  In this work we report a novel technique for simultaneous high-speed and
high-resolution interrogation of fiber Bragg grating (FBG) sensors. The method
uses the wavelength-to-time mapping effect in a chromatic dispersive medium and
a couple of intensity Gaussian filters. The Bragg wavelength is retrieved by
means of the amplitude comparison between the two filtered grating spectrums,
which are mapped into a time-domain waveform. In this way, measurement
distortions arising from residual power due to the grating sidelobes are
completely avoided, and the wavelength measurement range is considerably
extended with respect to the previously proposed schemes. We present the
mathematical background for the interrogation of FBGs with an arbitrary
bandwidth. In our proof-of-concept experiments, we achieved sensitivities of
~20 pm with ultra-fast rates up to 264 MHz.
