Optical parametric oscillators in a match box - Onera

Optical parametric oscillators 

in a match box 

M. Raybaut , B. Hardy, V. Faivre, J.B. Dherbecourt, 

A. Godard, J.M. Melkonian, M. Lefebvre 

DMPH / SLM

ONERA/DMPH/SLM - 2011- OPOs in a mtchbox 

2/ / 37 

OUTLINE 

• Context 

• Single frequency doubly-resonant OPO : 

• from the baseline set-up … 

• to the latest design 

• Applications : 

• Local and short range sensing 

• Long range sensing 

• OPO integration 

• Perspectives


Transmission 

3/ / 37 

Context 

OH 

PH3 

1 2 3 4 5 6 7 8 

Wavelength [µm] 

9 10 1 2 3 4 5 6 7 8 

Wavelength [µm] 

9 10 

Need: 

NO 

CO 

SO2 

HCl 

H2CO 

H2O 

CH4 

C2H2 

H2O2 

HCH3C 

HF 

HOCl 

Transmission 

Broadly tunable, pulsed, compact, laser sources able to provide multiple wavelengths at 

preselected values 

N2O 

CO2 

C2H6 

NO2 

O2 

ClO 

HBR 

HCN 

HI 

NH3 

O3 

OCS


• Energy conservation 

• Phase matching 

• Energy transfer : function of the relative phase 

4/ / 37 

Context 

Our approach : frequency conversion of a pump laser to the mid - IR 

Pump 

ω p 

χ (2) 

Nanosecond optical parametric oscillation : 

• Issue : wide spectral bandwidth 

• Our goals : 

Signal 

Depleted pump 

Idler 

ω c 

ω s 

Δϕ = ϕ p -ϕ s -ϕ c 

• to achieve SLM operation, to tune and lock the source on demand 

(computer control) 

• with a compact & robust set-up 

• and a low threshold (micro-laser pumping)


5/ / 37 

OUTLINE 

• Context 








• Perspectives


6/ / 37 

Baseline « ECOPO » cavity 

SLM operation : “Entangled Cavities DROPO” design 

ω p 

M1 

ω i 

M2 M3 

ω s 

PZT i PZT s 

• SLM, Narrow linewidth (Fourier transformed limited) 

• Short cavities (10-20mm) 

• Narrow PGB 

• Dissociation : 

M4 

ΔL/L ~ 5 % 

• Low threshold of oscillation ( few µJ ) 

ω i 

Parametric Gain Bandwidth 

Single longitudinal mode emission 

• Tuning principle : synchronous adjustment of signal and idler cavities 

ω s


7/ / 37 

Baseline ECOPO cavity 

« ECOPO - Extremely Carcinogen OPO » 

0,0 

0 2 4 6 8 10 12 14 16 18 20 22 

Main limitation : 

Tuning capability : manual tuning 1GHz only 

Imperfect coatings => parasitic Fabry-Perot cavities 

Idler energy [µJ] 

0,8 

0,7 

0,6 

0,5 

0,4 

0,3 

0,2 

0,1 

λ c = 3,8 µm 

λ c = 4,2 µm 

λ c = 4,3 µm 

Pump energy [µJ]


8/ / 37 

Double pump pass 5 mirrors ECOPO : the phase 

solution 

• Tuning limitation due to parasitic Fabry-Perot cavities 

• Solution : Phase-maintained double pump pass configuration (patented design) 

ω p 

M1 

ω i 

M2 M3 

ω s 

M4 

PZT i PZT s 

DROPO threshold (a.u.) 

12 

10 

8 

6 

4 

2 

M5 

PZT p 

Rp = 0 

Rp = 30% 

Rp = 80% 

0 

-1,0 -0,5 0,0 

Δν [cm s 

0,5 1,0 

-1 ] 

OPO efficiency 

1.0 

0.8 

0.6 

0.4 

0.2 

(a) 

0.0 

-10 -5 0 5 10 

δν s [cm -1 ] 

3 4 

R = 1% R = 1.5% 

p p 

R 

5 

p 

= 80%


9/ / 37 

Double pump pass 5 mirrors ECOPO 

Baby-shoe box OPO Baby-boot box ECOPO


10/ 10/ 

37 

5 mirrors ECOPO : A “frequency synthesizer” 

High Side Mode Suppression Ratio > 40 dB 

Power [dBm] 

-40 

-60 

-80 

1472.0 1472.5 1473.0 1473.5 1474.0 

Wavelength [nm] 

• Automated, computer controlled tuning and locking procedure 

• Wide tuning / high frequency stability 

• SLM operation – high resolution spectroscopy experiments on various green 

house gases 

• Low threshold of oscillation ( few µJ ) – microlaser pumping possible 

A. Berrou, et al., Appl Phys B, 2010 

PPLN, 3.8-4.2µm 

Signal Frequency [THz] 

207.32553 

207.32552 

207.32551 

207.32550 

207.32549 

207.32548 

207.32547 

0 20 40 60 80 

Frequency locking ±3 MHz @ 1.44 µm


11/ 11/ 

37 

3 mirrors NESCOPO cavity 

Our goal : DROPO integration in portable sensing instruments 

• Improved compacity 

• Improved mechanical stability 

• More simple tuning procedure 

ω p 

M1 

M2 

ω i 

ω s 

Gold coating 

M3 

PZT i PZT s 

New 3 mirrors DROPO cavity 

(patented design) 

NESted Cavity OPO 

« NESCOPO »


12/ 12/ 

37 

NESCOPO cavity 

ω p 

M1 

M2 

ω i 

ω s 


M3 

PZT i PZT s 

Within a simple package – as simple as a 

SROPO cavity : 

• Entangled cavities + 2 PZT actuators 

• Single mode operation, tunability 

• Within a package as simple as a SROPO 

• High finesse signal cavity 

• Narrow linewidth 

• Double pass for the pump 

• Low threshold 

• Ultra low threshold (~ 1µJ) : type 0 

PPLN/PPLT crystal 

• Near degeneracy set-up : type II PPLN crystal


ω p 

13/ 13/ 

37 

NESCOPO cavity : phase engineering 

M1 

M2 

ω i 

ω s 

PZT i PZT s 

Normalized threshold ratio 

1 

0.8 

0.6 

0.4 

0.2 

0 

PPLT 

+d -d +d 


M3 

-3 -2 -1 0 1 2 3 

DkLê2 

• Only one internal mirror 

• Less parasitic Fabry-Perot cavities 

• Gold coated rear mirror M3 

• Achromatic set-up 

• Wedged crystal 

⎯ single pump pass DROPO 

⎯ double pump pass DROPO, Δϕ’ = 0 

⎯ double pump pass DROPO, Δϕ’ = pi/2 

⎯ double pump pass DROPO, Δϕ’ = pi 

• Relative phase adjustment : 0 to Pi 

• Achromatic set-up : wedge adjusted once 

• Control of the PGB shape 

Wedge (∆φ) adjustment Experimental parametric 

gain bandwidth function of 

prism position


14/ 14/ 

37 


COPO 

«NESted Cavity OPO» 

COPO


15/ 15/ 

37 


Fibered microlaser pumping : Teem Photonics (SLM, 6 µJ) 

NESCOPO threshold ~1 µJ 

3.8-4.2 µm, SLM 

Duplicable in the whole mid-IR 

Rmax 1,06 µm 

Tmax 1,5 µm 

1,5µm 

Vers 

wavemeter 

1,06µm 

Sortie fibre 

micro-laser 

+ collimateur 

λ/2 

lentille 

Micro-laser fibré 

DROPO 

4,2µm 

COPO


16/ 16/ 

37 

OUTLINE 

• Context 








• Perspectives


17/ 17/ 

37 

NESCOPO - Fine frequency tuning 

ω p 

M1 

M2 

ω i 

ω s 

PZT i PZT s+i 

M3 

ω i 

δL 

Parametric gain bandwidth 

i 

⎛ ω ⎞ s i 

= − ⎜1+ ⎟δ 

⎝ ωi 

s ⎠ L 

L 

L 

M3 

ω s

Gas cell 


18/ 18/ 

37 

Local sensing measurements 

ECOPO 

IR 

detector 

Reference 

Transmission 

Mesure Théorie 

Transmission 


1.0 

0.5 

0.0 

1.0 

0.5 

0.0 

1.0 

0.9 

1.0 

0.9 

Gas cell absorption spectra of various green house gases 

recorded using a single ECOPO device 

N 2 O 10 hPa CO 2 10 hPa 

3895 3900 3905 3910 3915 

Longueur d'onde [nm] 

3975 3980 3985 3990 3995 4000 


Transmission 

Théorie 

Mesure 

Transmission 

Mesure Theory 

1.0 

0.5 

0.0 

1.0 

0.5 

0.0 

1.0 

0.9 

0.8 

1.0 

0.9 

0.8 

4185 4190 4195 4200 


SO 2 50 hPa CH 4 20 hPa 

3815 3820 3825 3830 3835 

Longueur d'onde [nm]

Photoacoustic cell 


19/ 19/ 

37 


ECOPO 

IR detector 

(reference) 

Signal photoacoustique [u.a.] 

10 

5 

0 

ECOPO + a direct absorption or a photoacoustic detection scheme 

Applications : 

• Security, manufacturing process monitoring 

• Motor emissions characterizations 

Design goal : 

• High resolution spectra (

Photoacoustic cell 


20/ 20/ 

37 


NESCOPO 

IR detector 

(reference) 

Current technology transfert towards Blue Industry and Science 

Applications : 

• Gas sensing for air quality monitoring in public buildings 

Design goal : 

• Ppm/ ppb level detection limit for main pollutants


Multi-λ operation by Vernier frequency sampling 

Principle 

ω i ω i 

21/ 21/ 

37 

T (%) 

M1 

M2 

λon1 

λon4 

λon3 

λon2 

λoff 

M3 

λ 

ω s 

“Vernier frequency 

Sampling” 

Sequences of frequencies 

with adjustable resolution & span


22/ 22/ 

37 

Configurable mode-hop patterns: examples 

PZT ajustement 

(1 cavity-length sinusoïdal modulation) 

ω p 

PZT 

T 

Temperature 

ajustement 

PZT 

2 cavity-length modifications 

Parametric gain displacement 

Frequency (GHz) 

Signal frequency (GHz) 

204800 

204700 

204600 

204500 

204400 

0 25 50 

Time (s) 

75 100 

204800 

204600 

204400 

204200 

204000 

203800 

203600 

203400 

0.5 cm -1 

60 65 70 75 80 85 90 95 

Crystal temperature (°C) 

40 cm -1


Intensity (a.u.) 

23/ 23/ 

37 

Short range multi-λ DIAL demonstration 

CO 2 detection in the atmosphere @ 4.2 µm 

• Short time CO 2 measurement (< 20 s, demonstration experiment) 

• Short range detection experiment : up to 30m 

1.0 

0.8 

0.6 

0.4 

0.2 

Experiment 

Hitran calculation 

0.0 

2384 2386 2388 2390 

Wavenumber (cm -1 ) 

µLaser 

+ 

ECOPO 

CaF2 prism 

Ref. 

MCT 

Wall diffusion 

Emission 

optics 

Reception 

optics 

LIDAR LIDAR LIDAR 

MCT MCT MCT


24/ 24/ 

37 

Long range LIDAR : ex. of specifications 

Main species 

of interest 

λ ON 

λ OFF 

2-λ IP-DIAL for probing the 

lower troposphere 

Species 

CO2 

CH4 

H20 

N2O 

O2 

λ λ (µm) 

1.57 / 2.05 

1.64 / 2.29 

0.935 / 0.942 

3.93 

0.764 

λ1 (frequency locking) 

λ 2 

λ 3 

multi-λ IP-DIAL 

λ OFF 

Courtesy of ESA/ESTEC 

H 2 0 

λ 2 

= 935.5611 

λ 1 

λ OFF 

= 935.6845 

λ 3 

= 935.9065 

multi-λ DIAL for probing different 

atmospheric layers (WALES study) 

Writh et al Appl. Phys B, 96 (2009)


25/ 25/ 

37 

Long range LIDAR : 2µm transmitter design 

• MOPA architecture 

• ECOPO (Master Oscillator) 

• Spectral performances 

• Spatial performances 

• Type II PPLN crystal 

(close to degeneracy) 

• Amplifiers (Power Amplifier) 

• High output energy 

• Frequency measurement : 

• Wavemeter 

• Frequency tuning 

and locking : 

• Special electronics control box 

Work funded through contract 19813, 

"Pulsed Laser Source in NIR for Lidar Applications", 

within the Technology Research Programme 

of the European Space Agency (ESA). 

DROPO 

Pump 

(1mJ) 

Type II 

ppLN 

DROPO 

10ns delayed 

OPA pump 

ω i 

Type 0 ppLN 

preamplifier 

ω i 

ω p 

ω s 

4 stages KTP 

amplifier


26/ 26/ 

37 

Long range LIDAR : 2µm transmitter performances 

SHG Frequency (THz) 

292,515720 

292,515700 

292,515680 

292,515660 

12 mJ @ 2050 nm 

Standard dev. 30s : < 3MHz 

@ 2050 nm 

0 10 20 30 

t (s) 

146,25786 

146,25785 

146,25784 

146,25783 

Short scale frequency fluctuations : 

< 3MHz rms over 30s 

(Pump dithering : +/- 6MHz) 

Signal Frequency (THz) 

40 

50 

60 

70 

80 

90 

100 

Signal beam 

(amplifier output) 

20 30 40 50 60 70 80 

M 2 < 1.9 

Already fully compliant with a CO2 

measurement 


M. Raybaut, et al., 

CLEO 2011, Baltimore


27/ 27/ 

37 

NESCOPO : overview 

Take advantage of the special properties of the NESCOPO design : 

• Dual cavity & Phase control 

• Wide tuning 

• & Frequency stability : a real « frequency synthetizer » 

• Continuous or mode-hops tuning for gas species detection 

demonstration of local or remote sensing capabilities 

• The latest design can be readily integrated 

into a micro-source 

portable devices 

high robustness 

Intensity [dBm] 

-40 

-50 

-60 

-70 

-80 


1464 1465 1466 1467 1468 

Wavelength [nm]


28/ 28/ 

37 

OUTLINE 

• Context 








• Conclusion & perspectives


29/ 29/ 

37 

OPO integration 

For another application (not gas sensing) 

Development of a compact ns frequency conversion module (FCM) 

• Collaboration with Sagem DS 

• Mechanical conception of the FCM 

with 

• special attention on compactness 

• simplicity 

• integration capabilities 

• Rugged optomechanical design with 

• a reduced number of components 

• self alignment of most of the optical 

components 

• high alignment stability


30/ 30/ 

37 


Adjustment free SROPO (UV light-curing) 

This work is supported by grants 

from Region Ile de France


31/ 31/ 

37 


Adjustment free SROPO 

Next step : adjustment free NESCOPO 

This work is supported by grants 

from Region Ile de France


32/ 32/ 

37 

OUTLINE 

• Context 








• Perspectives


33/ 33/ 

37 

Perspectives 

• NESCOPO miniaturisation 

• Miniature local gas sensing systems 

• Remote detection 

• Atmospheric pollutants : air-borne / space-borne multi-species 

LIDAR systems 

• Industrial pollutants : portable multi-species LIDAR systems 

• New non linear materials for > 6 µm 

• Defense & security : remote detection of contaminants or 

precursors


34/ 34/ 

37 

Insight : New non linear materials for > 6 µm 

• New phase matching schemes : ZnSe, GaAs … 

• Synthesis + growth of AgGaSe2 

• Growth of ZGP 

Onera/DMSC (J. Petit) 

Onera/DMPH


Transmission 


Transmission 


1.0 

0.5 

0.0 

1.0 

0.5 

35/ 35/ 

37 

Road map for gas sensing systems 

0.0 

3895 3900 3905 3910 3915 


1.0 

0.9 

1.0 

0.9 

Détection locale, 

quelques ppm, multi-gaz 

N 2 O 10 hPa CO 2 10 hPa 

3975 3980 3985 3990 3995 4000 


Transmission 


Transmission 

Mesure Theory 

1.0 

0.5 

0.0 

1.0 

0.5 

0.0 

1.0 

0.9 

0.8 

1.0 

0.9 

0.8 

4185 4190 4195 4200 


SO 2 50 hPa CH 4 20 hPa 

>100 cm 3 OPO seul 


36/ 36/ 

37 

Ackowledgements 

• Current and previous DMPH and DMPH SLM members 

• especially for the OPO developments 

• J.B. Dherbecourt, J. P. Faleni, A. Godard, J.M. Melkonian, M. Raybaut, T. Schmid 

• Post grad. & PhD students : M. Barbier, V. Faivre, B. Hardy, C. Laporte 

• Past team members & PhD students (since 2000) 

• DROPO : A. Berrou, A. Desormeaux, I. Ribet, B. Scherrer, C. Drag 

• Other NLO developments : F. Boitier, N. Forget, R. Haidar, A. Mustelier, C. 

Ventalon, Ph Kupecek 

• M. Lefebvre (now head of DMPH/SLM) 

• E. Rosencher (now Onera chief scientist, head of DMPH/SLM in 2000) 

• Private companies and agencies who contributed to, funded and/or 

are funding our various developments & students 

• Agilite, ANR, ANR-Carnot, Blue Industry and Science, CNES, DGA, DGAC, ESA, 

Région île de France, SAGEM DS, Triangle de la Physique, UE, … & Onera


Special ackowledgement 

37/ 37/ 

37

Optical parametric oscillators in a match box - Onera

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