Diffractive optical elements (DOEs) are components widely used for laser beam shaping and data storage. The aim of this study is the fabrication of efficient DOEs which correspond to current industrial needs, by a simple, reproducible and low-cost process. A first approach investigated adresses holographic recording of gratings in photopolymerisable materials with a three-components photo-initiator system. These systems are photochemically more efficient (high polymerisation speed and rate), corrected first-order diffraction efficiencies higher than 90% are obtained after optimisation of the materials. The second approach centres on DOE fabrication in a sol-gel hybrid material from the ORMOCER®s family. This new material is shown to be more efficient (transparency, thermal, chemical and mechanical stabilities) than photoresist, microstructured initially material. The final DOE is created by moulding from a photoresist prototype which is obtained by parallel direct-write photolithography at 436 nm. This process is developed, optimised and validated by several structural and functional characterisations, to obtain zero-order diffraction efficiencies lower than 1%. This fabrication method is used to realise prototypes and small series DOEs on substrates of different sizes and materials (silicon, glass, silica, ceramic and plastic) to extend their application field.
Fabrication of Diffractive Optical Elements by Microstructuration of Polymer Materials