Two-photon absorption of Tl1−xIn1−xSnxSe2 (x = 0, 0.1, 0.2, 0.25) single crystalline alloys and their nanocrystallites

Two-photon absorption (TPA) of Tl1−xIn1−xSnxSe2 (x = 0, 0.1, 0.2, 0.25) was studied at CO2 laser wavelength 9.4 μm with pulse duration 1 μs. The studies were performed at different temperatures and for the nanocrystallite sizes varying within the 7-200 nm. The nanocrystals were fabricated by mechanical milling with simultaneous acoustical field treatment and porous filter size separation. The studies have shown that the TPA may be enhanced during the decrease of the nanocrystallite sizes below 50-60 nm. There exists also some critical x value at which the TPA value begin substantially to increase. The comparison with other chalcogenide crystals is performed. The studied nanocrystallites are relatively stable to the infrared laser treatment and are not hygroscopic which allow to use them in different IR optoelectronic devices.