Broadband photoacoustic amplification method for sensitive multi-species detection

A system for amplified broadband photoacoustic detection of multi-species with high-sensitivity, comprising:

• a light source configured to generate a light beam having a wavelength covering absorption lines of target gaseous analytes;
• a controller configured to control wavelength and intensity of the light beam;
• an acoustic resonator configured to generate broadband frequency response configured to amplify generated acoustic waves over a wide frequency range;
• an acoustic transducer configured to detect the generated acoustic waves;
• an electrical sum circuit configured to add electrical signals from the acoustic transducer;
• an optical resonator configured to enhance power of the light beam;
• a gas cell configured to provide an absolute frequency standard;
• a first locking loop configured to stabilize absolute wavelength of a light source by referencing to a molecular absorption line;
• a second locking loop configured to stabilize longitudinal mode of the optical resonator by referencing to the stabilized light source;
• a third locking loop configured to maintain stable power enhancement of the optical resonator;
• a first photodetector configured to detect transmitted light from the gas cell to lock the light source to the absorption line of the gas filled in the gas cell;
• a second photodetector configured to detect reflected light from the optical resonator to lock the light source to a longitudinal mode of the optical resonator;
• an optical coupler configured to combine two light sources;
• a lens configured to match a transverse mode of the light beam with a transverse mode of the optical resonator;
• a combination of polarized beamsplitter (PBS) and quarter-wave plate (QWP) configured to separate the light reflected by a front mirror of the optical resonator from incident light;
• an electrical splitter configured to split the electrical signal configured to generate different error signals;
• three Pound-Drever-Hall (PDH) modules configured to extract the error signals and configured to generate feedback signals for the three locking loops;
• and
• a piezoelectric (PZT) actuator attached to a rear mirror of the optical resonator to control a length between the two mirrors.