Population lensing effect in Cr:LiSAF probed by Z-scan technique

Absorptions UV dans le fonctionnement des sources lasers solides à ions de terres rares

“…Nous avons démontré que les variations de polarisabilité 2F(2)−4I associées à la population du niveau métastable ultraviolet 2 F(2) 5/2 , en tenant compte de certains ajustements par rapport aux données reportées dans la référence [9] …”

“…D'un autre côté, la caractérisation et la compréhension de ces mécanismes de pompage optique multiphotonique et d'absorption dans les états excités aident grandement pour rendre compte des différences de polarisabilités des ions actifs dans leurs états fondamental et excités, différences qui semblent à l'origine du comportement auto-déclenché et de la formation des réseaux de diffraction transitoires observés dans des systèmes lasers fortement pompés tels que LiCAF:Cr [7][8][9] et YAG:Nd [10,11].…”

Nonlinear optical properties of Cr3+-doped laser crystals

“…Because they are under large laser irradiance, certain materials can exhibit self focusing, self modulation and hole-burning Shen (2002). Self-Q-switching operation has already been demonstrated in Cr3+: LiSAF with pulse duration of a few hundred nanoseconds Hirth (1996, 1998) and attributed to a nonlinear population lensing effect Hirth 1996, 1998;Passilly et al 2004;Passilly 2006;Powell 1998). …”

Modeling the population lens effect in thermal lens spectrometry

“…For instance, a photoinduced population change in the ground and excited states can alter the refractive index according in the excitation intensity profile and manifest as a transient absorption generally at a very short time. This effect is referred to as population lens (PL), and, although it is generally much weaker than the TL effect, it may be important for laser materials [3][4][5][6][7].Laser-induced refractive index changes produce lenslike optical elements in the sample. Each optical element introduces an optical path length change and an associated additional phase shift that can be probed by a laser beam that is passed through the illuminated volume in the sample and exhibits a corresponding on-axis intensity change.…”

“…The TL and PL effects are generally both present, usually appearing as a complex transient signal. Theoretical and experimental efforts have been made to describe properly and to discriminate these effects [4][5][6][7]. However, it still remains essential to identify individual contributions for a clear understanding of the dominant physical mechanisms in a TL experiment.…”