Photo-Writable Sulfide Glasses Used to Fabricate Core-Clad Fiber Doped with Pr³⁺ for Mid-IR Luminescence

Abstract

With the ultimate goal of developing rare-earth doped chalcogenide fiber fabrication for sensing, amplification, and laser applications, a core/clad germanium-gallium sulfide fiber doped with Pr3+ has been fabricated. The compositions of the core and the clad were selected to ensure the positive ∆n by adding CdI2 and CsCl, respectively, in the GeS2-Ga2S3 matrix. The choice of these compositions was also justified from experimental parameters, including characteristic temperatures and viscosity. Moreover, the permanent photo writability of the sulfide glass family by a femtosecond laser is investigated from the perspective of Bragg grating photo-inscription. Structural investigations by Raman spectroscopy are presented and the effect of the Pr3+ rare-earth ion on the structure is underlined. Finally, the emission of the step-index fiber, made by the rod-in-tube technique between 3.1 µm and 5.5 µm (by pumping at 1.55 µm), is demonstrated.

Keywords

• step index sulfide fiber
• Pr³⁺ doped chalcogenide glass
• ∆n modification by femtosecond laser