Shinya IKOMA, Akira TAKADA, and Shigenori NAGANO

Corporate R&D Center, Topcon Corporation, 75-1 Hasunuma-cho, Itabashi, Tokyo 174-8580, Japan

(Received July 15, 2008; Revised February 17, 2009; Accepted March 18, 2009)

We propose a novel wavelength-division-multiplexing WDM filter module which consists of minimum elements of an input fiber, two output fibers, and two lenses. A wavelength-selective multilayer is coated on a convex surface of one of the lenses. The direct splicing method is used to attach the lens to the fiber edge without adhesion, polishing or antireflection coating. Considering the theoretical beam-angle dependences of the fiber cutting angle and the lens length theoretically and fabrication constraints on the module design, we present an optimal fabrication condition. The fabricated modules showed less than 0.7-dB insertion losses, over 65-dB return losses, and over 20-dB isolations.

Key words: WDM filter module, fiber optics, fiber assembly, insertion loss, return loss, isolation