A polarization-preserving optical fiber with a high pump-radiation absorption efficiency including a core, a primary cladding surrounding the core, stress members disposed within the primary cladding, and a secondary cladding surrounding the core, primary cladding and stress members. A cryogen free cooling system has a cooling stage coupled to the heat radiation shield. Methods of using xerogel coatings are also included. Furthermore, stabilization of porous release layers can improve the qualities of resulting inorganic foils formed on the release layer.