Resonance enhancement of two-photon absorption of phthalocyanines for 3D optical storage in the presence of hot-band absorption

摘要

We study a new series of asymmetrical phthalocyanines with promising properties for two-photon 3D optical memory. The chromophores have a strong and narrow one-photon absorption (1PA) S_0 → S_1 band at 730-760 nm, with a 200-400 cm~(-1) width. Tuning the laser frequency 500-1000 cm~(-1) below the S_0→ S_1 band allows for very high values of two-photon absorption (2PA) cross-section σ_2 > 10~4 GM. At temperatures T < 110K the molecules can be switched between two tautomer forms by 2PA. We measure 2PA spectra as a function of frequency and sample temperature. We provide an analysis of changes in 2PA spectra and cross sections due to different substituent groups. As a result, we found that among the set of studied molecules, there is one which is the most promising for rewritable 3D optical memory.