Typical Failure Cases and Analysis of COTS Polarization Maintaining Fiber Couplers Used in Spacecraft

Polarization maintaining fiber coupler is a special type of fiber coupler with low additional loss, low polarization crosstalk, and the ability to maintain the polarization state of linearly polarized light in transmission. They are mainly used in optical communication equipment or fiber optic gyroscopes that require high precision and performance. With the increasing emphasis on cost control in the aerospace industry, COTS polarization maintaining fiber couplers have also been widely used in the aerospace field. This article lists two typical failure cases of COTS polarization maintaining fiber couplers during the evaluation and verification process. After analysis, it is believed that both issues are related to the materials and processes used in polarization maintaining fiber couplers. The COTS polarization maintaining fiber coupler is not designed and manufactured for space applications. In order to improve performance and reduce costs, the materials and processes used are different from similar products used in high reliability fields. However, due to its low cost and good performance parameters, spacecraft still choose a portion of COTS polarization maintaining fiber couplers. This article analyzes the mechanism for the failure of COTS polarization maintaining fiber couplers, and proposes suggestions for selecting COTS polarization maintaining fiber couplers for future spacecraft based on aerospace application requirements.