Heterogeneous 2D and 3D photonic integrated circuits

Abstract

Motivation for photonic integration can be summarized as reduction of cost, power consumption, size, packaging, and failures (FIT), and challenges in photonic integration are to achieve high yield. Heterogeneous photonic integration provides an opportunity for combining advantages from multiple photonic integration platforms. For instance heterogeneous integration of silicon, InP, and silica photonic integration platforms can combine compact waveguide bending radius (silicon photonics), gain and Pockel's effect (AlInGaAs/InP), and low loss (silica and silicon nitride) devices on relatively large silicon wafers. While achieving such monolithic integration of heterogeneous material platforms by hetero-epitaxy, etc., can ideally achieve intimate mechanical, thermal, optical, and electrical binding, it may be too challenging to realize process compatibility and high yield. On the other hand, hybrid integration of heterogeneous material platforms by utilizing wafer bonding, flip-chip bonding, etc., can prove to be a very practical approach. Motivation for 3D heterogeneous integration is to extend the benefit of 2D heterogeneous integration to 3D and to achieve higher density integration than 2D, although challenges compound in 3D compared to 2D. Laser inscribing provides a free-form method to create arbitrary shape embedded waveguides in 3D and also offers a method to achieve photonic wirebonding. Multilayer stacking facilitates creation of 3D photonic integrated circuits by using conventional lithography and deposition methods. 2D/3D heterogeneous photonic integration is essential for future microsystems aiming at scalability, high-performance, and cost effectiveness.