Quantum-Noise-Limited Cavity Ring-Down Spectroscopy in the ...
Precision Cavity-enhanced Dual-comb Spectroscopy: Application to the Gas Metrology of CO2, H2O, and N2O Adam J. Fleisher, David A. Long, Joseph T. Hodges Material Measurement Laboratory National Institute of Standards & Technology Gaithersburg, MD 20899, USA Quantitative CE-DCS Electro-optic frequency combs are an agile laser platform for rapid spectroscopy from 0.4 2.0 m. To perform quantitative cavityenhanced dual-comb spectroscopy (CE-DCS), we require an accurate model of the complex multiheterodyne signal.
D.A. Long et al., Opt. Lett. 39, 2688 (2014). A. J. Fleisher et al., Opt. Express 24, 10424 (2016). Electro-optic frequency combs Utilize two EOFCs originating from the same CW laser to perform DCS EOMLO FS AOMLO FS FL EC PD
FC EOMprobe FA FC FL Sample Local Oscillator + Probe or Local Oscillator + Reference ECDL
D.A. Long et al., Opt. Lett. 39, 2688 (2014). A. J. Fleisher et al., Opt. Express 24, 10424 (2016). Cavity-enhanced DCS Cavity locked to HeNe (dither) CW laser locked to cavity (PDH) fAOM phase locked to RF reference (Cs clock) EO comb spacing phase locked to RF reference (Cs clock) CW laser frequency measured against stabilized OFC (Cs clock) A.J. Fleisher et al., in preparation. Ideal case: frep = FSR frep = FSR
Model of CE-DCS ~ ~ = 0 ( + 0 ) (1 ) exp / 2 /2 ( ( 1 exp R+T+ =1 q = mode order (-M/2 0 M/2)
= mode spacing offset 0 = PDH lock offset 2 ( + 0 ) ) ) L = 74 cm F = 18,500 Leff = 4.4 km FSR = 203 MHz cav = 10 kHz A.J. Fleisher et al, in preparation. A. Foltynowicz et al., Appl. Phys. B 110, 163 (2013).
Carbon dioxide ( C O2) 12 30012 Band of 12C16O2 at cm1 16 R16e line at cm1 A.J. Fleisher et al., in preparation. Carbon dioxide ( C O2) 12 16 30012 Band of 12C16O2 at cm1 Fit transition frequencies vs. m
to obtain upper-state inertial parameters and origin frequency for 30012 band of 12C16O2 Uncertainty in Gv of 1.9 MHz () CE-DCS inertial parameters and origin frequency are in good agreement with FS-CRDS A.J. Fleisher et al, in preparation. D.A. Long et al., JQSRT 161, 35 (2015). Water (H2 O) 16 040 000 101,10 90,9 and
040 000 62,5 61,6 Obs. Calc. 0.01 rms in 1 s Pressures of 2.68, 4.50, and 6.20 Torr A.J. Fleisher et al., in preparation. Water (H2 O) 16 040 Band of H216O from = 6300 - 6335 cm1 Deviations from HITRAN12 are as large as 20 MHz. Absolute transition frequencies for H2O measured by CE-CRDS agree with highly accurate
FS-CRDS experiments. A.J. Fleisher et al., in preparation. Nitrous Oxide ( N2 O) 14 16 Analysis of the 4200 band of N2O currently in progress 65 transitions at low pressure P = 0.55 Torr A.J. Fleisher et al., in preparation. Performance and Outlook
Single-element noise-equivalent absorption coefficient cm1 Hz1/2 Broadband applications Octave-spanning EO combs High-resolution applications Self-heterodyne read-out to reduce K. Beha et al, Optica 4, 406 (2017). D.A. Long et al., Phys. Rev. A 94, 061801(R) (2016). Acknowledgements MML David Long Zachary Reed Joseph Hodges PML David Plusquellic
NIST Greenhouse Gas Measurements and Climate Research Program NRC Postdocs opportunities: [email protected] Blank A.J. Fleisher et al., Opt. Express 24, 10424 (2016) Model A.J. Fleisher et al., in preparation. Model evaluation I = 2 kHz PDH = 2 kHz P = 13 Pa (0.1 Torr) CO2 0 = 6364.750 cm1
0 = 1571 nm G.-W. Truong et al., J. Chem. Phys. 138, 094201 (2013) Model evaluation II = 2 kHz PDH = 0 P = 13 Pa (0.1 Torr) CO2 0 = 6364.750 cm1 0 = 1571 nm Model evaluation III = +2 kHz PDH = 0 P = 13 Pa (0.1 Torr) CO2 0 = 6364.750 cm1 0 = 1571 nm
Carbon dioxide ( C O2) 12 16 30012 Band of 12C16O2 at cm1 Spectroscopic constants in MHz Gv Bv Dv (103) Hv (109) 11698.469997536
14(22) 11585.62636(69) A.J. Fleisher et al, in preparation. D.A. Long et al., JQSRT 161, 35 (2015). EOM comb outline Explore MULTIHETERODYNE (DualComb) using commercially-available low V fiber-coupled waveguide electro-optic modulators (EOMs) and tunable CW lasers in the near-IR Retro-fit to existing CW lasers throughout the laboratory (fiber, DFB, ECDL, etc.) Interrogate samples using existing optical cavities throughout the laboratory (i.e., no need to construct
a cavity of specific FSR) Dual-Drive MZM + + <4 Vrms 6dB 6dB <10 kHz 18 GHz T. Sakamoto et al., Opt. Lett. 32, 1515 (2007) Amplitude
Detector BPF Amp Phase Frequency Detector Loop Filter AOM VCO Local Oscillator
Probe or Ref. Laser RF Cable Optical Fiber A.J. Fleisher et al., Opt. Express 24, 10424 (2016) Reduction in RF linewidth t = 10 s RBW = 10 Hz inset: t = 10 s RBW = 200 mHz A.J. Fleisher et al., Opt. Express 24, 10424 (2016)
Coherent averaging Without the AOM phase lock, successively triggered interferograms can not be coherently averaged With the AOM phase lock, the signal-to-noise on a single comb tooth amplitude improves by Coherent averaging for more than 2 hours! 6 TB/h A.J. Fleisher et al., Opt. Express 24, 10424 (2016) Coherent averaging tacq = 200 ss fmod = 300 kHz
N = 1000 noise reduction by Fast acquisition tacq = 10 ss fmod = 300 kHz N = 1000 noise reduction by Nitrous Oxide ( N2 O) 14 16 4200 Band of 14N216O at cm1
Spectroscopic constants in MHz Gv Bv Dv (103) Hv (109) 12561.6338 5.279910 -0.49552 4200e (Toth)
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