{'fraction_non_alphanumeric': 0.029714285714285714, 'fraction_numerical': 0.0034285714285714284, 'mean_word_length': 5.169014084507042, '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}}
Frequency control of semiconductor lasers

The requirement of a stable single-wavelength coherent source [1] for high-speed, long-distance optical-fiber communication systems has imposed severe conditions on the frequency control of semiconductor lasers. The two main candidates for a dynamic single-wavelength source are (1) the DFB and DBR lasers and (2) the interference lasers. In this paper, we first review the performances of interference lasers of the internal-reflection type. Then, we compare the outstanding features and problems of the Bragg lasers and the interference lasers of both internal- and external reflection types. Finally, we propose a new laser structure, called the interference-DFB laser, to take advantage of the interference and DFB lasers. An analysis of this laser also provides valuable insights in understanding the behavior of the DFB laser.