Abstract

Trebino and Rahn¹ observed subharmonic resonances in high-order wave-mixing spectra of the sodium atom in flames. They used two pulse-amplified, single-mode dye lasers to generate two nearly degenerate pump beams at 590 nm. The pump beams were tuned 2 cm⁻¹ away from the sodium D₁ line resonance, as shown in Fig. 1. At low laser intensity, hyperfine resonances at a frequency difference of 0.06 cm⁻¹ and the Zeeman resonance at zero frequency difference were clearly visible. At higher intensities, the hyperfine resonances broadened, and a subharmonic resonance at ½ the hyperfine splitting ω_hfs appeared.

© 1991 Optical Society of America