mid-infrared semiconductor laser based trace gas ... · innovative long path, small volume...

Mid-infrared semiconductor laser based trace gas technologies: recent advances and applicationstechnologies: recent advances and applications

F. K. Tittel1, R. Lewicki1,4, M. Jahjah1, P. Stefanski1,4, J. Tarka1,4, L. Gong2, R. Griffin2 S. So4, D.Thomazy4 W. Jiang1, J. Zhang1,6, P.

OUTLINE

g , , y g , g ,Lane5, R.Talbot5

1 Department of Electrical and Computer Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA2 Department of Civil and Environmental Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA

3 Laser and Fiber Electronics Group, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, Wroclaw, Poland

UAB I ti

4 Sentinel Photonics, Monmouth Junction, NJ 08852, USA5 University of Houston, Department of Earth & Atmospheric Sciences, Houston, TX 77204, USA

6 Northeast Forestry University, Department of Electromechanical Engineering, Harbin, China

• New Laser Based Trace Gas Sensor TechnologyInnovative Forum

Center for Optical

• New Laser Based Trace Gas Sensor Technology Novel Multipass Absorption Cell & ElectronicsQuartz Enhanced Photoacoustic Spectroscopy

l f id f d hip

Sensors and Spectroscopies Birmingham

AL

• Examples of Mid-Infrared Sensor Architectures C2H6, NH3, NO, CO, and SO2Future Directions of Laser Based Gas Sensor

May 14, 2013

Research support by NSF ERC MIRTHE, NSF-ANR NexCILAS, the Robert Welch Foundation, Scinovation, Inc., Testo AG and Sentinel Photonics Inc. via an EPA Phase 1 SBIR sub-award is acknowledged

Technology and Conclusions

Mid-IR and THz Spectroscopic Phenomena

Provided by: Prof. Daniel Mittleman, Rice University

Wide Range of Trace Gas Sensing Applications• Urban and Industrial Emission Measurements• Urban and Industrial Emission Measurements

Industrial PlantsCombustion Sources and Processes (e.g. fire detection)Automobile Truck Aircraft and Marine EmissionsAutomobile, Truck, Aircraft and Marine Emissions

• Rural Emission MeasurementsAgriculture & Forestry, Livestocki i i• Environmental Monitoring

Atmospheric Chemistry (e.g isotopologues, climate modeling,…)Volcanic Emissions

• Chemical Analysis and Industrial Process ControlPetrochemical, Semiconductor, Pharmaceutical, Metals Processing, Food & Beverage Industries; Nuclear Technology & Safeguards

• Spacecraft and Planetary Surface MonitoringCrew Health Maintenance & Life Support

• Applications in Medical Diagnostics and the Life Sciences pp g• Technologies for Law Enforcement, Defense and Security• Fundamental Science and Photochemistry

“Curiosity” landed on Mars on August 6, 2012

Laser based Trace Gas Sensing Techniques • Optimum Molecular Absorbing Transition• Optimum Molecular Absorbing Transition

Overtone or Combination Bands (NIR)Fundamental Absorption Bands (Mid-IR)

• Long Optical PathlengthMultipass Absorption Cell (White, Herriot, Chernin, Sentinel Photonics))Cavity Enhanced and Cavity Ringdown SpectroscopyOpen Path Monitoring (with retro-reflector): Standoff and Remote DetectionRemote Detection Fiberoptic Evanescent Wave Spectroscopy

• Spectroscopic Detection SchemesFrequency or Wavelength ModulationBalanced DetectionZero-air SubtractionPhotoacoustic & Quartz Enhanced Photoacoustic Spectroscopy (QEPAS)

Other spectroscopic methods

• Faraday Rotation Spectroscopy (limited to paramagnetic chemical species)

• Differential Optical Dispersion Spectroscop (DODiS)• Differential Optical Dispersion Spectroscopy (DODiS)• Noise Immune Cavity Enhanced-Optical Heterodyne

Molecular Spectroscopy (NICE-OHMS)p py ( )• Frequency Comb Spectroscopy • Laser Induced Breakdown Spectroscopy (LIBS)

HITRAN Simulated Mid-Infrared Molecular Absorption Spectra

CO: 4.66 µm CH2O: 3.6 µm

CO2: 4.2 µm

COS: 4.86 µm

NO: 5.26 µm

µ

CH4: 3.3 µm

3.1 µm5.5 µm

NH3: 10.6 µm O3: 10 µmN20, CH4: 7.66 µm

12.5 µm 7.6 µm

Source: HITRAN 2000 database

Mid-IR Source Requirements for Laser Spectroscopy

REQUIREMENTS IR LASER SOURCE

Sensitivity (% to ppt) Optimum Wavelength, Power

Selectivity (Spectral Resolution) Stable Single Mode Operation and Narrow Linewidth

Multi-gas Components, Multiple Absorption Lines and Broadband Absorbers

Mode Hop-free WavelengthTunability

Directionality or Cavity Mode Matching

Beam Quality

Rapid Data Acquisition Fast Time Response

Room Temperature Operation High wall plug efficiency, no cryogenics lior cooling water

Field deployable in harsh environments

Compact & Robust

Key Characteristics of Mid-IR QCL & ICL Sources – May 2013

• Band – structure engineered devices Emission wavelength is determined by layer thickness – MBE or MOCVD; Type I QCLs operate in the 3 to 24 µm spectral region; Type II and GaSb based ICLs can cover the 3 to 6 µm spectral range.

Compact, reliable, stable, long lifetime, and commercial availability Fabry-Perot (FP), single mode (DFB) and multi-wavelength devices

• Wide spectral tuning ranges in the mid-IR4

p g g1.5 cm-1 using injection current control for DFB devices10-20 cm-1 using temperature control for DFB devices ~100cm-1 using current and temperature control for QCL DFB Array ~ 525 cm-1 (22% of c.w.) using an external grating element and FP chips

ith h t d ti i d i l QCL DFB A

4 mm

with heterogeneous cascade active region design; also QCL DFB Array

• Narrow spectral linewidths CW: 0.1 - 3 MHz & <10kHz with frequency stabilization (0.0004 cm-1) Pulsed: ~ 300 MHz

• High pulsed and CW powers of QCLs at TEC/RT temperatures

Room temperature pulsed power of > 30 W with 27% wall plug p p p p gefficiency and CW powers of ~ 5 W with 21% wall plug efficiency > 1W, TEC CW DFB @ 4.6 µm > 600 mW (CW FP) @ RT; wall plug efficiency of ~17 % at 4.6 µm;

Improvements and New Capabilities of QCLs and ICLs

• Optimum wavelength ( > 3 to < 20 µm) and power ( >10 mw to < 1 W)at room temperature (> 15 ºC and < 30 ºC) with state-of-the-artfabrication/processing methods based on MBE and MOCVD, good wallplug efficiency and lifetime (> 20,000 hours) for detection sensitivitiesplug efficiency and lifetime (> 20,000 hours) for detection sensitivitiesfrom % to pptv with low electrical power budget

• Stable single TEM00 transverse and axial mode, CW and pulsed operationof mid-infrared laser sources (narrow linewidth of ~ 300 MHz to <10k )10kHz)

• Mode hop-free ultra-broad wavelength tunability for detection of broadband absorbers and multiple absorption lines based on external cavity ormid infrared semiconductor arraysmid-infrared semiconductor arrays

• Good beam quality for directionality and/or cavity mode matching.Implementation of innovative collimation concepts.

• Rapid data acquisition based on fast time responseRapid data acquisition based on fast time response • Compact, robust, readily commercially available and affordable in order

to be field deployable in harsh operating environments (temperature,pressure, etc…)

Motivation for Mid-infrared C2H6 Detection

• Atmospheric chemistry and climate Fossil fuel and biofuel consumption, bi b ibiomass burning,vegetation/soil,natural gas loss

• Oil and gas prospecting• Oil and gas prospecting • Application in medical breath analysis

(a non-invasive method to identify and monitor different diseases):

asthma, schizophremia,Lung cancer,llung cancer,vitamin E deficiency.

HITRAN absorption spectra of C H CH and H OHITRAN absorption spectra of C2H6, CH4, and H2O

C2H6 Detection with a 3.36 µm CW DFB LD using a Novel Compact Multipass Absorption Cell and Control Electronics

Innovative long path, small volume multipassgas cell:57 6m with 459 passes

Schematic of a C2H6 gas sensor using a Nanoplus 3.36 µm DFB laser diode as an excitation source. M – mirror, CL – collimating lens, DM – dichroic mirror, MC – multipass cell, L – lens, SCB – sensor control board.

gas cell:57.6m with 459 passes

2f WMS signal for a C2H6 line

1at 2976.8 cm-1

at a pressure of 200 Torr

MC dimensions: 17 x 6.5 x 5.5 (cm)Distance between the MGC mirrors: 13 cm

Minimum detectable C2H6 concentration is: ~ 130 pptv (1σ; 1 s time resolution)

NOAA Monitoring & Sampling Location: Alert, Nunavut, Canada

ALT, Ethane Concentration Measurements

General View on the FacilityLatitude: 82.4508º NorthLongitude: 62.5056º WestLongitude: 62.5056 WestElevation: 200.00 m

Motivation for NH3 Detection

• Atmospheric chemistry• Pollution gas monitoringg g• Monitoring NH3 concentrations in the exhaust

stream of NOx removal systems based on selective l i d i ( ) h icatalytic reduction (SCR) techniques

• Spacecraft related trace gas monitoringS i d i i & l• Semiconductor process monitoring & control

• Monitoring of industrial refrigeration facilitiesi i f i• Monitoring of gas separation processes

• Medical diagnostics (kidney & liver diseases)D i f i i l i• Detection of ammonium-nitrate explosives

Conventional PASCell is OPTIONAL!

Laser beam, power P

Cell is OPTIONAL!

V-effective volume

Absorption αModulated (P or λ) at for f/2

VfPQS α~

Sensitive microphone

⎥⎦

⎤⎢⎣

⎡ ×∆

α=

HzWcm-1

min

fPNNEA

⎦⎣∆ Hzf

Atmospheric NH3 Measurements using an EC-QCL PAS Sensor

NH3 sensor deployed at the UH MoodyTower rooftop monitoring site.

Schematic of a Daylight Solutions 10.36 µm CW TEC EC-QCL based PAS NH3 Sensor.pb

)

14

16

18

tion

(#/c

m3 )

40000

50000

NH3 Particle Number Concentrationo

(ppb

)

1 21 41 61 8

NH

3 m

ixin

g ra

tio (p

2

4

6

8

10

12

cle

Num

ber C

once

ntra

t

10000

20000

30000

NH

3 m

ixin

g ra

tio

02468

1 0

Diurnal profile of atmospheric NH3 levels in Houston, TX.

Comparison between NH3 and particle number concentration time series from July 19 to July 31 2012.

Time

0

Par

tic07/19 7/20 7/21 7/22 7/23 7/24 7/25 7/26 7/27 7/28 7/29 7/30 7/31H o u r o f d ay

fro m 7 /1 9 /1 2 to 7 /3 1 /1 2

0 5 1 0 1 5 2 0

NH3 Detection due to a Fire resulting from a Truck Collision

Accidental release of NH3

ppb)

20

24

August 14, 2010

NH3 c

once

ntra

tion

(p

8

12

16

Hour of day

0 5 10 15 20

N

0

4

Downwind of the Houston Ship Channel

A chemical incident occurred at ~ 6 a.m. after two trucks collided on I-59. Both trucks caught fire. [www.chron.com]

yAugust 14, 2010

o d o t e ousto S p C a e

n (p

pb)

20

25

30

NH3 c

once

ntra

tion

10

15

Hour of daySeptember 17, 2010

0 5 10 15 200

5

Estimated hourly NH3 emission from the Houston Ship Channel area is about 0.25 ton. Mellqvist et al., (2007) Final Report, HARC Project H-53.

photo: Public Domain / RJN2

Sporadic increased NH3 Concentration Levels related to Emissions by the Parish Electric Power Plant, TX y ,

The Parish electric power plant is located near the Brazos River in Fort Bend County, Texas (~27 miles SW fromRiver in Fort Bend County, Texas ( 27 miles SW from

downtown Houston)

NH3 Detection due to a Fire resulting from a Truck Collision

Accidental release of NH3

ppb)

20

24

August 14, 2010

NH3 c

once

ntra

tion

(p

8

12

16

Hour of day

0 5 10 15 20

N

0

4

Downwind of the Houston Ship Channel

A chemical incident occurred at ~ 6 a.m. after two trucks collided on I-59. Both trucks caught fire. [www.chron.com]

yAugust 14, 2010

o d o t e ousto S p C a e

n (p

pb)

20

25

30

NH3 c

once

ntra

tion

10

15

Hour of daySeptember 17, 2010

0 5 10 15 200

5

Estimated hourly NH3 emission from the Houston Ship Channel area is about 0.25 ton. Mellqvist et al., (2007) Final Report, HARC Project H-53.

photo: Public Domain / RJN2

Fort-Worth, Dallas(TX) CAMS 75 & TCEQ monitoring site

Eagle Mountain Lake ti bi t it i

Laboratory trailer continuous ambient monitoring station (CAMS 75) operated by Texas Commission on Environmental Quality (TCEQ)

in this study

Environmental Quality (TCEQ)

Instrumentation available at CAMS 75 & TCEQ monitoring site

Species/parameter Measurement technique

NH3 Daylight Solutions External Cavity Quantum Cascade Laser (Photo-acoustic Spectroscopy)

CO Thermo Electron Corp. 48C Trace Level CO Analyzer (Gas Filter Correlation)

SO2 Thermo Electron Corp. 43C Trace Level SO2 Analyzer (Pulsed Fluorescence)

NO Thermo Electron Corp 42C Trace Le el NO NO NO Anal er (Chemil minescence)NOx Thermo Electron Corp. 42C Trace Level NO-NO2-NOX Analyzer (Chemiluminescence)

NOy Thermo Electron Corp. 42C-Y NOY Analyzer (Molybdenum Converter)

HNO3 Mist Chamber coupled to Ion Chromatography (Dionex, Model CD20-1)

HCl Mist Chamber coupled to Ion Chromatography (Dionex, Model CD20-1)

VOCs IONICON Analytik Proton Transfer Reaction Mass Spectrometer and TCEQ Automated Gas ChromatographChromatograph

PBL height Vaisala Ceilometer CL31 with updated firmware to work with Vaisala Boundary Layer View software

Temperature Campbell Scientific HMP45C Platinum Resistance Thermometer

Wind speed Campbell Scientific 05103 R. M. Young Wind Monitor

Wind direction Campbell Scientific 05103 R. M. Young Wind Monitor

NH3 source attribution & temperature variationsE i i t f ifi d• Emission events from specified point sources (i.e., industrial facilities)

ppb) 8

10

12

• Estimated NH3 emissions from cows (1.3 tons/day)

• Estimated NH3 emissions from NH

3 mix

ing

ratio

(p

2

4

6

st ated 3 e ss o s osoil and vegetation (0.15 tons/day)

• EPA PMF (biogenic: 74 1%;40

N

0

• EPA PMF (biogenic: 74.1%; light duty vehicles: 12.1%; natural gas/industry: 9.4%; and heavy duty vehicles: 4 4%) ra

ture

(o C)

30

35

heavy duty vehicles: 4.4%)• Livestock might account for

approximately 66.4% of total NH i i

Tem

pe

25

photo: Public Domain / RJN2 NH3 emissions• Increased contribution from

industry ( 18.9%)Hour of day (CST)

30 May 2011 - 30 June 2011

0 5 10 15 2020

From Conventional PAS to QEPASQ>>1000

Laser beam, power P

Q>>1000

Cell is OPTIONAL!

V-effective volume

Absorption αModulated

SWAP RESONATING ELEMENT!!!

(P or λ) at for f/2

PiezoelectricVfPQS α~

Piezoelectric crystalResonant at f⎥

⎦

⎤⎢⎣

⎡ ×∆

α=

HzWcm-1

min

fPNNEA

quality factor Q⎦⎣∆ Hzf

Quartz Tuning Fork as a Resonant Microphone for QEPAS

Unique propertiesUnique properties• Extremely low internal losses:

Q~10 000 at 1 atmQ~100 000 in vacuumQ

• Acoustic quadrupole geometryLow sensitivity to external sound

• Large dynamic range (~106) – linear from h l i b kd d f ithermal noise to breakdown deformation

300K noise: x~10-11 cmBreakdown: x~10-2 cm

• Wide temperature range: from 1 6K to 700K• Wide temperature range: from 1.6K to ~700KAcoustic Micro-resonator (mR) tubes

• Optimum inner diameter:0.6 mm; mR-QTF i 25 50gap is 25-50 µm

• Optimum mR tubes must be ~ 4.4 mm long (~λ/4<l<λ/2 for sound at 32.8 kHz)

• SNR of QTF with mR tubes: ×30 (depending on gas composition and pressure)

Optimum NH3 Line Selection for a 10.34 µm CW TEC DFB QCL

9

%] 10 ppb NH3

5% CO2

Pressure = 130 Torr300

a.u.

] 2.5 ppm NH3 in N2

5% CO2, 1% H2O and residual NH3

6965.35 cm-1

n x

10-3 [% 5% H2O

967.35 cm-1

100

200 967.71 cm-1

CO2 line

Sig

nal [

a

3

Abs

orpt

ion

-200

-100

0

QE

PA

S

967.35 cm-1

964 965 966 967 9680A

Wavenumber [cm-1]1240 1220 1200 1180 1160 1140 1120

200

Current [mA]

P= 130 Torr NH3 line

Simulated HITRAN high resolution spectra @ 130 Torr indicating two NH3 absorption li f i t t

No overlap between NH3 and CO2 absorptionlines was observed for the selected 967.35 cm-1

NH b ti li i th R b dlines of interest NH3 absorption line in the ν2 R band.

QEPAS based NH3 Gas Sensor Architecture

Gas out Gas in

Pressure sensor port

Gas out Gas in

Pressure sensor port

Quartz TF withMicroresonatorTwo glass tubesOptical windows,

Ø10 mm

Quartz TF withMicroresonatorTwo glass tubesOptical windows,

Ø10 mm

Electrical feedthroughElectrical feedthrough

CW TEC DFB QCL in HHL package (Hamamatsu)

Real-time exhaled human NH3 Breath Measurements400

Pressure

250

300

350

n [p

pb]

Breath data from NH3 Rice sensor

Max NH3 concentration is: 351 ppb

8

10

12

150

200

250

atio

n [%

]e

[mba

r]

Pressure CO2

NH3

on [p

pb]

100

150

200

conc

entra

tio

2

4

6

50

100

150

O2 c

once

ntra

way

Pre

ssur

e

3 con

cnet

ratio

14:24:00 14:24:20 14:24:40 14:25:00 14:25:200

50NH

3

Time [HH:MM:SS]0 1000 2000 3000 4000

0

2

0

50

CO

Airw

Point [-]

NH

3

Successful testing of a 2nd generation breath

Time [HH:MM:SS]Airway pressure (black), CO2 (red), and NH3 (blue) profiles of a single breath exhalation lasting 40sec.

Successful testing of a 2nd generation breath ammonia monitor installed in a clinical environment.(Johns Hopkins, Baltimore, MD and St. Luke’s Hospital, Bethlehem, PA)

Minimum detectable concentration of NH3 is:~ 6 ppbv at 967.35 cm-1 (1σ; 1 s time resolution)

Motivation for Nitric Oxide Detection• Atmospheric Chemistry• Atmospheric Chemistry• Environmental pollutant gas monitoring

NO monitoring from automobile exhaust andNOX monitoring from automobile exhaust and power plant emissions Precursor of smog and acid rain

• Industrial process controlFormation of oxynitride gates in CMOS Devices

• NO in medicine and biologyImportant signaling molecule in physiological

i h d l (1998 N b lprocesses in humans and mammals (1998 Nobel Prize in Physiology/Medicine) Treatment of asthma, COPD, acute lung rejection, , g j

• Photofragmentation of nitro-based explosives

Molecular Absorption Spectra within two Mid-IR Atmospheric Windows and NO absorption @ 5.26µm

CO2: 4.2 µm

COS: 4.86 µm0.16

1ppm NO at 250 Torr, L=1 m

CO: 4.66 µm CH2O: 3.6 µm

CH4: 3.3 µm

COS: 4.86 µm

0.10

0.12

0.14

on [%

]

NO: 5.26 µm

3.1 µm5.5 µm 0.04

0.06

0.08

Abs

orpt

ioNH3: 10.6 µm O3: 10 µm

N20, CH4: 7.66 µm

1800 1850 1900 19500.00

0.02

Wavenumber [cm-1]Wavenumber [cm ]

12.5 µm 7.6 µm

Source: HITRAN 2000 database

Performance of a 5.26 µm CW HHL TEC DFB-QCL

MAXION _5.26 um DFB_QCL 20.5deg_603mA


MAXION 5 26 DFB QCL 20 5d 633 AMAXION _5.26 um DFB_QCL 20.5deg_633mA






MAXION _5.26 um DFB_QCL 20.5deg_723mA 708090

100110

ADM

(mW

)

T=19 °C T=20.5 °C






MAXION _5.26 um DFB_QCL 20.5deg_813mA 2030405060

pow

er a

fter A T=22 °C







189919001901190219031904

0 600 650 700 750 800 850 9000

10

Opt

ical

Current (mA)

Single frequency QCL radiation recorded with FTIR for different laser current values at a QCL temperature of 20.5oC.

CW DFB-QCL optical power and current tuningat three different temperatures.

1899 1900 1901 1902 1903 1904

Wavenumbers (cm-1)

Emission spectra of a 1900cm-1 TEC CW DFB QCL and HITRAN Simulated spectra p

20

20

16

20

%]

16

20

%]

8

12

orpt

ion

[%

8

12

orpt

ion

[%4

8

Abso

4

8

Abso

1895 1900 19050

Wavenumber [cm-1]P=1 atm, L=1m1895 1900 1905

0

Wavenumber [cm-1]P=1 atm, L=1m 100 ppm of NO 5% of H2O 5% of CO2 100 ppm of NO 5% of H2O 5% of CO2

Output power: 117 mW @ 25 C

CW TEC DFB QCL based QEPAS NO Gas Sensor

Schematic of a DFB-QCL based Gas Sensor.QPcL – plano-convex lens, Ph – pinhole, QTF – quartz tuning fork, mR – microresonator, RC- reference cell, P-elec D – pyro electric detector

Performance of CW DFB-QCL based WMS QEPAS NO Sensor Platform

0.1% NO at P=200 Torr, 5 cm ref. cell

100

]

95 ppb NO reference cylinderNO

6

8

10

nal [

a.u.

] 1ppm NO + 2.4% H2O, P= 240 Torr

100

200

nal [

a.u.

]

60

80

atio

n [p

pb] NO

0

2

4

AS 2

f sig

n

0

100

AS 3

f sig

n

20

40

O c

once

ntra

N2N2

900 890 880 870 860 850

-4

-2

QE

PA

Laser current [mA]

-100 QE

PA

13:37 13:40 13:43 13:46 13:49

0

NO

Time [HH:MM]

2f QEPAS signal amplitude for 95 ppb NO when DFB-QCL was locked to the 1900.08 cm-1 line.

Laser current [mA]

2f QEPAS signal (navy) and reference 3f signal (red) when DFB-QCL was tuned across 1900.08 cm-1 NO line.

[ ]

Minimum detectable NO concentration is: ~ 3 ppbv (1σ; 1 s time resolution)

Motivation for Carbon Monoxide Detection• Atmospheric Chemistry• Atmospheric Chemistry

Incomplete combustion of natural gas, fossil fuel and other carbon containing fuels.gImpact on atmospheric chemistry through its reaction with hydroxyl (OH) for troposphere ozone formation and changing the level of greenhouseformation and changing the level of greenhouse gases (e.g. CH4).

• Public HealthExtremely dangerous to human life even at a low concentrations. Therefore CO must be carefully monitored at low concentration levelsmonitored at low concentration levels.

• CO in medicine and biologyHypertension, neurodegenerations, heart failure andHypertension, neurodegenerations, heart failure and inflammation have been linked to abnormality in CO metabolism and function.

Performance of a NWU 4.61 µm high power CW TEC DFB QCL

12 T 10 oC

9

10

11

12 λ~4.6 µm DFB QCLcw operation

r(mW

)

V)

6007008009001000

2169.02169.62170.22170.82171.4

R6 CO linecm-1)

T=10 oC T=12.5 oC T=15 oC T=18 oC

6

7

8

T=12 5 oC Opt

ical

pow

er

Vol

tage

(V

200300400500600

T=10 oC

2166.62167.22167.82168.4

R6 CO line

Wav

enum

ber(

0 200 400 600 800 1000 1200

4

5

T=18 oC

T=12.5 CT=15 oC

O

Current (mA)

0100

500 600 700 800 900 1000 1100 1200 13002164.82165.42166.0W

Current (mA)

R5 CO line

CW DFB-QCL optical power and current tuning at a four different QCL temperatures.

1.5x10-5

n 200 ppb CO 2% H2O

x10-5

0.4 300 ppb N2O

0 30.60.91.2 R8R7

Abso

rptio R6R5

0.1

0.2

0.3

bsor

ptio

n Estimated max wall-plug efficiency (WPE) is ~ 7% at 1.25A QCL drive-current.

2166 2168 2170 2172 2174 21760.00.3A

Wavenumber (cm-1)

0.0

0.1

A drive current.

CW DFB-QCL based CO QEPAS Sensor Resultsx104

800900 P=760 Torr

b)

From cigarette

015304560 Modulation depth=50 mA

P=760 Torr

igna

l (C

nts)

with 2.6% H2O dry gas

500600700800

atio

n (p

pb

-30-15

-4500

450900

QEP

AS

Si

(a)

Pure Nitrogen

(b)

200300400500

once

ntra

2f QEPAS signal for dry (red) and moisturized (blue)5 ppm CO:N2 mixture near 2169.2 cm-1.

2169.1 2169.2 2169.3Wavenumber (cm-1)

x104

10:00 11:00 12:00 13:00 14:00 15:000

100200

CO

co

30

40

1.52.0

50 ppb

x104

nal (

Cnt

s)

x10

P=760 TorrModulation depth=40 mA

nal (

Cnt

s)

5000 ppb

Gas with 2.6% H2O

Time (HH:MM)

Minimum detectable CO concentration is:10

20

17:00 17:05 17:10 17:150.00.51.0

N2

50 ppb

QEP

AS

Sign

Time (HH:MM)

100 b250 ppb

500 ppb

1000 ppb

2500 ppb

QE

PA

S S

ign

Atmospheric CO concentration levels on Rice University campus, Houston, TX

Dilution of a 5 ppm CO reference gas mixture whenthe CW DFB-QCL is locked to the 2169.2 cm-1 R6 CO line.

Minimum detectable CO concentration is: ~ 2 ppbv (1σ; 1 s time resolution)17:00 17:20 17:40 18:00 18:20

0 N2N250 ppb 100 ppbQ

Time (HH:MM)

CW DFB-QCL based SO2 QEPAS Results M i i f S lf Di id D iMotivation for Sulfur Dioxide Detection• Prominent air pollutant• Emitted from coal fired power plants (~73%)and other industrial facilities (~20%)

• In atmosphere SO2 converts to sulfuric acidprimary contributors to acid rain

• SO2 reacts to form sulfate aerosols• Primary SO2 exposure for 1 hour is 75 ppb

SO ff l d b hi• SO2 exposure affects lungs and causes breathingdifficulties•Currently, reported annual average atmospheric SO2concentrations range from ~ 1 - 6 ppb

7.24 µm CW DFB-QCL optical power and current tuning at three different operating temperatures.

2f WMS QEPAS signals for different SO2 concentrations when laser was tuned across 1380.9 cm-1 line.

Minimum detectable SO2 concentration is: ~ 100 ppbv (1σ; 1 s time resolution)Molecular Absorption Spectra within two Mid-IR Atmospheric Windows

QCL based QEPAS Performance for10 Trace Gas Species (May 2013)p ( y )

Molecule (carrier gas)

Frequency cm-1

Pressure Torr

NNEA cm-1W/Hz½

QCL Power mW

NEC (τ=1s)ppbV

CH2O (N2:75% RH)* 2804.90 75 8.7×10-9 7.2 120

CO (N2+ 2 2% H2O)* 2176 28 100 1 57×10-8 71 2CO (N2+ 2.2% H2O) 2176.28 100 1.57×10 71 2

CO (propylene) 2196.66 50 7.4×10-8 6.5 140

N2O (air+5%SF6) 2195.63 50 1.5×10-8 19 7

N2O (N2+2.37%H2O) 2201.75 200 2.9×10-8 70 2.5

C2H5OH (N2)** 1934.2 770 2.2×10-7 10 9x104

NO (N2+H2O) 1900.07 250 7.5×10-9 100 3.6

SO2 (N2+2.4%H2O) 1380.94 100 2.0×10-8 40 100 8N2O (air) 1275.49 230 5.3×10-8 100 30

CH4 (air) 1275.39 230 1.7×10-7 100 118

C2HF5 (N2)*** 1208.62 770 7.8×10-9 6.6 9

NH3 (N2)* 1046.39 110 1.6×10-8 20 6

* - Improved microresonator ** - Improved microresonator and double optical pass through ADM *** - With amplitude modulation and metal microresonator

3 ( )

SF6*** 943.73 75 2.7×10-10 40 5×10-2

p

NNEA – normalized noise equivalent absorption coefficient. NEC – noise equivalent concentration for available laser power and τ=1s time constant, 18 dB/oct filter slope.

For comparison: conventional PAS 2.2 (2.6)×10-9 cm-1W/√Hz (1,800; 10,300 Hz) for NH3*, (**)

* M. E. Webber et al, Appl. Opt. 42, 2119-2126 (2003); ** J. S. Pilgrim et al, SAE Intl. ICES 2007-01-3152; *** - V. Spagnolo, et al. University and Politecnico of Bari, Italy

Merits of QEPAS based Trace Gas Detection• Very small sensing module and sample volume (a few mm3 to ~2cm2)y g p ( )• Extremely low dissipative losses• Optical detector is not required• Wide dynamic range• Wide dynamic range• Frequency and spatial selectivity of acoustic signals• Rugged transducer – quartz monocrystal; can operate in a wide range of

d t tpressures and temperatures• Immune to environmental acoustic noise, sensitivity is limited by the

fundamental thermal TF noise: kBT energy in the TF symmetric modeAb f l f i SNR l √ t 3 h• Absence of low-frequency noise: SNR scales as √t, up to t=3 hours as experimentally verified

QEPAS: some challenges C t f S t h bl• Cost of Spectrophone assembly

• Sensitivity scales with laser power• Effect of H2O• Responsivity depends on the speed of sound and molecular energy

transfer processes• Cross sensitivity issues

Potential Integration of a CW DFB- QCL and QEPAS Absorption Detection Module

2012 QEPAS ADM HHL package fiber coupled DFB-QCL

A. Lyakh, et al “1.6 W high wall plug efficiency, continuous-wave room temperature quantum cascade laser emitting at 4.6 µm”, Appl. Phys. Lett. 92, 111110 (2008)

Hollow core waveguideCoating

GlassAgAgI300 µm

b))

QCL-fiber beam profile and losses

HWGHWG FiberFiber withwithHWG HWG FiberFiber with with 300 µm bore 300 µm bore sizesize

allowsallows single mode single mode beam delivery @ beam delivery @

10,5 µm10,5 µm

λλ 10 510 5 Bore Size 300 µm

Straight L

1 dB/m

λλ = 8,7 µm= 8,7 µmλλ = 10,5 µm= 10,5 µm

LossesBending Losses

0,1 dB/m

λλ = 10,5 µm= 10,5 µmλλ 10,5 µm 10,5 µm

Future Directions and Outlook

• New target analytes such as carbonyl sulfide (OCS), formaldehyde (CH2O), nitrous acid (HNO ) h d id (H O ) th l(HNO2), hydrogen peroxide (H2O2), ethylene (C2H4), ozone (O3), nitrate (NO3), propane (C H ) and benzene (C H )(C3H8), and benzene (C6H6)

• Ultra-compact, low cost, robust sensors (e.g. C2H6, NO, CO……)C2H6, NO, CO……)

• Monitoring of broadband absorbers: acetone (C3H6O), acetone peroxide (TATP) , UF6……( 3 6 ), p ( ) , 6

• Optical power build-up cavity designs• Development of trace gas sensor networksDevelopment of trace gas sensor networks

Mid- IR and THz Ring Cavity Surface Emitting QCLs

(a) Two-dimensional far-field plot emanating from a MIR RCSE QCL and recorded with afrom a MIR RCSE-QCL and recorded with a micro-bolometer camera in a distance of 40 mm. (b) Polarization dependent intensity measurement.

(a) Three-dimensional illustration of a ring cavity surface emitting laser. (b) Scanning electron microscopy image of a processed MIRelectron microscopy image of a processed MIR device. Close-up of a (c) MIR and (d) a THz waveguide section holding second order gratings.

Summary

• Laser spectroscopy with a mid-infrared, room temperature, continuous wave, DFB laser diodes and high performance DFB QCL is a promising analytical approach for real time atmospheric measurements and breath analysis.

• Six infrared semiconductor lasers from Nanoplus, Daylight Solutions, MaxionTechnologies (PSI), Hamamatsu, Northwestern University and AdtechOptics were used recently (2011-2012) by means of TDLAS, PAS and QEPAS

• Seven target trace gas species were detected with a 1 sec sampling time:C2H6 at ~ 3.36 µm with a detection sensitivity of 130 pptv using TDLAS2 6 µ y pp gNH3 at ~ 10.4 µm with a detection sensitivity of ~1 ppbv (200 sec averaging time);NO at ~5.26µm with a detection limit of 3 ppbvCO at ~ 4.61µm with minimum detection limit of 2 ppbvSO2 at ~7.24µm with a detection limit of 100 ppbvSO2 at 7.24µm with a detection limit of 100 ppbvCH4 and N2O at ~7.28 µm currently in progress with detection limits of 20 and 7 ppbv, respectively.

• New target analytes such as OCS, CH2O, HONO, H2O2, C2H4, • Monitoring of broadband absorbers such as acetone C3H8 C6H6 and UF6Monitoring of broadband absorbers such as acetone, C3H8, C6H6 and UF6• Compact, robust sensitive and selective single frequency, mid-infrared sensor

technology that is capable of performing precise, accurate and autonomous concentration measurements of trace gases relevant in environmental, biomedical, industrial monitoring and national security.

mid-infrared semiconductor laser based trace gas ... · innovative long path, small volume...

Documents