Two-photon absorption spectroscopy of As2S3 glass

Abstract

Spectral dependence of two-photon absorption in a chalcogenide glass, As 2 S 3 , has been studied using a tunable light source. The result shows that two-photon and two-step absorptions occur, and the two-photon absorption spectrum appears to be exponential. These results and roles of nonlinear processes in photoinduced phenomena are discussed.

Two-photon optical absorption in PbO-SiO2 glasses

“…2͒, consistent with theoretical calculations. 36 As 2 S 3 shows a similar feature, 10 and this may be a general rule in binary systems. In contrast, in PbO-SiO 2 , the two-photon absorption edge ͑ϳ2 eV͒ is located at ϳ2/3 of the Urbach edge ͑ϳ3 eV͒.…”

“…In contrast, under repeated pulse exposures, 1/T depended upon illumination history. It should be mentioned here that no signatures of two-step absorption 10,28 have been detected. Figure 1 shows the composition dependence of ␣͑ប ͒ ͑open symbols͒ and ␤͑ប ͒ ͑solid symbols͒.…”

“…First, the spectra are not exponential, which is in marked contrast to those in other glasses, such as SiO 2 ͑replotted in the figure͒ 8 and As 2 S 3 . 10 With increasing x, the spectra may show a redshift. However, all the spectra seem to have a common rise at ϳ2.0 eV, which is more-or-less conspicuous in amorphous materials having nonsharp absorption edges.…”

“…On the other hand, two-photon absorption spectra ␤͑ប ͒ were evaluated using a pulsed laser system consisting of a Nd:YAG laser ͑Continuum, Surelite I͒ and an optical parametric oscillator ͑GMU, C-355͒, the details of which were reported previously. 10 A simple calculation gives 1/T ϭexp(␣L)/(1ϪR) 2 ϩ͓exp(␣L)Ϫ1͔␤I 0 /͓␣(1ϪR)͔, where L is the sample thickness, R the reflectivity at sample surfaces, and I 0 the incident light intensity. 3,10 Accordingly, by measuring 1/T as a function of I 0 , we can evaluate ␤.…”

“…Specifically, most previous work investigates twophoton absorption coefficients at selected wavelengths. [2][3][4][5][6][7] Spectral studies are fewer, [8][9][10] and interpretation of the spectra has been preliminary, taking into account only the density-of-states, while neglecting the role of transition amplitudes. However, since the transition amplitudes of oneand two-photon absorption are contrastive, 1 parallel studies on both absorptions can provide unified insights into optical absorption mechanisms, which are still ambiguous in disordered materials.…”