A non-destructive characterization and real time monitor technique for low-loss, polymeric waveguide circuits

Optical polymer waveguide is a key passive component for the optical interconnection. Design, fabrication, and characterization of high performance waveguides have critical importance for the success of optoelectronic integration. In addition, defect effect, coupling, leakages and cross talk etc. are big concerns for the lightwave circuits. We present here a fast, non-destructive, sensitive, and real-time technique for detailed investigation of the propagation properties of planar optical waveguides and lightwave circuits. We use this technique to measure low loss polymer waveguides on printed circuit board (PCB) substrates and have measured the propagation loss of 0.065 dB/cm at 850 nm and 0.046 dB/cm at 980 nm. To the best of our knowledge, these are among the lowest loss data reported for polymer waveguides on PCB substrates to date. A high sensitive CCD camera with a built-in integration function is utilized to observe the light streak in two dimensions through a two lens imaging system. A few seconds to a few ten seconds is required for a complete measurement, compared to several hours for the sliding prism method and even longer for time cutback method. This technique can be used to evaluate not only the overall performance of a waveguide but also the local waveguide performance and the in-situ propagation properties (i.e., defect effect, bending effect, coupling and leakages, etc.). It can be extended to monitor the process of waveguide fabrication and alignment control during the assembly for the lightwave circuit integration.