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

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

LRRP LaRC Funding

$M FY02 FY03 FY04 FY05 FY06 FY07 Totals

ESMD (T), formerly

OATE(R)

Gross*

Procurement

CS FTE

PBC WYE

1.8

1.4

2.5

1.8

5.2

2.3**

9.7

1.2

0.7

1.7

1.3

3.25 3.25 7.7

Science/ESTO, formerly

OESE(Y)/ESTO

Gross*

Procurement

CS FTE

PBC WYE

2.0

1.5

2.0

1.4

4.4

2.0

7.3

3.4

1.9

6.0

3.7

3.4 0 6.7

Total Gross*

Procurement

CS FTE

PBC WYE

3.8

2.9

~12

4.5

3.2

~12

9.6

4.3

17.0***

4.6

2.6

7.7

5.0

6.65 3.25 14.4

Begin NASA’s Exploration Initiative

Begin Full Cost Accounting* Different definitions under BAU & FCA** Was 2.6 until 11/30/04*** Includes ~ 4 surfeit FTEs

Begin Laser/Lidar 4 ExplorationBegin Laser Risk Reduction Program

• 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

LaRC Components Of LRRP, FY02-04

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

Power and Polarization

Pulse Width

Wavelength and Linewidth

Beam Profile and Divergence

Optical Spectrum Analyzer

Power Meter

Integrating Sphere

Laser Diode

ThermalInterface

LD Characterization LD Lifetime Test

Current, Voltage, Temp, and PRF

Near FieldEmitters Image

Laser DiodeThermalProfile

Power and Polarization

Pulse Width

Wavelength and Linewidth

Beam Profile and Divergence

Optical Spectrum Analyzer

Power Meter

Integrating Sphere

Laser Diode

ThermalInterface

LD Characterization LD Lifetime Test

Current, Voltage, Temp, and PRF

Near FieldEmitters Image

Laser DiodeThermalProfile

Vb1 Vb2

GND

Vcc1 Vcc2

Out 1 Out 2

75 m InGaAs Detectors

TransimpedanceAmplifiers

Al2O3 Substrate

Capacitor

LaRC Components Of LRRP, FY05-07

Task 1. 2-Micron Pulsed Laser Transmitter

2-Micron Testbed

Compact 2-Micron Laser (1a)

12/04 Develop 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

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

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 DIAL3/05 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

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

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?