Authors

C. M. Cirloganu; L. A. Padilha; D. A. Fishman; S. Webster; D. J. Hagan;E. W. Van Stryland

Comments

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Abbreviated Journal Title

Opt. Express

Keywords

ZINC BLENDE SEMICONDUCTORS; SOLIDS; NONLINEARITIES; SPECTROSCOPY; SPECTRA; ENERGY; FIELD; ZNSE; Optics

Abstract

Two-photon absorption (2PA) spectra with pairs of extremely nondegenerate photons are measured in several direct-gap semiconductors (GaAs, CdTe, ZnO, ZnS and ZnSe) using picosecond or femtosecond pulses. In ZnSe, using photons with a ratio of energies of similar to 12, we obtain a 270-fold enhancement of 2PA when comparing to the corresponding degenerate 2PA coefficient at the average photon energy (eta omega(1) + eta omega(2))/2. This corresponds to a pump photon energy of 8% of the bandgap. 2PA coefficients as large as 1 cm/MW are measured. Thus, by using two widely different wavelengths we are able to access the large 2PA observed previously only in narrow gap semiconductors. We also calculate the corresponding enhancement of nonlinear refraction, consisting of two-photon, AC-Stark and Raman contributions. The net effect is a smaller enhancement, but exhibits very large dispersion within the 2PA regime.

Journal Title

Optics Express

Volume

19

Issue/Number

23

Publication Date

1-1-2011

Document Type

Article

Language

English

First Page

22951

Last Page

22960

WOS Identifier

WOS:000296904700077

ISSN

1094-4087

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