We consider the interaction of a fully amplitude-modulated, narrow-band laser with a strongly inhomogeneously broadened two-level medium and show that harmonics of the fluorescence of susceptibility, unlike the time-averaged fluorescence, retain the characteristic multiphoton resonance structure that is found in the absence of inhomogeneous broadening. This behavior correlates with the existence of double branches of the corresponding Bloch–Siegert resonance curves. For strong fields, the depth of modulation and the phase shift of the lowest fluorescence harmonic may deviate significantly from the results for weak, broadband excitation.
© 1989 Optical Society of America
Original Manuscript: December 5, 1988
Manuscript Accepted: March 1, 1989
Published: May 15, 1989
Wilhelmus M. Ruyten, "Multiphoton resonances in the modulated fluorescence from an inhomogeneously broadened medium," Opt. Lett. 14, 506-508 (1989)