From 393 to 1167 nm Tunable Third-Harmonic Generation in a Mid-Infrared Tellurite Optical Fiber

A widely tunable third-harmonic generation (THG) in a mid-infrared step-index tellurite optical fiber was investigated in this work. By pumping a 3 cm-long tellurite optical fiber using an optical parametric oscillator with the pump wavelength of 1180~3500 nm, a tunable THG from 393 to 1167 nm was achieved. To the best of our knowledge, this is the broadest THG in the optical fiber. The THG conversion efficiency with different fiber lengths was investigated, which showed that the THG conversion efficiency decreased with the fiber length increasing. In addition, the third-harmonic (TH) signal pattern showed that it did not arise from phase matching between the fundamental mode of the pump and the higher-order mode of the TH signal, but rather resulted from the tellurite optical fiber’s high nonlinearity. It provides a unique pathway for the development of new light sources.