{'fraction_non_alphanumeric': 0.011764705882352941, 'fraction_numerical': 0.0, 'mean_word_length': 5.410958904109589, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Propagation characteristics of thermally diffused expanded core fibers with complex refractive index profiles

In this paper, we investigate the propagation characteristics of thermally diffused expanded core (TEC) fibers with complex refractive index using the numerical Galerkin’s method. Complex modal profiles and propagation constants for TEC fibers of different expanded core radii are calculated. The imaginary part of the electric field results in wavefront distortion showing that the power flows out of or into the doped region according to the sign of the imaginary part of the refractive index. The gain or loss as a function of both mode field radius and operating wavelength is calculated numerically. Moreover, an approximate formula for the loss or gain coefficient of these fibers is given and the obtained approximate results agree well with those from Galerkin’s method applied to the complex refractive index fiber.