Cantilever enhanced photoacoustic detection of carbon dioxide using a tunable diode laser source

Recently introduced cantilever enhanced photoacoustic sensing has been applied to the tunable diode laser-based trace gas detection. The pressure variations due to the photoacoustic signal are detected with a miniature silicon cantilever, whose displacement is measured with a compact Michelson type laser interferometer. The system has been used to detect carbon dioxide (CO₂) at 1572 nm with a distributed feedback diode laser. With a new photoacoustic cell, that was optimized for the laser sources, a normalized noise equivalent sensitivity of 1.7×10^-10 cm^-1W/ at atmospheric pressure was realized. The result obtained in the non-resonant operation mode is at least 10 times better than in previous reports. The future improvements of the technique are also discussed. PACS 07.07.Df; 42.55.Px; 82.80.Kq