Status of the Laser Risk Reduction Program at LaRC Michael Kavaya, Upendra Singh NASA/LaRC

1. Status of the Laser Risk Reduction Program at LaRC Michael Kavaya, Upendra Singh NASA/LaRC Working Group on Space-Based Lidar Winds Sedona, AZ Feb. 1-3, 2005

2. X-Centric • LRRP was R&D-centric and knowledge-centric • LRRP was jointly funded by Earth Science Enterprise and Aerospace Technology Enterprise: ~50/50 • Jan. 14, 2004 – NASA began Exploration Initiative • NASA HQ Reorganization • ATE part of LRRP given to Exploration Systems Mission Directorate • ESMD held ICP competition: ESTO/LaRC/GSFC proposal accepted – LLTE; funding is 50% x (15%, 42.5%, 42.5%) • FY05 – big drop in total funding • Now LRRP is Exploration-centric • LRRP never has been earth science mission-centric

3. LRRP LaRC Funding Begin Laser/Lidar 4 Exploration Begin Laser Risk Reduction Program Begin NASA’s Exploration Initiative * Different definitions under BAU & FCA ** Was 2.6 until 11/30/04 *** Includes ~ 4 surfeit FTEs Begin Full Cost Accounting

4. LaRC Components Of LRRP, FY02-04 • 2-Micron Pulsed Transmitter Laser Development • Pump Laser Diode Arrays Development, Characterization, & Qualification (792 nm) • Wavelength Conversion From 1-Micron to UV, High E • Detector/Receiver Advancement For Direct and Coherent Detection at 2-Microns • Laser Physics, New Materials

5. Out 1 Out 2 Transimpedance Amplifiers V V cc1 cc2 Capacitor GND V V b1 b2 Al2O3 Substrate 75 mm InGaAs Detectors LaRC LRRP Accomplishments • Discovered more efficient 2-micron laser material - mitigates large resource req’t of s/c • Demonstrated over 1 Joule pulse energy at 2 microns; (world record by order of magnitude) - enables active wind & CO2 measurement • Designed fully conductively cooled 2 micron laser head - mitigates thermal mgmt risk of high-power lasers • Developed diode laser characterization and lifetime facilities - to understand failure modes of future solid state lasers • Developed innovative UV generation architectures - enablers for trop ozone • Developed 2-micron detector characterization facility - to enable better detector fabrication • Developed high responsivity detector • Built first integrated receiver breadboard for 2-micron coherent lidar - more compact & robust

6. LaRC Components Of LRRP, FY05-07 Task 1. 2-Micron Pulsed Laser Transmitter 2-Micron Testbed Compact 2-Micron Laser (1a) 12/04Develop requirements for an engineering hardened 2-micron laser 3/05 Develop conceptual engineering design for a hardened 2-micron laser test bed 8/05 Complete mechanical design 9/05 Critical design review Amplifier Development (1b) 10/04 Complete laser diode coupling efficiency analysis 1/05 Complete thermal and stress analysis 4/05 Complete amplifier head design 8/05 Complete amplifier module design Phase Conjugate Mirror (1c) 12/04 Develop criteria for selecting potential PCM approaches compatible with 2-micron lasers 5/05 Develop and improve amplifier models to optimize the amplifier performance with PCM technology

7. LaRC Components Of LRRP, FY05-07 Task 1. 2-Micron Pulsed Laser Transmitter (cont.) Tm Fiber Pumped Ho Laser (1d) 3/05 Develop a model to simulate an end-pumped Ho laser 3/05 Characterize the commercial Tm fiber laser 6/05 Complete a design for a CW Ho laser directly pumped by Tm fiber laser 9/05 Complete a continuous wave Ho laser directly pumped by Tm fiber laser Radiation & Contamination Mitigation (1e) 4/05 Define the radiation hardness levels and generate parts list of potential space-bound components 9/05 Develop and design contamination testing station Task 2. Mars Orbiter Lidar Modeling & Requirements (2a) 7/05 Lidar performance model of Mars wind measurement 7/05 Rapidly switched seed source 8/05 Lidar performance model of Mars CO2 measurement 9/05 Design of orbiting lidar system 9/05 Double-pulsed wavelength-switched injection seeding validation

8. LaRC Components Of LRRP, FY05-07 Task 3. 792-nm Laser Diode Arrays Characterization and Qualification (3a) 6/05 Develop a setup for measuring package-induced stresses 9/05 Evaluate different LDAs from different suppliers Technology Advancement Addressing Reliability Issues (3b) 1/05 Design and fabricate LDAs with improved geometry 6/05 Fabricate experimental LDAs using advanced composite submount materials Task 4. Detector Development For 2-Micron Direct DIAL 3/05 Develop phototransistors suitable for 2 micron with sensitivity > 1000 A/W at 2 microns, 200 micron diameter collecting area, NEP < 2E-14 W/Hz**0.5, and QE of 80% 4/05 Validate detector performance in subsystem 7/05 Design and build a mask with standard collecting area diameter of 1000 microns

9. LaRC Components Of LRRP, FY05-07 Task 5. UV Wavelength Conversion Technologies from 1 Micron 6/05 Complete RISTRA OPO and SFG based nonlinear optics setup generating 320 nm wavelength 9/05 Complete the integration of the Nd:YAG pump laser and nonlinear optics setup generating 308 nm wavelength Task 6. Advanced Receiver For 2-Micron Coherent Doppler Lidar 3/05 Design optimized wideband receiver boards (0.5, 1.0, 5.0 GHz) 9/05 Fabricate and test 500 MHz receiver board

10. Conclusions • LRRP is a great idea, but by no means the only thing that needs doing • LRRP has survived so far the upheavals at NASA • The new form of LRRP will continue to advance technology helpful to the global winds measurement • NASA does not appoint a measurement “shepherd” with a budget to oversee theory, modeling, technology devel., technology and technique validation, and space readiness validation related to that one measurement. I wonder if that approach would succeed? • Will Mars be a stepping stone to earth?