Design of Thin Cladding BIF Using Cutoff Wavelength Shortening Effect

We experimentally investigate the cutoff wavelength shortening effect that occurs when the cladding diameter is reduced. The influence of coating thickness, and thus, cladding diameter, on the transmission loss is also discussed. We derive an empirical model of cutoff wavelength and transmission loss as a function of the cladding diameter and coating thickness. The empirical model reveals that a further reduction in the cladding diameter of step index type bending-loss insensitive fiber (BIF) is possible. The validity of the proposed BIF design is confirmed using a 70-μm cladding diameter BIF and jumper cords. This BIF enables us to construct optical fiber networks with higher reliability.