Porous Biomimetic Microlens Arrays as Multifunctional Optical Structures

Microlenses are important optical components that image, detect and couple light. Most synthetic microlenses, however, have fixed position and shape once they are fabricated. Therefore, the attainable range of their tunability and complexity is rather limited. In comparison, biological world provides a multitude of varied, new paradigms for the development of adaptive optical networks. This review discusses a few inspirational examples of biological lenses and their synthetic analogs. We focus on the fabrication and characterization of biomimetic microlens arrays with integrated pores, whose appearance and function are similar to a highly efficient optical element formed by brittlestars. The complex microlens design can be created by three-beam interference lithography. These synthetic microlenses have strong focusing ability, and the structure can be, therefore, used as an adjustable lithographic mask, and a tunable optical device coupled with the microfluidic system. The replacement of rigid microlenses with soft hydrogels provides means for changing the lens geometry and refractive index continuously in response to external stimuli, resulting in intelligent, multifunctional, tunable optics.