advances in mid and far infrared coherent sources and their applications valdas pasiskevicius...
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Advances in mid and far infrared coherent sources and their
applications
Valdas Pasiskevicius
Applied Physics, KTH
Outline
• Spectral ranges• Application areas• Radiation sources:
coherent vs incoherent• MIR, FIR coherent sources:
technology options• Developments at KTH• Beyond state of the art
Spectral ranges
MIR: = 2 µm – 30 µm (150 THz – 10 THz)
Cr2+, Fe3+
Spectral ranges
FIR: = 300 µm – 30 µm (0.1 THz – 10 THz)
Options: coherent vs incoherent
0 20 40 60 80 10010-6
10-4
10-2
100
102
104
106
QCL LD
Er:ZBLAN
NLONLO
TBB
=2000 K, =1cm-1, A=10 mm2
P,
W/c
m-1
, m
[G. P. Williams, Rev. Sci.Instr. 73, 1461 (2002)]Advantages of coherent sources:• High power• High spectral power density• High brightness• High wall-plug efficiency
Benefiting Applications:• All except simple spectroscopy
Advantages of incoherent sources:• Broad range• Inexpensive
Main application:• Spectroscopy
Applications: Sensing• Strong transitions at fundamental frequencies• Molecular fingerprints • MIR – ro-vibrational transitions (all material states)• FIR – rotational transitions (gasses, liquids)• FIR – collective vibrational modes (solids)
Sensing (monitoring) requirements:• Several fixed (tunable) wavelengths• Narrow linewidth: ~GHz or less• High power and high brightness for DIAL and countermeasures
Applications: Proteomics
[T.J.Johnson et al Chem.Phys.Lett. 403, 152 (2005)][C. Kötting et al Proc.Nat.Acad.Sci. 103, 13911 (2006)]
• Label-free• Site specific information• Time resolved protein reactions
Spores of B. thuringiensis ssp. kurstaki and B. subtilis 49760
Applications:Imaging, Inspection
Fuel tank of Schuttle launch rocket behind foam
THz stress-induced birefringence imagingCarbon-fiber composite helicopter stator
[M.Koch, OPN, 18,21 (2007)]
[Picometrix, Inc.]
• Dielectric solids: no rotational DoFs• Transparent in FIR• Low scattering losses
Applications: Fuel industry
[M.A. Aliske et al Fuel, 86, 1461 (2007)]
Applications:Surgical
MIR lasers: • High H2O absorption• Less tissue-specific• Smaller heated volume• Lower collateral damage
Applications:SurgicalDefficiencies of current procedures
[A.Vogel et al Chem.Rev. 103, 577 (2003)]
Laser induced shock-wave effect on waterEr:YAG 100 ns, 50 MW/cm2 Shock-wave damage
Applications: Detection of explosives
Applications: XUV and as pulse generation
Atom in high optical field: Tunnel ionization , classical axceleration in electric field
XUV photon cutoff energy: 20
2
17.3~17.3
EIUI pppXUV
Ionization potential + Ponderomotive energy
High intensity (ultrashort) in MIR are advantageous
[M. Levenstein et al, PRA, 49, 2117 (1994)]
Applications: XUV and as pulse generation
[R. Kienbergeret al Nature, 427, 817 (2004)]
• CEP phase-stabilized pulses required• Currently all-passive CEP stabilization by (2):(2) or (3) NLO processes
State of the art: QCL
[B. S. Williams, Nature Photonics, 1, 517 (2007) ]
Main breakthroughs:• Resonant optical-phonon depopulation• Metal-metal waveguides
1THz ~ 4.1 meV ~ 47.6 K hphonon ~ 30meV
State of the art: Solid state lasers
Engineering toolbox:• Crystal field – Tailorable transition energies• Structural disorder - inhomogeneous broadening – Gain spectral width (fs)• Phonon Spectrum – thermal conductivity, nonratiative lifetime• Growth technologies – size, cost • Coating technologies – damage threshold• Laser diode technology – reliability, power, new materials (1.9µm InGaAsSb/GaSb)
MIR high power (W-kW) laser options:CO2 – 10µmCO - 5µmEr3+ - 3µmCr2+ – 2.2 -2.8 µmHo3+ - 2.1 µmTm3+ - 1.85µm – 2.1 µm
Beyond state of the art: New SSL materials
Main search strategy:• Low phonon energy materials• Enhanced transparency in MIR
Generic formula: Re3+:MePb2Hal5
Re=Pr, Nd, Er, Tb, Dy, HoMe=K,RbHal=Cl, Br
Transparency regions:KPb2Cl5 0.4 µm – 20 µmKPb2Br5 0.4 µm – 30 µmRbPb2Br5 0.37 µm – 30 µm
Nonlinear optical sources
Characteristics:• Tunable – depends on nonlinear material• No quantum defect – High peak and average power• From CW to fs • High efficiency
DFGOPA
OPO
spi
isp
Nonlinear optical materials for MIR, FIR
Required and Desirable properties:• High transmission at pump wavelength around 1µm• Absence of two-photon absorption at pump wavelength • High transmission in MIR• High nonlinearity• High optical damage threshold• Engineerability (QPM structuring or composition variation)• Non-hygroscopic• Feasibility of large-volume crystal growth
Main classes of MIR, FIR NLO materials:• Oxides: KTiOPO4 (KTP), RbTiOPO4 (RTP), LiNbO3, LiTaO3...
Engineerable, can be pumped in NIRMIR Transmission limited to ~4 µm, 80µm - 300µm
• Semiconductors: GaAs, GaP, ZnGeP2 (ZGP), AgGa1−x InxS2, ...MIR tranmission to 20 µm, FIR 60µm – 300 µmAbsorbing at 1 µm
• Organic: 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST)Very high nonlinearity 30xKTP, good MIR, FIR transmissionVery difficult to grow, Hygroscopic
Engineerable nonlinear optical materials
OP-GaAs (Stanford)
PP-KTP (KTH) period 800 nm, over 5 mm
[L.A.Eyres et al APL, 79, 904 (2001)]
[C. Canalias et al Nature Photonics,1, 459 (2001)]
State of the art: OPOs
20 40 60 80 100 120 140 160 180
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
38.2 m 37.8 m
37.4 m
36.4 m
36.0 m
S
ign
al /
Id
ler
wa
vele
ngt
h (
m)
Temperature (°C)
35.4 m
PP-RbTiOPO4
High-energy ns tunable OPO
[A.Fragemann, Optics Lett., 83, 3092 (2003)]
State of the art: OPOs
Cascaded PPKTP – ZGP OPO for active countermeasures
[M.Henriksson, Appl. Phys.B, 88, 37 (2007)]
Beyond state of the art: OPO
Surgical ns OPO at 6.45 µm and 6.1 µm
Target: Peak power 0.5 MW, average power 1W
1000 2000 3000 4000-30
-20
-10
0
p=827nm, =28µm
Po
we
r, lo
g s
cale
Wavelength , nm
[M.Tiihonen, etal, Appl. Phys. B, 85, 73 (2006)]
State of the art: OPAs
Optical parametric amplifiers for ultrashort pulses
[P.S.Kuo, etal, Optics Lett., 31, 71 (2006)]
PP-KTP OPA (KTH) OP-GaAs (Stanford)
FWHM 115 THz (~1 octave)1.08 µm - 3.8 µm
Beyond state of the art: Near-field MIR-FIR• MIR, FIR polariton optics in ferroelectrics• Tailoring polaritonic FIR waves with photonic crystals • Functionalized surfaces • Sub-wavelength sensing
[K. A. Nelson etal Nature Materials, 1, 95 (2002)][J. Faist, etal Optics Express, 15, 4499 (2007)]
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