Resonantly Enhanced Axion-Photon Regeneration

Photon-regeneration experiments which search for the axion, or axionlike particles, may be resonantly enhanced by employing matched Fabry-Perot optical cavities encompassing both the axion production and conversion magnetic field regions. Compared to a simple photon-regeneration experiment, which uses the laser in a single-pass geometry, this technique can result in a gain in rate of order F{sup 2}, where F is the finesse of the cavities. This gain could feasibly be 10{sup (10-12)}, corresponding to an improvement in sensitivity in the axion-photon coupling g{sub a{gamma}}{sub {gamma}} of order F{sup 1/2}{approx}10{sup (2.5-3)}, permitting a practical purely laboratory search to probe axion-photon couplings not previously excluded by stellar evolution limits or solar axion searches.