Treatment and Characterization of ZBLAN Fibers for Infrared Astronomy
Abstract
Significant development of Infrared (IR) detectors in recent years sparked growing interest in topics that require IR spectroscopy, such as higher redshift objects (z >1) and exoplanet atmospheres. Traditional fused silica based fibers are often used as waveguides in spectrographs, but this limits astronomers to the optical and near-IR range due to significant attenuation in wavelengths beyond 2 microns in those fibers. We seek to test the feasibility of developing a new IR spectrograph for the Magellan Telescopes in Chile using IR-optimized zirconium fluoride (ZBLAN) fibers with <10dB/km loss rate from 1-3 microns (J, H, & K bands). We have treated the fibers and characterized fiber throughput as well as focal ratio degradation (FRD) at different wavelengths under various conditions. Adjustable and motorized stages are used to accurately transmit light from an LED source through a test fiber segment to a CMOS detector. In the meantime, we developed a python based data processing pipeline for performance characterization. We also refined tension cleaving techniques for ZBLAN fibers. Preliminary results show that stress significantly degrades measured signal, suggesting that the ZBLAN fibers are quite fragile and will likely require extreme care in cleaving and in general treatment to prevent unpredictable signal loss due to poor handling. Future designs of protective ferrules that hold the fibers should focus on reducing stress due to telescope movements and stress introduced by interfacing fiber ends to ferrules with epoxy. We are in the process of acquiring more data and further refining our fiber treatment methods to determine if ZBLAN fibers can perform with reasonable stability and durability under intensive telescope use.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23517502Q