Measurements of beat length in short low-birefringence fibers

摘要

We describe a new experimental method to determine low-birefringence in fibers. This method is based on adjusting the fiber's twist in a fiber optical loop mirror. It allows simple birefringence measurement in fibers with beat length within the range of 0.4 m - 100 m. Our measurement technique requires a fiber span whose length is shorter than a half beat length. To demonstrate the measurement technique we present experimental results for two optical fibers whose beat lengths were 1.04 and 30 m.