CO 2 Remote Detection Using a 2-µm DIAL Instrument Erwan Cadiou 1,2, Dominique Mammez 1,2, Jean-Baptiste Dherbecourt 1,, Guillaume Gorju 1, Myriam Raybaut 1, Jean-Michel Melkonian 1, Antoine Godard 1, Jacques Pelon 3, Michel Lefebvre 1 1 ONERA - the French Aerospace Lab, Palaiseau, France 2 CNES Toulouse, France 3 LATMOS, Université Pierre et Marie Curie, Paris, France ICSO Biarritz 19/1/216 myriam.raybaut@onera.fr
Outline 2 Objective Develop a high energy 2 µm direct detection DIAL system to demonstrate multiple greenhouse gases concentration measurements (CO2, CH4, water vapor) with a generic emitter architecture Background and context Lidar system approach NesCOPO / OPA : a generic configuration for the lidar emitter Output properties of the emitter (energy, spectrum) Receiver configuration Ground based demonstration off CO 2 remote sensing at 251 nm Summary & future work
Space-borne remote sensing of greenhouse gases by IP-DIAL l ON l OFF Wavelengths of interest for space applications* Species l (µm) CO 2 1.57 / 2.5 λ1, λ2, λ3, λ4 Classic DIAL : 2-λ l 1 l 2 l 3 l 4 l5 Species 2 l OFF CH 4 1.64 / 2.29 H 2 O.94 / 1.9 2.1 Credits : ESA Species 1 DIAL multi-l / multi-species Space-borne instrument : IP-DIAL measurement Interest of a generic approach : 1 spatialization process for 3 missions, reconfigurable missions Airborne / ground based instrument : DIAL, Cal/Val of different active or passive missions Highly demanding performances required for the laser source in terms of peak power, tunability, spectral linewidth, purity, and stability for accurate measurement Our approach = Nested Cavity OPO (NesCOPO) + parametric amplification 3 *G. Ehret, & al., Applied Physics B, 28, 9, p 593
Parametric conversion the tool box OPO & OPA Q- phase matching Wide frequency tuning Gain process G g 2 L 2 f(dkl) Phase matching condition k p = k s +k i +k G Pump laser (w p ) c (2) Signal (w s ) Depleted pump Idler (w i ) w p = w s + w i D = p ( s + i ) Energy conservation NL phase 3-l mixing specific cavities spectral filtering NL functions Gain shaping 4
Vernier spectral filtering principle - NesCOPO architecture Principle M1 Vernier effect a single pair of signal and idler modes is selected within the parametric gain curve M3 ω p ω i Parametric gain curve PZT i M2 ω s PZT s+i DRO with separate signal and idler cavities that can be adjusted independently ω i Δω i Δω s Single-Longitudinal-Mode emission ω s Properties : Short cavities / compactness Low threshold of oscillation SLM operation without seeder Finely tunable with PZT on mirrors Widely tunable (sev. 1 nm with a single device) 5 Scherrer et al, JOSAB 17 (2) 1716-1729 Hardy et al, Opt. Lett. 36 (211) 678-68 Barrientos Barria et al, Opt. Lett. 39 (214) 6719-6722
NesCOPO / OPA configuration for high energy long range lidar application NesCOPO / OPA Multiple species ability 3 Hz, 2 mj, 1 ns, M 2 ~1.5 PULSNIR ESA TRP (26-29) Signal Idler output Optical - Wavelength Species output energy Optical (nm) energy efficiency CO 2 λ s = 251 2 mj 17 mj 37 % H 2 O λ s = 257 2 mj 16 mj 36 % CH 4 λ i = 2211 2 mj 16 mj 36 % λ i = 229 2 mj 17 mj 37 % 6 Barrientos Barria et al, Opt. Lett. 39 (214) 6719-6722
NesCOPO / OPA configuration for high energy long range lidar application CNES R&T project R-S11/OT-2-7 Barrientos Barria et al, Opt. Lett. 39 (214) 6719-6722
Relevant Spectral properties for Differential absorption Lidar applications Spectral agility Ex : Optical length modulation synchronous with pump laser pulses (3 Hz) 2-l DIAL 4-l DIAL 25.98 25.6 Wavelength (nm) 25.96 25.94 25.92 25.9 25.88 1 FSR 5 1 15 2 Shot number Wavelength (nm) 25.5 25.4 25.3 25.2 3 FSR 5 1 15 2 Shot number Fast wavelength switching immunity to backscattering variations Multi-l abilities Spectral stability Free running or OPO cavity locked on a reference (calibrated wavemeter) 25 1 Servo characteristic response time Df (MHz) Df (MHz) -25 2 Free-running OPO Locked OPO -2 1 2 3 4 5 6 Time (s) llan (MHz) 1,1 white noise type slope Free-running OPO Locked OPO Wavemeter precision,1,1 1 1 1 Time (s) Short term stability +/- 4 MHz Locked frequency averaged over 1 s Sub MHz 8
Spectral purity characterization 9 Wavelength (nm) Experimental set up OPO / OPA Cell transmission 2 1 25.9674 25.9672 25.967 3 x 1-3 Coupler Attenuator 1 Multi-pass CO 2 cell (5 mbar, 3 m) center CO 2 line transmission < 1-4 over 1GHz Reference arm 5 1 15 2 25 3 5 1 15 2 25 3 Shot number photodiode Reference signal CO 2 cell transmitted signal Spectral purity > 1 T CO2 Purity ~ 99,98% t
Direct detection and receiver configuration z Received power (W) 6 x 1-7 4 2 Signal OFF Signal ON 5 1 Range (m) λ OFF λ ON 1 Transmitter Receiver Pulse energy 1 mj Telescope diameter 2 cm Pulse duration 1 ns Field of view 8 µrad Repetition rate 3 Hz Detector Type InGaAs PIN OFF-line wavelength 25.963 nm Detector diameter 3 µm ON-line wavelength 251.47 nm Detector NEP 3.1-12 W/ Hz Linewidth < 6 MHz Bandwidth 3 MHz Divergence angle 5 µrad Sampling rate 5 MHz P λ R = K 1 R 2 β z e OD λ r OD λ = ln P λ OFF P λon R R CNES R&T projects R-S13/OT-2-61 R-S15/OT-2-61
Experimental lidar signals - CO 2 concentration retrieval at 251 nm Lidar signal (SNR) 25 2 15 1 5 Signal OFF Signal ON Diffusion on transmitting optics Aerosols Clouds 5 1 15 Range (m) Optical depth 1.5 1.5 11 397 ppm Experimental 5 1 15 Range (m) Palaiseau, France, july 216 ON / OFF sequence visualization on clouds λ ON = 25,883 λ OFF = 25,97 Numerical filtering 1 MHz Averaging over 1 shots 1 25.8 251 251.2 Wavelength (nm) IP DIAL Concentration estimation : 397 ±3 ppm Transmission (%) 8 6
Experimental lidar signals - CO 2 concentration retrieval at 251 nm Signal (SNR) 6 4 2 Signal OFF Signal ON λ ON = 25,883 λ OFF = 25,97 Numerical filtering 1 MHz Averaging over 2 shots Transmission (%) 1 8 6 25.8 251 251.2 Wavelength (nm) Optical depth 5 1 15 2 25 Range (m) 2 Palaiseau, France, july 216 1.5 DIAL Concentration estimation : 1.5 CO2 VMR (ppm) 7 6 5 4 3 2 1 ) 12 5 1 15 2 25 Range (m) 2 4 6 8 1 12 14 Range (m)
Conclusion and outlooks Summary Development of a ground based DIAL system for multiple greenhouse species concentration measurement High energy emitter based on a generic architecture with high spectral performances Development of a direct detection receiver First demonstrations on CO 2 concentration measurements 13
Conclusion and outlooks Future work and outlooks Improvement of the accuracy with increase rep. rate or double pulse operation Increase TRL and compactness of the source (environmental testing) On-going ESA TRP GENUIN project Compact NesCOPO for vibration testing LIDT on some core optical components Specific non linear crystals development and radiation testing Use of High aperture ppktp for high conversion efficiency and spatial quality in a more compact set-up => ICSO paper n 6 (presented on Tuesday 18th) => ICSO poster n 47 (presented on Tuesday 18th) Demonstration of multi-wavelengths and multi-species measurements in progress Comparison campaigns with other DIAL systems 14
Acknowledgments Thank you for your attention 15