Asymmetric properties between the forward and backward stimulated emission generated by ultrafast three- and four-photon excitation
- Institute for Lasers, Photonics and Biophotonics, State University of New York at Buffalo, Buffalo, New York 14260 (United States)
This paper presents the observation of asymmetric behavior between the forward and backward stimulated emission, generated in multiphoton active dye solutions, through three- or four-photon excitation of subpicosecond laser pulses. At a pump energy level considerably higher than the lasing threshold value, the peak wavelengths of the forward stimulated emission are 20-30-nm shorter than those of the backward stimulated emission for the two investigated stilbazolium dye solutions (PRL-L3 and PRL-L10). This obvious spectral asymmetry can be explained by the following three considerations: (i) the difference of spatial/temporal sequences between the forward and backward stimulated emission pulses; (ii) blueshift of the peak wavelength of transient gain experienced by the forward stimulated emission pulse; and (iii) saturation of reabsorption at the forward lasing wavelength range. These proposed explanations are verified by a specially designed pump-probe experiment, utilizing a white-light continuum as the probe beam and the {approx}1300-nm laser radiation as the pump beam for three-photon excitation. The experimental results have clearly shown the existence of the saturation effect of reabsorption and the gain-peak blueshift effect as well as their transient features.
- OSTI ID:
- 20786995
- Journal Information:
- Physical Review. A, Journal Name: Physical Review. A Journal Issue: 3 Vol. 73; ISSN 1050-2947; ISSN PLRAAN
- Country of Publication:
- United States
- Language:
- English
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