Theory of femtosecond coherent anti-Stokes Raman backscattering enhanced by quantum coherence for standoff detection of bacterial spores Academic Article uri icon


  • Backscattered signal of coherent anti-Stokes Raman spectroscopy can be an extremely useful tool for remote identification of airborne particles, provided the signal is sufficiently large. We formulate a semiclassical theory of nonlinear scattering to estimate the number of detectable photons from a bacterial spore at a distance. For the first time, the theory incorporates enhanced quantum coherence via femtosecond pulses and a nonlinear process into the classical scattering problem. Our result shows a large backscattered signal in the far field, using typical parameters of an anthrax spore with maximally prepared vibrational coherence. Using train pulses of 1 kHz of repetition rate each with energy of 10 mJ, we estimate that about parparpar107parparpar photons can be detected by a 1 m diameter detector placed 1 km away from the spore in the backward scattering direction. The result shows the feasibility of developing a real time remote detection of hazardous microparticles in the atmosphere, particularly biopathogenic spores. 2005 The American Physical Society.

published proceedings


author list (cited authors)

  • Ooi, C., Beadie, G., Kattawar, G. W., Reintjes, J. F., Rostovtsev, Y., Zubairy, M. S., & Scully, M. O.

citation count

  • 23

complete list of authors

  • Ooi, CHR||Beadie, G||Kattawar, GW||Reintjes, JF||Rostovtsev, Y||Zubairy, MS||Scully, MO

publication date

  • August 2005