Abstract

We present the novel use of a well-known angular interrogation method [1] for characterizing the absorption and loss of multimode doped fibers [2] and high-power fiber laser components, such as cladding mode-strippers [3]. Both meridional and skew rays can be excited by launching light at an angle to the axis of the fiber under test, as shown in the setup of Fig. 1(a). After propagating through the fiber under test, the power of the received light is measured with an integrating sphere that captures all angles. Fig. 1(c) shows the characterization of different cladding mode-strippers (MS). The reference fiber is a circular coreless fiber formed by low-loss synthetic silica glass and low-index polymer. It has a numerical aperture (NA) of ~0.44 and it is typically used for pump power delivery. MS#1 is less effective than MS#2 at attenuating both low- and higher-order cladding modes. The MS#2 results on the other hand, show that only light in the core (NA<0.1) remains, which is ideal for a cladding mode stripper.

© 2015 IEEE