A fast response time atomic filter at 423 nm

Jerry A. Gelbwachs, Yat C. Chan

Zhichao Xu, Xiaobo Xue, Duo Pan +3 more

Jerry A. Gelbwachs

Y. C. Chan, Jerry A. Gelbwachs

Atomic resonance filters are optical bandpass filters that employ sharp atomic transitions to perform ultra-narrow-band (0.001 nm) filtering of light.1 Further, the bandwidth is independent of aperture size and field-of-view, These devices are designed to exclude sunlight in laser receivers. Applications include laser radar, lasercom, remote sensing, and underwater communications.

Frederick G. Walther

An optically pumped active Ca atomic resonance filter is demonstrated, applicable to background-limited optical communications through scatter channels. In pump saturation, the filter should detect 50% of the incident 423-nm signal power with an internal photon gain of 6 and a response time of 10 micros, 2 orders of magnitude faster than a passive Ca filter. Response time of 100 micros has been demonstrated, limited by available pump power. The filter maintains the wide field of view and reduced solar background associated with atomic absorption at the Ca Fraunhofer line while permitting higher data rate communications.

Jerry A. Gelbwachs, Yat C. Chan