Development of microlens arrays for integration with optoelectronic devices

Optoelectronic integrated devices can be found in an increasing number of applications in optical systems and are expected to play a major role in future optical systems. They offer the potential of compact, lightweight optics that can be mass-produced in polymeric materials by low-cost replication techniques. The fabrication technology that can achieve such micro-optical elements has been well developed. The direct He-Cd laser writing system is adopted to fabricate micro-optical elements in this work. Continuous-relief microlens elements and microlens arrays fabrication process, which can be used in applications requiring integration of optoelectronic devices, are described. The continuous-relief microlens elements and microlens arrays are fabricated at different conditions and the optimum conditions have been determined. The intensity of the laser beam, the moving speed of the movable stages, the distance between the top surface of the photoresist coated on the substrate to the UV objective lens, and the overlap of the adjacent patterns are the key parameters that significantly influence the surface roughness, profile and surface-relief height of the drawn continuous-relief microlens elements.