A Real-Time Precision Characterization Technique for Low-Loss Optical Polymeric Waveguide and Lightwave Circuits

Abstract

An 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 effects, coupling, leakages, crosstalk, etc. are great concerns for the lightwave circuits. We present herein a fast, nondestructive, sensitive, 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 we have measured propagation losses 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 losses reported to date for polymer waveguides on PCB substrates. A high-sensitivity 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 tens of seconds is needed for one complete measurement, compared with the sliding prism method, which requires several hours, and the cutback method, which requires even longer times. This technique can be used to evaluate not only the overall performance of a waveguide but also the local waveguide performance, as well as perform in-situ investigation of propagation properties (defect effect, bending effect, coupling, leakage, etc.). It can be extended to monitor the process of waveguide fabrication and alignment control during assembly for lightwave circuit integration.