Two-photon Absorption In Direct Bandgap Semiconductors Quantum Dots

We present degenerate and nondegenerate two-photon absorption spectra in a series of CdSe and CdTe quantum dots. The measurements show that the two-photon absorption (2PA) spectrum is strongly dependent on the quantum dot size and that the 2PA coefficient decreases as the quantum dot size decreases, and it is larger for the frequency nondegenerate process. Previously we had shown a theoretical analysis of these results based on a simple model using the effective mass approximation. Although this model works well for larger quantum dots, it fails for the smaller ones. Here we use the more realistic k→ p→ model for the band structure and consider the hole band mixing in quantum dots to describe our data. This theory better describes the spectral structures for smaller quantum dots and also predicts the decrease of the 2PA coefficient with the decrease of quantum dot size. This is due to the reduction of the number of possible transitions and the blue shift of the optical bandgap from quantum confinement. This theory predicts the reduction of the 2PA coefficient with size, although our experimental results show an even stronger reduction.6327Larson, D.R., Zipfel, W.R., Willians, R.M., Clark, S.W., Bruchez, M.P., Wise, F.W., Webb, W.W., (2003) Science, 300, pp. 1434-1436Sargent, E.H., (2005) Adv. Matt., 17, pp. 515-522Padilha, L.A., Neves, A.A.R., Rodriguez, E., Cesar, C.L., Barobosa, L.C., Cruz, C.H.B., (2005) Appl. Phys. Lett., 86, pp. 1611111-1611113Uskov, A.V., O'Reilly, E.P., Manning, R.J., Webb, R.P., Cotter, D., Laemmlin, M., Ledentsov, N.N., Bimberg, D., (2004) IEEE Phot. Tech. Lett, 16, pp. 1265-1267Cerletti, V., Coish, W.A., Gywat, O., Loss, D., (2005) Nanotech., 16, pp. R27-R49Sercel, P.C., Vahala, K.J., (1990) Phys. Rev. B, 42, pp. 3690-3710Cotter, D., Burt, M.G., Manning, R.J., (1992) Phys. Rev. Lett., 68, pp. 1200-1203Seo, J.T., Yang, Q., Creekmore, S., Temple, D., Qu, L., Yu, W., Wang, A., Kim, J.H., (2003) Phys. E, 17, pp. 101-103Banfi, G.P., Degiorgio, V., Ricard, D., (1998) Adv. Phys., 47, pp. 447-510Padilha, L.A., Fu, J., Hagan, D.J., Van Stryland, E.W., Cesar, C.L., Barbosa, L.C., Cruz, C.H.B., (2005) Opt. Exp., 13, pp. 6460-6467Padilha, L.A., Fu, J., Hagan, D.J., Van Stryland, E.W., Cesar, C.L., Barbosa, L.C., Cruz, C.H.B., (2005) Proc. SPIE, 5931, pp. 226-235Fedorov, A.V., Baranv, A.V., Inoue, K., (1996) Phys. Rev. B, 54, pp. 8627-8632Sheik-Bahae, M., Said, A.A., Wei, T.H., Hagan, D.J., Van Stryland, E.W., (1990) IEEE J. of Quantum Electron., 26, pp. 760-769Negres, R.A., Hales, J.M., Kobyakov, A., Hagan, D.J., Van Stryland, E.W., (2002) IEEE J. Quantum Electron., 38, pp. 1205-1216Hales, J.M., Hagan, D.J., Van Stryland, E.W., Schafer, K.J., Morales, A.R., Belfield, K.D., Pacher, P., Bredas, J.L., (2004) J. Chem. Phys., 121, pp. 3152-3160Barbosa, L.C., Reynoso, V.C.S., De Paula, A.M., De Oliveira, C.R.M., Alves, O.L., Craievich, A.F., Marotti, R.E., Cesar, C.L., (1997) J. Non-cryst. Solids, 219, pp. 205-211Yu, W.W., Qu, L.H., Guo, W.Z., Peng, X.G., (2003) Chem. Mater., 15, p. 2854Bunge, S.D., Krueger, K.M., Boyle, T.J., Rodriguez, M.A., Headley, T.J., Colvin, V.L., (2003) J. Mater. Chem., 13, p. 1705Qu, L.H., Peng, X.G., (2002) J. Am. Chem. Soc., 124, p. 2049L.A. Padilha, J. Fu, D.J. Hagan, E.W. Van Stryland, C.L. Cesar, L.C. Barbosa, C.H.B. Cruz, D. Buso, and A. Martucci, to be published (2006)Kane, E.O., Semiconductors & Semimetals, 1. , Cap. 3Ekimov, A.I., Hache, F., Schanne-Klein, M.C., Richard, D., Flytzanis, C., Kudryavtsev, I.A., Yazeva, T.V., Efros, Al.L., (1993) J. Opt. Soc. Am. B, 10, pp. 100-10

Optical Nonlinearities In Cdte Quantum-dot Doped Glass For Optical Switching

Nonlinear refraction and absorption are studied in CdTe quantum-dots in a glass host. We find that the nonlinearities differ from those of bulk CdTe. An ultrafast polarization-rotation switch with on-off ratio of 42:1 is demonstrated. © 2005 Optical Society of America.1651653Cotter, D., Burt, M.G., Manning, R.J., Bellow-band-gap third-order optical nonlinearity of nanometer size semiconductor crystallites (1992) Phys. Rev. Lett., 68, pp. 1200-1203Padilha, L.A., Neves, A.A.R., Cesar, C.L., Barbosa, L.C., Cruz, C.H.B., Recombination processes in CdTe quantum-dot-doped glasses (2004) Appl. Phys. Lett., 85, pp. 3256-3258Padilha, L.A., Neves, A.A.R., Rodriguez, E., Cesar, C.L., Barbosa, L.C., Cruz, C.H.B., Ultrafast optical switching demonstrated with CdTe nanocrystals (2004) App. Phys. Lett., , submitted for publicationVan Stryland, E.W., Woodall, M.A., Vanherseele, H., Soileau, M.J., Energy band-gap dependence of two-photon absorption (1985) Opt. Lett., 10, pp. 490-492Falcao-Filho, E.L., Bosco, C.A.C., Maciel, G.S., Acioli, L.H., De Araujo, C.B., Lipovskii, A.A., Tagantsev, D.K., Third-order optical nonlinearity of a transparent glass ceramic containing sodium niobate nanocrystals (2004) Phys. Rev. B, 69, pp. 1342041-1342048Sheik-Bahae, M., Hagan, D.J., Van Stryland, E.W., Dispersion and band-gap scaling of the electronic Kerr effect in solids associated with two-photon absorption (1990) Phys. Rev. Lett., 65, pp. 96-99Rogers, D.C., Manning, R.J., Ainslie, B.J., Cotter, D., Yates, M.J., Parker, J.M., Morgan, S., Concentration dependence of nonresonant nonlinearity in CdS xSe 1-x Doped Glasses (1994) IEEE J. of Phot Tech. Lett., 6, pp. 1017-1019Dinu, M., Quochi, F., Garcia, H., Third order noninearities in silicon at telecom wavelenghts (2003) Appl. Phys. Lett., 82, pp. 2954-2956Elim, H.I., Ji, W., Yuwono, A.H., Xue, J.M., Wang, J., Ultrafast optical nonlinearity in poly(methylmethacrylate)-TiO 2 nanocomposites (2003) Appl. Phys. Lett., 82, pp. 2691-269

Two-photon Absorption Study Of Polymethine And Squarylium Molecules

The degenerate two-photon absorption spectra for a series of symmetric and asymmetric polymethine and squarylium dyes were measured by femtosecond Z-scan and upconverted fluorescence methods. Structure-property relationships were revealed and explained with quantum-chemical analysis. © 2005 Optical Society of America.Hales, J.M., Resonant enhancement of two-photon absorption in substituted fluorence molecules (2004) J. Chem. Phys, 121 (7), pp. 3152-316

Two-photon Absorption Studies Of Polymethine And Squaraine Dyes With Analogous Structures

We compare two-photon absorption spectra of polymethines and squaraines experimentally and quantum-chemically. Squaraines display two-photon cross-sections considerably larger (7×103GM) than polymethines, due to an extra band introduced by the squaraine structure in the conjugated chain. © 2006 Optical Society of America.Albota, M., Beljonne, D., Bradas, J.L., Ehrlich, J.E., Fu, J.-Y., Heikai, A.A., Hess, S., Xu, C., Design of organic molecules with large two-photon absorption cross sections (1998) Science, 281, pp. 1653-1656Rumi, M., Ehrlich, J.E., Heikal, A.A., Perry, J.W., Barlow, S., Hu, Z., McCord-Maughon, D., Bredas, J.L., Structure-property relationships for two-photon absorpbing chromophores: Bis-donor diphenylpolyene and bis(styryl)benzene derivatives (2000) J. Am. Chem. Soc, 122, pp. 9500-9510Hales, J.M., et., al., Resonant enhancement of two-photon absorption in substituted fluorene molecules (2004) J. Chem. Phys, 121 (7), pp. 3152-316

Optical-limiting properties of neutral nickel dithiolenes

Applied Physics B: Lasers and Optics702-6809-812APBO

Optical limiting with neutral nickel dithiolene complexes

Materials Research Society Symposium - Proceedings597413-418MRSP

Investigation of an optical limiting mechanism in multiwalled carbon nanotubes

Applied Optics39121998-2001APOP