In-line fiber grating-type optical bandpass filter tuned by applying lateral stress

An in-line tunable optical bandpass filter consisting of an optical circulator and a fiber grating has been demonstrated by applying lateral stress to the grating. The center wavelength can be tuned over 8 nm (2 nm shorter and 6 nm longer). The shift rate is estimated to be 1.26 nm per Newton at around 1.55 µm for a dispersion shifted fiber, which results in a measured Young’s modulus of 9.97 x 10¹⁰ N/m².