{'fraction_non_alphanumeric': 0.00903225806451613, 'fraction_numerical': 0.0, 'mean_word_length': 5.632478632478633, '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}}
Temperature dependence of polymer waveguide directional coupler

Temperature dependence of the coupling characteristics between a single-mode fiber and thin film directional coupler is studied. Matching condition of the propagation constants of the fiber half-coupler and thin film waveguide required for maximum power coupling into the thin film guide is investigated. A relation of the coupled power with the change in temperature of the coupler is developed and the temperature sensitivity of the coupled power is compared for both uniform and tapered coupling structures. Experimental results of temperature dependent coupling between the fiber half-coupler and uniform thin film PMMA waveguides of different molecular weights are verified with the theoretical estimates.