{'fraction_non_alphanumeric': 0.029850746268656716, 'fraction_numerical': 0.02771855010660981, 'mean_word_length': 4.465116279069767, '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}}
A Broadband Pulsed External-Cavity Quantum Cascade Laser Operating near 6.9 μm

We report an external cavity quantum cascade laser (EC-QCL) operating near 6.9 μm using the Littman–Metcalf configuration. The EC-QCL works in a pulsed mode and can be tuned continuously from 1340 to 1640 cm−1 by only tilting the tuning mirror. The fine tuning ability of the EC-QCL is demonstrated by measuring the absorption spectrum of water in the ambient air with a lock-in amplifier.