Thermal optimization of single crystal fiber manufacturing based on heat loss compensation

Abstract

Single crystal fiber (SCF) manufacturing, occupying most of the difficulties in the application of next generation high power lasers, has gained significant interest over the years. The thermal optimization of the SCF growth system is imperative to solve the low output laser power and slope efficiency limited by the cracking problem. Using both experimental and simulation approaches that efficiently explore the growth process of sesquioxide crystals in the laser-heated pedestal growth (LHPG) system, the present study explains the reason why the traditional resistance afterheater does not reduce the thermal stress in the SCF from the perspective of the first and second-order derivatives of the temperature field. On the basis, a thermal optimization model based on the idea of thermal compensation is proposed. This form of heat input greatly improves the thermal stress concentration in the crystal and reduces the maximum Von Mises stress by 95%, while perfectly maintaining the uniformity of the overall temperature field. Furthermore, a semi-Gaussian fitting is performed on the optimization model hinting at the possibility of its application in practical engineering. Notably, this thermal compensation idea based on heat loss can be used for reference by other materials and growth systems in the SCF manufacturing field, because heat transfer is always the basis.