Micro-optics is usually associated with planar waveguides or integrated optical circuits. In this case the propagation of light is restricted to one or two dimensions, and the three-dimensional nature of light propagation is disregarded. We present a method of fabricating three-dimensional micro-optical components by the so-called LIGA process, a lithography, electroforming, and plastic molding process in which poly(methyl methacrylate) is structured by high-energy synchrotron radiation. We demonstrate an experimental system of image formation that uses microprisms and microlenses for a threedimensional microintegration of optical components.

For the conversion of light from edge-emitting laser diodes into symmetric laser beams two main tasks have to be performed: collimation and beam shaping. Generally these two jobs are performed separately. Because of the inherently different divergence angles of the emitted light, collimation with astigmatic lenses generally results in a beam with an elliptically shaped amplitude distribution. This asymmetry has to be compensated for by an anamorphic imaging step to obtain the desired spherical beam profile. It can be advantageous to combine both jobs in one element. We demonstrate the design, the fabrication, and the application of refractive gradient-index elements, which allow one to perform both jobs with a single element. Our astigmatic lenses were fabricated by silver-sodium ion exchange in glass.

An optical backplane for high bit rate data transmission between processor boards is presented. The backplane consists of lowloss polymer multimode waveguides, integrated micromirrors and lenses for focusing/collimation. Free space transmission is used for the coupling between processor boards and the backplane. Due to an expanded beam, high alignment tolerances between the boards and the backplane are obtained. Backplanes are realized for a 55 cm (21 in.) interconnection length, for a ring network and for a 4ϫ4 star network. For each backplane, data transmission with a bit rate Ͼ1 Gbit/s is demonstrated and first environmental tests are successfully passed.

A new concept for a common interface between passive and active single-mode devices is proposed. The submicrometer alignment accuracy necessary for efficient coupling of single-mode devices is extended to the range of some 10 mum by beam expansion with planar gradient-index microlenses; the increased angular sensitivity is satisfied by the use of planar surfaces. The imaging system is used off axis, resulting in a suppression of backreflections in the range >60 dB. Of many possible variations of components (fibers, waveguides, optoelectronic integrated circuits, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodiodes), the coupling of fibers and waveguides is examined in detail. Expected coupling efficiency and sensitivity to lateral misalignment are calculated by use of a modified beam-propagation method. In this way, the overall performance of the connector can be compared with existing connector concepts, and the feasibility of the concept is proven. Experimental results for the fiber-fiber connector are given.