Jürgen Jahns
With the adaptation of microfabrication techniques from semiconductor processing it has become possible to make a variety of refractive and diffractive microoptical elements [1]. We use the microoptics technology to build miniaturized integrated free- space optical systems in a planar configuration [2]. In the "planar optics" approach microlenses and beamsplitters are integrated on one or both surfaces of a transparent substrate (Fig. 1). The folding the 3-D optics into a 2-D geometry allows one to process all the optics simultaneously by using standard planar fabrication techniques. The positioning of the microoptic elements is achieved with lithographic precision. Mechanical assembly, as required in conventional optics, is eliminated. Light propagation takes place inside the substrate along a zigzag path. The substrate, which is typically several millimeters thick, serves both as a medium for light propagation as well as a board onto which other components can be mounted. Optoelectronic chips like arrays of vertical cavity surface emitting microlasers and detector arrays can be bonded onto the substrate by using hybrid integration techniques such as flip-chip bonding.
Figure 1: Schematic of an integrated planar optical imaging system. Light signals travel inside a thick transparent substrate. Chips are mounted to the substrate by solder bump bonding.
Planar optics is a technology that lends itself to build miniaturized, robust optoelectronic microsystems. It can be applied to various areas such as optical interconnections for computer communications, sensor technology, and optical data storage. Several demonstration experiments are described in ref. [3]. In our work, we consider theoretical, experimental and technological aspects of planar optics and investigate potential applications. Some of these ongoing projects are described on the following pages.
References:[1] H.-P. Herzig (ed.), "Microoptics" (1996) Taylor&Francis, London.
[2] J. Jahns and A. Huang, Appl. Opt. 28 (1989) 1602-1605.
[3] J. Jahns, Proc. IEEE 82 (1994) 1623-1631.