Photon-gated hole burning: a new mechanism using two-step photoionization.
We have observed photon-gated spectral hole burning, i.e., hole burning that occurs only in the presence of an additional gating-light source. Gating enhancement factors of 10(4) were observed. In BaClF:Sm(2+) this involves two step photoionization of Sm(2+) and leads to persistent holes in the (4)F(0) --> (5)D(0) (687.9-nm) and (7)F(0) --> (5)D(1) (629.7-nm) absorption lines. The hole widths of 25 MHz at 2 K are much narrower than the inhomogeneous broadening of 16 GHz. The action spectrum of the gating shows a threshold behavior around 2.5 eV. Erasing studies show that Sm(3)+ acts as a trap for the released electrons. A remarkable and novel feature is that the holes can be recovered after temperature cycling to 300 K.
Winnacker
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IBM Research Laboratory, San Jose, California 95193, USA.
Shelby
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Macfarlane
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