Efficient broadband parametric conversion: Reaching for the Mid IR

Abstract

In this paper, we report recent results on the efficient generation of SWIR sources exploiting broadband wavelength conversion in silica fibers. Optimized cavity-less designs of fiber parametric amplifiers (FOPA) associated with Thulium amplification capable of high CW powers, wide tunability and modulation will be presented. We also present how parametric conversion can be extended deeper in the Mid-IR by engineering of non-silica mixing platforms.Keywords: Mid-infrared sources, nonlinear optics, wavelength conversion IntroductionThe short-wave infrared (SWIR) and middle-infrared (Mid-IR) are a core bands for molecular detection and identification. Hence, it hosts critical applications ranging from spectroscopy, health monitoring, sensing as well as free space communication [1]. To fully exploit the advantages of such spectral bands, versatile light generation and all optical processing capabilities are key elements. Recent developments in fiber lasers have shown the emergence of medium power tunable continuouswave (CW) thulium-doped fiber lasers [2]. Pulsed operation can be achieved with optical parametric oscillators (OPO) or modelocked thulium-doped fiber lasers. They are widespread solutions despite possibly bulky setups, low repetition rates or limited tunability. Combining different mode of operations is also extremely difficult for a single architecture. An alternative approach to the generation of versatile sources is to rely on broadband wavelength conversion via degenerate four-wave mixing (FWM) [3]. The single pass and parametric nature of the process leads to replication of an initial signal to the targeted spectral band. However the low conversion efficiency of such broadband wavelength conversion limits achievable CW power or requires extremely high pump peak powers [4].Here we will cover some of the recent advances made on versatile SWIR sources based on broadband wavelength conversion in silica fibers. We will first show how such cavity-less design associating telecom-driven parametric conversion and thulium amplification can lead to efficient light generation in the 2 micron spectral band. Various optimized designs capable of providing wide versatility in terms of operating modes will be described. The cavity-less nature, parametric origin and flexibility of the proposed source can offer new opportunities for Mid-IR applications.