2025/08/13 by Luo, Xijie, Alvarez, Carlos E. Rodriguez, Rahman, Aashia +7
#FOS: Physical sciences #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Optics (physics.optics)
paper · doi:10.48550/arxiv.2508.09854
Multi-channel aperiodic fiber Bragg grating (FBG) based hydroxyl (OH) line filters have attracted significant interest in ground-based near-infrared (NIR) astronomical observations. In this paper, we present the performance of a new self-compensating enclosure for the filters, that can be used in non-temperature-controlled environments. Our prototype encloses a 110 mm long single-mode photosensitive optical fiber with three 10 mm filter gratings. A fourth grating was used as a reference outside the package to measure the uncompensated wavelength shift. The prototype was tested over three thermal cycles, and showed a maximum wavelength deviation of 12 pm, a wavelength drift of only 0.37 pm/∘C, over the temperature range of -17∘C to 15∘C. The athermalization factor, i.e., the ratio of the maximum wavelength shift of the compensated grating to the uncompensated reference filter grating was (1)/(22). The results demonstrate the capability of the prototype for stabilizing multi-channel long-length FBGs or chirped FBGs, particularly for astronomical applications that require sub-picometer stability.