Temperature induced refractive index changes are an important aspect in today’s fiber amplifiers with high average power. For many processes, their time dependence is critical. Here, we analyze the impact of radial heat diffusion on the optical phase. We modulated the pump power in a 10 W amplifier and measured the frequency response of the optical phase. We compared the result with the calculated frequency response of the temperature in the fiber core, which shows the same characteristics. Additionally, we analyzed the influence of fiber parameters on the temperature dynamics.
© 2012 Optical Society of America
Original Manuscript: June 12, 2012
Manuscript Accepted: July 12, 2012
Published: August 24, 2012
Henrik Tünnermann, Jörg Neumann, Dietmar Kracht, and Peter Weßels, "Frequency resolved analysis of thermally induced refractive index changes in fiber amplifiers," Opt. Lett. 37, 3597-3599 (2012)