Control of thermal effects in fast-switching femtosecond UV laser system
| Autor: | Egle Gabryte, Mikas Vengris, Simas Sobutas, Romualdas Danielius |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Applied Physics B. 120:31-39 |
| ISSN: | 1432-0649 0946-2171 |
| DOI: | 10.1007/s00340-015-6090-4 |
| Popis: | Femtosecond laser systems are becoming essential tools in various areas of material processing, medicine and scientific research. In order to tailor the wavelength of radiation to the absorptivity of materials being processed, UV harmonic generators are often employed. At high average powers and high repetition rates, the long warm-up time of harmonic generators, caused by UV absorption in nonlinear crystals, can be a serious obstacle for efficient and fast processing. To increase the speed and reduce the cost of technological processes, new methods are required to speed up the settling of the output power when the harmonic generators are switched on after longer idle period. We have investigated a fourth-harmonic generator of a high-repetition rate femtosecond laser and studied the properties of the output radiation in order to optimize its fast-switching capabilities. Theoretical modeling of thermal effects in the nonlinear crystal allowed us to explain temporal dependencies of temperature and output power after switching the laser on. Based on these results, we were able to optimize the trajectory of nonlinear crystal rotation following the system start-up and reduce the switching-on time from tens of seconds to 50 ms without any negative effect on the output power. |
| Databáze: | OpenAIRE |
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