{'fraction_non_alphanumeric': 0.014797507788161994, 'fraction_numerical': 0.003894080996884735, 'mean_word_length': 5.330049261083744, '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}}
Application of nonlinear optical techniques to characterization of glass and high-power near-IR cw laser beams

We have applied z-scan technique for measuring absorption coefficients of highly transparent optical materials (glass) and have used those for characterizing the power and power density of high power near IR laser beams. Self-phase modulation due to thermal indexing is the process underlying this technique. Glass plates with appreciable absorption coefficients are used for calibration purposes and for verifying the results of measurements. Fundamentally, as low absorption coefficients as 10-5 cm-1 can be measured by scanning a plate of a transparent optical material in the focal region of a lens. The sensitivity of this technique proved to be high enough to reveal strong variation between the absorption coefficients of optical windows made of the same material BK7 but obtained from different sources. We have suggested and used a novel procedure, scanning nonlinear lens profiling, for characterization of homogeneity of optical glasses and other transparent optical materials. Most importantly, the technique can be used for fast and high precision measurement of power of high power laser beams without evoking large temperature increase and related problems.