic band-gap crystal fibers, generating fibers that retain their bandgap and transmission properties but present different surface properties to atomic gases. By combining novel microfluidic chemical synthesis with laser-induced atomic desorption techniques, we have generated dense atomic vapors inside the core of PBGFs.

By creating dense atomic vapors inside PBGFs, we have been able to demonstrate EIT at light irradiances several orders of magnitude lower than previous work, moving us significantly closer to our long-term vision of single-photon switching for quantum networks.

Archival Publications

PDF version of Ghosh, Bhagwat, Renshaw, Goh, Gaeta, Kirby: Low-light-level optical interactions with rubidium vapor in a photonic band-gap fiber

Ghosh S, Bhagwat AR, Renshaw CK, Goh S, Gaeta AL, Kirby BJ
"Low-light-level optical interactions with rubidium vapor in a photonic band-gap fiber," Physical Review Letters 97:023603 (2006). doi pdf arxiv

Presentations and Other Publications

7-11 Oct 2007

Tandon V, Ghosh S, Bhagwat AR, Renshaw CK, Goh S, Gaeta AL, Kirby BJ
"In-situ microfluidic synthesis of materials for nonlinear optical devices: control of atomic vapor populations in microchannel waveguides", MicroTAS 2007, Paris, France, October 2007.

May 2006

Ghosh S, Bhagwat AR, Renshaw CK, Goh S, Gaeta AL, Kirby BJ
"Nonlinear optical interactions with rubidium atoms confined in a hollow-core photonic crystal fiber," CLEO-QELS 2006 Long Beach, CA.

May 2006

Ghosh S, Bhagwat AR, Renshaw CK, Goh S, Gaeta AL, Kirby BJ
"Coherent interactions with rubidium atoms confined in a hollow-core photonic bnad-gap fiber," APS DAMOP 2006 Annual Meeting Knoxville, TN.

End view of . Typical diameter of the central core is ~10 microns. The honeycomb structure serves as a diffractive element that confines light in a certain range of wavelengths.
Schematic of paraffin-modified PBGF core. By creating paraffin-like properties at the core surface, atoms retain their spin coherence and can be detached with light-induced atomic desorption.
V-system electromagnetically induced trasparency in rubidium in a PBGF core. These results were achieved with a pump power of 10 nW, approximately 1000 times less power than previous work. (click here for source).