Applied Physics B

, Volume 32, Issue 3, pp 145–152

Frequency modulation (FM) spectroscopy

Theory of lineshapes and signal-to-noise analysis


  • G. C. Bjorklund
    • IBM Research Laboratory
  • M. D. Levenson
    • IBM Research Laboratory
  • W. Lenth
    • MIT Lincoln Laboratory
  • C. Ortiz
    • Instituto de Optica
Invited Papers

DOI: 10.1007/BF00688820

Cite this article as:
Bjorklund, G.C., Levenson, M.D., Lenth, W. et al. Appl. Phys. B (1983) 32: 145. doi:10.1007/BF00688820


Frequency modulation (FM) spectroscopy is a new method of optical heterodyne spectroscopy capable of sensitive and rapid measurement of the absorption or dispersion associated with narrow spectral features. The absorption or dispersion is measured by detecting the heterodyne beat signal that occurs when the FM optical spectrum of the probe wave is distorted by the spectral feature of interest. A short historical perspective and survey of the FM spectroscopy work performed to date is presented. Expressions describing the nature of the beat signal are derived. Theoretical lineshapes for a variety of experimental conditions are given. A signal-to-noise analysis is carried out to determine the ultimate sensitivity limits.



Copyright information

© Springer-Verlag 1983