The 2- to 6- mid-infrared supercontinuum generation in cascaded ZBLAN and As2Se3 step-index fibers**Project supported by the National Natural Science Foundation of China (Grant Nos. 61435009, 61235008, and 61405254), the Fund from China Scholarship Council (Grant No. 201803170210), and Hunan Provincial Innovation Foundation for Postgraduate (Grant No. CX2018B008).

Abstract

Fiber-based mid-infrared (MIR) supercontinuum (SC) sources benefit from their spectral brightness and spatial coherence that are needed for many applications, such as spectroscopy and metrology. In this paper, an SC spanning from to is demonstrated in cascaded ZrF4–BaF2–LaF3–AlF3–NaF (ZBLAN) and As2Se3 step-index fibers. The pump source is a ZBLAN fiber-based MIR SC laser with abundant high-peak-power soliton pulses between 3000 nm and 4200 nm. By concatenating the ZBLAN fiber and the As2Se3 fiber, efficient cascading red-shifts are obtained in the normal dispersion region of the As2Se3 fiber. The spectral behavior of cascaded SC generation shows that the long-wavelength proportion of MIR SC generated in the ZBLAN fiber plays a critical role for further spectral extension in the As2Se3 fiber.