Diffractive beam splitting microlens for fiber coupling fabricated by UV imprinting process

A polymeric diffractive microlens (DML) for coupling the incident light to two individually plastic optical fibers was designed and fabricated by imprinting process. The DML pattern of this dual-focal-point DML was designed with an optimal rotation-angle and realized by template fabrication and UV imprinting. Tetraethoxysilane oxide etching was developed and employed in the template fabrication process to minimize the related processing errors such as misalignment and dimension accuracy. A modified imprinting process is proposed in the experiment; DML with flexible polyethylene terphthalate substrate was imprinted by roller. After curing and demolding, the DML structure was successfully duplicated on polyethylene terphthalate substrate. The prototype was inspected and to confirm the optical properties and the results showed that the diffraction efficiency is 51% (designed value is 57%) and the uniformity error is only 1.5%.