{'fraction_non_alphanumeric': 0.015901060070671377, 'fraction_numerical': 0.022968197879858657, 'mean_word_length': 4.870466321243524, '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}}
High-power and pulse energy picosecond narrow linewidth laser system based on tapered fiber amplifier for second harmonic generation

We present the results of compact and cost-efficient high-power and energy laser system based on a picosecond gain-switched DFB laser diode operating at a wavelength of 1064 nm with spectral linewidth less than 0.1 nm and pulse duration of 50 ps and tapered double clad fiber (T-DCF) amplifier. The unique properties of T-DCF as efficient amplification of low power seed signal and suppressed threshold of nonlinearities allow achievement of both high peak power of 170 kW and pulse energy of 9 μJ at pulse repetition rate of 10 MHz while maintaining spectrum linewidth as narrow as 0.1 nm. High average output power of 150 W was obtained with slightly broader laser linewidth. We also demonstrate second harmonic generation with over 30 W at 532 nm wavelength with conversion efficiency of 38%. These results make MOPA system based on gain-switched DFB laser diode and T-DCF amplifier an attractive source for material processing and sensing application including time resolved Raman spectroscopy.