{'fraction_non_alphanumeric': 0.031862745098039214, 'fraction_numerical': 0.004901960784313725, 'mean_word_length': 5.051851851851852, '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}}
Design of phase-shifted long-period grating device and its application as gain-flattening fiber filter

The transmission characteristics of phase-shifted long-period gratings (LPGs) are simulated theoretically by a combination of coupled-mode theory and fundamental-matrix method. It is suggested that a phase-shifted LPG device cascaded with another normal LPG can be used to flatten the gain spectrum of an erbium-doped fiber amplifier (EDFA) with all three gain peaks. The results of simulations have shown that a broadband amplifier with peak-to-peak 0.7 dB gain variation over 36 nm can be practically realized. It proves that such a gain- flattening fiber filter is indeed plausible, and has a potential application in gain-flattening in dense wavelength- division multiplexed (DWDM) telecommunication systems.