Demonstration of an etched cladding fiber Bragg grating filter with reduced tuning force requirement

A novel tunable fiber Bragg grating (FBG) filter with a chemically etched cladding has been demonstrated. By reducing the cladding diameter of a FBG through etching with HF, the tension tuning force can be lowered by over an order of magnitude. Wavelength tuning up to a failure point of 21.2 nm has been demonstrated along with repeated cycling over a 9 nm tuning range. Observations of increased coupling to resonant cladding modes in the etched FBG´s are also noted.