Overview of the handling of the fiber optic for femtosecond laser writing of Fiber Bragg Gratings

CRYST^3 plans to deliver the main contribution to the laser cooling of individual atoms encapsulated in the hollow core of a fully functionalized, hermetically sealed photonic crystal fiber integrated and excited by external light sources such as lasers.

In the framework of the project, ALPhANOV is responsible for functionalizing solid fibers by inscribing Fiber Bragg Gratings (FBGs) at 780 nm using femtosecond laser writing. Two FBGs will be inscribed inside solid fibers to form a Fabry-Perot (FP) cavity. Following that, a Hollow Core Fiber (HCF) in which the Rb atoms will be filled will be spliced in between the two FBGs. CRYST^3 foresees, that the FP cavity effect produced by the two FBGs will cool and crystallize the atoms inside the HCF fiber.

In the following picture, we observe the handling of the fiber optic on the nano 3D translation stages to perform the femtosecond laser writing of the FBGs. The femtosecond laser beam is focused inside the core of the fiber using a microscope objective shown in silver and red in the photo.

In the next picture, we can see on the computer screens the imaging of the fiber core and the written FBGs inside it. This represents the ongoing work on the realization and optimization of FBGs in the framework of the CRYST^3 project.