Achievement

The ultimate limits on classical information transmission at optical frequencies are set by quantum mechanics, because high-sensitivity photodetection systems have long been limited by quantum noise. As part of an effort to show how to achieve high photon efficiency (10 bits/photon) and high spectral efficiency (5 bits/sec-Hz) optical communication over a line-of-sight atmospheric path, iQuISE Trainee Nivedita Chandrasekaran has evaluated the cross-talk behaviors of focused-beam, Hermite-Gaussian, and Laguerre-Gaussian spatial modes that are candidate mode sets for this application and used her results to instantiate upper and lower bounds on the ultimate (Holevo) capacities that they achieve. Her work shows that adaptive optics will be necessary to realize the desired photon and spectral efficiencies. Nivedita will be reporting her cross-talk results at the CLEO 2012 conference this May and her capacity bounds at the SPIE Optics and Photonics Conference this summer.