TY - JOUR
T1 - Reduction of residual amplitude modulation in frequency-Modulation spectroscopy by using harmonic frequency modulation
AU - Whittaker, Edward A.
AU - Shum, Chi Man
PY - 1988/6
Y1 - 1988/6
N2 - A new technique to improve the sensitivity of frequency-modulation laser absorption spectroscopy is reported.Theoretical analysis and experimental demonstration show that the application of two harmonically related, appropriately phase-shifted rf waves to the electro-optic modulator can reduce the residual amplitude-modulation background signal in the photodetector output current without reducing the absorption-induced signal. When the new method was used, the residual amplitude-modulation background was reduced by a factor of 4. Our results suggest that shot-noise-limited detection sensitivity may eventually be achieved without using dual-beam compensation or dc-biased modulators.
AB - A new technique to improve the sensitivity of frequency-modulation laser absorption spectroscopy is reported.Theoretical analysis and experimental demonstration show that the application of two harmonically related, appropriately phase-shifted rf waves to the electro-optic modulator can reduce the residual amplitude-modulation background signal in the photodetector output current without reducing the absorption-induced signal. When the new method was used, the residual amplitude-modulation background was reduced by a factor of 4. Our results suggest that shot-noise-limited detection sensitivity may eventually be achieved without using dual-beam compensation or dc-biased modulators.
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U2 - 10.1364/JOSAB.5.001253
DO - 10.1364/JOSAB.5.001253
M3 - Article
AN - SCOPUS:84975582289
SN - 0740-3224
VL - 5
SP - 1253
EP - 1256
JO - Journal of the Optical Society of America B: Optical Physics
JF - Journal of the Optical Society of America B: Optical Physics
IS - 6
ER -