Planar hybrid polymer-silica microlenses with tunable beamwidth and focal length

Thermally tunable planar microlenses have been fabricated with a hybrid process utilizing silica-on-silicon and polymer planar lightwave circuit technologies. The silica microlens has a double concave gap filled with an optical polymer. The lens collimates the light beam with a beamwidth of less than 450 μm at distances up to 100 mm. The experiments presented demonstrate that by varying the lens temperature in a range of 60/spl deg/C the beamwidth can be tuned by /spl plusmn/40% at different distances from the lens. The beam-propagation-method simulations show that adjusting the lens curvature can control the beamwidth tunability range and thermal sensitivity. That allows optimization of the lens designs for different applications.