Study of fiber-optic alignment automation for photonic devices packaging.

摘要

In this work, the effects of pitch, yaw, and roll angular misalignments for a few coupling schemes, including butt-coupling, wedged fiber to laser diode coupling and fiber array to lens array coupling, are studied. It is demonstrated that the coupling efficiency and misalignment tolerance are more sensitive to tilt, i.e., pitch and yaw angular misalignments than lateral ones. It is further demonstrated that, the time for locating the optimal coupling position using conventional hillclimbing automation searching algorithm is a strong function of angular misalignments.; In the mean time, the coupling and alignment tolerance also are optimized based on a theoretical analysis for the coupling between a highly elliptical laser diode and a wedge-shaped end face single mode fiber. The design parameters including the working distance, wedged angle are obtained for various aspect ratios of the laser diode. It is demonstrated that the coupling efficiency is a strong function of initial tilt, i.e., pitch and yaw angular misalignments, and the angular misalignments strongly reduce the search efficiency for obtaining the initial coupling of light or the “first light”.; From the understanding of roll alignment behavior, a novel method is developed for the roll alignment automation of nonplanarly misaligned fiber-optic systems.; For fiber-optic array alignment, a general formula for determining the optimal coupling efficiency between two single mode fibers with two GRIN collimator lenses in between is derived. By use of Gaussian beam approximation, the tolerances considering collimating distance, lateral offset and angular misalignments are given. An optical design of collimator arrays is then proposed based the coupling and tolerance analysis. A low-cost approach using adhesives is also presented for assembling of 1 x 8 collimator arrays. Three different UV-curable adhesives are tested for the bonding of the fiber array and lens array together, the curing induced coupling loss turns out to be very stable and within 1dB. The work promises a new approach for making collimator array successfully. The angular alignment and automation presented in this study will be a great help in fiber-optic coupling for reducing cycle time and increasing yield of production. (Abstract shortened by UMI.)