Hot Embossing of LCP using Silicon Master Tool for Short Distance Optical Interconnects Kamal Yadav, Scott Kirkpatrick, Azad Siahmakoun Center for Applied Optics Studies, Department of Physics and Optical Engineering, Rose Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN, USA 47803- 3999 ABSTRACT A novel method has been developed for using 45˚ mirror surfaces for the vertical coupling of light into a channel for short distance optical interconnects. The method includes the structuring of silicon (100) wafer to act as a master tool, then using anisotropic etching followed by hot embossing of the master tool onto a desired substrate, in this case Liquid Crystal Polymer ( LCP). In this paper, the process flow to develop such a master tool is discussed, followed by an explanation of the process of hot embossing the master tool onto the LCP. Free space light transmission is shown in the stamped LCP substrate in a channel which is 8cm long and ~60 micrometer deep. Keywords: 45˚ etching of silicon, hot embossing, optical interconnects, master tool, and vertical coupling 1. INTRODUCTION Advancements in processor technology have introduced the possibility of data transmission rates of up to several gigabytes per second [1]. At these rates, conventional metallic interconnects exhibit higher crosstalk and attenuation, thereby limiting channel density and having high power dissipation [2]. Optical interconnects can be a solution to these problems [2]; however, there are technical challenges that need to be overcome to make way for board level optical interconnects. Several methods and techniques, most of which are waveguide based, have also been developed for board level optical interconnects [2] – [6]. Additionally, several challenges need to be overcome when integrating optic components into a circuit board. VCSELs (Vertical cavity surface emitting lasers) and optical detectors are commonly used as sources and detectors, respectively, for short distance optical interconnects. Light from VCSEL must be directed at 90˚ in order to couple to the optical channel or interconnect as shown in Fig.1. Fig. 1. Schematic of an optical interconnect Different methods, such as implanting a 45˚ mirror [2] [3], using tilted gratings [4], fabricating 45˚ micromirrors with the soft molding technique [5], cutting the waveguide by a microtome blade [6], etc. have been used to