MIDASMIDAS : Multiplexed infrared diodes forMIDAS : Multiplexed infrared diodes forMIDAS : Multiplexed infrared diodes for pabsorption spectroscopyabsorption spectroscopyabsorption spectroscopyp p pyP2N 2011P2N 2011P2N 2011P2N 2011

B Adelin A Monmayrant G Almuneau F Lozes Dupuy O Gauthier Lafaye LAAS CNRS ToulouseB. Adelin, A. Monmayrant, G. Almuneau, F. Lozes-Dupuy , O. Gauthier-Lafaye LAAS-CNRS, ToulouseYves Rouillard Guilhem Boissier Michael Bahriz A Vicet IES MontpellierYves Rouillard, Guilhem Boissier , Michael Bahriz, A. Vicet IES Montpellier

Moti ationsMotivationsMotivationsThe mid IR wavelength range extending from 2 to 5 µm exhibits several transparency windows (around 2 3 µm and from

5 4.5 4 3.5 3 2.5 2

The mid-IR wavelength range extending from 2 to 5 µm exhibits several transparency windows (around 2.3 µm and from1E-22

1E-24

3.4 to 4 µm) where absorption by water vapor and carbon dioxide is very weak. In these regions, the detection of other 1E-20

1E-22

µ ) p y p y ggaseous molecules in the atmosphere can be carried out without interferences. Absorption lines of gaseous molecules are

1E-18

gaseous molecules in the atmosphere can be carried out without interferences. Absorption lines of gaseous molecules aremore intense at high wavelengths For example CH absorption at 3 26 µm is a factor of 40 stronger than at 2 31 µm and

H2OCO2more intense at high wavelengths. For example, CH4 absorption at 3.26 µm is a factor of 40 stronger than at 2.31 µm and

200 ti t th t 1 65 A th 2 5 i f h i f t It i CO2

200 times stronger than at 1.65 µm. As a consequence, the 2-5 µm range is a range of choice for spectroscopy. It givesaccess to many applications going from pollutants detection in the neighborhood of industries or vehicles (CH4, CO, CO2,y pp g g p g ( 4, , 2,HCl) control of industrial processes (NH HF) isotopic ratio measurement of water (HDO/H O) for paleoclimatilogy or toolHCl), control of industrial processes (NH3, HF), isotopic ratio measurement of water (HDO/H2O) for paleoclimatilogy or toolfor medical diagnostic (CO ) For these applications the s al approach is t nable diode laser absorption spectroscopfor medical diagnostic (CO2). For these applications, the usual approach is tunable diode laser absorption spectroscopy(TDLAS) that requires one single-frequency tunable laser covering the entire range of interest. TDLAS has proven( ) q g q y g g pextremely efficient in many wavelength regions and many laser developments have been driven by that sole applicationextremely efficient in many wavelength regions, and many laser developments have been driven by that sole application.However in the 2 5 µm range developing a laser source fulfilling all the requirements of TDLAS remains a challenge It isHowever, in the 2-5 µm range, developing a laser source fulfilling all the requirements of TDLAS remains a challenge. It is

i ll h d t bt i b th t bl i l d i i d id h t bilit Hespecially hard to obtain both stable single-mode emission and a wide enough tunability range. Here, we propose an Figure 1 Absorption lines strength from 2 to 5 µmAbsorption lines strength from 2 to 5 µmalternative that relies on an array of tunable single-frequency lasers with emission wavelengths evenly spread across the

Figure 1. Absorption lines strength from 2 to 5 µm. (HITRAN 96 d t b [1])

Absorption lines strength from 2 to 5 µm (from HITRAN database)alternative that relies on an array of tunable single frequency lasers with emission wavelengths evenly spread across the

range of interest This method of multiplexed tunable diode laser absorption spectroscopy (MTDLAS) will grant access to a(HITRAN 96 database[1]) (from HITRAN database)

range of interest. This method of multiplexed tunable diode laser absorption spectroscopy (MTDLAS) will grant access to aid t l b bi i l l ff i di t i It i th f thi j t t d lwide spectral range by combining several lasers offering medium tuning ranges. It is the purpose of this project to develop 15

such an integrated array. 10m)g y

To realize this array we plan to use an optimization scheme for all photonic crystal 2nd order DFB lasers [Larrue PTL 2008 n lin

e (n

m

Laser 1

Laser 2To realize this array, we plan to use an optimization scheme for all photonic crystal 2nd order DFB lasers [Larrue PTL 2008,Larrue JSTQE 2011] combining an affine deformation of the PhC with a waveguide width fine tuning This optimization

5

sorp

tion

Laser 2

Laser 3

Larrue JSTQE 2011], combining an affine deformation of the PhC with a waveguide width fine tuning. This optimization0

th /

Abs Laser 4

Laser 5

scheme has already been used on GaAs optically pumped lasers to demonstrate the fabrication of arrays of single-mode5av

elen

gt

Laser 6

Laser 7y p y p p y glasers the fabrication of arrays with closely spaced emission wavelengths Furthermore it allowed the fabrication of single-

-5

ssio

n W

a Laser 7

Laser 8

L 9lasers, the fabrication of arrays with closely spaced emission wavelengths. Furthermore, it allowed the fabrication of singlemode laser array with high robustness towards optical feedback 3D FDTD Simulations of infinitely long defect PhC

-10Emis Laser 9

Laser 10

mode laser array with high robustness towards optical feedback. 3D FDTD Simulations of infinitely long defect PhCid h th l ti f DFB d ti f ti f b th d i t l d f t d ffi

-15

Laser 11

waveguides show the evolution of DFB modes properties as a function of both design parameters namely defect and affine 0 2 4 6 8 10 12

Laser number

deformations. As shown on figure 5 quality factors in excess of 600 000 can be theoretically achieved for the 1st DFBLaser number

P i i l f ideformations. As shown on figure 5 quality factors in excess of 600 000 can be theoretically achieved for the 1st DFBmode while keeping the quality factor of the 2nd DFB mode one order of magnitude lower This ensures both low losses

Principle of spectrometry using a mode, while keeping the quality factor of the 2nd DFB mode one order of magnitude lower. This ensures both low lossesf th 1 t DFB d d hi h d l l ti lti i t bl b t i l d i i th 1 t DFB d

single mode lasers arrayfor the 1st DFB mode and a high modal selection resulting in stable, robust single-mode emission on the 1st DFB mode.More interestingly, this high Q area corresponds to a smooth area for emission reduced frequency, so lasers arrays withg y, g p q y, yboth high Q and smooth wavelength variations from laser to laser can be designedboth high Q and smooth wavelength variations from laser to laser can be designed.

First Res ltsFirst ResultsFirst Results

Laser structures for λ = 3 3 µm emissionLaser structures for λ = 3.3 µm emissionµX ray diffractionTh l t t b d th G Sb V1732 V1732

1.E+06Band Band diagramdiagram: X ray diffractionV1732-1280-15 PI-v1732-0980-08The laser structures are based on the GaSb

1.8 Al0.90Ga0.10As0.07Sb0.93cladding n+

Al0.90Ga0.10As0.07Sb0.93cladding p+

1 E+05Al0.25Ga0.51In0.24As0.22Sb0.78

D / +0 26 10 3

GaSb450

0.25295 K, 0.2 %technology which is the only semiconductor

1 3

1.E+05

-1)

Da/a = +0.26 x 10-3

Ga0 45In0 55As0 27Sb0 73 350

400 22°C, D.C.=0.2 %, P.W.=0.2 µs0.20 ith = 833 mA

Jth = 850 A/cm²

gy ytechnology covering the whole mid-IR 1.3

Al0.25Ga0.45In0.24As0.22Sb0.78di i l id

1.E+04

(cts

.s- Ga0.45In0.55As0.27Sb0.73

Da/a = +1.53 x 10-2 300

350

a.u.

) Lambda Peak = 3.28 µm0.15

Jth 850 A/cmtechnology covering the whole mid-IR wavelength range GaInAsSb/AlGa(In)AsSb 0.8

digital w aveguide

1.E+03nsity

(

200

250

sity

(a

0.15

P (m

W)

Jth = 850 A/cm²wavelength range. GaInAsSb/AlGa(In)AsSb

0 3 Ga0 45In0 55As0 29Sb0 71

Inte

n

100

150

200

Inte

n 0.10

P th /quantum well structures are grown by

0.3 Ga0.45In0.55As0.29Sb0.713 w ells 9.3 nm 1.E+02

50

1000.05 T0 ~ 30 K

q g ymolecular-beam epitaxy at IES (Institut

-0.21.5 µm 1.5 µm

1.E+010

3 3 1 3 2 3 3 3 4 3 5 0.00

molecular beam epitaxy at IES (Institutd’Electronique du Sud UMR CNRS 5214) in

-0.70.65 µm

µ28.80 29.30 29.80 30.30 30.80

Omega (°)

3 3.1 3.2 3.3 3.4 3.5

Wavelength (µm)0 500 1000 1500 2000 2500 3000 3500 4000

i (mA)d Electronique du Sud, UMR CNRS 5214), in M t lli U i it

QW d id d f di it l ll

0.7

Li hLi h (( l dl d 2222°°C)C)

( )

Strain less waveguide of quinary materialMontpellier UniversityQWs and waveguide made of digital alloys Light Light currentcurrent curvescurves ((pulsedpulsed, 22, 22°°C)C)Optical Optical emissionemission spectrumspectrum ((pulsedpulsed, 22, 22°°C)C)

Strain less waveguide of quinary material

W id d i d f b i tiWaveguides design and fabricationWaveguides design and fabricationF l t i l i l id f d d t W3 id l d d t t d d ti l iFor electrical pumping, large waveguides are prefered as compared to W3 waveguides already demonstrated under optical pumping.Theoretical investigations are then carried out to optimize W5 waveguides.g p gIn parallel investigations are ongoing to check the feasability of trenches based W5 waveguides since this kind of features are easier to fabricateIn parallel, investigations are ongoing to check the feasability of trenches based W5 waveguides, since this kind of features are easier to fabricate.

W5 waveguides with air holes : FDTD Q factor determintation with large modal selectivityW5 waveguides with air holes : FDTD Q factor determintation, with large modal selectivity.SEM i f d l t h d H l l tti f t h fi t li ti i G ASEM image of deeply etched Hexagonal lattice of trenches : first realisation in GaAs

Bibli h d k l d tair hole in GaAs

Bibliography and acknowledgementsBibliography and acknowledgements

[Larrue PTL 2008] : A. Larrue et al., Precise frequency spacing in photonic crystal DFB laser arrays, IEEE Phot. Tech. Lett., 20 (24), pp 2120-2122, 2008.[Larrue PTL 2008] : A. Larrue et al., Precise frequency spacing in photonic crystal DFB laser arrays, IEEE Phot. Tech. Lett., 20 (24), pp 2120 2122, 2008.[ Larrue JSTQE 2011] : A Larrue& al All photonic crystal DFB lasers robust towards optical feedback IEEE JSTQE 17 pp1236 (2011)[ Larrue JSTQE 2011] : A. Larrue& al., All photonic crystal DFB lasers robust towards optical feedback, IEEE JSTQE, 17, pp1236 (2011)A k l d t FDTD l l ti i d t i MEEP ft f MIT CALMIP l tAcknowledgments : FDTD calculations are carried out using MEEP software from MIT, on CALMIP cluster

CONTACT :CONTACT :xxx@xxx frOlivier Gauthier-LafayeOlivier Gauthier-Lafayexxx@xxx.frOlivier Gauthier-LafayeOlivier Gauthier-Lafaye

LAAS-CNRS, 7 avenue du colonel roche, 31077 LAAS-CNRS, 7 avenue du colonel roche, 31077 Toulouse Cedex 4Toulouse Cedex 4

li i thi l f @l fli i thi l f @l folivier.gauthier-lafaue@laas.frolivier.gauthier-lafaue@laas.fr

Journées Nationales en Nanosciences et Nanotechnologies 2012Journées Nationales en Nanosciences et Nanotechnologies 2012g