National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Brian M. WalshNorman P. Barnes

NASA Langley Research CenterHampton, VA 23681 USA

Dual Wavelength Lasers

Laser Physics Workshop - Barcelona, Spain (July 13 - 17, 2009)

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

• Dual wavelength concept• I. Two Wavelength Oscillation (TWO)

- Er:Tm:Ho:YAG (2.0 and 2.9 µm)

• II. Synchronous Tunable Optical Pulses (STOP)- Nd:YAG (1.0xx and 1.3xx µm)

• IIa. Non-linear optics- SHG, sum frequency techniques

• III. Other dual-λ lasers- Er:Nd:YAG (2.9 µm and 1 µm)- Ho:Nd:YAG (3 µm and 1 µm)

• Summary

Outline

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Dual Wavelength Concept

• Dual wavelength lasing on separate dopant ions:- Energy transfer dynamics between the ions- Lifetimes of the upper laser manifolds- Duration of the pump pulse

• Dual wavelength lasing on same dopant ion:- System design (e.g., prisms, mirrors, resonator design)- Laser transition cross section

• Advantages- Can produce widely or closely separated wavelengths- Sum frequency, difference frequency readily implemented- One laser serves dual purpose (efficient & cost effective)- Medicine, remote sensing, surveillance, machining

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

I. Er:Tm:Ho dual-λ laser

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

TWO Laser schematic

Laser

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

1.)2.)3.)4.)5.)

R. Balda, et. al., Optics Express, 17, 8788 (2009)

Er:Tm Energy Transfer

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Er:Tm:Ho Energy Transfer

0

5000

10000

15000

En

erg

y (

cm-1

)

Tm3 + YAG Ho3 + YAG

4I15/2

4I13/2

3F4

5I8

5I7

3H6

Er3 + YAG

4I11/2

(! = 100 µs)

(! = 9 ms)

(! = 14 ms)(! = 8 ms)

4I9/2

3H55I6

23

1

2

4

2.9 µm

2.1 µm34

Short pump pulse - 2.9 µm Er lasing Long pump pulse - 2.1 µm Ho lasing Intermediate pump pulse - Er and Ho

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Pump Pulse Wavelength Tuning

Time

2.9 µm

Time

2.9 µm 2.1 µm

Time

2.1 µm

Short, high intensity Long, low intensity

Moderate length, mid-intensity

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Er Lifetime Quenching

0.0

0.2

0.4

0.6

0.8

1.0

0 50 100 150 200 250 300

Time (µs)

Norm

aliz

ed I

nte

nsi

ty

Er 4!11/2 Manifold Lifetime"2.9 µm upper laser level"

30%, 50%,60% Er YAG

10% Er 1% Ho

10% Er 4% Tm

10% Er 4% Tm 0.5% Ho

10% Er 5% Tm 1.0% Ho

4I11/2

Lifetime

90 µsec

80 µsec

50 µsec

40 µsec

35 µsec

Sample

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Er:Tm:Ho pulse switched lasing

0.0

0.20

0.40

0.60

0.80

1.0

1.2

0 50 100 150 200

Er 2.9 µm, 100 µs pump pulse, 0.90R OC

Ho 2.1 µm, 1 ms pump pulse, 0.95R OC

Las

er E

ner

gy

(J)

Electrical energy (J)

Cr(1)Er(35)Tm(0.7)Ho(0.35) YAG6x122 mm laser rod

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Er:Tm:Ho Simultaneous lasing

0

50

100

150

200

250

300

350

50 100 150 200

2.1 micron (0.95R)2.9 micron (0.85R)

Las

er E

ner

gy (

mJ)

Electrical energy (J)

1 ms 100 µs

0

50

100

150

200

250

300

350

10 20 30 40 50 60 70 80 90

2.1 micron (0.95R)2.9 micron (0.85R)

Las

er E

ner

gy (

mJ)

Electrical energy (J)

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

II. Nd:YAG dual-λ laser

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

STOP laser schematic

Output

Mirror

Nd:YAG diode

Pumped HeadQ-Switch

Quartz

Prisms

1.0xx µm

HR mirror

1.3xx µm

HR mirror

Synchronous

laser pulses

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Dispersive Tuning in Nd:YAGL( m) e(10-20 cm2) (cm-1) EETH(J) s

1.0520 9.62 5.7 4.93 0.0123 1.0614 20.62 4.8 2.60 0.0184 1.0641 27.74 6.0 1.99 0.0193 1.0737 15.15 5.2 3.62 0.0139 1.0779 6.26 9.9 7.63 0.0095 1.1120 3.97 12.1 10.28 0.0113 1.1160 3.95 14.4 11.48 0.0104 1.1225 3.97 11.4 11.26 0.0112

L( m) e(10-20 cm2) (cm-1) EETH(J) s 1.3187 8.92 4.5 6.64 0.0127 1.3336 4.03 3.7 11.82 0.0104 1.3381 9.57 5.0 6.53 0.0131 1.3564 7.35 6.6 8.42 0.0107

4F3/2 → 4I13/2 Parameters

4F3/2 → 4I11/2Parameters

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Synchronous Pulses

5000

0

1000

4000

3000

2000

12000

11000

Nd3+:YAG

4F3/2

4I9/2

4I11/2

4I13/2

852

0

133

199

312

11506

11421

3925

3932

4035

4050

4494

?

4432

2003

2029

2111

2146

2515

2462

Z5

Z1

Z2

Z3

Z4

Y1

Y2

Y3

Y6Y5

Y4

X1

X2

X3

X4

X7

X5

X6

R2R1 • Synchronous pulses require equal

pulse evolution time intervals- Different emission cross sections- Resonator lengths adjustable- Output losses adjustable (output coupling)

1

!c

"c

2lc

ln RMRL( ) + 2# e

l$c

2lc

%

&'(

)*EEP+ E

LTH( ),

-.

/

01

-1 0 1 2 3 4

Time (µs)

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

STOP light laser performance

0.0

0.10

0.20

0.30

0.40

0.50

0.60

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

1.052

1.319

Inv

erse

of

pu

lse

evo

luti

on

in

terv

al

( µs-1

)

Electrical energy (J)

0

5

10

15

20

25

30

35

0.6 0.8 1.0 1.2 1.4 1.6

1.052 QS1.319 QSBoth QS

La

ser

En

erg

y (

mJ

)

Electrical Energy (J)

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

IIa. Non-linear optics

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Non-linear Conversion

Red Orange Green~ 0.660 mm ~ 0.585 mm ~ 0.526 mm

SHG sum frequency SHG

SynchronousTunableOpticalPulses

BBO

Crystal

waveplate

1/2 waveat 0.59 µm

BBO

Crystal

VIS UV

Synchronous

laser pulses

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

One dual laser - 172 wavelengths

2B3BB+2A4B

A+B2AA+2B3A2(A+B)4A

1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40

Wavelength ( µm)

0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70

Wavelength ( µm)

A

B3F3/2 → 4I11/2

3F3/2 → 4I13/2

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

III. Other dual-λ lasers

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

0

2000

4000

6000

8000

10000

12000

En

erg

y (

cm-1

)

Er:YAG

4I15/2

4I13/24I15/2

4F3/2

Nd:YAG

4I11/2

(! = 100 µs)

(! = 9 ms)

(! = 240 µs)

4I13/2

4I11/2

4I9/2

4I9/2

1.06 µm2.9 µm1

1 2

2

3

Nd:Er:YAG

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

0

2000

4000

6000

8000

10000

12000

En

erg

y (

cm-1

)

Ho:YAG

5I8

5I6

4I15/2

4F3/2

Nd:YAG

5I5

(! = 50 µs)

(! = 1 µs)(! = 240 µs)

4I13/2

4I11/2

4I9/2

5I7

(! = 8 ms)

1.06 µm

3.0 µm

1

1 2

Nd:Ho:YAG

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

• Dual-λ lasers discussed and demonstrated- Er:Tm:Ho:YAG (TWO laser)- Nd:YAG (STOP laser)

• Physics & engineering criteria- energy transfer, lifetime, transition cross section- Optics, resonator design, pumping schemes

• Non-linear techniques- SHG and sum frequency techniques- Multitude of harmonic wavelengths realized

• Future work- What new potential dual- λ lasers exist?- Driven by application needs, multiple solutions

Summary

National Aeronautics andSpace Administration

Laser Physics WorkshopBarcelona, Spain (July 13-17, 2009)

Brian M. WalshLaser Remote Sensing BranchEmail: brian.m.walsh@nasa.govPhone: 757 864-7112

NASA LangleyResearch Center