FIBERTEK, INC.

Performance Testing of a Risk Reduction Space Winds Lidar Laser Transmitter

Floyd Hovis, Fibertek, Inc.

Jinxue Wang, Raytheon Space and Airborne Systems

February 8, 2006

FIBERTEK, INC. Approach to Developing Space-Qualified 355 nm Lasers

Develop a robust, single frequency 355 nm laser for airborne and space-based direct detection wind lidar systems

–All solid-state, diode pumped–Robust packaging–Tolerant of moderate vibration levels during operation–Space-qualifiable design

Incorporate first generation laser transmitters into ground-based and airborne field systems to demonstrate and evaluate designs

–Goddard Lidar Observatory for Winds (GLOW)–Balloon based Doppler wind lidar being developed by Michigan Aerospace and

the University of New Hampshire for NOAA

Develop scaling to higher powers and pulse energies–Raytheon funded Space Winds Lidar Risk Reduction Laser Transmitter–Air Force SBIR to develop a 500 mJ, 100 Hz 1064 nm pump source

Iterate designs for improved compatibility with a space-based mission–Lighter and smaller–Radiation hardened electronics

FIBERTEK, INC. Status of Related Laser Development Programs

Customer Application Required 1 m Performance Program Status

Univ. of NH Doppler Wind Lidar 150 mJ at 50 Hz Delivery complete

NASA Langley Ozone DIAL 1000 mJ/pulse at 50 Hz Delivery complete

Raytheon Doppler Wind Lidar 1000 mJ at 50 Hz Delivery complete

Air Force Remote Imaging Lidar 500 mJ at 100 Hz Testing in progress

NASA Langley Phase II SBIR Seed & Metrology Laser 50 mW single frequency Prototype demonstrated

NASA Langley High Spectral Res. Lidar IIP 200 mJ at 200 Hz Final build in progress

NASA Langley Mars exploration 40 mJ at 20 Hz Delivery complete

Navy SBIR Rangefinder/Designator 300 mJ at 25 Hz Final build in progress

NASA GSFC Doppler Wind Lidar IIP 100 mJ at 200 Hz Final build in progress

Single frequency pump head & resonator technology will support a significant number of next generation lidar applications

Single frequency laser development has a broad support base

FIBERTEK, INC.

Summary of Technical Approach

An all solid-state diode-pumped laser transmitter featuring:

Injection seeded ring laser Improves emission brightness (M2)

Diode-pumped zigzag slab amplifiers Robust and efficient design for use in space

Advanced E-O phase modulator material Allows high frequency cavity modulation for improved stability injection seeding

Alignment insensitive / boresight Stable and reliable operation over stable 1.0 m cavity and optical bench environment

Conduction cooled Eliminates circulating liquids w/in cavity

High efficiency third harmonic generation Reduces on orbit power requirements

Space-qualifiable electrical design Reduces cost and schedule risk for a future space-based mission

FIBERTEK, INC. Raytheon 1 J Risk Reduction Laser Optical Layout

Final System Optical Configuration

Both the original NASA Ozone amplifiers and the power amplifier have been shown to be capable of 100 Hz operation

Power amplifier

Expansiontelescope

Amplifier #2

Amplifier #1

LBO doubler

355 nm output

LBO tripler

Fiber port

Ring Resonator

Fiber-coupled 1 m seed laser

Optical isolator

FIBERTEK, INC. Raytheon 1 J Risk Reduction Laser Optical Layout

Final System Optical Configuration

Both the original NASA Ozone amplifiers and the power amplifier have been shown to be capable of 100 Hz operation

Ring oscillator

Amp #2

Power amp

Amp #1

FIBERTEK, INC.Solid Model of Integrated LaserTop View - Electrical Connection End

Laser Optics Module (LOM)

Laser Electronics Unit

(LEU)

LEU cooling plates

LOM/LEU electrical interconnections

28 VDC terminals

FIBERTEK, INC. Solid Model of Integrated LaserTop View - Optical Output End

Laser Optics Module (LOM)

Laser Electronics Unit

(LEU)

LEU cooling plates

Output windows

FIBERTEK, INC. Solid Model of Integrated LaserBottom View

Laser Optics Module (LOM)

Laser Electronics Unit

(LEU)

LOM cooling plates

Mounting foot

Mounting foot

Mounting foot

FIBERTEK, INC. Acceptance Testing of Space Winds Lidar Laser Transmitter Is Complete

Final acceptance testing was completed in November 2006

Space-Winds Lidar Laser Transmitter

Design uses all three amplifiers

Autonomous operation controlled through RS232 serial interface

Nominal 28 VDC primary power

Space-qualifiable electrical design

Thermal control through conductive cooling to liquid cooled plates bolted to bottom of laser module

355 nm single frequency output of over 460 mJ/pulse @ 50 Hz (23 W)

Delivered system will undergo extended life testing at Raytheon

Laser module

Electronics module

FIBERTEK, INC. Acceptance Testing1064 nm Power & Energy Test Results

50 Hz operation

Final 1064 nm power - 44.4 W (888 mJ/pulse)

Input electrical power - 684W

Wall plug efficiency - 6.5%

77% of final power is reached in 1 min

99% of final power is reached in 2 minutes

Short term (20 s) shot to shot energy stability is 0.8% (3)

Long term (30 min) energy stability is 3.7% (3)

Pulse width - 14 ns

1064 nm power vs. time after Armed to High Power transition

Time (minutes)

0 10 20 30 40 50 60

1064 nm output power (W)

0

10

20

30

40

50

FIBERTEK, INC.Acceptance Testing

355 nm Power & Energy Test Results

50 Hz operation

Final 355 nm power - 23.9 W (478 mJ/pulse)

Input electrical power - 684W

355 nm conversion efficiency - 53.8%

Wall plug efficiency - 3.5%

74% of final power is reached in 1 min

93% of final power is reached in 2 minutes

Short term (20 s) shot to shot energy stability is 3.5% (3)

Long term (30 min) energy stability is 4.3% (3)

Pulse width - 14 ns

355 nm power vs. time after Armed to High Power transition

Time (minutes)

0 10 20 30 40 50 60

355 nm output power (W)

0

5

10

15

20

25

30

FIBERTEK, INC.

Acceptance Testing 1064 nm M2

Near field profile Beam quality data

M2x = 2.2

M2y = 2.3

FIBERTEK, INC.

Acceptance Testing 355 nm M2

Near field profile Beam quality data

M2x = 4.0

M2y =5.7

FIBERTEK, INC. Acceptance Testing Pointing Stability

1064 nm data 355 nm data

1064 nm pointing stability < 64 µrad (<5% of raw beam divergence) 355 nm pointing stability < 71 µrad (<10% of raw beam divergence)

X position (µm)

3150 3200 3250 3300 3350 3400 3450

Y position (µm)

3350

3400

3450

3500

3550

3600

3650

Circle containing 90% of centroid values

X position (µm)

3400 3420 3440 3460 3480 3500 3520 3540 3560 3580 3600

Y position (µm)

3100

3150

3200

3250

3300

Circle containing 90% of centroid values

FIBERTEK, INC. Acceptance Testing 1064 nm Frequency Stability

Frequency drift is < 1 MHz/min and appears to bedominated by seed laser frequency drift

1064 nm relative frequency drift

Time (minutes)

0 20 40 60 80 100

Relative frequency (MHz)

0

10

20

30

40

FIBERTEK, INC.

Acknowledgements

BalloonWinds laser transmitter was funded by NOAA BalloonWinds

Program through UNH and MAC

Space Doppler Winds LIDAR risk-reduction laser transmitter was funded by

Raytheon Internal Research and Development (IRAD)

NASA support through the SBIR and Advanced Technology Initiative

programs

Air Force SBIR funding for 100 Hz laser development