Variable light attenuator of improved air-gap type with extremelylow returning light

摘要

This paper presents an in-line variable light attenuator ofimproved air-gap type with extremely low return light loss forsingle-mode transmission, constructed using the modified structure ofthe optical connector. Optical attenuation is adjustable throughchanging the axial distance between the slanted end-faces of a pair ofthe ferrules aligned within an aligning sleeve. As the result, maximumattenuation was 30 dB at a slanted angle of 8 degrees, and 40 dB at aslanted angle of 12 degrees, at an air-gap of 1.5 mm and at a wavelengthof 1.31 μm. The return light loss achieved was less than 60 dB at aslanted angle of 8 degrees or more