We present a semi-analytic numerical model to estimate the transverse modal instability (TMI) threshold for photonic crystal rod amplifiers. The model includes thermally induced waveguide perturbations in the fiber cross section modeled with finite element simulations, and the relative intensity noise (RIN) of the seed laser, which seeds mode coupling between the fundamental and higher order mode. The TMI threshold is predicted to ~370 W – 440 W depending on RIN for the distributed modal filtering rod fiber.
Optics Express, 2013, Vol 21, Issue 13, p. 15409-15417
Fiber design and fabrication; Fiber optics amplifiers and oscillators; Thermal effects; Microstructured fibers