Accelerated aging of annealed proton-exchanged waveguides

Low temperature hydrogen diffusion in annealed proton-exchanged (APE) waveguides has the potential of degrading device performance over a period of several years. An accelerated aging study was performed in order to determine its impact on device performance. The effect of aging was modeled as a second anneal. Both planar waveguides and Y-fed balanced-bridge modulator (YBBM) devices were aged at elevated temperatures. The hydrogen concentration profile of the planar waveguides was measured after aging with secondary ion mass spectrometry (SIMS) and compared to the profile from a control sample. The YBBM characteristics were measured as a function of aging time as well. Measured activation energies indicate that hydrogen diffusion is the dominant aging mechanism in the YBBM. Extrapolations indicate that device degradation is negligible at temperatures of 95°C or below. An operating/storage temperature as high as 125°C can be sustained for 13 years with little effect. A method for determining the effect of aging on any device is outlined