1. Upendra Singh, LaRC 1 NASA’s Laser Risk Reduction Program- Accomplishments and Update Upendra N. Singh William S. Heaps Chief Technologist, SEC, NASA LaRC NASA/GSFC 757-864-1570 u.n.singh@larc.nasa.gov

2. Upendra Singh, LaRC 2 Background LRRP Strategy and Synergies Objectives and deliverables Recent Accomplishments Future Plans Conclusions

3. Upendra Singh, LaRC 3 Laser Risk Reduction Program Origins Earth Science Independent Laser Review Board empanelled in 2000 in response to multiple laser instrument mission issues Panel reviewed past and present NASA ESE laser remote sensing missions: –CALIPSO, ICESat, LITE, SPARCLE (NMP/EO-2), VCL Panel report included 11 recommendations, the most key being: –NASA should identify and intensively develop critical fundamental technologies applicable to multiple missions and investigate formation of interagency coalition to assure supply of diode pumped lasers –NASA should create a “Laser Research Super Center” managed by NASA HQ and drawing from laser research teams at the field centers –An interagency technology alliance should be formed for the development of space-based active optical sensors and associated critical enabling technologies (especially transmitter- class lasers) NASA Administrator mandated formulation of an Agency-level lidar technology development plan –Laser Risk Reduction Program (LRRP) was established, based on recommendations from joint LaRC/GSFC strategy team –Program initiated in FY02 –Co-funded by ESTO and Code R Enabling Concepts and Technologies (ECT) program

4. Upendra Singh, LaRC 4 Develop lidar technology for NASA’s future measurements Assemble in-house NASA team with end-to-end lidar capability (theory to hardware to validation) Collaborate with industry, academia, and government Validate technology to reduce risk of space-based lidar missions before the proposal process Transfer technology to industry

5. Upendra Singh, LaRC 5 Laser based instruments are applicable to a wide range of Earth Science, Aerospace Technology, Space Science, and Space Flight Enterprise needs Risk in lidar missions can be significantly reduced by progress in a few key technologies Modest NASA investment towards proposed strategy will have significant impact on future space-based active remote sensing missions Strategic alliance with other government organizations, industry, and academia for leveraging and accelerating advancement of key technologies

6. Upendra Singh, LaRC 6 Presentation to Daniel S. Goldin, NASA Administrator By Ghassem R. AsrarSamuel L. VenneriAssociate Administrator Earth Science EnterpriseAerospace Technology Enterprise Jeremiah F. CreedonAlphonso V. Diaz Director, NASA LaRC Director, NASA GSFC Upendra N. Singh and William S. Heaps Co-Leaders Integrated NASA Lidar Systems Strategy Team (INLSST) June 18, 2001 Preliminary Draft – For Agency Use Only

7. Upendra Singh, LaRC 7 Turbulence detection Wind shear detection Wake vortices Automatic Rendezvous and Docking for ISS Wind profiling for shuttle launch and landing Mars Lander Guidance/Control Mars Atmospheric Sensing Earth Science Aerospace Technology Space Science Clouds/Aerosols Tropospheric Winds Ozone Carbon Dioxide Biomass Burning Water Vapor Surface Mapping Laser Altimetry Oceanography Space Flight Lidar is a Multi-Enterprise Need

8. Upendra Singh, LaRC 8 Key Priority Measurements for Earth Science Enterprise –Cloud/Aerosols and Radiative Forcing –Tropospheric Winds/River Flow –Tropospheric Ozone –Carbon Cycle (CO2, Biomass) –Surface Mapping –Oceanography Earth Sciences Application Foci

9. Upendra Singh, LaRC 9 Backscatter Lidar Cloud Aerosol Differential Absorption Lidar (DIAL) Ozone Carbon Dioxide Doppler Lidar Wind Fields River Flow Altimetry Lidar Ice Sheet Mass Balance Vegetation Canopy Land Topography f Doppler Frequency Transmit Pulse Return Velocity = ( /2) f Doppler T Arrival Time Transmit Pulse Return Range = (c/2)T Arrival T Arrival Time Transmit Pulse Return Density = I S /I T Range = (c/2)T arrival ITIT ISIS off on Transmit Pulses Returns Concentration = log[ I( on )/ I( off )] Wavelength Lidar Techniques and Measurements

10. Upendra Singh, LaRC 10 Pulsed Laser Development Atmosphere: Lower Upper DIAL: CO 2 X3 OPO DIAL: Ozone 2 Lasers, 4 Techniques, 6 Priority Measurements 0.30-0.32 micron Backscatter Lidar: Aerosols/Clouds X2 Surface Mapping, Oceanography X2 0.355 micron Altimetry: 1.06 micron 2.05 micron 1 MICRON Doppler Lidar: Wind Backscatter Lidar: Aerosols/Clouds Coherent Direct 0.532 micron 2 MICRON Key Technologies in Common Laser Diodes Laser Induced Damage Frequency Control Electrical Efficiency Heat Removal Ruggedness Lifetime Contamination Tolerance Earth Sciences Application Foci 2.05 micron Coherent Ocean/River Surface Currents Coherent Winds Noncoherent Winds

11. Upendra Singh, LaRC 11 2 µ Test Bed 1 µ Test Bed Knowledge Laser Induced Damage Now: 15 J/cm 2 for 5 nsec Goal: 60 J/cm 2 for 5 nsec Frequency Control Now: <.25 pm Goal: <.005 pm Lifetime Now: 850? M shots Goal: 2 G shots Heat Removal Now: 110 Watts Goal: 300 Watts Contamination Tolerance Now: 50, A/10 Goal: Better Tolerance Electrical Efficiency Now: 3-4% Goal: 6% Ruggedness Now: 1 min @ 10G Goal: 1 min @ 15 G Laser Transmitter Testbeds

12. Upendra Singh, LaRC 12  Establishing Space-hardened Laser Transmitter Test Beds (1µm laser at GSFC & 2µm at LaRC)  Development and Qualifications of Space-based Laser Diode Arrays ( 808nm diodes at GSFC & 792nm at LaRC)  Advancing Wavelength Conversion Technology for Space-based Lidars ( Low Energy/HRT at GSFC & High Energy/LRT at LaRC)

13. Upendra Singh, LaRC 13 Deliverables Space-hardened 1- and 2-micron Laser Transmitters (Efficient, Conductively-cooled) Space-hardened Conductively Cooled Laser Diode Arrays Non-linear Optical Parametric and Harmonic Generation for Ozone, Chemical and Biological Species, and Water Vapor Detection NASA Laser Risk Reduction Program Funding ($M): FY 03FY 04FY 05FY 06FY 07FY 08 OAT555555 OES444444 Total999999

14. Upendra Singh, LaRC 14 Laser Risk Reduction Management Model Project Manager (Kavaya) LaRC LaRC Co-PI (U. Singh) GSFC Project Manager (Cazeau) GSFC Co-PI (W. Heaps) NASA HQ OES Code Y OAT Code R

15. Upendra Singh, LaRC 15 LRRP Description Pro-actively targets deficiencies in laser technology for focused development and risk mitigation –Technology readiness overestimated in past due to extrapolation from prior heritage –Flight lasers are still at the “build-to-order” R&D stage Primary focus is on high-power (i.e., transmitter- class) lasers for space-based remote sensing applications –High-performance Nd:YAG systems (1 µm) –Emerging holmium- and thulium-doped lasant materials (2 µm) –Nonlinear generation schemes based on 1- and 2- µ m pump sources Harmonic generation Optical parametric amplification/oscillation (OPA/OPO) Small investments in ancillary enhancing and enabling technologies which offer potential to reduce demand for laser power (detectors, innovative receiver approaches)

16. Upendra Singh, LaRC 16 2-micron laser transmitter –Demonstrate technologies leading to a conductively cooled, diode-pumped 2-micron laser suitable for space-based lidar application –Address major laser development issues: High energy, high efficiency, laser-induced optical and thermal damage, system thermal management High-power diode laser pump arrays –Develop, scale, and qualify long-lived, space-compatible laser diode arrays with current vendors –Evaluate currently available laser diode arrays for performance, life and configuration required for future space-based laser missions –Establish Characterization and Lifetime Test Facility to address laser diode issues: Limited reliability and lifetime Lack of statistical and analytical bases for performance and lifetime prediction –Conceive advanced laser diode array architectures with improved efficiency and thermal characteristics Nonlinear optics research for space-based ozone DIAL –Spectrally narrow, tunable, robust UV laser architectures –Develop long-lived, efficient, space-compatible, nonlinear optical materials/techniques Receiver technologies –Develop integrated heterodyne receiver to demonstrate 3-dB improvement of coherent lidar system efficiency with 80% reduction of required local oscillator power –Develop improved quantum efficiency photon-counting detectors at 2 micron Laser physics and advanced materials research –Develop line tunable diode-pumped Nd laser system for pumping nonlinear UV generation schemes –Develop narrowband, long pulse, low average power pump laser for wavelength control of lidar systems LRRP Application Driven Elements

17. Upendra Singh, LaRC 17 NASA Laser Risk Reduction Program 20032007 Missions Backscatter Lidar Cloud Aerosol Differential Absorption Lidar (DIAL) Carbon Dioxide Ozone Doppler Lidar Wind Fields River Flow Laser Altimeter Ice Sheet Mass and Topography Vegetation Canopy Land Topography Ocean Mixed Layer Depth S/C-S/C Ranging Wavelength Conversion 1-Micron Laser 2-Micron Laser Efficiency (Green=30% UV=20%) SHG/THG OPO/OPA Space Qualification Heat Removal (All Conductive) Contamination Optics Damage (2G/3 yr) Lifetime (2G Shots) Pump Diodes Coupling Packaging Failure Mechanisms Availability (COTS) Lifetime Effects Performance Beam Quality Laser Design Efficiency (4% WPE) Modeling Laser Physics Energy (1 J)/ Power (10-100W) Materials Beam Quality/ Spectrum Compact Heritage derived from both Earth and Solar System apps.

18. Upendra Singh, LaRC 18 Lidar Technologies ScannerReceiverAutoAlignPointing Telescope Detector Y S CO 2 Profiling X Global Winds X Ozone Profiling X Chem/Bio Sensing X Landing/Rendezvous X Water Vapor Profiling X Laser Transmitter Technologies Measurements X Ranging/Altimetry X Clouds/Aerosols X Customers Enabling Technology Elements X 2-Micron Lidar Transmitter Frequency Controller Amplifier IR Wavelength Converter UV Wavelength Converter 1-Micron Lidar Transmitter X X X

19. Upendra Singh, LaRC 19 Laser Risk Reduction Program A.Pump Laser Diodes Risk Reduction –LaRC to advance diodes in 790 nm wavelength region –Lifetime and characterization testing –Radiation testing performed at GSFC B.Conductively cooled laser –2-micron partially conductively-cooled laser is precursor to fully conductively-cooled space- capable design C.Contamination –GSFC Contamination protocols will be made available to support the contamination & lifetime study and tests at LaRC D.Non-Linear Material & OPO Modeling –LaRC to develop high peak power OPO’s –Non-linear materials to be included in diode radiation test E.Design and Packaging –Packaging methodology for space flight-capable laser A E D C B

20. Upendra Singh, LaRC 20 Laser Resonator Power Efficiency Laser Diodes Availability Life/Quality Wavelength Conversion Power Efficiency Receiver Subsystem Efficiency Size/Mass Material Res & Quantum Mech. Modeling Laser Amplifier Rad & Damage Tests Multi-Joule 12Hz 2-micron Transmitter Laser Define Reqmts & Innovations Test Perf./Reliability Test/Charact. Facility Life Test Quality C Contamination & Lifetime Study and Tests Laser Oscillator A Contamination & Handling Protocols Qualification Procedures Global Winds & CO 2 Global Ozone Highly-Efficient Heterodyne Receiver Define Reqmts & Innovations Low-Noise Detector for CO 2 Meas. Characterization Facilities Lightweight Scanning Telescope Dual Pump Parametric Oscillator Lab Demo High Power Conversion to UV Normal Mode Intra-cavity SHG Pump Laser Efficient conversion to UV Damage/Rad/ Life Tests Packaging 100mJ @ 100Hz 308nm & 320nm 2% efficiency FY 02FY 03FY 04FY 05FY 06 FY 07 A Rad Th/Vac Tests D Non-linear material & OPO modeling B Conductively-Cooled Laser Head E Packaging (Flight-Hardened System) A Advance Laser Diode Technologies Laser Risk Reduction Program LaRC Component

21. Upendra Singh, LaRC 21 Laser Resonator Design 1.5J, 10Hz Fully conductively-cooled 2-micron laser FY 02FY 03FY 04FY 05FY 06 FY 07 Partially conductively- cooled laser head Laser Risk Reduction Program 2-micron technology roadmap Partially conductively- cooled osc Partially conductively- cooled amp 1.5J, 2Hz Partially conductively- cooled 2-micron laser Fully conductively- cooled laser head Fully conductively- cooled osc Fully conductively- cooled amp Design Lessons Design Lessons Validation tool Design Lessons Space-capable design

22. Upendra Singh, LaRC 22 2-Micron Pulsed Transmitter Laser Objective: Develop a high energy, high efficiency, conductively-cooled solid-state 2-micron laser for space lidar applications. Application: Measurement of global CO 2 and winds from LEO. Accomplishments Successful demonstration of Ho,Tm:LuLF laser system with 1050 mJ Q-switched output energy. This was accomplished by one power oscillator and two amplifiers operating in double pulse mode. Single-pulse output is 0.6 J. Notional space-based wind profiling missions require pulse energies from 1 to 5 J, depending on the scenario Milestone achieved with 2-Hz PRF; >12 Hz desired for LEO 1 J

23. Upendra Singh, LaRC 23 Pump Laser Diode Advancement and Validation Objective  Develop state-of-the-art characterization and life-time test facility and address 792- nm laser diode issues: Limited reliability and lifetime Lack of statistical and analytical bases for performance and lifetime prediction Limited commercial availability  Develop advanced laser diode array (LDA) architectures with improved efficiency and thermal characteristics Accomplishments Fabricated and tested an advanced LDA package utilizing diamond substrate and heatsink. Demonstrated 17% reduction in thermal resistance relative to the standard BeO/Cu package that can translate to increased lifetime and reliability. Thermal Image of Diamond LDA Diamond Package cools 36% faster

24. Upendra Singh, LaRC 24 Reached 150 mJ (record) of UV at 320 nm with 10% (record) 1 µm -UV efficiency; reached 115 mJ at 308 nm Developed innovative UV generation architectures Critical to trop ozone profile measurement from space LRRP Recent Accomplishments

25. Upendra Singh, LaRC 25 Current partnerships and collaborations Laser Risk Reduction Program- Collaborations Industry University Government NASA Laser/Lidar Risk Reduction Program LaRC GSFC JPL Tunable LO Laser Integrated Receiver DOE UV Laser DOD Laser Diodes, EO Scanner Coherent, CEO, Laser Diodes ITT UV Laser Sci. Material Laser Crystals Swales, UMD Cond. Cool. Pkg. Boston College Quan. Mech. Model. VLOC, CVI Optics Coatings Northrop Gruman Solid State Lasers Schafer, Plasma Processes Lightweight Telescopes JHU, APL Non Linear Op

26. Upendra Singh, LaRC 26 National Consortium for Excellence in Active Optical Remote Sensing (AORS) Purpose: To establish and maintain critical national expertise needed to ensure long term progress in AORS; mount compelling case for new USG initiative in FY05-06 timeframe –Participants: A multi-agency entity (e.g., NASA, NOAA, IPO, DoD, DoE, FAA, Homeland) Engages members of academia and industry –Approach: Leverages complementary activities ongoing in each of those organizations Primary interchange through open discussions Proposal for a Multi-Agency AORS Consortium

27. Upendra Singh, LaRC 27 Chem-Bio Det Aerosols Wind Aviation Safety Multi-Agency Active Optical Remote Sensing Consortium Industry Home- land NASA NOAA IPO DoE DoD Academia Clouds/Aerosols Wind Trop. Chemistry Carbon dioxide Biomass Water Vapor Land/Ice Topography Wake Vortices Ocean Mixed Layer Solar System Science Wind Water Vapor CO 2 Aerosols Wind Aerosols Chem-Bio Detection Target Recognition Tactical Imaging Water Vapor Chem- Bio Detection Clouds and Aerosols Wind Humidity Aerosols FAA Chem-Bio Detection Aviation Safety Wake Vortices Turbulence Wind Shear Proposed Consortium Partners and Measurement Needs NSF

28. Upendra Singh, LaRC 28 Executive Council Steering Committee Wind NOAA NASA IPO DOD Homeland Chem-Bio NASA DoE DOD Homeland FAA CO 2 /O 3 NOAA NASA EPA NSF Wake Vortices FAA NASA DOD Water Vapor NOAA NASA IPO DOE EPA Clouds/ Aerosol s NOAA NASA IPO DOD Homeland Aviation Safety NASA FAA DOD Homeland Ranging NASA USGS DOD Homeland Working Groups Consortium Structure

29. Upendra Singh, LaRC 29 DETECTOR RECEIVER TELESCOPE SCANNER Auto-Alignment POINTING AORS System Demonstration Packaging & Hardening Flight Validation Advanced AORS Technology Elements LASER 1 micron Laser Testbed 2 micron Laser Testbed Wavelength Conversion Laser Diode Pump Space Hardening Packaging

30. Upendra Singh, LaRC 30 Summary Developing AORS technology supports NASA’s Vision and Mission and enables a key “building block” A focused technology effort will enable the promise of AORS by closing critical remaining gaps in capability AORS will address key high resolution measurement needs within Codes Y and S and support other national needs

31. Upendra Singh, LaRC 31 Backup Charts

32. Upendra Singh, LaRC 32 Technology Roadmap: 2-micron & UV Sources

33. Upendra Singh, LaRC 33 Developed diode laser characterization facility Diagnostics to understand failure modes of solid state lasers Enables active wind & CO 2 measurement from space LRRP Recent Accomplishments

34. Upendra Singh, LaRC 34 792 nm Diamond Package LDA Diamond Package dissipates excess heat more efficiently than standard BeO/Cu package resulting in increased lifetime. Thermal resistance of diamond package is 17% lower than BeO/Cu package Pulsewidth0.1 – 1.0 msec Current80 A Rep Rate10 Hz Op Temp 15 o C LRRP Recent Accomplishments

35. Upendra Singh, LaRC 35 Diamond Package cools 36% faster Thermal Characteristics of Diamond LDA Enables all lidar measurements