Two-photon absorption and excited state absorption properties of an organic dye PSPI

• Published in: Optics communications Vol. 241; no. 1-3; pp. 215 - 219
• Main Authors: Zhou, Guangyong, Wang, Dong, Wang, Xiaomei, Shao, Zongshu, Jiang, Minhua
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2004; Elsevier Science
• Subjects: Exact sciences and technology; Excited state absorption; Frequency conversion ; harmonic generation, including high-order harmonic generation; Fundamental areas of phenomenology (including applications); Nonlinear optics; Optics; Organic dye; Physics; Two-photon absorption; Ultrafast processes; optical pulse generation and pulse compression; 78.47.+p; Excited state absorption; Organic dye; 42.65.Re; 42.66Ky; Two-photon absorption; 78.20.Ek; Red shift; Upconversion; Light matter interaction; Laser pumping; Theoretical study; Excited states; Experimental study; Transmittance; Pulsed lasers; Non linear process; Optical properties; Three-level systems; Two photon absorption; Nonlinear optics; Cross sections
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2004.06.059

The reason why there is a 90 nm red-shift for the highest upconversion wavelength compared with the strongest nonlinear absorption wavelength is given. A three-level energy model is proposed for an organic dye, trans-4-[p-(pyrrolidinyl)styryl]-N-methylpyridinium iodide (abbreviated as PSPI). It is the excited state absorption (ESA) that leads to the reduction of the upconversion efficient at wavelength shorter than 950 nm. The three-level energy model is proved to be right by using the femtosecond pumped two-photon excited spectrum. The TPA cross-sections and the ESA coefficients at various wavelengths are calculated using the measured nonlinear transmittance and upconverison efficiencies. The largest TPA cross-section σ2′ is 14.1×10−48 cm4s/photon at 960 nm. The experimental results show that the electrons are excited to the same excited states for both the TPA and one-photon absorption processes.