Tunable Broadband Comb Source Using Compact FP-SA Laser for High-Precision Quasi-Distributed FBG Sensing

We develop a novel broadband comb light source for sensing multiple fiber Bragg gratings (FBGs). This broadband light source is realized through a Fabry-Pérot laser with intracavity saturable absorbers (FP-SA), which is a new type of low-cost and highly integrated semiconductor laser solution. The laser chip measures 1500 μm in length and 300 μm in width. Based on a waveform shaper and the FP-SA laser, we successfully generated the output of a broadband comb light source. By adjusting the filter bandwidth, laser gain voltage, and reverse voltage, we were able to tune the output bandwidth of the light source across a wide range from 2.5 nm to 25 nm. We propose a fitting method that leverages peak value extraction, tailored to the unique output characteristics of this source. Experimental results demonstrate that, when utilizing the FP-SA laser with a comb wavelength spacing of 0.23 nm, the demodulation repeatability achieves ±3.5 pm, and the demodulation linearity exceeds 0.9996. To the best of our knowledge, this work presents a new high-performance integrated broadband light source option for quasi-distributed FBGs array sensing systems.