Blue-green Fraunhofer-wavelength atomic filters

Jerry A. Gelbwachs

Jerry A. Gelbwachs, Yat C. Chan

Jerry A. Gelbwachs

Jerry A. Gelbwachs

Jerry A. Gelbwachs

The atomic resonance filter (ARF) is art ultra- high-Q (105–106) optical filter that is isotropic and insensitive to environmental factors and possesses a 180° acceptance angle.1 We are developing a novel ARF for satellite applications. Our filter operates in a Fraunhofer dip in the solar spectrum, thereby offering the key advantage of reduced solar background noise. Other important operational characteristics of the filter are: a projected conversion efficiency of blue-green light into the wavelength-shifted output light of ~90%, a 10-ns response time, and an output in the near UV, a spectral region that is efficiently detected by commercial large-area long-lived photomultiplier tubes.

Y. C. Chan, Martin D. Tabat, Jerry A. Gelbwachs

We describe what is to our knowledge the first experimental demonstration of internal wavelength conversion in the metastable Mg atomic filter. The filter operates at a Fraunhofer line, thereby offering intrinsic solar background rejection. Incoming green Fraunhofer photons (518 nm) are absorbed by metastable Mg atoms in an oven cell and are converted into UV (384-nm) photons. We observed a green-to-UV conversion efficiency of greater than 50%.