VCSEL to waveguide coupling for optical backplanes

Abstract

Hybrid OECB (Opto-Electrical Circuit Boards) are expected to make a significant impact in the telecomm switches arena within the next five years, creating optical backplanes with high speed point-to-point optical interconnects. The critical aspect in the manufacture of the optical backplane is the successful coupling between VCSEL (Vertical Cavity Surface Emitting Laser) device and embedded waveguide in the OECB. Optical performance will be affected by CTE mismatch in the material properties, and manufacturing tolerances. This paper will discuss results from a multidisciplinary research project involving both experimentation and modelling. Key process parameters are being investigated using Design of Experiments and Finite Element Modelling. Simulations have been undertaken that predict the temperature in the VCSEL during normal operation, and the subsequent misalignment that this imposes. The results from the thermomechanical analysis are being used with optimisation software and the experimental DOE (Design of Experiments) to identify packaging parameters that minimise misalignment. These results are also imported into an optical model which solves optical energy and attenuation from the VCSEL aperture into, and then through, the waveguide. Results from the thermomechanical and optical models will be discussed as will the experimental results from the DOE.

Development of Underfilling Method for Flip Chip Mounted VCSEL

“…Although filling with transparent underfill resin is a possible solution, it was reported that the reliability of VCSELs will get worse by underfill resin. [6] This paper describes the method which enables the reliable flip chip mounting structure of VCSELs without hermetic sealing. It is realized by avoiding the arrangement of underfill resin of high Young's modulus on the mesa parts of VCSELs.…”