Arrays of anamorphic phase-matched Fresnel elements for diode-to-fiber coupling.

A method for designing microlens arrays that inherently takes into account application requirements and fabrication constraints is presented. Elements with numerical apertures of up to 0.5 have been designed and fabricated by laser beam writing in photoresist and replication in plastic material. In a laser-diode-to-fiber array coupling experiment, an overall optical throughput of 60% was achieved. By means of anamorphic microlens arrays, correction of the laser-diode longitudinal astigmatism and circularization of the image-plane irradiance distribution are demonstrated.