As data rates increase, optical interconnections at the boards and substrate levels become interesting alternatives for high performance interconnections [1, 2]. Optical interconnection using embedded thin film photodetectors (PDs) in polymer waveguides is a chip to chip optical interconnection implementation that offers high speed interconnections with the potential for high integration density. This paper reports upon the integration of independently optimized waveguides and embedded PDs onto a Si substrate that utilizes a different material for each of these three components in the integrated interconnection. For the first time, reported herein are comparative measurements of the impulse responses and coupling efficiencies for two different directly coupled waveguide structures with embedded thin film InGaAs-based photodetectors. The difference between these two structures is the position of the thin film photodetector in the waveguide core. This information enables the designer to optimize embedded active photodetector/passive waveguide interconnections, particularly for high speed or multi-drop applications. © 2005 IEEE.