3V -1 - mirthe-erc.org multiheterodyne spectroscopy using quantum and interband cascade lasers Jonas...
1
Mid-infrared multiheterodyne spectroscopy using quantum and interband cascade lasers Jonas Westberg 1* , Lukasz Sterczewski 1 , Link Patrick 1 , and Gerard Wysocki 1 1 Department of Electrical Engineering, Princeton University, Princeton N.J. 08544 *email: [email protected] Princeton University Laser Sensing Laboratory pulse.princeton.edu October, 2016 Motivation Acknowledgments Future work Results Experimental methods and procedures Conclusions • Broadband, non-invasive trace gas sensing with multimode Fabry-Pérot Quantum Cascade Lasers (QCLs) or Interband Cascade Lasers (ICLs). • Direct down-conversion of optical modes to multiheterodyne beat notes. • Separate access to individual radio- frequency (RF) beat notes for broadband measurement. • Conventional (wavelength modulation) and advanced modulation techniques (e.g. Faraday modulation) to increase sensitivity of multiheterodyne beat note spectroscopy. 3060 3070 3080 3090 3100 3110 3120 LO Sig. sample cell + - FSR sig ν opt. -1 -2 +1 +2 0 -3 ν opt. 0 -1 -2 -3 +1 +2 FSR LO sig. det. ν opt. -1 -2 +1 +2 0 -3 ν RF ν RF absorption dispersion + - 50 mA 3V ν opt . -1 -2 +1 +2 0 -3 20 GS/s ICL 1 ICL 2 FTIR 50 mA 3V a * cm -1 * b Locking procedure Frequency discriminator log PID 28-46 MHz RF Toptica mFALC 110 LO RF 40 MHz OPLL Sample signal LO Sig. sample cell absorption dispersion QCL 1 QCL 2 Reference signal Discriminator voltage (V) 70 mV/MHz Locking stability Figure a: Experimental schematic of the multiheterodyne setup. The light sources in this particular example are a pair of ICLs operating around 3.2 μm. The setup is based on the conventional dual-comb spectroscopy configuration. Figure b: FITR spectra of the signal and local oscillator multi-mode lasers. 115 120 125 -80 -60 -40 -20 2 MHz 2 kHz † 720 725 730 735 -70 -60 -50 -40 * Frequency (MHz) 0 200 400 600 800 -80 -70 -60 -50 -40 -30 -20 * † Power (dB) Frequency (MHz) Offset and repetition rate corrected -80 -70 -60 -50 -40 -30 -20 Power (dB) Offset-corrected † * -80 -70 -60 -50 -40 -30 -20 Power (dB) Raw spectrum † * 3108 3110 3112 3114 3116 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Transmission Wavenumber (cm -1 ) MH Measurement HITRAN fit 3110 3112 3114 3116 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Transmission Wavenumber (cm -1 ) MH Measurement HITRAN fit -0.2 -0.1 0.0 0.1 0.2 0.3 40 80 120 160 200 Amplitude (a.u.) Time (ms) MH DAS Ref.-corr. -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 1 s averaging Detuning (GHz) 0.2 0.4 0.6 0.8 1.0 Transmission -0.2 -0.1 0.0 0.1 0.2 0.3 -40 -20 0 20 40 1 s averaging Phase (°) Time (ms) MH DS meas. Neighbor-corr. -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 Detuning (GHz) 20 μs acq. time Frequency [MHz] Detector signal [V] 0 -1 +1 -2 +2 -3 +3 -4 +4 -5 +5 -6 +6 -7 +7 -8 +8 -9 +9 -10 +10 -11 FWHM 1.9 MHz QCL RF beat note spectrum • Multiheterodyne spectroscopy using FP- QCLs and ICLs • Intermutual frequency stabilization/locking • Frequency discriminator (low cost) • OPLL • Single mode detection • swept direct absorption (ramp rate 1 kHz) • wavelength modulation (f m = 10 kHz, 2f lock-in det.) • dispersion spectroscopy (ramp rate 1 kHz) • Multimode (broadband) detection • 25 cm -1 coverage • Rapid response time (10 μs) • Fully electronically controlled • Seamless switching between detection modes • Opto-mechanically simple setup • Complexity on the detection/signal processing side • Phase and timing correction. • Post-processing algorithm to improve SNR and enable coherent averaging. • ICL multiheterodyne spectroscopy of ethylene and methane. • Swept absorption and dispersion measurements at 1 kHz ramp rate. • Short acquisition times (20 μs) for broadband measurements. • QCL multiheterodyne measurements of N 2 O at low pressure • absorption • dispersion • QCL multiheterodyne measurement of N 2 O at low pressure using 2f wavelength modulation. • Broadband QCL multiheterodyne measurement of isobutane. • 10 μs acquisition time. • 25 cm -1 spectral coverage. ref. det. ν RF ν RF RSA RSA 40 MHz 40 MHz phase det. P(t) t P(t) oscilloscope t sig. det. • Dispersion engineering of devices to expand stable bias and temperature regions. • Explore THz QCL multiheterodyne spectroscopy. • Coherent averaging to increase sensitivity for longer acquisition times. • Broadband measurements ( 100 cm -1 ) • Rapid response time ( μs) • High resolution ( MHz) Challenges: The authors gratefully acknowledge F. Capasso, L. Diehl, M. Troccoli for providing FP-QCLs, and J. Meyer from the Naval Research Laboratory for providing the FP-ICLs used in this study. The work is supported by • DARPA SCOUT program (W31P4Q161001), • U.S. Environmental Protection Agency (U.S. EPA), RD-83513701-0 • National Science Foundation (NSF ERC MIRTHE), EEC-0540832.
Transcript of 3V -1 - mirthe-erc.org multiheterodyne spectroscopy using quantum and interband cascade lasers Jonas...
Mid-infrared multiheterodyne spectroscopy using quantum and interband cascade lasers
Jonas Westberg1*, Lukasz Sterczewski1, Link Patrick1, and Gerard Wysocki11Department of Electrical Engineering, Princeton University, Princeton N.J. 08544
*email: [email protected]
PrincetonUniversity
Laser
Sensing
Laboratorypulse.princeton.edu
October, 2016
Motivation
Acknowledgments
Future work
Results
Experimental methods and procedures
Conclusions
• Broadband, non-invasive trace gas sensing with multimode Fabry-Pérot Quantum Cascade Lasers (QCLs) or Interband Cascade Lasers (ICLs).
• Direct down-conversion of optical modes to multiheterodyne beat notes.
• Separate access to individual radio-frequency (RF) beat notes for broadband measurement.
• Conventional (wavelength modulation) and advanced modulation techniques (e.g. Faraday modulation) to increase sensitivity of multiheterodyne beat note spectroscopy.
3060 3070 3080 3090 3100 3110 3120
LO
Sig. sample cell+
-
FSRsig
νopt.
-1
-2+1
+2
0
-3
νopt.
0
-1-2
-3
+1
+2
FSRLO
sig. det.
νopt.
-1
-2+1
+2
0
-3
νRF
νRF
absorption dispersion
+
-
50 mA 3V
νopt.
-1
-2+1
+2
0
-3
20 GS/s
ICL1
ICL2
FTIR
50 mA 3V
a
*
cm-1
*
b
Locking procedure
Frequency discriminator
log PID
28-46 MHz
RFToptica
mFALC 110LO
RF
40 MHz
OPLL
Sam
ple
sig
nal
LO
Sig.sample cell
absorption dispersion
QCL1
QCL2
Reference signal
Dis
crim
inat
or
volt
age
(V)
70 mV/MHz
Locking stability
Figure a: Experimental schematic of the multiheterodyne setup. The light sources in this particular example are a pair of ICLs operating around 3.2 μm. The setup is based on the conventional dual-comb spectroscopy configuration.
Figure b: FITR spectra of the signal and local oscillator multi-mode lasers.
115 120 125
-80
-60
-40
-20
2 MHz
2 kHz†
720 725 730 735
-70
-60
-50
-40 *
Frequency (MHz)
0 200 400 600 800
-80
-70
-60
-50
-40
-30
-20
*†
Pow
er
(dB
)
Frequency (MHz)
Offset and repetition rate corrected
-80
-70
-60
-50
-40
-30
-20
Pow
er
(dB
)
Offset-corrected†
*
-80
-70
-60
-50
-40
-30
-20
Pow
er
(dB
)
Raw spectrum†
*
3108 3110 3112 3114 3116
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Tra
nsm
issio
n
Wavenumber (cm-1)
MH Measurement
HITRAN fit
3110 3112 3114 3116
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Tra
nsm
issio
n
Wavenumber (cm-1)
MH Measurement
HITRAN fit
-0.2 -0.1 0.0 0.1 0.2 0.340
80
120
160
200
Am
plit
ude (
a.u
.)
Time (ms)
MH DAS
Ref.-corr.
-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3
1 s averaging
Detuning (GHz)
0.2
0.4
0.6
0.8
1.0
Tra
nsm
issio
n
-0.2 -0.1 0.0 0.1 0.2 0.3-40
-20
0
20
40 1 s averaging
Phase (
°)
Time (ms)
MH DS meas.
Neighbor-corr.
-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3
Detuning (GHz)
20 μs acq. time
Frequency [MHz]
Dete
cto
r sig
nal [V
] 0 -1+1 -2
+2-3 +3 -4 +4
-5 +5 -6 +6-7
+7-8 +8
-9 +9-10 +10 -11
FWHM 1.9 MHz
QCL RF beat note spectrum
• Multiheterodyne spectroscopy using FP-QCLs and ICLs
• Intermutual frequency stabilization/locking• Frequency discriminator (low cost)• OPLL
• Single mode detection• swept direct absorption (ramp rate 1 kHz)• wavelength modulation (fm = 10 kHz, 2f lock-in
det.)• dispersion spectroscopy (ramp rate 1 kHz)
• Multimode (broadband) detection• 25 cm-1 coverage• Rapid response time (10 μs)
• Fully electronically controlled• Seamless switching between detection modes
• Opto-mechanically simple setup• Complexity on the detection/signal
processing side
• Phase and timing correction.
• Post-processing algorithm to improve SNR and enable coherent averaging.
• ICL multiheterodyne spectroscopy of ethylene and methane.
• Swept absorption and dispersion measurements at 1 kHz ramp rate.
• Short acquisition times (20 μs) for broadband measurements.
• QCL multiheterodyne measurements of N2O at low pressure
• absorption
• dispersion
• QCL multiheterodyne measurement of N2O at low pressure using 2fwavelength modulation.
• Broadband QCL multiheterodyne measurement of isobutane.
• 10 μs acquisition time.
• 25 cm-1 spectral coverage.
ref. det.
νRF
νRF
RSA
RSA
40 MHz
40 MHz
phase det.
P(t
)
t
P(t
)
oscilloscope
t
sig. det.
• Dispersion engineering of devices to expand stable bias and temperature regions.
• Explore THz QCL multiheterodyne spectroscopy.
• Coherent averaging to increase sensitivity for longer acquisition times.
• Broadband measurements ( 100 cm-1)• Rapid response time ( μs)• High resolution ( MHz)
Challenges:
The authors gratefully acknowledge F. Capasso, L. Diehl, M. Troccoli for providing FP-QCLs, and J. Meyerfrom the Naval Research Laboratory for providing the FP-ICLs used in this study.
The work is supported by • DARPA SCOUT program (W31P4Q161001), • U.S. Environmental Protection Agency (U.S.
EPA), RD-83513701-0 • National Science Foundation (NSF ERC
MIRTHE), EEC-0540832.
