Optical applications of silicon micromachining technology

摘要

To implement optical submodules or systems of the future we have identified a few key components and technologies necessary to build optical products at Hewlett Packard. To be competitive these optical assemblies must be smaller, cheaper and more functional, than current optical products while maintaining or exceeding the existing performance level. To accomplish this task we will introduce the idea of a Silicon Micro-Optical Bench (SMOB). The focus of the micro-optical bench has been laser submounts and collimators. However, while making advances in these platform technologies, the importance of micro parts which can be used to augment and expand the optical functions has become apparent. In this paper the role of silicon as a micro-optical bench substrate will be described along with implementations of micro-optical benches. Silicon is an excellent choice as a base platform for SMOB technology because of its availability and excellent material properties and advanced processing technology. Structures to aid in batch assembly processes are easily constructed from silicon wafers. We will show how to create structures which allow placement of ball lenses and other three dimensional structures to 1 um accuracy. This can be accomplished in a batch process with the potential for reductions in cost of assembly We have built generic laser submounts and collimators with various sizes of ball lenses. We will show how the performance of these submounts agrees with the theoretical predictions. For fiber to ball coupling Gaussian methods work well. However, for laser to fiber coupling via ball lenses it is necessary to use a Maxwell equation solver in spherical coordinates to correctly predict the spherical aberration effects. The ball lenses can collect the laser light with great efficiency at a fraction of the cost for conventional GRIN or aspheric lenses. Furthermore, the small size allows the whole optical part to fit within standard hermetic packages.