# New Candidate Multicomponent Chalcogenide Glasses for Supercontinuum Generation
## 1 Introduction  
Broadband infrared (IR) supercontinuum (SC) light sources have gained tremendous interest in the last decade, due to their potential use in a variety of telecommunication, sensing [1], lasing, and defense-related applications [2; 3]. Most important for consideration of use in SC applications are material attributes related to the medium's optical properties, including transmission window related to pump wavelength and spectral window of use, linear and nonlinear refractive indices, material dispersion, zero-dispersion wavelength, and single/multi-photon absorption behavior. As high intensity material response is also important, further consideration as to the likelihood of photo-structural modification, laser damage resistance, and other physical properties influenced by thermal effects (thermo-mechanical robustness, coefficient of thermal expansion (CTE), and environmental stability) is necessary. Lastly, the final form of the SC material requires attention to specific manufacturing-related material behavior to achieve the final form of the SC component/device(film deposition behavior and fiber drawing attributes such as viscosity temperature behavior and multi-material compatibility). As can be seen, such a material performance checklist extends beyond the typical optical property criteria that evaluates candidate materials only based on their linear and nonlinear refractive indices and low optical loss in the mid- and long-wave IR (MWIR and LWIR, respectively) [3]. The investigation of these properties has largely focused on candidate glass materials in bulk (three-dimensional, 3-D) and fiber (one-dimensional, 1-D) geometries [4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28]. Additionally, intermediate geometries, such as bulk planar disks (two-and-a-half-dimensional, 2.5-D) and thin films (two-dimensional, 2-D), have been discussed as attractive for photonic device integration where on-chip sources are desired for multispectral sensing and detection applications [4; 5; 6]. Furthermore, the availability of candidate SC materials suitable for broadband use in such planar forms would enable expanded understanding of chemistry/structure/property/form behavior across a spectrum of material dimensions providing insight into ideal geometries, performance limitations, and optimal property potential, for specific applications. To date, IR transparent candidates for SC have largely relied on existing, commercially available materials with known (finite and unoptimized for the application) physical property attributes. Operating in a regime of anomalous dispersion ensures that nonlinear effects including cascaded four wave mixing and soliton fission may occur. These effects are favorable for extending the supercontinuum bandwidth. Similarly, maximizing the optical nonlinearity of the medium ensures that a supercontinuum can be efficiently generated at lower powers. Strategies to maximize the optical nonlinearity while maintaining broadband operability include: (1) geometric engineering of the fiber/waveguide to maximize the nonlinear parameter, and (2) utilizing material platforms with large intrinsic nonlinearities. From a material standpoint, most efforts to date have focused on increasing the optical nonlinearity of homogeneous glasses, characterized in bulk, fiber, or waveguide form [29; 30; 31; 32; 33; 34; 35]. Non-oxide glasses' transmission typically extend well beyond the intrinsic multi-phonon absorption edge of oxides (silicates, phosphates, and tellurites), and thus, are more suited for truly broadband IR (defined here as being near-IR, MWIR, and LWIR transmissive).