quantum-noise-limited cavity ring-down spectroscopy in the mid-infrared adam j. fleisher,* david a....
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Quantum-Noise-LimitedCavity Ring-Down Spectroscopyin the Mid-InfraredAdam J. Fleisher,* David A. Long, Qingnan Liu, and Joseph T. Hodges
Material Measurement LaboratoryNational Institute of Standards & TechnologyGaithersburg, MD 20899, USA
Strong molecular transitions
Near-infrared CRDS• mature technology• lasers, modulators, detectors,
mirrors
• overtone + combination bands
• S = 1.7x10−23 cm/molecule• CO2 at 1.57 µm
Retrieved from HITRANonline at hitran.org on 6/23/2015
Mid-infrared CRDS• maturing technology• lasers, modulators, detectors,
mirrors
• fundamental vibrations
• S = 3.5x10−18 cm/molecule• CO2 at 4.23 µm
Targeting weak isotopologues
Zoom in 60,000,000,000X
12CO2 14CO2
14CO2
I. Galli et al., PRL 107, 270802 (2011); Erratum 108, 179902 (2012).
Motivation at NIST
14C
Partitioning GHG sourcesBiobased
product verification
Biofuel feedstock identification
Pollutantsource identification
Motivation at NIST
Photo from LLNL
Accelerator Mass Spectrometry (AMS)
• Very sensitive (<1 fmol/mol)
• Expensive (~$6M/facility)• Require large faculty and highly
trained staff• Only ~10 facilities in the U.S.• Lead time >10 days
Status update
• Detail instrument design – quantum cascade laser
• Demonstrate spectrometer performance – quantum-noise-limited decays
• Coarse spectral scanning and high-resolution scanning
• Future low-temperature CRDS (≥185 K)
Experimental methods
PC
L1
InSb
PD
Optical C
avity
Wavem
eter
AOM
DFB
QCL
λ/2
L2 L3
trigger
servo + tr
igger
λ DFB-QCL
T DFB-QCL, I D
FB-QCL
TEM00
Autocorrelation of the decay
Quantum-Noise-Limited Fit ResidualsDetector-Noise-Limited Fit Residuals
low noise PDhigh noise PD
QNL decays recorded at DC
Quantum-Noise-Limited Fit Residuals
low noise PD
H. Huang and K.K. Lehman, JPCA 117, 13399 (2013).
Pdet < 100 µW NEP < 70 fW Hz−1/2 facq > 30 Hz
NEA = 2.3x10−11 cm−1 Hz−1/2
Allan variance of the decay time
MDA < 2×10−11 cm−1 at 3 s
NEA = 2.3x10−11 cm−1 Hz−1/2
MDA < 6×10−12 cm−1 at 4 s
NEA = 1.0x10−11 cm−1 Hz−1/2
L0 ≈ 100 ppm τ0 ≈ 50 µs
Coarse scanning
αnoise < 4x10−10 cm−1
change temperature of QCLor
change current of QCLto jump between FSR
100 MHz coarse scanning
Improved CO2 detection limits
Near-infrared CRDHS• S = 1.7x10−23 cm/molecule• CO2 at 1.57 µm
• NEA = 6x10−14 cm−1 Hz−1/2
• NEC < 130 ppt Hz−1/2
• 10 Torr of total pressure
Retrieved from HITRANonline at hitran.org on 6/24/2015
Mid-infrared CRDS• S = 3.5x10−18 cm/molecule• CO2 at 4.23 µm
• NEA = 2x10−11 cm−1 Hz−1/2
• NEC < 80 ppq Hz−1/2
• 10 Torr of total pressure
D.A. Long et al., Opt. Lett. 39, 2688 (2014)
Low-temperature CRDS
S. Kassi et al., CPL 477, 17 (2009).
invar rods
mirror mount
assembly
sample cold cell
vacuum
sample
cooling liquid
Status update
• Detail instrument design – quantum cascade laser
• Demonstrate spectrometer performance – quantum-noise-limited decays
• Coarse spectral scanning and high-resolution scanning
• Future low-temperature CRDS (≥185 K)
Acknowledgements
David Long, Joseph Hodges, Roger van Zee, Zachary Reed
K. Bielska, M. Ghysels, H. Lin, Q. Liu, V. Sironneau, S. Wójtewicz, H. Yi
NIST Innovation in Measurement Science (IMS) Award
Good postdocs always wanted: [email protected]
Mirror birefringence
Effects of birefringence
Non-exponential decays
Blank
Comparison with the literature
3.00 3.50 4.00 4.50 5.00 5.50 6.001.00E-12
1.00E-11
1.00E-10
1.00E-09
1.00E-08
Fleisher
MaisonSilanderGalli
Lee
Foltynowicz
Halmer
HalmerBasum
Gorrotxategi-Carbajo
PoramboCrabtree
Malara Mürtz
Wang
McManus
GalliNIST
Mid-IR Sensitivities in the Literature
Wavelength (µm)
NEA
coe
ffici
ent (
cm−1
Hz−
1/2)