Luminescent patterns recorded by laser irradiation of a PMMA matrix with a soluble CdS precursor

Abstract

Direct laser writing of luminescent patterns within the material consisting of the polymer (PMMA) matrix with dissolved precursor (TEDBCd) molecules is demonstrated. The luminescence here is related to the UV induced growth of CdS nanoparticles. The irradiation was performed by the third harmonic of a Nd:YAG laser with a pulse duration of 15 ns. The irradiated polymer films were kept at ambient temperatures of about 100 °C. At the maximum scanning speed, the luminescent signal is very low. A decrease in the scanning speed results in an increase in the luminescent signal and a shift of the luminescent spectrum towards longer wavelengths. However, at some speed, the increase in the luminescent signal is changed by its descent. This suggests the existence of an optimal laser exposure for the laser-induced luminescent pattering. This observation was confirmed when recording separate spots by a focused laser beam at different laser fluences. The luminescent hexagonal pattern consisting of micron-sized spots within the material bulk is obtained by means of irradiation of a single layer of closely packed ten-micron polystyrene spheres deposited on the material surface. The shape of these spots is discussed by comparing it with the calculated laser intensity space distribution within photonic jets.