Laser Development at Q-Peak for Remote Sensing

Peter MoultonQ-Peak, Inc.

MRS Spring MeetingMarch 29, 2005

Paper FF1.1

Outline

• Introduction to Q-Peak• Early systems: lamp-pumped (mostly)

– High-energy Ti:sapphire lasers– High-energy eyesafe parametric oscillators

• Recent systems: diode-pumped– Basic lasers– Parametric oscillators for IR coverage– Amplified microchip laser for precision ranging– Single-frequency UV laser for direct-detection wind

sensing• Under development:

– High-energy pump for ozone lidar– QCL-seeded IR parametric oscillator– Fiber-laser-pumped Ho:YLF/ZGP OPO

Q-Peak History

• Previously Research Division of SEO, founded 1985– Established to provide SEO with the latest in solid state laser technology, leveraging

outside funding as much as possible– Conducted Government, commercial and internally funded R&D– Developed multi-wavelength, lamp-pumped lasers and Ti:sapphire lasers as scientific

and OEM products– SBIR’s (> 22 Phase II programs) a large component– Developed key technology for BSDS $40 million Government contract in Orlando– Developed high-power, diode-pumped solid state laser as basis for new product line– Accumulated contract R&D sales through 1998: > $25 million

• Spun out as Q-Peak, July 1, 1998, a subsidiary of SEO– Continued Government and commercial Contract R&D work and further developed a

commercial business in diode-pumped lasers

• Acquired by Physical Sciences Inc. (Andover, MA) on October 15, 2001– Continuing contract R&D work, custom product sales, limited production and

developing partners for large-scale production of commercial lasers– Establishing synergies with PSI in photonics areas

High-Energy Ti:sapphire Lasers

Ti:sapphire laser is pumped with blue-green wavelengths and lases in near-IR

400 500 600 700 800 900 1,0000

0.2

0.4

0.6

0.8

1

0

0.2

0.4

0.6

0.8

1

WAVELENGTH (nm)

AB

SOR

PTIO

N C

OEF

FIC

IEN

T (a

rb. u

nits

)

FLU

OR

ESC

ENC

E IN

TESI

TY (a

rb. u

nits

)

Fluorescence and gain in Ti:sapphire spans a large wavelength region

600 700 800 900 1000

0.2

0.4

0.6

0.8

1

WAVELENGTH (nm)

INTE

NSI

TY (a

rb. u

nits

)

GAIN

PI

SIGMA

Laser-pumped, high-energy Ti:sapphire laser design uses unstable resonator

Pump #1

Pump #2

Output

GRM

HR

Ti:sapphirecrystals

Prisms

Developed with NASA Langley, DARPA support, 1986-1992Continuing to build systems for specialized sensing

applications in the near-IR and UV

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

•The seed source is a single-frequency diode laser operating around 815 nm

•The pump laser produces two pulses spaced less than a msec apart, to provide on-line, off-line data for a “frozen” atmosphere

•LASE has flown > 30 times on an ER-2 and on a P-3 aircraft since 1995. Now being adapted for DC-8

DARPA/ONR SLC Ti:sapphire achieved 250 mJ, 455-nm, narrow-linewidth power

But, program cancelled

Harmonic conversion of Ti:sapphire lasers: applied to DIAL, fluorescence lidar

700 750 800 850 900 950Wavelength (nm)

NO2

Benzene

Hg

Toluene Ozone

NO

SO2

Cl2

2nd

3rd

4th

Harmonic

50 mJ at 253 nm, 28 MHz linewidth source for Hg resonance filter

Frequency-doubled,Flash lamp-pumped,

Nd:YAG laser

Pulsed Ti:sapphirelaser

Ti:sapphireseed laser

Ramp & Lock electronics

10HzMaster clock

High voltageOp-amp

Photo-diode PZT

FlashlampTrigger

Pulses from seeded lasers

50 mJ, 290-nm source used solid state green laser to pump cw Ti:sapphire seed laser

Pulsed Ti:Sapphire LaserTHG Module SHG Module

SHG Module

Lamp DriverCooler Pump LaserNd:YLF

Isolator

532-nm CW Pump Laser CW Ti:Sapphire Laser

Output

290 nm50 mJ 200 mJ, 870 nm

1 J, two beam lines

BBO crystals

1.75 J, two beam lines

900 mW, 870 nm5 W, 532 nm

Ozone lidar transmitter for NASA Langley used diode-laser seed sources

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:YLF Pump Laser

Pulsed Ti:sapphire Unstable-Resonator

LaserBBO- orLBO-based

1996, Phase II NASA SBIR

THG efficiency and energy exceeded 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)

Photo of NASA ozone Ti:sapphire system

Facility for Airborne Atmospheric Measurements (FAAM)

BAE 146-301 Large Atmospheric Research Aircraft G-LUXE

FAAM is the result of a collaboration between the Met Office(TM) and the Natural Environment Research Council (NERC) to provide an aircraft measurement platform for use by all the UK atmospheric research community. The aircraft is owned by BAE Systems and operated for them by Directflight. The Home Base is at Cranfield University, Bedfordshire.

Detailed block diagram of NIR/UV Lidar source for FAAM

Pulsed Ti:sapphire Laser

HarmonicGeneration

Ramp /LockElectronics

Pump LaserLamp Drivers

Lasers Cooling

WavemeterWavemeterComputer

NIROutput

Optical bench

Electronics rackElectrical CoolantOptical

ECDLSEED

ECDLSEED

ECDLSEED

ECDLSEED

ECDLSEED

Switch

Seed LaserControl/Drive

MasterControl

Big SkyPump Lasers

UVOutput

Toptica DL100 ECDL seed source with Laserscope accessory

High-energy eyesafe parametric oscillators

Test system for high-energy KTP OPO

KTP OPO

InputMirror

OutputMirror

Q-switched Nd:YLF1053 nm, 0-240 mJ,

10 ns, 10-50 Hz- or -

625 mJ, 30 Hz

Q-switched Nd:YAGOsc / Amp

1064 nm, 0-1.1 J,10 ns, 10 Hz

-or-

Telescope

OPOSignalOutput

OPO resonator designs

pump

signalRING

pump signal

HT pump HR signal

PR signal HR 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)

Compact, ruggedized lamp-pumped laser with internal OPO

Complete OPO-based lidar system built for NASA Langley

Complete CLEAR lidar system at UCLA used Q-Peak eyesafe OPO transmitter

Application of CLEAR lidar to urban areas

Army biological standoff detection system (LR-BSDS) used Q-Peak high-power OPO

Plot of KTP and KTA IR transmission

3000 3200 3400 3600 3800 40000

20

40

60

80

100T = 75% @ 3297nm

T = 23% @ 3297nm

KTA 2cm KTP 2cm

Wavelength (nm)

%T

Design for high-power KTA OPO

signal out

pump in

pump& idler out

CaF2prism

KTA x-cut

Four KTA Crystals 1 x 1 x 2 cm each

0 20 40 60 80 100 1200

5

10

15

20

25

30

35

Pump Power (Watts)

Sign

al P

ower

(Wat

ts)

M.S. Webb et al. Opt.Lett. 23, 1161 (1998)

Detail of BSDS system mounted in UH-60

Recent systems: diode-pumped

Basic lasers

SALTS 2-micron coherent lidar source built for for wind profiling off ships

Inside of SALTS hermetic-sealed laser head – mirrors aligned and then hard-mounted

Q-Peak’s DPSSL design obtains high efficiency and high beam quality with side-pumping

Diode laser

Diode laser

Laser crystal

Cylinder lens Laser beam

Pump beam

Multi-Pass Slab (MPS)US Patent 5,774,489

“Gain Module”Applied to Nd:YLF, Nd:YVO4 , Nd:YAG Yb:S-FAP, Yb:YAG, Tm:YLF, Er:YLF, Cr:LiSAF

MPS Tm:YLF cw laser operation provides tunable IR output

0

1

2

3

4

5

6

1900 1920 1940 1960 1980 2000 2020 2040 2060 2080

Wavelength, nm

Out

put p

ower

, W

T=3 %T=13%

Wavelength tuning of Tm:YLF laser with a 2-plate birefringent filter (TEMoo operation) for two values of output coupler transmission.

Technology of efficient diode-pumped, conduction-cooled Nd:YLF rod laser

Design concept CAD model

I/O curve for conduction-cooled rod laser

0

0.1

0.2

0.3

0.4

0.5

0 0.2 0.4 0.6 0.8 1 1.2 1.4Pump Energy (J)

Out

put E

nerg

y (J

)

R = 70%

R = 60%

No Pockels cell or polarizer in the resonator, cavity length 15 cm, rep rate 10Hz, pump pulsewidth 400ms

40% slope efficiency

Q-switched results: 110 mJ/pulse in double-pulse format

Recent systems:

Parametric oscillators for IR coverage

Amplified microchip laser for precision ranging

Single-frequency UV laser for direct-detection wind sensing

Tuning curve for MPS-driven KTA OPO

0

1

2

3

4

5

6

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2

Wavelength (um)

Pow

er (W

)

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 m

3.3 - 11 m

Or: PPLN, other KTP isomorphs

Or: AgGaSe2 ZnGeP2

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

Overall design of SBCCOM, rapidly tunable, 1-kHz PRR Tandem OPO

Legend:Laser diode currentMPL control (current settings, burst mode)AOBD control (RF, burst mode)Rotation control (angle)Trigger pulseBurst pulse

AOBD

MPL RF Synthesizer(rapid tuning)

Rotation control(slow tuning)

OSC AMP 3AMP 2

PC 2

Mid IR output

Rotary stages

External burst

PC 1

AMP 1

Legend:Laser diode currentMPL control (current settings, burst mode)AOBD control (RF, burst mode)Rotation control (angle)Trigger pulseBurst pulse

AOBD

MPL RF Synthesizer(rapid tuning)

Rotation control(slow tuning)

OSC AMP 3AMP 2

PC 2

Mid IR output

Rotary stages

External burst

PC 1

AMP 1

Microchip laser schematic and performance

Pump optics

Dielectric coatingHR laserHT pump

Fiber-coupled diode laser

Nd:YAG(laser)

Cr:YAG(Q-switch)

Dielectric coatingPR laser

Microchip laser output

1.5 mm

0.7 W pump power at 809.0 nm 440 ps pulse duration

SLR2000 transmitter for precision satellite ranging based on amplified microchip

Fiber

Nd:YAG/Cr:YAG Microlaser

TelescopeIsolatorplate

Cylindrical lens

HR Mirror

Nd:YVO4 Multipass Amplifier

/2 plate

SHG

Diode laser

532-nmbeam

Design: MPV-amplified microchip laserPulse duration: 200-300 psPulse energy: 200 uJ at 532 nmPulse rate: 2 kHz

Photograph of hardwaredesigned for remote, autonomous operation

4 mJ, 1 kHz PRR single-frequency source at 349 nm for incoherent-detection wind-sensing

4

11

11

2

5

3

79

8

10

11

1

12

12

1

13, 14

Amplifier Gain Modulew/ 90-W Lightstone diodes

NCPM LBO(SHG) crystal

15 CPM LBO(THG) crystal

17

16

1047-nmoutput

349-nmoutput

Beamdump

SLM

Seed

Lase

r

Seeder ElectronicsPhotodetector

Optical Isolator

Oscillator Gain Modulew/ 40-W diodes

UV-ContollerPhotodetector

6

G-5398

Under Development

100 W, 1-kHz IR source for ozone lidar

Nd:YLF oscillator1-1.5 mJ, 6-9 ns

1 kHzTandem optical

isolatorDouble-passpreamplifierRetro-mirror

14-18 mJ

Final stageamplifier

Pre-finalamplifier

100 mJ, 6-9 ns1 kHz

Required Pump Laser Parameter Units Wavelength 1047 nm Linewidth <500 MHz SLM (no multimode

permitted) Average Power 100 W combined Main leg Secondary leg ** after OPO isolator

70 W 30 W **

Pulse width 6-8 ns (critical not to exceed) Beam diameter < 2 mm 1/e^2 points Beam quality M^2 < 1.3 in both axis Beam shape Near circular > 90% Pulse shape >95 % gaussian , no after pulsing

Results to date: 28 mJ at 1 kHzfrom a single crystal

Quantum-cascade-laser (QCL) seeded OPO for atmospheric sensing

MIROPO

QCLseeder

2.05-umpump laser

2.2 to 4.0 umsignal output

4.0 to 22 umidler output

Design goal:200 mJ/pulse>50-Hz PRRpump laser

Photograph of Phase IZGP OPO demonstration

Scale-up of Ho:YLF-driven ZGP OPO will use 350 W of Tm-fiber-laser pumping

HR

OC AOM

Ho:YLF

Tm-fiber laser

DM DM

Ho:YLF

PBS

/2

Results to date: 40 W of cw power 40 mJ of Q-switched energy in 17-ns pulse

0

5

10

15

20

25

30

35

40

45

0 20 40 60 80 100 120

Total Tm-pump power, W

Ho:

YLF

ener

gy p

er p

ulse

, mJ

1000 Hz400 Hz200 Hz

Tuning curve for Ho:YLF-pumped ZGP OPO

2

3

4

5

6

7

8

9

51 52 53 54 55 56 57 58

Angle (degrees)

Sign

al, i

dler

wav

elen

gths

(um

)

ZGP OPO operation – pulse energy at 3200 nm

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30

Pump pulse energy, mJ

OPO

pul

se e

nerg

y, m

J

50 Hz200 Hz400 Hz

Slope efficiency:50 Hz 60%200 Hz 56%400 Hz 63%

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 IR, visible and UV wavelengths for a variety of species detection

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

• Diode-pumped laser extend the performance of solid state lasers and provide the basis for satellite-based active remote sensors

• Nonlinear optics based on improved nonlinear crystals provide extended, tunable wavelength coverage from LWIR to the UV