Abstract

Optical phase conjugation with high efficiency and fast response is of interest in many applications. Previously¹ we used dye lasers and sodium vapor to demonstrate such a conjugator, via hyperfine coherence gratings induced by coherent population trapping (CPT). To make a practical device, however, it is necessary to use atoms that can be excited by diode lasers. The best candidate is ⁸⁷Rb, for which the hyperfine manifold is identical to that of sodium, except for the absolute magnitudes of the level splittings. In particular, the ground state hyperfine splitting is about 6.8 GHz. To duplicate the sodium experiment, the probe beam has to be generated by modulation of the pump beam at this frequency. At such a high frequency, modulation is typically achieved electro-optically, or by direct modulation of the diode laser current. In either of these methods, it is difficult to filter the desired probe beam, spectrally as well as spatially.

© 1997 Optical Society of America