Security Applications Using Broadly Tunable Security Applications Using Broadly Tunable External Cavity Quantum Cascade Lasers for the Mid‐IR (EC‐QCL) the Mid IR (EC QCL) Timothy Day, David Arnone, Miles J. Weida, Michael Pushkarsky, Dave Caffey, Vince Cook, Chris Armacost Daylight Solutions, Inc. www.daylightsolutions.com www.daylightsolutions.com
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Security Applications UsingBroadlyUsing Broadly Tunable ... · Security Applications UsingBroadlyUsing Broadly Tunable ... Faist, J et al Science 264 pg 553 (1994)J., et al., Science,
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Security Applications Using Broadly TunableSecurity Applications Using Broadly TunableExternal Cavity Quantum Cascade Lasers for
the Mid‐IR (EC‐QCL)the Mid IR (EC QCL)
Timothy Day, David Arnone, Miles J. Weida, Michael Pushkarsky, Dave Caffey,
Why is Broad Tunability Important?Narrow tuning reveals only a snapshot.
Laser scan
Lasers Technical Seminar, Lahat Technologies Ltd.
The Source for all Applications in the Mid-IR
d b l
so you can seeLaser scan Broad tunability reveals
Broad Tunability
…so you can see the whole picture!!!
Broad tunability reveals the entire fingerprint…
Lasers Technical Seminar, Lahat Technologies Ltd.
Why is Broad Tunability Important?Composite spectrum Deconvolved spectrum
H2OEthanol
Daylight Solutions broad tuning >250 cm-1
Daylight Solutions broad tuning >250 cm-1
ce e H2O
CO2
Ethanol
Abso
rban
c
Abso
rban
ce
950 1000 1050 1100 1150 1200Wavenumber (cm-1)
950 1000 1050 1100 1150 1200Wavenumber (cm-1)
• “Fingerprint” analysis yields multi-species detection with single laser• High degree of selectivity from background interference• Pattern recognition algorithms and embedded DSP can determine specific
constituents and concentrations
External Cavity QCL Review and Recent Tuning ResultsTuning Results
Sub‐threshold GainCO2
> 700 cm‐1
B d i t b d t id bl li ht4 µm 5 µm
• Broad gain must be managed to provide usable light– Distributed Feedback (DFB) QCLs
• Sacrifice gain and yieldQCL d ’ f i SLD– QCLs don’t function as SLDs
– External Cavity Laser
Coherence Collapse• Bandwidth as function of drive current for mirror feedback
– No easy predictor of bandwidth behavior– Need external control of bandwidth
850 mA
rren
tea
sing
Cur
920 mA30 cm‐1
Incr
e
920 mA
4.0 µm
External Cavity quantum cascade Laser (ECqcL™)
• Grating feedback narrows output• Grating feedback narrows output • Rotation of grating accesses gain bandwidth
US Patent # 7,424,042, 7,466,734, 7,492,806, 7,535,656, 7,535,936, & 7,796,341
Broadening QCL Gain
CW Tuning Ranges (Average power)
Pulsed Tuning Ranges g g(Peak. power)
Beam Characteristics• Beam Divergence - < 5 mrad
P l i ti Li 100 1• Polarization - Linear 100:1• Beam Quality - TEM00• Pointing Stability - < 1 mrad for Tunable, < 0.1 mrad for Fixed
Beam Profile — M2 Typical 1.3
Current QCL Capabilities – Tuning Range
External Cavity QCL Tuning Range
• Tuning range for single lasers continues to increaseFaist J et al Science 264 pg 553 (1994) Maulini R et al Appl Phys Lett 88 (20) pg201113 (2006)Faist, J., et al., Science, 264, pg. 553 (1994)Luo, G.P. et al., Appl. Phy. Lett. 78, pg 2834 (2001)Gmachl, C., et al. IEEE J. Quant. Elec., 38(6) pg 569 (2002)Maulini, R., et al. Appl. Phys. Lett., 84 (10), pg. 1659 (2004)
Maulini, R., et al., Appl. Phys. Lett., 88 (20), pg201113 (2006)Wittmann, A., et al., IEEE J. Quant. Elec., 44 (11), pg. 1083 (2008)Hugi, A., et al., Appl. Phy. Lett., 95, pg. 061103 (2009)
Molecular Detection Applications and Recent PerformancePerformance
Accessing 3.x µm
• Type I GaSb diodes incorporated in external cavities for access to “short” wavelengthscavities for access to “short” wavelengths
500 cm‐1
2.86 µm 3.33 µm
Ridge Waveguide Laser Diode Sub-threshold gain
ECDL Tuning Performance
6
Pulsed Tuning Performance • Pulsed and cw operation at 3 15
2
3
4
5
Pow
er(m
W)
500 mA
400 mA Access to acetylene and methane C H stretch
3.15 µm
CW Tuning Curve
0
1
3070317032703370
Wavenumber (cm-1)
375 mA methane C‐H stretch absorption spectra (PNNL simulations)
4
5
6
(mW
)
CW Tuning Curve• cw tuning
• 2.93-3.26 µm • 345 cm-1 of tuning (11%
0
1
2
3
Powe
r ( 500 mA400 mA300 mA
345 cm of tuning (11% of center wavelength)
• Next generation at 3.25 um3070317032703370
Wavenumber (cm-1) and reached 9 mW CW
Extremely sensitive detection of NO2 employing off-axis integrated cavity output spectroscopy coupled with multiple-line integrated absorption spectroscopy
Data processing and analysis:• frequency modulated spectroscopy techniques to i th i l t i tiimprove the signal-to-noise ratio • multiple-line integrated absorption spectroscopy to improve the sensitivity of p ydetection.
Enables detection of trace amounts of explosive compounds
- Rao* and Karpf – Adelphi University
Trace concentrations of NO2 with ahigh sensitivity of the order of 28 ppt
This spectrum was used to select a region with a dense NO2spectrum that was free from interference due to water lines. The region used for the reported work (between 1655:3cm−1 and1657:3cm−1) is highlighted in the1657:3cm 1) is highlighted in the chart with a white background.
Distributed nerve gases sensor based on IR absorption in hollow optical fiber – CREO & Selex Sistemi Integrati
Concept design of the line-sensor
Laser drilling micro holes
Layout illustrating a cross section of the cell f i t f i th HCF ith th IRfor interfacing the HCF with the IR source/detector and the air sampling circuit.
Distributed nerve gases sensor continued…
Comparison between the IR absorption spectrum of ethyl alcohol, as obtained by integrating 14 spectral scans, and
Grid of line-sensors indoor applications
the corresponding IR spectrum retrieved from the PNNL database.
Quantum Cascade Laser‐Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination
• US Army Research Labs: Ellen Holthoff 1,John Bender 1, Paul Pellegrino 1
Quantum Cascade Laser‐Based Photoacoustic Spectroscopy for Trace Vapor Detection and Molecular Discrimination
• US Army Research Labs: Ellen Holthoff 1,*, John Bender 1, Paul Pellegrino 1
Mid‐IR Illumination Applications and Recent PerformancePerformance
Standoff Detection of Explosives with EC‐QCLFrank Fuchs - Fraunhofer-Institut
The sensor head comprises the tunable external quantum cascade cavity laser,an IR imager, and a visible camera. The system
ft bl t ti id tifi tisoftware enables automatic identification.
Pump–probe Photothermal Spectroscopy EC-QCL
R H Farahi1, A Passian1,2, L Tetard1R H Farahi , A Passian , L Tetardand T Thundat3
1 Oak Ridge National Laboratory2 University of Tennessee3 University of Alberta
Pump–probe standoff HSI using QCL-based photothermal
3 University of Alberta
QCL-based photothermalspectroscopy of a target surface:
• QCL pump thermo-optically stimulates the surface •The minimally invasive probe beam (red) same location monitorsthermal response of the specimen,thermal response of the specimen,yielding the absorption spectra.
Active Infrared Multispectral Imaging to Identify Chemicals on Surfaces
- Anish K. Goyal
Summary
• Mid‐IR fingerprint is rich region• Broad Tuning facilitates spectral sensing• Broad Tuning facilitates spectral sensing• ECqcL™ architecture harnesses broad gain• Single chip tuning continues to increase• Enables molecular detection for solids, liquids and gas.
• Absorption Spectroscopy and Imaging effectivep p py g g