COUPLING CHARACTERISTIC ANALYSIS OF SINGLE-MODE AND MULTIMODE OPTICAL-FIBER CONNECTORS USING GRADIENT-INDEX-ROD LENSES

The coupling characteristics of optical-fiber connectors using gradient-index (GRIN)-rod lenses are analyzed for both single-mode and multimode use. We deal with six types of commercially available GRIN-rod lens. In the single-mode case the coupling characteristics are analyzed by the Gaussian beam approximation, and the effects of the deviation in lens length from a one-quarter pitch, the lens separation, and the lateral shift of the lens are clarified. In the multimode case the coupling characteristics are analyzed by the ray-trace method, and the effect of the third-order aberration of the GRIN-rod lens is clarified in addition to those in the single-mode case. In both cases a type SLS 2.0-mm lens is found to be best. By adjusting the lens length to be slightly longer than a one-quarter pitch, the lens separation and the tolerance for the lateral shift of the lens were improved.