R.I. Ismagilova – Engineer,
Fryazino branch of Kotel’nikov Institute of Radioengineering ang Electronics of RAS
E-mail: is.ren.id@gmail.com
R.I. Shaidullin – Ph.D. (Phys.-Math.), Senior Research Scientist,
Fryazino branch of Kotel’nikov Institute of Radioengineering ang Electronics of RAS
E-mail: rs-mipt@mail.com
O.A. Ryabushkin – Ph.D. (Phys.-Math.), Associate Professor, Head of the Laboratory,
Fryazino branch of Kotel’nikov Institute of Radioengineering ang Electronics of RAS E-mail: roa228@mail.ru
Problem formulating. Thermal degradation of the polymer coating of silica fibers is one of the main limiting factors of fiber laser power scaling. This problem is especially relevant for industrial fiber laser units, in which active fiber is poured with additional polymer layer. It turned out that silicone polymers are able to absorb scattered pump, photoluminescence and laser radiation, becoming a secondary heating source and accelerating fiber unit thermal degradation. Thus, thermal and optical characteristics of the polymers used in fiber optics are important for the further development of high power lasers.
Goal. To investigate optical transmission spectra and radiation absorption coefficients of silicone polymers used in fiber optics. To measure experimentally and calculate theoretically the fiber unit temperature distribution under laser generation conditions.
Result. Transmission spectra of the polymers used in fiber optics in near IR range were obtained. Temperature dependences of polymers absorption coefficients at the operating wavelengths of ytterbium (1.06 μm) and erbium (1.55 μm) doped fiber lasers were measured. A method for measuring the surface polymer temperature in industrial fiber laser unit was proposed. Mathematical modeling of the fiber laser unit heating was carried out. Fraction of optical pump power converting into heat under conditions of laser generation was estimated.
Practical meaning. When operating a fiber laser unit, it should be taken into account that a certain fraction of the pump radiation power will inevitably be absorbed in the polymer layer, leading to its accelerated degradation and laser failure.
- http://www.ipgphotonics.com/laser/view/133/Lasers/High_Power_CW_Fiber_Lasers/1_micron/YLS_ECO__1_10_kW
- Ryabushkin O.A., Shaidullin R.I., and Zaytsev I.A. Radio-frequency spectroscopy of the active fiber heating under condition of high-power lasing generation. Opt. Lett. 2015. № 40. Р, 1972−1975.
- Shaidullin I., Ismagilova R.I., Ryabushkin O.A. Influence of optical absorption of polysiloxane polymers on active fiber heating under lasing conditions. Optical Materials Express. 2019. № 9. Р. 1577. 10.1364/OME.9.001577.