TENSION ADJUSTED INLINE OPTICAL FIBER ATTENUATOR

摘要

An single-mode fiber attenuator is disclosed which may be formed by a tandem combination of a birefringent polarization-preserving fiber and a single polarization fiber. The birefringent fiber functions as a variable wave plate and the single polarization fiber functions as a fiber polarizer. By continuously changing the local birefringence of the birefringent fiber with, For example, tension, pressure, or temperature, the phase difference between the two polarization components of light traveling through the birefringent fiber is continuously modified. The difference in phase causes suppression of one of the polarization components as it enters the fiber polarizer and, therefore, the output of the fiber polarizer, the sum of the two polarizations, is attenuated. The attenuator may be tuned by changing the local birefringence of the birefringent fiber. An inline optical fiber bandpass filter may be formed by cascading a plurality of appropriately arranged inline fiber attenuators formed in accordance with the present invention. In addition the device is adaptable for use as an inline attenuator or a gauge.