PhD students:

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Lasers and Nonlinear Optics group at
KTH Department of Laser physics and quantum optics
PhD students Anna Fragemann Carlota
Canalias Shunhua Wang Sandra Johansson Jonas
Hellström Mikael Tiihonen Stefan Holmgren Stefan
Spiekermann Björn Jacobsson Stefan
Bjurshagen Markus Henriksson
Senior Staff Fredrik Laurell Valdas
Pasiskevicius Jens A. Tellefsen, Jr.
Visiting scientist Junji Hirohashi
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Current areas of research

• Nonlinear optical materials
• material properties of nonlinear ferroelectrics
• poling technology
• nanostructuring
• Applications of QPM NLO materials
• broadband parametric sources
• cascaded parametric processes
• tunable parametric MIR sources
• tunable parametric UV sources
• Laser technology
• tunable single-frequency solid state lasers
• applications of novel solid state laser
  materials
• visible solid state laser sources

3
Quasi-phase-matched NLO materials
In QPM the phase mismatch,

• compensated by periodic modulation of the
  relative phase

• modulation period corresponds to the coherence
  length

4
Material properties of nonlinear ferroelectrics
Dynamics of light-induced polaron absorption
Stimulated Raman Scattering

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

Color center formation
5
Poling technology
Materials KTiOPO4, RbTiOPO4, RbTiOAsO4,
s-LiTaO3, MgOs-LiTaO3, MgOLiNbO3
Domain nucleation and growth
Domain wall stability

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

Characterization methods
6
Nanostructuring
400 nm domains in PPKTP

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

Nanostructured electrooptic Bragg reflector
7
Broadband parametric sources
2-stage OPA-fiber ns supercontinuum source

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

Two-stage fs 125 µJ CPOPA
t270fs
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Cascaded parametric processes
Cascaded QPM mode-locking

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

10 ps, 100 200 MHz
Cascaded QPM EO modulation
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Tunable parametric MIR and UV sources

• 280-340 nm for early-warning biohazard detection
  systems.
• 3-5 µm Doppler velocimetry radar and
  countermeasure
• systems.
• 2 µm surgery.
• 1.2 µm - 1.3 µm bioimaging applications.

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

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Visible solid state laser sources
Multipass single-frequency CW SHG in PPKTP

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

3.4 W _at_ 1064 nm 1.6 W _at_ 532 nm
Choose your l CW SFM in PPKTP
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Coming up

• Single-frequency tunable fiber Bragg grating
  stabilized lasers.
• New laser materials (EU FP6 project DT-CRYS)
• Double tungstate crystals KLn(WO4)2 Ln Ho, Er,
  Pr, Nd, Yb, Tm.
• Up to stoichiometric doping.
• Emission from 0.86 µm to 2.94 µm.
• Well suited for LD pumping.
• Excellent Raman converters.
• Possibility for self-frequency doubling.
• Possibility for self-cooled lasers.

• Nonlinear optical materials
• Applications of QPM materials
• Laser technology

12
Experimental nonlinear optics at JONLO

• Planned research directions
• Novel coherent light sources
• Properties of light
• Material modification with light
• Imaging

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Coherent control of bradband signals
QPM Bandwidth tailoring (synchroOPO)
Temporal chirp multiplication
Pump
0.5 mm
1 mm

• Novel light sources
• Properties of light
• Material modification
• Imaging

Temporal chirp reversal and compression
Also GV matching in noncollinear QPM interactions
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Wavelength-agile CPOPA new paradigm

• Laser-based CPA
• bulky, inefficient and more or less fixed l.
• CPOPA should replace laser multipass and
  regenerative amplifiers
• Simple,efficient, less expensive, no heat
  generation, at any l.

• Novel light sources
• Properties of light
• Material modification
• Imaging

Generic wavelength agile CPOPA

• Other parametric sources of interest
• Couterpropagating parametric generator in
  nanostructures
• mirror-less counter-pumped OPO, etc.

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Parametric solitons etc.
Limiting of diffraction and limiting of spectral
bandwidth in OPG/OPA Parametric spatial
solitons ?

• Novel light sources
• Properties of light
• Material modification
• Imaging

3D localisation of light? X-waves Possible
applications in remote sensing
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If you think you know everything about photons
think again
Evolution of orbital angular momentum in cascaded
parametric interactions

• Novel light sources
• Properties of light
• Material modification
• Imaging

Nonlinear interactions of axially symmetric
linearly polarized beams spin-orbital coupling
for photons?
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Material modification with light

• Essential processes responsible for stability of
  laminar polar structures as well as optical
  breakdown
• Electron and hole localization and lattice
  relaxation dynamics in ferroelectrics and glasses
• Investigation of phonon-phonon and
  phonon-polariton scattering dynamics in nonlinear
  optical materials
• Technology we wish to develop
• Optically induced color-center engineering in
  ferroelectrics control over nucleation in the
  second-order phase transitions

• Novel light sources
• Properties of light
• Material modification
• Imaging

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Imaging

• Wide-field OCT
• For sub-30fs pulses - spatial resolution below 2
  µm in tissue.
• Use supercontinuum from ps system-PCF for OCT.
• Ballistic photon imaging
• Nonlinear optical gating in QPM,
• Nonlinear polarization gating
• THz imaging
• High intensity 100 fs pulses generation of THz
  power large enough for large-field imaging.

• Novel light sources
• Properties of light
• Material modification
• Imaging