Half mJ Supercontinuum Generation in a Telecommunication Multimode Fiber by a Q-switched Tm, Ho:YVO4Laser

Abstract

Up to <TEX>${\sim}520{\mu}J$</TEX> broadband mid-infrared (IR) supercontinuum (SC) generation in telecommunication multimode fiber (MMF) directly pumped by a <TEX>$2.054{\mu}m$</TEX> nanosecond Q-switched Tm, <TEX>$Ho:YVO_4$</TEX> laser is demonstrated. An average output power of 3.64 W is obtained in the band of ~1900 to ~2600 nm, and the corresponding optic-to-optic conversion efficiency is 67% by considering the coupling efficiency. The spectrum has extremely high flatness with negligible intensity variation (<2%) in the wavelength interval of ~2070 to ~2475 nm. The SC long-wavelength edge is limited by the silicon glass material loss, and by optimizing the MMF length, the SC spectrum could extend out to <TEX>${\sim}2.6{\mu}m$</TEX>. The output SC pulse shapes are measured at different output powers, and no splits are found. The SC laser beam is nearly diffraction limited with an <TEX>$M^2=1.15$</TEX> in <TEX>$2.1{\mu}m$</TEX> measured by the traveling knife-edge method, and the laser beam spot is monitored by an infrared vidicon camera.