Thermal Modeling, Heat Mitigation, and Radiative Cooling for Double-Clad Fiber Amplifiers

Abstract

We report a detailed formalism aimed at the thermal modeling and heat mitigation in high-power double-clad fiber amplifiers. Closed form analytical formulas are developed that take into account the spatial profile of the amplified signal and pump in the double-clad geometry, the presence of the amplified spontaneous emission, and the possibility of radiative cooling due to anti-Stokes fluorescence emission. The formalism is applied to a high-power Yb-doped silica fiber amplifier. The contributions to the heat-load from the pump-signal quantum defect, as well as the pump and signal parasitic absorptions are compared to the radiative cooling. It is shown that for realistic cases, the local heat generation in kiloWatt-class fiber amplifiers is either dominated by the quantum defect or the parasitic absorption depending on the pump wavelength. In conventional designs, radiative cooling can be substantial only in properly designed amplifiers, when the pump power is tens of watts or lower, unless the parasitic absorption is reduced compared to the commonly reported values in the literature. We also explore the impact of the non-ideal quantum efficiency of the gain material. The developed formalism can be used to design fiber amplifiers and lasers for optimal heat mitigation, especially due to radiative cooling.

References in corpus (2)

• Improvement of the Tm3+:3H4 level lifetime in silica optical fibres by lowering the local phonon energy
• Precise Determination of Minimum Achievable Temperature for Solid-State Optical Refrigeration

Cited by in corpus (9)

• Laser Cooling of Silica Glass
• Spectroscopic Investigation of Yb-doped Silica Glass for Solid-State Optical Refrigeration
• Laser Cooling of a Yb Doped Silica Fiber by 18 Kelvin From Room Temperature
• Heat mitigation of a core/cladding Yb-doped fiber amplifier using anti-Stokes fluorescence cooling
• Temperature distribution inside a double-cladding optical fiber laser or amplifier
• A novel method for measuring the resonant absorption coefficient of rare-earth-doped optical fibers
• Heat Evacuation from Active Raman Media Heat Evacuation from Active Raman Media Using Quasi-PT Symmetry Coupling
• Laser Cooling Characterization of Yb-Doped ZBLAN Fiber as a Platform for Radiation Balanced Lasers
• Laser-induced anti-Stokes fluorescence cooling of ytterbium-doped silica glass by more than 6 Kelvin