Chalcogenide glasses are a family of non-oxide amorphous solids formed from one or more chalcogen elements—sulfur, selenium, or tellurium—combined with network-forming elements such as germanium, arsenic, silicon, or antimony, and with modifier elements, so that the material lacks long-range crystalline order ^[1]. Because the constituent atoms are heavier and more polarizable than those of silica, these glasses possess a high refractive index and a broad optical transmission window extending into the mid-infrared, well beyond the transparent range of silicate glasses. Their structure is a covalent, disordered network in which the average coordination number and the connectivity of the chalcogen chains determine glass-forming ability, thermal stability, and properties such as the glass transition temperature. The glasses also exhibit pronounced infrared transparency, high nonlinear optical response, and photosensitivity, in which illumination can induce structural or refractive changes. The material is therefore defined as an amorphous, covalently bonded infrared-transmitting chalcogen network rather than an oxide glass ^[2]. Their behavior is governed by the chemical bonding and rigidity of the disordered chalcogen network ^[3].