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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
400
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
10
15
20
25
30
35
40
45
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
1
2
3
4
5
6
7
8
9
10
11
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
0
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
1
2
3
4
5
6
7
8
9
10
11
12
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