A gas species monitoring system includes a laser system, where the laser system includes a multisection DBR laser, and a plurality of measurement points disposed at different locations within the system. The laser system is configured to selectively deliver a laser beam from the multisection DBR laser to each measurement point within the system to determine a concentration of at least one gas species at each measurement point. A chemical detection grid is aligned with the ITU-GRID to facilitate use of a multisection DRB laser that operates within one or more of the defined bands of the ITU-GRID.