Planar microlens relay optics utilizing lateral focusing.

We have proposed a novel concept of planar microlens relay optics with the goal of realizing alignment-free and multifunctional integrated optical subsystems. Since the planar microlens is one of its key elements, its lateral focusing characteristics were examined. The measured focusing spot size was 3 microm x 7 microm, which is comparable with the core of single-mode optical fibers. By measuring the refractive-index distribution, we found that the planar microlens produced by the electromigration method has a desirable index distribution that resembles that of a Luneburg lens. Thus we conclude that planar microlens relay optics may be facilitated when the lateral focusing property of planar microlenses is used.