Michel Neumeier

Micro-optical components for parallel optical networks

Key components for parallel optical links are fabricated cost-effectively using LIGA technology. Multifiber ferrules and mechanical splices, 1/spl times/2 and 4/spl times/4 single-mode matrix switches and micro lens arrays with passive alignment structures are presented.

Polymer microsystems by excimer laser ablation: from rapid prototyping to large-number fabrication

Excimer laser ablation of polymers is demonstrated to be a well suited technology for cost effective fabrication of prototypes of polymer microstructures in relatively short times. Prototyping is realized by ArF excimer laser ablation (193 nm) using mask projection techniques in combination with high precision sample movement as well as mask movement. Different techniques and their restrictions in structural diversity are illustrated by examples from micro-optics, like fiber switches and waveguide couplers. Microparts the functionality of which has been proven by prototypes can be fabricated in large numbers by the Laser-LIGA technique. For the Laser-LIGA process a master structure is generated in PMMA that is coated onto a titanium wafer, using the same CNC data as for rapid prototyping without additional expenditure. From the PMMA master a mould insert of Ni or Cu can be generated by electroforming that allows time and cost effective mass fabrication via hot embossing or injection moulding if the required part numbers are large. Advantages and disadvantages of the laser ablation prototyping technique compared to other rapid prototyping methods are discussed and the Laser-LIGA technique is compared to the standard LIGA process using deep X-ray lithography.

Polymeric optical MEMS

As micro-opto-electro-mechanical systems and devices evolve from prototypes to products, the need for cost-effective mass production techniques becomes crucial. This challenging cost goal can be reached using mass replication techniques like injection molding and hot embossing.In order to meet the special demands of miniaturization these replication techniques have been modified incorporating variothermal process control, an evacuation of the mold chamber and a modification of the molding parameters including elevated temperatures. Based on these techniques numerous micro- optical systems have been developed including a twelve fold multi-fiber connectors with an average insertion loss of 0.35 dB, an optical bench using polymeric alignment structures on a silicon substrate, a 4 by 4 star coupler with passive fiber alignment, a 1 by 2 singlemode fiber switch, and a singlemode 4 by 4 optical matrix switch. In these systems geometrical tolerances of one micrometers and below have been obtained allowing passive alignment of multimode and singlemode fibers during the assembly process and high precision positioning of fibers during operation.

Micro-Optical Components for Information Technology Fabricated Via Liga Technique

We present the design and technical realization of exemplary micro-optical structures and devices for optical communication technology: A precision ferrule with (0.35 ± 0.2) dB coupling loss for 12-fold fibre ribbons, a 4 x 4 fibre-optical cross connect with non-moving mirrors, and a 4 x 4 multimode integrated-optical star coupler with less than 2dB uniformity have been fabricated by combination of the LIGA technique with precision engineering methods, e. g. electro discharge machining or diamond fly-cut milling. Further, “contactless embossing” for the in-place production of microlenses is introduced and discussed. The structures and devices presented are characterized by high precision, high performance, ease of assembly, and mass production capability via standard replication methods. All the main components have been made from thermoplastic materials via precision injection or compression moulding.

Miniaturized fiber optical switches with nonmoving polymeric mirrors for tele- and data-communication networks fabricated using the LIGA technology

Fiber optical switches for telecom and datacom purposes become more and more important with the growth of fiber- based networks. This paper proposes a new principle for manipulating optical light paths through switchable, but non-moving polymeric mirrors in free-space optical interconnects. To achieve this a polymeric body and a thin liquid film are moved within a cavity. By moving the body up and down perpendicular to the light path the cavity wall can be switched from total reflective to transmissive state while the liquid film remains between body and wall due to capillary forces. The body can be moved with integrated electro-magnetic actuators and so the whole concept allows the realization of very compact switching elements. The coupling of single mode optical fibers requires a lateral and angular alignment precision in the micron and millirad range for both direct coupling and expanded beam coupling concepts. To meet these requirements, the LIGA technology provides a promising approach with respect to the high precision and also low-cost fabrication by mass replication processes. The combination of LIGA technology with other precision machining technologies allows the fabrication of miniaturized systems with both micro-optic and micromechanic components which fulfill the required tolerances for optical coupling. First demonstrators of 1 X 2 and 2 X 2 switches with bistable electro-magnetic actuators have been fabricated to show the feasibility of the proposed principle. The measured insertion loss is less than 2 dB at 1300 nm with -40 dB crosstalk. The switching time was measured 100 ms. The capabilities of the proposed non-moving mirror principle can be applied to 1 X 2 repair switches for the access area as well as to FDDI-switching-nodes up to compact N X M cross-connect switches for reconfiguration purposes or parallel interconnects to optical backplanes for the office area.