Abstract
A technique is proposed to interrogate a distributed
photonic sensor composed of seven standard fiber Bragg gratings
in cascade. A microwave-modulated optical signal is launched into
an FBG cascade and subsequently undergoes dispersion in standard
single-mode fiber, so that the different Bragg wavelengths are
mapped into the radio-frequency (RF) delays that determine the
peaks in the electrical impulse response of the optical link. Shifts
in Bragg wavelengths have been determined from the shifts in the
impulse responses peaks by recording the links RF response in
the range dc-20 GHz using a vector network analyzer (VNA), and
then performing its inverse Fourier transform. A resolution of 14
pm is experimentally demonstrated after zero-padding the VNA
traces.
