Doppler-Free Nonlinear Absorption in Ethylene by Use of Continuous-Wave Cavity Ringdown Spectroscopy

Published

June 1, 2000

Author(s)

C R. Bucher, K K. Lehmann, David F. Plusquellic, Gerald T. Fraser

Abstract

We report the first systematic study of Doppler-free, nonlinear absorption using cavity ring-down spectroscopy. We have developed a variant of cavity ring-down spectroscopy for the mid-infrared region between 9-11 m exploiting the intracavity power buildup that is possible using continuous wave lasers. The light source consists of a continuous wave CO₂ laser with 1 mW of tunable infrared sidebands and couples into a high finesse stable resonator. The cavity is filled with a mixture of 0.5% ethylene (C₂H₄) in He (by volume) at a total pressure of 1.3 Pa. We tune the sideband frequencies to observe a saturated, Doppler-free Lamb dip in the υ₇, 11_1,10 11_2,10 rovibrational transition of ethylene (C₂H₄) centered at 949.2 cm ^-1 . Power studies on the Lamb dip are presented to understand the effect of saturation on the Lamb dip linewidth, the peak depth and the broadband absorption.

Citation

Applied Optics

Volume

39

Issue

No. 18

Pub Type

Journals

Keywords

cavity ring-down spectroscopy, CW, Doppler-free, ethylene, mid-infrared, nonlinear absorption, saturation

Citation

Bucher, C. , Lehmann, K. , Plusquellic, D. and Fraser, G. (2000), Doppler-Free Nonlinear Absorption in Ethylene by Use of Continuous-Wave Cavity Ringdown Spectroscopy, Applied Optics (Accessed October 2, 2025)