Investigation on butt-coupling of vcsel into pcb integrated waveguides

Abstract

Optical interconnections on printed circuit boards are a promising approach to increase the bandwidth in future links. Polymer waveguides are one possible solution for creating such optical connections. The coupling of a light source into such a structure is a crucial point in optical interconnection to obtain low transmission loss.

Purpose of this work is to show butt-coupling conditions between the vertical cavity surface emitting lasers (VCSEL) and highly multimode PCB integrated waveguide realized using “waveguide-in-Copper” technology. Two types of VCSELs are used – a lensed one and a naked laser chip without any optics. The influence of lateral and axial laser displacement on coupling efficiency will be demonstrated. One the basis of this experiments the optimal mutual position of the laser and the waveguide will be found to get acceptable quality of transmission.
Autorzy: Piotr HORMANSKI, Krzysztof NIEWEGLOWSKI, Klaus-Jürgen WOLTER, Sergiusz PATELA

1. INTRODUCTION

Integration of optical polymer waveguides in printed circuit boards is an auspicious treatment to increase the data rate on board level. The investigation are nowadays in the initial stage. Not meaningless is here the coupling of light from laser source into the waveguide. The coupling efficiency must be sufficient for achieving low transmission loss optical link. This paper will describe the various existing coupling methods, which are nowadays under investigation. The goal of the performed investigation is to demonstrate direct coupling (butt-coupling) properties between semiconductor laser (VCSEL) and highly multimode PCB integrated waveguide realized using “waveguide-in-copper” technology. For practical reasons it is required to know the boundary coupling conditions. Therefore the dependence of spatial (axial and lateral) source displacement on coupling efficiency will be characterized.