This technology relates to detecting radiation by directing an optical beam into a volume of gas, ionizing a portion of the volume of gas with the optical beam to produce a plasma, and then detecting an acoustic signal produced from an interaction of a radiation wave with the plasma. This technology relates to the phenomenon of enhanced acoustic emission from laser-induced plasma under the influence of a single-cycle terahertz pulse. Aspects of this technology bridge the unintentional gap between THz photonics and photo-acoustics.