We review the recent developments in optical fiber-based gas sensors utilizing light-induced acoustic/elastic techniques based on photoacoustic spectroscopy, Brillouin scattering, and light-induced thermoelastic spectroscopy (LITES). Optical fibre gas sensors are capable of remote sensing, working in various environments, and have the potential to outperform conventional metal oxide semiconductor (MOS) gas sensors. Researchers are studying a number of configurations and mechanisms to detect specific gases and ways to enhance. Gas sensing detects gas properties, such as physical, molecular, optical, thermodynamic, and dynamic properties. Fiber-based gas sensing is important because it offers several unique advantages.