Copper Sulfate Pentahydrate Target Behavior During Pulsed Laser Deposition to Produce Dichroic Coatings for Beam Splitters

Abstract

Copper sulfate pentahydrate (CuSO4·5H2O) used as target in the pulsed laser deposition (PLD) process led to producing thin films with dichroic properties. The coatings were applied on glass slab and hemp fabrics. Investigation of CuSO4·5H2O transformation during ablation and deposition based on FTIR analysis showed that the thin film chemical composition is a mixture of different products resulted from CuSO4·5H2O dehydration and decomposition, followed by melting and vaporization of the CuO and recombination of the different species in the plasma of ablation. Simulation in COMSOL of the CuSO4·5H2O laser heating anticipates the processes and phenomena to be expected during PLD. Optical properties of the thin films are investigated in UV-Vis as reflecting properties and by laser induced fluorescence (LIF). Applications are considered for dichroic plate beamsplitters, as well as others. Dichroic beamsplitters have a large range of applications among which they are useful for combining / splitting laser beams of different color. When the chemical composition provides also electrical conductivity specific properties, the coating may bring more value to the new device or material. In order to ascertain whether a dichroic system can be produced one way or the other achieving at the same time specific characteristics, it is important to understand the physico – chemical processes behind that. With this study, we determine the method to produce dichroic coatings on glass and on hemp fabric, looking at the same time into the mechanism that leads to the result.