A Complete Design Procedure of an Aperiodic Multichannel FBG for Astronomical OH Suppression

Fiber Bragg gratings (FBGs) have proven to be an effective and efficient solution for suppressing OH lines in near-infrared astronomical spectroscopy. Previous studies have focused on designing and fabricating FBGs for astronomy H band (1.45–1.7 microns), but the OH lines in J band (1.1–1.4 microns) remain unresolved. In this study, we present a full step-by-step design process for FBGs used for OH suppression in astronomical spectroscopy for the first time. This process includes an improved removal method for OH doublets, optimization techniques, and compensation for visibility degradation. We also demonstrate the success of this process by presenting the first ever fabricated FBGs for use in the J band. Our results show that the capability to design and fabricate FBG filters for any wavelength range within the J and H bands has been achieved.