Recent Advances in Solid State Lasers and Nonlinear Optics for Remote Sensing

Peter F. MoultonQ-Peak, Inc.

Lidar Remote Sensing for Industry and Environment Monitoring III (Conference 4893)

SPIE’s Third International Asia-Pacific Environmental Remote Sensing Symposium 2002

Hangzhou, ChinaOctober 25, 2002

Outline

• Ti:sapphire lasers for UV-based sensors– NASA Langley– Alex Dergachev, Bhabana Pati

• High-energy OPO for aerosol sensing– NASA Langley– Glen Rines

• Tandem OPO for infrared DIAL– AFRL– Yelena Isyanova

• Other efforts

Ti:sapphire absorption and gain spectra

0.E+00

1.E-20

2.E-20

3.E-20

4.E-20

5.E-20

6.E-20

7.E-20

400 500 600 700 800 900 1000 1100

Wavelength (nm)

Abs

orpt

ion

cros

s se

ctio

n (c

m2)

0

5E-20

1E-19

1.5E-19

2E-19

2.5E-19

3E-19

3.5E-19

Gai

n cr

oss

sect

ion

(cm

2)

Laser-pumped, pulsed Ti:sapphire laser combines high energy and high beam quality

Pump #1

Pump #2

Output

GRM

Ti:sapphirecrystals

Prisms

HR

Gain-switched operation, similar to Q-switched Nd lasers

Pulsed Ti:sapphire input-output, 727-960 nm

0

50

100

150

200

250

300

350

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450

500

0 200 400 600 800 1000 1200 1400

Green pump energy (mJ)

Ti:s

apph

ire

outp

ut e

nerg

y (m

J)

790 nm727 nm911 nm960 nm

LASE system with Ti:sapphire laser has measured global water-vapor profiles

Harmonic conversion of Ti:sapphirelasers for species sensing

700 750 800 850 900 950Wavelength (nm)

NO2

Benzene

Hg

Toluene Ozone

NO

SO2

Cl2

2nd

3rd

4th

Harmonic

Block diagram of ozone lidar transmitter

Double-PulseLamp Driver

SLM Diode Laser -On-Line Seeder

Isolator

Passive SHGModule

Passive THGModule

Double-Pulse UV Output

SLM Diode Laser -Off-Line Seeder

DichroicMirror

CLH Nd:YLFPump Laser

Pulsed Ti:sapphireUnstable-Resonator

LaserBBO- orLBO-based

THG efficiency and energyexceeded 45% and 30 mJ

0

5

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50

0 10 20 30 40 50 60 70 80

Input Energy (mJ)

THG

Effi

cien

cy

0

5

10

15

20

25

30

35

40

45

50

THG

Out

put E

nerg

y (m

J)

High-energy OPO for eye-safe aerosol sensing

Compact Nd:YAG/YLF laser head (CLH)

Laser performance with Nd:YLF andKTP/KTA OPO angle tuning

0 20 40 60 800

200

400

600

800

Lamp Energy (J)

1053

-nm

Out

put (

mJ)

10 Hz

20 Hz

30 Hz

M2 = 10-15

1.41.51.61.71.81.9

22.12.22.32.42.52.6

40 45 50 55 60 65 70 75 80 85 90 95Theta (degrees)

Sign

al w

avel

engt

h (u

m)

x-cuty-cut

OPO resonator designs

pump

signalRING

pump signal

HT pumpHR signal

PR signalHR pump

20 mm KTPSTANDING-WAVE M1

pump

450 mJ, 10 Hz41% conversionLimits: M1 damagePump feedback

TIR prism

4, 10-mm KTP

240 mJ, 30 Hz34% conversionNo feedbackNo damage atfull power

(with KTA330 mJ, 100 Hz>30% conversion)

KTP OPO engineered for CLH

Complete OPO-based lidar system

Application of CLEAR lidar to urban areashttp://www.ioe.ucla.edu/clear/default.htm

Tandem OPO for infrared DIAL

Tandem OPO scheme

Nd-doped,Q-switched laser KTA OPO CdSe OPO

IR seed source

IR seed source

Nd-dopedseed laser

1.5 - 3.6 μm

3.3 - 11 μm

Or: PPLN,other KTP isomorphs

Or: AgGaSe2ZnGeP2

Angle-tuned Pump-tuned, NCPM

Tandem OPO tuning with x- and y-cut KTA

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12

45 50 55 60 65 70 75 80 85 90

KTA Phasematch angle (degrees)

Wav

elen

gth

(um

)

y-cut KTA

x-cut KTACdSe signal and idler

KTA signal and idler

Seeded Nd:YLF ring pump laser

HR Seed laser

Optical isolator

PD

LockingElectronics

PZT

OC

HR

HR

Dove prism

Pockels cell

λ/2

Nd:YLF rod

60 mJ@ 1053 nm

Polarizer

Aperture

Tandem OPO demonstration

Nd:YLF pump laser

CdSe

KTA

CdSe OPO idler8.3-10.6 um

3-4.5 mJ

KTA OPO idler3.0-3.45 um

CdSe OPO signal

KTA OPO idler

EOSI 2010 ExternalCavity Diode Laser

1530-1560 nm

Seed laser

Optical isolator

>200 mJ, 20 Hz

40-50 mJ signal25 mJ idler

Other remote-sensing efforts

• Amplified, diode-pumped, short-pulse lasers for precision altimetry (NASA Goddard)– < 1 ns, 0.2 mJ, 2 kHz, 532 nm (SLR2000)– < 10 ns, 10 mJ, 1 kHz, 1064 nm (satellite?)

• High-energy Nd:YLF lasers for space (NASA Langley)– Conduction-cooled, diode-pumped, 23% slope efficiency– Diode-pumped rod, 110 mJ/pulse, double-pulse, 10 Hz

• High-power, single-frequency UV (349 nm) sourcesfor edge-filter wind sensing (NASA Goddard)– Efficient design, kHz pulse rate– Aircraft based– Scalable to space-based

Conclusions

• Advances in solid state laser and nonlinear optical materials have allowed development of new sources for active remote sensing

• Tunable Ti:sapphire lasers with nonlinear conversion generate tunable UV for a variety of species detection, including ozone

• Large-aperture KTP and KTA crystals can shift the output of Nd-doped lasers into the eyesafe wavelength region, for ground-based aerosol sensing in populated areas

• Tandem OPO systems provide broad infrared wavelength coverage, to detect a number of molecules with DIAL systems

• Diode-pumped lasers are now being developed to operate with higher efficiency and better reliability, suited for space-based sensors

Lamp-pumped, Nd oscillator-amplifier

EO Q-switchRisley wedges

HR mirror

Waveplate

Risley wedge

Polarizer

Prism

Output mirror

Prism

Flashlamp

Nd:YAG or YLF rodsOutput at

1064 nm (YAG)1053 nm (YLF)Pump cavity

Ti:sapphire based ozone lidar transmitter schematic

Nd:YLF Oscillator

CW SeedDiode Laser #1925 nm, 20 mW

Beam Dump

Beam Dump

λ/2

CW SeedDiode Laser #2945 nm, 20 mW

ReshapingOptics

ReshapingOptics

SHG

THG

λ/2

SHG

SHGNd:YLF

AmplifierIsolator

Isolator925 nm

Isolator945 nm

Seed Laser Module

HR onscanner Output

coupler(GRM)

Beam Dump

FaradayRotator

Pump Laser

Ti:SapphirecrystalsTi:Sapphire Laser

Telescope

Telescope

LBO BBO

BBO

LBO

Angle-tuning data on KTA OPO

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

45 50 55 60 65 70 75 80 85 90Angle (degrees)

Wav

elen

gth

(um

)

y-cut idler data

x-cut idler data

x-cut signal data

y-cut signal data

I/O data for x- and y-cut KTA

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10

20

30

40

50

60

0 50 100 150 200 250Pump energy (mJ)

OPO

out

put e

nerg

y (m

J)

y-cut NCPM signal

y-cut NCPM idler

x-cut 66 deg. signal

x-cut 66 deg. idler

CdSe OPO I/O data

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 5 10 15 20 25 30

Pump energy (mJ)

Tota

l OPO

ene

rgy

(mJ)

3.45 um pump

3.18 um pump

CdSe OPO pump and signal pulse profiles

Composite actual tuning curve for Tandem OPO

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45 50 55 60 65 70 75 80 85 90Angle (degrees)

KTA signal

Wav

elen

gth

(m

)

CdSe signal

KTA idler

CdSe idlerx-cut KTA