监测燃烧过程中产生的气体（主要是CO）来探测火灾逐渐成为火灾探测中的一个重要领域。各种现有的气体传感器灵敏度比较低，不利于火灾的早期报警,利用基于光声原理的复合气体探测技术来进行火灾探测，能极大地提高探测器的灵敏度。将CO和CO₂的检测结合起来，可降低探测器的误报率，有利于提高早期报警。

Smoke particles and heat will be generated in fire , conventional fire detectors detect fire just by these physical effects. But the measurement of physical parameters is not enough for an early fire detection. Nowadays another method has been an area of major interest for early fire dtection which make use of the gases (for example CO) generated from combustion process to detect fire. A majority of existing gas sensors are not good for a early fire detection because of their low sensitivity. A detection method for measuring the gas concentration based on photoacoustic principle is reported in this work, which increased the sensitivity enomously. The rate of false alarm is decreased greatly also by combining carbon monoxide detection with carbon dioxide detection.