recent advances in mid-ir solid state lasers, opos and qcls · commercial products developed by...
TRANSCRIPT
Recent Advances in Mid-IR Solid State Lasers, OPOs and QCLs
Peter MoultonVP/CTO
Q-Peak, Inc.
Outline
• Diode-pumped mid-IR sources– Er:YLF– Tm-laser-pumped Ho:YLF
• OPOs– ZnGeP2
(ZGP) OPO pumped by Ho:YLF laser– Tandem OPO (KTA –
CdSe)• QCL-based sources
Commercial products developed by Q-Peak
Laser 1-2-3 Titan CW, P, ML
MPS Lasers (early)
MPS Gain Module
MPS LaserHead
The Laser 1-2-3 provided a range of wavelengths, into the mid-IR
Pump cavity, rod and mirrors for solid state laser
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
Er3+
Energy Level Diagram
4F7/2
4S3/2
2H11/2
4F9/2
4I9/2
4I11/2
4I13/2
4I15/2
Pump
2.8 m
W11
W11
W22
W22
N2
N1
W50
W50
Earlier end-pumped work produced cw
powers from several materials
0 500 1000 1500 2000 2500 30000
100
200
300
400
500
Diode power (mW)
Pow
er (m
W)
Er:YSGG
Er:GGG
Er:BYF
Er:YAG
Previous results –
Diode-pumped Er:YLF-lasers
• Maximum slope efficiency :– ~ 40% -
Ti:Sapphire excitation (970 nm, longitudinal)M.Pollnau
et al., “Efficiency of Erbium 3-m crystal and fiber lasers”
IEEE J. of Quantum Electronics, 32, 657-663 (1996)– ~ 35% -
Diode-Pumped (970 nm, longitudinal) T. Jensen, A. Diening, G. Huber, and B.H.T. Chai, “Investigation
of diode-pumped 2.8-m Er:LiYF4 lasers with various doping levels, Opt. Lett., 21, 585-587 (1996).
• Maximum CW output:– ~ 1.1 W Diode-pumped (970 nm, longitudinal, fiber-coupled diode
laser)T. Jensen et al. (see above)
• Drawbacks:• difficult to scale to higher powers• fracture of the laser elements at 4-6 W pump power (0.3-0.5 mm
spot)
Absorption Properties of Er:YLF
Laser Crystals
Polarized absorption spectra for 15% Er:YLF
crystal at 300 K.
0
5
10
15
20
25
30
960 965 970 975 980 985 990
Wavelength, nm
Abs
orpt
ion
coef
ficie
nt, c
m-1
0
5
10
15
20
25
30
PiSigma
Brewster-angle design for side-pumped Er:YLF
laser
Er:YLF
Active Element:Brewster/Brewster-cut slab: 28-mm longClear aperture 1.25 x 6 mm.
Experimental Set-Up
DL
15% Er:YLF DL
HR r=10 cmcc
HR
OC r=10 cmcc
HR
a) Compact 3-pass resonator
DL
15% Er:YLF DL
HR r=30 cmcc
HR
OC r=10 cmcc
HR
BRF
b) “Long” resonator
Rate equations:dN2 /dt = W + W11 (N1 )2 – W22 (N2 )2 – N2 /2 ,
dN1 /dt = 21 N2 /2 + W22 (N2 )2 - 2 W11 (N1 )2 – N1 /1 ,
The net gain coefficient:g =
(b2 N2 –b1 N1 ),
Definitions:W11 , W22 - up-conversion rate parameters,
1 and 2 - lifetimes for spontaneous decay and
21 - the branching ratio.
- spectroscopic cross section for the transition and
b1 , b2 - Boltzmann factors for the lower and upper manifolds.
1 10 msec
2 4.0 msec
W11 3x10-17
cm3/sec
W22 1.8x10-17
cm3/sec
21 0.39
3x10-20
cm2
b1 0.113
b2 0.2
Theoretical Model
Table. Values for 15% Er:YLF used in the calculations (Based on the data from: M.Pollnau et al. IEEE J. QE, 321, 657-663 (1996)).
Gain Calculation
0.01
0.1
1
1.00E+21 1.00E+22 1.00E+23
Pump Rate, cm-3
Gai
n co
effc
ient
, cm
-1Linear
Square root
Calculation
20-W pump
Experiment
10-W
Er:YLF
CW Laser Operation
Three-Pass Geometry
~ 40 cm~ 20 cmResonator lengthT ~ 4% at 2600-2900 nmT ~ 4% at ~ 2600-2900 nmOutput coupling
2600-3000 nmHR mirrorlongshort
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 5 10 15 20 25 30 35 40Total diode power, W
Out
put p
ower
, W
shortlong
15% slope efficiency
16.5% slope efficiency
Er:YLF
quasi-CW Laser Operation
Three-Pass Geometry
~ 40 cmResonator lengthT ~ 4% at 2600-2900 nmOutput coupling
2600-3000 nmHR mirror
0
2
4
6
8
10
12
0 5 10 15 20 25 30 35 40 45 50Diode current, A
Peak
pow
er, W 25%
33%50%CW
Calculated Wavelengths for Transitions Between 4I11/2
and 4I13/2
Manifolds in Er:YLF
Manifold 4I/11/2 Level 1 2 3 4 5 Energy,
cm-1 10222 10235 10283 10289 10315
nm nm nm nm nm 7 6738 2870.3 2859.6 2820.9 2816.1 2795.6 6 6724 2858.8 2848.2 2809.8 2805.0 2784.7 5 6697 2836.9 2826.5 2788.6 2784.0 2764.0 4 6674 2818.5 2808.2 2770.9 2766.3 2746.5 3 6579 2745.0 2735.2 2699.8 2695.4 2676.7 2 6539 2715.2 2705.6 2670.9 2666.7 2648.3
4I13/2
1 6535 2712.2 2702.7 2668.1 2663.8 2645.5
Note:
Bold numbers indicate wavelengths for which lasing has been obtained in prior work.
Er:YLF
CW laser operation
wavelength tuning
Wavelength tuning of Er:YLF
laser with a 1-plate birefringent filter
0
200
400
600
800
1000
1200
1400
2700 2720 2740 2760 2780 2800 2820 2840Wavelength, nm
Out
put P
ower
, mW
Mid-IR source: Tm-doped laser-pumped, Ho:YLF laser pumped, ZGP OPO
ZGPOPO
Ho:YLFlaser
Tmlaser
100 mJ2050 nmCW
1940 nmQ-switched
2050 nm
Broadly tunablemid-IR
Why a laser pumping a laser pumping a laser?
• Semiconductor diode laser– high electrical-optical efficiency but– only cw-like output, poor beam quality at high powers
• Tm solid state laser (bulk or fiber)– good (in theory) conversion of poor quality beam from diode
lasers into diffraction-limited beam but– limitations in stored energy and nonlinear/damage issues
prevent generation of high pulse energies• Bulk solid state Ho:YLF laser
– good conversion of pump power to output power– high energy storage and extraction capability allows
generation of high-peak-power pulses
References on resonantly pumped Ho lasers
P.F. Moulton, “Industry R&D related to 2-m lidars,”
Second Review of 2-m Solid State Laser Technology, NASA Headquarters, Washington, DC, May 18-19, 1992.
R.C. Stoneman
and L. Esterowitz, Opt. Lett. 17, 736 (1992).
D.W Hart, M. Jani
and N.P. Barnes, Opt. Lett. 21, 728 (1996).
M. Petros, J. Yu, U. N. Singh and N.P. Barnes, “High energy directly pumped Ho:YLF laser,”
in Advanced Solid State Lasers, OSA Technical Digest (Optical Society of America, Washington, DC, 2000), pp. 79-81.
P.A. Budni, M.L. Lemons, J.R. Mosto, and E.P. Chicklis, IEEE J. Sel. Topics in Quantum Electron. 6, 629 (2000).
P.A. Budni, M.L. Lemons, C.A. Miller, P.A. Ketteridge, L.A. Pomeranz, T.M. Pollak, P.G. Schuneman, K.L. Lanier, J.R. Mosto, and E.P. Chicklis, “High power 1.9 micron pumped solid state holmium lasers,”
in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optical Society of America, Washington, DC, 2000), p 564.
L.D. DeLoach, S.A. Payne, L.L. Chase, L.K. Smith, W.L. Kway
and W.F. Krupke, IEEE J. Quantum Electron. 29, 1179 (1993).
W.F. Krupke
and L.L. Chase, Optical and Quantum Electron. 22, S1 (1989).
1D2
3F2
1G4
3F33H4
3H5 3F4
3H6
Pump~790 nm 1.9 m
N1
N0
Cross-relaxation
Lasing
N3~14 ms
~1 ms
(1%)
•1 2 pump process due to cross-relaxation•low up-conversion•low heat generation (~20 %)
Tm3+
Energy Level Diagram
Emission Cross-Section –
3.5% Tm:YLF
0.0E+00
5.0E-22
1.0E-21
1.5E-21
2.0E-21
2.5E-21
3.0E-21
3.5E-21
4.0E-21
4.5E-21
5.0E-21
1600 1650 1700 1750 1800 1850 1900 1950 2000
Wavelength, nm
Cro
ss s
ectio
n, c
m 2
Polarized emission cross-section 3F4 3H6 for Tm:YLF (calculated from absorption spectra).
Gain Calculation –
3.5% Tm:YLF
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
1800 1825 1850 1875 1900 1925 1950 1975 2000
Wavelength, nm
Gai
n co
effic
ient
, cm
-1
Inversion fraction
Polarized gain in Tm:YLF at two values of inversion fractiong() = N [ pem () - (1-p)abs () ],where p – inversion fraction, N - Tm-concentration
Tunable power from Tm:YLF laser
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%
Tm:YLF Active Element:Rectangular slab: 22-mm longClear aperture 2x6 mm.
Experimental Set-Up –
Tm:YLF Laser
Tm:YLF DL
HR
OC
DL
BRF
Tm:YLF DL
DL
Tm:YLF –
Dual GM Oscillator –
3 passes
0
5
10
15
20
25
30
0 20 40 60 80 100 120 140 160 180
Diode pump power, W
Out
put p
ower
, W
25% slope efficiency
Ho:YLF vs. Ho:YAG
• Why Ho:YLF (Q-Peak, NASA) ?– Long upper laser level lifetime ~ 15 ms (in theory)– Highest emission cross-section known for Ho-doped crystals
= 1.84 x 10-20
cm2
– Esat
= 5.3 J/cm2
– Naturally birefringent material– Low dn/dT
–> weak thermal lensing– ~5% quantum defect
• Compared to Ho:YAG (BAE, SORC)– Upper state lifetime 7 ms– Emission cross section 0.98 x 10-20
cm2
– Esat
= 9.6 J/cm2
– 10% quantum defect– Isotropic, higher thermal lensing, stress birefringence– Superior thermo-mechanical properties
Pumping Ho:YLF with Tm:YLF laser
0
0.5
1
1.5
2
2.5
3
3.5
1800 1850 1900 1950 2000 2050 2100 2150
Wavelength, nm
Abs
orpt
ion
coef
ficie
nt, c
m-1
Ho abs - PiTm-tuning
2.0% Ho:YLF
Ho:YLF gain is predicted to be high for a 59% inversion fraction
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
1800 1850 1900 1950 2000 2050 2100 2150
Wavelength, nm
Gai
n, c
m-1
0.590.2
Schematic layout of the end-pumped Ho:YLF laser
HR
OC
AOM
Ho:YLF
Tm:YLF laser #1
Tm:YLF laser #2
DM
DM
DM –
Dichroic
Mirror, AOM –
Acousto-Optic Modulator, OC –
Output Coupler, HR –
High Reflector
CW Ho:YLF Laser Operation (TEMoo
)
0
5
10
15
20
25
0 10 20 30 40 50 60
Total Tm pump power, W
Ho:
YLF
CW
out
put,
W
10%15%40%70%
54% slope efficiency
45% slope efficiency
Toc
Ho:YLF laser operation is in TEMoo
mode
Ho:YLF –
Q-Switched Operation (TEMoo)
0
2
4
6
8
10
12
14
16
18
0 500 1000 1500 2000 2500
Repetition rate, Hz
Out
put p
ower
, W
0
5
10
15
20
25
30
35
40
Puls
e en
ergy
, mJ
PE
Ho:YLF –
Pulsewidth vs
repetition rate
0
5
10
15
20
25
0 200 400 600 800 1000 1200
Repetition rate, Hz
Puls
ewid
th, n
s
Ho-laser Power Scaling
• CW Tm:fiber lasers with output >100 W emerge as alternative to bulk Tm-laser:
– Turn key operation– Cost-effective– Maintenance-free– Fiber delivery (no surprise!)
Operation regime CW
Operational temperature RT
Output power ≥
100 W
Lasing wavelength range: 1750-2200 nm
Polarization: Random
Linewidth ≤
2 nm
Tm-fiber laser TLR-100-1940 (IPG Photonics, www.ipgphotonics.com
)
Schematic layout of the fiber-pumped Ho:YLF laser shows two-crystal design
HR
OC AOM Ho:YLF
Tm:fiber laser
DMDM
Ho:YLF
PBS
/2
DM DM
DM – Dichroic Mirror, AOM – Acousto-Optic Modulator, OC – Output Coupler, HR – High Reflector
CW laser operation provides 40-W of output power
0
5
10
15
20
25
30
35
40
45
50
0 20 40 60 80 100 120
Total Tm-pump power, W
Ho:
YLF
outp
ut, W
40%70%
Slope Efficiency 42%Quantum efficiency 74% (absorbed)
Output transmission
Ho:YLF Q-switched laser operation observed at pulse rates from 200-1000 Hz
0
5
10
15
20
25
30
35
40
45
50
0 20 40 60 80 100 120
Total Tm-pump power, W
Ho:
YLF
puls
e en
ergy
, mJ
w1-1kw1-400w1-200w2-200w2-400
"Moderate" focusing
"Loose" focusing
28 ns
20 ns
17 ns
32 ns
22 ns
We chicken out
Ho:YLF effective storage time is around 2 msec
based on energy vs. pulse rate data
0
5
10
15
20
25
30
35
40
0 2 4 6 8 10 12 14 16 18 20
Period (msec)
Puls
e en
ergy
(mJ)
Data
Theory, 1.89 msec
Reasons: Bleaching, upconversion?
OPOs
Theoretical 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 -
Layout
• ZGP OPO:– ZGP 1 cm-long– Type I, 53o-cut – Flat/flat resonator– Singly resonant cavity– Pump –
double pass– ~6 cm-long resonator– OC 38% at 3.2 um
R=38% 3.2 um
HR 2.05 um
HT 5.7 um
HR 3.2 um
HT 2.05 and 5.7 um
ZGP
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%
Packaged Tm:YLF, Ho:YLF, ZGP OPO system
Conclusions
• Fiber-laser pumped Ho:YLF crystal (and similar materials) combines best features of fiber and bulk solid state lasers
– High beam quality and efficiency of fiber lasers– Energy storage capability of bulk lasers
• Recent advances in commercial (IPG) Tm:fiber lasers have made 100-W devices available. Future powers even higher?
• Ho:YLF laser has a favorable combination of energy storage and high gain cross section, suitable for high-energy, short-pulse
Q-switched oscillators and amplifiers at 2050 nm
• 2050-nm wavelength is eyesafe, transmits well through the atmosphere and is a good pump wavelength for ZGP OPOs
providing coverage of entire mid-IR wavelength region
• Scaling to 40 W average power, 45 mJ
pulses at 20 ns to date• Stayed tuned, another 200 W of pump power yet to go!
Early Nd:YLF
MOPA system generated
40 W Q-switched at 5 kHz
EOQ-switch
Two-module Nd:YLF Oscillator1st StageAmplifier
2nd StageAmplifier
50 W CW40 W Q-Sw
@ 5 kHz14-ns pulsewidth
Cylinderlens
Cylinderlens
Two-Gain-Module oscillator generated 14-ns pulses at a 5-kHz pulse rate
10 ns per division
Data on IR OPOs pumped by MPS system
• Pump source: 40 W, 5 kHz, 15 ns Nd:YLF
MOPA• KTA OPO
– 60-mm crystal length, 80-degree cut• 30 W pump, 5 kHz PRR• 10 W at 1530 nm, 3 W at 3340 nm
– 40-mm crystal length, 60-degree cut• 31 W pump, 5 kHz PRR• 2.5-5 W of idler tunable from 2100-3100 nm
• PPLN OPO– 19-mm crystal length, 30.8-um pitch
• 30 W pump, 5 kHz PRR• 5.2 W at 2610-nm idler, 3W at 1720-nm signal
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
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
)
Design for high-power KTA OPO
Moderate threshold Moderate efficiency High damage Low feedback
signal out
pump in
pump& idler out
CaF2prism
KTA x-cut
Four KTA Crystals 1 x 1 x 2 cm each
Highest-average-power OPO uses KTA
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)
High-average-power, 100-Hz OPO used KTA
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)
M2
= 30 M2
= 41
Results with two different pump lasers, pump laser pulsewidths
22.5 and 17.5 ns
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 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
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 90
Angle (degrees)
Wav
elen
gth
(um
)
y-cut idler data
x-cut idler data
x-cut signal data
y-cut signal data
Seeded Nd:YLF ring pump laser (lamp pumped(
HR Seed laser
Optical isolator
PD
LockingElectronics
PZT
OC
HR
HR
Dove prism
Pockels
cell
/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
KTA OPO pumping: seeded and unseeded laser
0
10
20
30
40
50
60
70
0 50 100 150 200 250Pump energy, mJ
KTA
OPO
tota
l out
put e
nerg
y, m
J
Seeded pump
Unseeded pump
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
KTA OPO pump and signal pulse profiles
Seeded pump Unseeded pump
1 - pump pulse2 - signal pulse
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
Diode-pumped, 1-kHz Nd:YLF
OPO pump-system layout
L1 & L4, collimating lenses,L2 & L3, relay-imaging lenses
QCW-end-pumped, AO Q-switched, Nd:YLF
Oscillator
1st StageAmplifier
2nd StageAmplifier
Isolator /2plate L1
L4
L2L3OPO pump beam
Nd:YLF
pump generates 18 mJ/pulse at 1 kHz, with 10-nsec-duration pulses, TEMoo
output
0
5
10
15
20
25
20 40 60 80 100 120 140
Total amplifier pump power (W)
Out
put p
ulse
ene
rgy
(mJ)
0.9 mJ1.9 mJ2.8 mJ3.6 mJ4.7 mJ
KTA OPO performance
(signal 1.504 m, idler 3.45 m)
y = 0.4738x - 0.9086
0
1
2
3
4
5
6
7
8
0 5 10 15 20
Pump energy (mJ)
KTA
OPO
out
put e
nerg
y (m
J) Total
Signal
Idler
CdSe
OPO performance
(signal 5 m, idler 10.5 m)
0
50
100
150
200
250
300
350
0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5
KTA OPO idler pulse energy (mJ)
CdS
eO
PO to
tal p
ulse
ene
rgy
(J)
Overall design of 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
QCL-based systems
PSI (parent company of Q-Peak) now adding QCLs
into gas sensing systems
• Direct current injection devices from 0.43 2.0 m; 3.3 105 m• Frequency converted devices from 0.22 0.43 m (SHG); 2.3
4.5 m (DFG, OPO)
0.1 1.00.5 10.05.0
InGaAsAIGaAs
InGaAIPGaN
Type II IC
Type I QC
InGaAs
E-3757a
Wavelength (m)
SHG Si-Fiber Optic Win
dowPPLN-basedDFG, OPO
NO, OH
NO2O2
H2OCOOH NO
CO2
CONOCH4
NO
SO2
Ro. Vibronic Vibration Overtones FundamentalVibrational Modes
10-24
10-22
10-20
10-18
Abs
o rpt
ion
Str e
ngth
(cm
/Mo l
e cul
e,Lo
gSc
ale)
Typical Type I QCL Temperature/Current Tuning
• 7.16 micron DFB from Alpes
Lasers• 4 cm-1
total tuning range with TE cooler• 1 cm-1
high-speed current tuning range at fixed T
TE-Cooled QCL Mount
• Integral current pulser – 3 ns pulsewidth, 3 MHz rep rate• Typical average power ~ 1 mW
• Dual-Stage TE-cooler for 270 – 320 K operation
3.35 m ICL Laser
Manufactured by Maxion Technology
Singlemode
over full current tuning range >19 dB SMSR
>5 mW output power
0 5 10 15 205.0
5.5
6.0
6.5
7.0
7.5
cw - pin #3T = 80 K521 nm grating
M115C ; epi-up DFB ICL8.5-µm x 1.013-mm mesa
Volta
ge(V
)
Current (mA)
0
1
2
3
4
5
6
Pow
er(m
W/f
acet
)
3.30 3.33 3.36 3.39 3.42 3.45 3.481x10-3
0.01
0.1
1
10
100
cwT = 120KI = 11.51mA
~ 19.2 dB
= 3.3564-µm
M115C ; Epi-Up DFB ICL8.5-µm x 1.013-mm mesa
Inte
nsity
(arb
)Wavelength (µm) G-5705
DFB IC Laser Characterization
Injection Current Tuning
• Compared to simulated ethane absorption spectrum• FTIR-limited laser bandwidth
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980Wavenumber (cm
Rel
ativ
eSi
gnal
(a.u
.)
75
80
85
90
95
100
Tran
smis
sion
(%)
32mA28mA20mA22mA16mA12mAC2H6 (100ppm-m)
T= 121.8K @ 22mA
G-5708
• ~ 1.5 cm-1
current tuning range at fixed T
Quantum-cascade-laser (QCL) seeded OPO
for atmospheric sensing (NASA-funded)
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 ring-cavityZGP OPO
Seed laser is 4.6-m, cw
QCL
Seed laser can be current-tuned
Summary