Exploring control parameters of two photon processes in solutions

Journal of Chemical Sciences

Debabrata Goswami1¹  Amit Nag1¹ 

[1] Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India$$

关键词: Nonlinear optical control;    two photon absorption;    two photon absorption cross-section;    polarization;    pulse repetition rate;    nonlinear index of refraction.;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

Two-photon microscopy depends extensively on the two-photon absorption cross-sections of biologically relevant chromophores. High repetition rate (HRR) lasers are essential in multiphoton microscopy for generating satisfactory signal to noise at low average powers. However, HRR lasers generate thermal distortions in samples even with the slightest single photon absorption. We use an optical chopper with HRR lasers to intermittently `blank’ irradiation and effectively minimize thermal effects to result in a femtosecond z-scan setup that precisely measures the two-photon absorption (TPA) cross-sections of chromophores. Though several experimental factors impact such TPA measurements, a systematic effort to modulate and influence TPA characteristics is yet to evolve. Here, we present the effect of several control parameters on the TPA process that are independent of chromophore characteristics for femtosecond laser pulse based measurements; and demonstrate how the femtosecond laser pulse repetition rate, chromophore environment and incident laser polarization can become effective control parameters for such nonlinear optical properties.

【 授权许可】

Unknown