Suppression of Frequency Modulation to Amplitude Modulation Conversion with Modified Group Velocity Dispersion Compensation Device in the Front End of High-Power Lasers

The group velocity dispersion (GVD) occurring in the front end of high-power lasers is one of the primary factors leading to the conversion of frequency modulation (FM) to amplitude modulation (AM). In this paper, we propose a modified, active, closed-loop feedback compensation device for GVD-induced FM–AM conversion, using a two-dimensional, electric, adjustable mirror mount and parallel grating pair to improve the long-term stability, efficiency of adjustment, and accuracy of compensation. Experimental results of a 12 h FM–AM depth test revealed that the depth varied between 2.28% and 5.22%. Moreover, we formulated a mathematical relationship between the dispersion parameters and temperature in optical fibers to analyze the intrinsic effect of temperature on FM–AM. The related simulation and experimental results consistently validated the quantitative relationship between the temperature and FM–AM depth.

A New Method of Healing (Wounds, Burns, Grafts and Scars) Through low Level Lasers (LLLT)

This article is the result of six months of study and clinical work on several patients with wounds such as burns, cosmetic surgery, sutures, skin grafts or crash scars and fractures that are treated with low power laser with a power of 1 to 10J/cm2 with a maximum power of 400 mW After final evaluation, patients who had to undergo cosmetic surgery or high-power lasers were treated with this method of laser therapy. Objective: Creating a suitable substrate for treating all kinds of wounds and scars with low power laser Conclusion: Low power lasers can replace the old methods and tools in the treatment of wounds and scars. This method is safer and more economical for the patient and the set of medical services.

GHz femtosecond processing with agile high-power laser

Bursts of GHz repetition rate pulses can significantly improve the ablation efficiency of femtosecond lasers. Depending on the process conditions, thermal mechanisms can be promoted and controlled. GHz ablation therefore combines thermal and non-thermal ablation mechanisms. With an optimal choice of the burst duration, the non-thermal ablation can be highly enhanced by a heating phase due to the first pulses in the burst. The GHz burst mode can be considered as a key function for the “agility” of new high-power lasers.