Authors: Guocheng Shao Ziliang Cai Zhengyu Miao Wanjun Wang
Publish Date: 2013/04/07
Volume: 19, Issue: 11, Pages: 1823-1828
Abstract
Outofplane microlenses are an important component for integrated optics Unlike their inplane counterparts the fabrication of outofplane microlenses is more complicated which limits their applications In this paper a new technique that is capable of fabricating outofplane microlenses is described The resulting lenses have predefinable focal length and can focus light beams not only in the horizontal plane but also in the vertical plane The fabrication process is completely compatible with the soft lithography technique The lens chamber with two thin polydimethylsiloxane PDMS membranes was designed and fabricated together with microfluidic or other components using the same UV lithography mask The lens was then formed in an insitu fashion Curable polymers were injected into the lens chamber and cured while pneumatic pressure was applied to keep the PDMS membranes deformed in a quasispherical profile Pneumatic pressure and membrane thickness can be adjusted to control the resulting lens focal length With a group of lens chambers with different membrane thickness a single pressure line can be used to fabricate microlenses with different focal lengths Since cured polymer was used as the lens filling material the resulting lens can be used without a pressure source Different polymers can be selected for desirable optical properties The simulation and experimental results have proved the feasibility of this technique and resulting lens showed good focusing ability for a divergent light beam from an onchip multimode optical fiber The small design footprint total compatibility with soft lithography and technical versatility of this technique make it particularly useful for intergrating outofplane microlens into microfluidic chips which may open new possibilities for the development of onchip optical detection system
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