RESUMO
We demonstrate an optically controlled Kerr phase shifter using a room-temperature 85Rb vapor operating in a Raman gain scheme. Phase shifts from zero to π relative to an unshifted reference wave are observed, and gated operations are demonstrated. We further demonstrate the versatile digital manipulation of encoded signal light with an encoded phase-control light field using an unbalanced Mach-Zehnder interferometer. Generalizations of this scheme should be capable of full manipulation of a digitized signal field at high speed, opening the door to future applications.
RESUMO
We have demonstrated the exchange of sifted quantum cryptographic key over a 730 meter free-space link at rates of up to 1.0 Mbps, two orders of magnitude faster than previously reported results. A classical channel at 1550 nm operates in parallel with a quantum channel at 845 nm. Clock recovery techniques on the classical channel at 1.25 Gbps enable quantum transmission at up to the clock rate. System performance is currently limited by the timing resolution of our silicon avalanche photodiode detectors. With improved detector resolution, our technique will yield another order of magnitude increase in performance, with existing technology.
RESUMO
The power scaling and frequency stabilization of a high-power, injection-locked, arc-lamp-pumped Nd:YAG laser at 1064 nm are discussed theoretically and experimentally. Thermal lensing and induced birefringence at high pump powers are modeled, and the effectiveness of the model for compensating thermal lensing is demonstrated with four different laser heads. Two distinct active frequency-stabilization schemes for injection-locked lasers are also compared theoretically and experimentally. These efforts yield a 24-W, linearly polarized, continuous-wave, TEM00 output with a spectral linewidth of 1.5 Hz measured by heterodyne detection.
