Photoinduced Reversible Local Deformation of the Surface Relief in Bulk Single Crystals of TlInSe2, TlGaTe2, and TlSe

Giant macroscopic expansion of the surface relief, localized within a laser spot size, has been observed in bulk single crystals of TlInSe 2 , TlGaTe 2 , and TlSe at room temperature and laser radiation densities lower by at least two orders of magnitude than the material optical damage threshold. Quantitative estimations of the deformation magnitude in this local region were obtained using an interference dilatometer. The photon absorption length was determined with the aid of spectroscopic ellipsometry. It is established that the surface deformation amounts to 2.6 × 10 –3 at a laser radiation intensity of 19 mW/mm 2 . The observed phenomenon has a thermal nature and is probably related to a low thermal conductivity of the materials studied.