An Hybrid WDM/TDM Reflectometric Array

Abstract
We present experimental results describing: (i) inter-elemental cross-talk and (ii) improved noise performance by RF modulation of the laser frequency, in an high performance WDW/TDM reflectometric array. The array, operating on a single fiber, is comprised of four high sensitivity Fabry-Perot interferometric sensors each formed by a pair of in-fiber Bragg gratings acting as reflection elements. Cross-talk between sensors operating at dissimilar wavelengths is measured to be below -60 dB (sensor noise limit) when wavelength filtering is used and is ~ -35 dB when wavelength filtering is avoided at the array output. Crosstalk between sensors operating at same wavelength is measured to be < -30 dB. An improvement in array noise of > 15 dB was measured by RF modulation of the laser frequency.