Embedded Photodetectors in Polymer Waveguides for Optical Interconnect Integrated with a Si-Ge Transimpedance Amplifier Circuit Operating at 2.5 Gbit/s

摘要

Optical interconnection that can be integrated into electrical interconnection systems where high performance lines are necessary offer designers flexible interconnections options as component performance taxes interconnections, and also enables some preferable architectural alternatives [1-4]. Embedding thin film active optoelectronic devices in a substrate/optical waveguide structure can address packaging and alignment issues in the integration of optical interconnections in electrical systems. Thin film devices such as photodetectors and edge emitting lasers can be embedded in waveguides structures and addressed using either direct or evanescent field coupling [1], thus eliminating the need for optical beam turning out of the plane of the interconnection substrate. Since the polymer waveguide is deposited and patterned after the optoelectronic device is bonded to the interconnection substrate, the waveguide to active device alignment is defined through a photolithographic masking step. Finally, the optoelectronic active device/waveguide interfaces are embedded in the waveguide/substrate structure, thus eliminating the need for underfill or hermetic sealing (which applies to bump bonded optoelectronic devices). In this paper, the first report of a photodetector embedded in a polymer waveguide with output to a Si-Ge transimpedance amplifier is reported. This system was tested with an endfire coupled optical input to the multimode polymer waveguide, and, through direct coupling of this light to the photodetector from the waveguide followed by photodetector current output to a Maxim Si-Ge transimpedance amplifier, operation of this interconnection channel at 2.5 Gbps has been demonstrated.