MEMS-based VCSEL beam steering using replicated polymer diffractive lens

This paper describes a fully integrated micro-optical system, in which dynamic angular control of the beam from a vertical cavity surface emitting laser (VCSEL) is realized by laterally moving a collimating diffractive lens in the light path. The lens is mounted on a translatable silicon stage, which consists of a frame with an opening for the light to traverse the lens and electro-statically driven comb actuators, by which the lateral movement is achieved. Devices implementing both one- (1D) and two-dimensional (2D) scanning have been fabricated and evaluated. Integration of the lens onto the translatable silicon stage is done using a newly developed fabrication process based on hot embossing of an amorphous fluorocarbon polymer. This fabrication process relies on a reversed-order protocol, where the structuring of the optical element precedes the silicon microstructuring. Assembly and packaging of the VCSEL-MOEMS system, using low temperature cofired ceramic (LTCC) technique, is also demonstrated. Optical evaluation of the system and beam steering function shows significant beam deflection for a relatively low driving voltage (∼70 V).