In Photothermal Spectroscopy (PTS) system, the signal strength is shown to increase with optical power while being inversely proportional to the mode field volume [1]. A 2-mirror optical cavity offers power amplification and tight focusing beam but is limited in stability for small beam sizes [2] particularly when there is a requirement to tune the cavity length, and it requires an isolator to prevent laser feedback. In this work, the Bow-Tie cavity comprising 4 mirrors is introduced to address these limitations, enabling PTS signal enhancement while maintaining stability. The study includes ABCD Matrix theory and Ray tracing time-dependent simulation. The cavity is characterized in air. The PTS experiment is conducted in the near-infrared region to detect methane resulting minimum detectable concentration 20 ppm which is not achievable in absorption spectroscopy with the same optical components. For demodulation bandwidth 12.4 mHz and laser power 10 mW, the normalized noise equivalent absorption 5.75 × 10-7 cm-1 W Hz1/2 is obtained.