Passive alignment of optic fiber array using silicon V-grooves monolithically integrated with polymer waveguide devices

Abstract

Packaging is the crucial link between a laboratory demonstrated device and a reliable component in a practical system. To achieve and maintain the sub-micron alignment tolerances between fiber and waveguide is the major factor that makes the packaging of photonic devices labor intensive, time consuming, and costly[1, 2]. Fiber arrays are important in WDM multiplexers and demultiplexers where multiple fiber attachment is essential. To avoid the complexity of the active alignment and attachment of individual fiber to each waveguide, we experimented with the passive alignment of fiber arrays with silicon V-grooves. The V-grooves are made on the same substrate that the polymer device is built on. The waveguide channels aligned to the center of the V-grooves are also processed together with the V-grooves using the same photolithography and etching technology. This technique is fundamentally different from the use of silicon V-grooves as fiber carrier for LiNbO3 and semiconductor devices, in which V-groove and devices are made on different substrate and bonded together later[3,4]. The width and the position of V-grooves can be fabricated in submicron precision with mature microelectronics technology. The fiber placed in the V-groove is entirely self-aligned in both vertical and lateral directions. The idea and some fabrication results of this approach have been presented earlier[5]. In this paper, our recent results of fiber coupling experiments are reported.