An early fire gas sensor based on 2.33 μm DFB laser

We report the development of a distribution feedback (DFB) laser sensor for high precision and high sensitivity detection of the early fire gas carbon monoxide (CO). This system relied on a continuous wave (CW), distributed feedback laser emitting at a wavelength of around 2.33 μm as excitation source. A 2f/1f wavelength modulation spectroscopy (WMS) strategy was adopted to isolate complex, overlapping spectral absorption features typical of ambient pressures and to achieve excellent specificity and high detection sensitivity. Allan-Werle deviation analysis was used to evaluate the long-term performance of the CO sensor system, and limit of detection (LoD) of 1.18 parts per million by volume (ppmv) was achieved while a measurement precision of 0.08 ppmv was observed with an optimal integration time of ∼205-s. As a field measurement, early fire detection of paper, cotton and pine wood were conducted, which verified the reliable and robust operation of the developed sensor.