Tunable Cr:F Tunable Cr:F Femtosecond LasersFemtosecond Lasers

Charlie Barnes & Andy CarsonCharlie Barnes & Andy Carson

Del Mar VenturesDel Mar Ventures

Research and Industrial ApplicationsResearch and Industrial Applications

Femtosecond Products Offered Femtosecond Products Offered ByBy

Del Mar VenturesDel Mar Ventures►Pulse PickersPulse Pickers►Femtosecond AutocorrelatorsFemtosecond Autocorrelators►Femtosecond Fluorescence SystemsFemtosecond Fluorescence Systems►Wavelength ConvertersWavelength Converters►Ti:Sapphire LasersTi:Sapphire Lasers►Ti:Sapphire Multipass Amplification Ti:Sapphire Multipass Amplification

SystemsSystems►Cr:Forsterite Lasers and TW SystemsCr:Forsterite Lasers and TW Systems

Introduction to Cr:F LasersIntroduction to Cr:F Lasers

►Center wavelength of 1250 nmCenter wavelength of 1250 nm►Tunable from 1100—1400nmTunable from 1100—1400nm►Broadband absorptionBroadband absorption►Directly pumped by Ytterbium Fiber Directly pumped by Ytterbium Fiber

LaserLaser►Sensitive to thermal effectsSensitive to thermal effects

Continuous Beam vs. Ultrashort Continuous Beam vs. Ultrashort PulsesPulses

Frequency

Frequency Spectrum

Time

Power Spectrum

Time

Power Spectrum

Continuous Beam (Ideal Case)

Ultrashort Pulses (Ideal Case)

Frequency

Frequency Spectrum

Short Pulses vs. Long PulsesShort Pulses vs. Long Pulses

Time

Power Spectrum

Frequency

Frequency Spectrum

Frequency

Frequency Spectrum

Time

Power Spectrum

Mode-locking Multimode Mode-locking Multimode LasersLasers

Out of phaseOut of phase

TimeTimeTimeTime

RANDOMRANDOM phase for all the laser phase for all the laser modesmodes

Irradiance vs. TimeIrradiance vs. Time

Out of phaseOut of phase

TimeTime

Out of phaseOut of phaseIn phaseIn phase Irradiance vs. TimeIrradiance vs. Time

TimeTime

LOCKEDLOCKED phases for all the laser modes phases for all the laser modes

Mode-locking Multimode Mode-locking Multimode LasersLasers

Mode-locked pulsesMode-locked pulses

Ultrafast lasers have thousands of modes!Ultrafast lasers have thousands of modes!

How do we mode-lock the laser?How do we mode-lock the laser?Kerr-LensingKerr-Lensing

Low-intensity beamLow-intensity beam

High-intensity ultrashort pulseHigh-intensity ultrashort pulse

Kerr medium (n = nKerr medium (n = n00 + + nn22I)I)

Focused pulseFocused pulse

Making a mode-locked laserMaking a mode-locked laser

CWCW

PulsedPulsed

Pow

er

Pow

er

TimeTime

Pow

erP

ower

TimeTime

c/2lc/2l

BarrierBarrier

HighHigh lossloss

LowLow lossloss

Elements of Cr:F ultrafast Elements of Cr:F ultrafast laserlaser

Output CouplerOutput Coupler

DispersionDispersionCompensatingCompensating

PrismsPrisms

Yb:fiberYb:fiberPump LaserPump Laser

LensLens Curved MirrorsCurved Mirrors

Cr:F Laser CrystalCr:F Laser Crystal

HighHighReflectorReflector

High ReflectorHigh Reflector

Pump LaserPump Laser

►Yb:fiber pump laserYb:fiber pump laser►Extremely compact sizeExtremely compact size►No mode-beatingNo mode-beating►Noise level < 0.1%Noise level < 0.1%►Longer lifetimeLonger lifetime►Costs 50% less than comparable Costs 50% less than comparable

Nd:YAGNd:YAG

Chirped Pulse AmplificationChirped Pulse Amplification

Oscillator Stretcher Amplifier Compressor

TerraWatt SystemTerraWatt SystemPump Laser:Pump Laser:

PYL-10PYL-101060 nm, 10 W1060 nm, 10 W

Pump Laser:Pump Laser: 1060 1060 nmnm

30 ns, 30 mJ, 10 Hz30 ns, 30 mJ, 10 Hz

OscillatorOscillator Regenerative Regenerative AmplifierAmplifier

StretcherStretcher

1250 nm40- 80 fs100 МHz

2 nJ

1250 nm1250 nm200 ps200 ps10 Hz10 Hz0.5 mJ0.5 mJ

1250 nm1250 nm200 ps, 10 Hz, 200 200 ps, 10 Hz, 200

mJmJ

1250 nm1250 nm60 – 80 fs, 10 60 – 80 fs, 10

Hz, 120 mJHz, 120 mJ1 – 2 TW1 – 2 TW

Pump Laser:Pump Laser: 1060 nm 1060 nm30 ns, 0.7 J, 10 Hz30 ns, 0.7 J, 10 Hz

CompressorCompressor

Pump Laser:Pump Laser: 1060 1060 nmnm

30 ns, 1 J, 10 Hz30 ns, 1 J, 10 Hz 1250 nm1250 nm200 ps200 ps10 Hz10 Hz50 mJ50 mJ

Multipass Multipass AmplifiersAmplifiers

Research and Industrial Research and Industrial ApplicationsApplications

►High Resolution Imaging High Resolution Imaging ►Photochemistry And PhotobiologyPhotochemistry And Photobiology►Material ProcessingMaterial Processing►Medical ApplicationsMedical Applications►High Energy PhysicsHigh Energy Physics

Advantages Femtosecond Advantages Femtosecond LasersLasers

►Short pulse durationShort pulse duration►BroadbandBroadband►Very high resolutionsVery high resolutions►Less dispersion Less dispersion

Emission SpectraEmission Spectra Cr:Forsterite Cr:Forsterite

Ti:SapphireTi:Sapphire Cr:ForsteriteCr:Forsterite Cr:YAGCr:YAG

1500 nm1500 nm1250 nm1250 nm800 nm800 nm

Advantages CrAdvantages Cr4+4+:Fosterite:Fosterite

Ti:SapphireTi:Sapphire

Cr:ForsteriteCr:Forsterite

Cr:YAGCr:YAG

CrCr4+4+:Fosterite :Fosterite High speed High speed

communicationscommunicationsDispersion Attenuation

Imaging with Ultrashort Laser Imaging with Ultrashort Laser PulsesPulses

► Non Linear EffectsNon Linear Effects

► in vivoin vivo

► Significantly Significantly improve the depth improve the depth resolutionresolution

Third harmonicgeneration

Three photonfluorescence

Two photonfluorescence

tt

Multi-Photon Multi-Photon MicroscopyMicroscopy

Third Harmonic ImagingThird Harmonic Imaging

Index change breaks symmetry

High intensities create non-linear optical effects

THL destructively interferes

THL both sides of focus

0

5000

1 104

1.5 104

2 104

2.5 104

3 104

0 5 10 15 20 25 30

TH

G in

tens

ity (

arb.

uni

ts)

Axial distance (micrometers)

Oil immersion interface

Glass GlassIndex matching

fluid

Interfaces

Third Harmonic ImagingThird Harmonic Imaging

THGTHG

125 µm

Neurons

15 µm

Optical fiber in index-matching fluid

D. Yelin and Y. Silberberg

Optical Coherence Optical Coherence TomographyTomography

► Micron-scale cross-Micron-scale cross-sectionalsectional

► in vivo in vivo imagingimaging

► Real timeReal time

Low Coherence InterferometryLow Coherence Interferometry

Low-Coherence Source

CoherenceLength

Mirror Displacement

Det

ecto

r

Reference

Detector

SampleSource

Mirror Displacement

High-coherence Source/2

Det

ecto

r

Michelson Interferometer

OCT ImagesOCT ImagesLive Tadpole

Blood Vessel

Femtosecond SpectroscopyFemtosecond Spectroscopy

► Most chemical reactions Most chemical reactions occur in 10occur in 10-15-15 sec sec

► Femtosecond Femtosecond spectroscopy spectroscopy monitoring reactions in monitoring reactions in real timereal time

► Short pulse duration Short pulse duration allows the detection allows the detection short-lived transient short-lived transient chemical reactionschemical reactions

Pump and Probe Pump and Probe ► Medium is excited with Medium is excited with

femtosecond pulse femtosecond pulse ► Delayed probe pulse by Delayed probe pulse by

increasing path length increasing path length (microns)(microns)

► Short pulse duration Short pulse duration allows short-lived allows short-lived reactions to be studiedreactions to be studied

► Very high resolutionsVery high resolutions

Material ProcessingMaterial Processing

► High peak power, TW with amplified systems High peak power, TW with amplified systems ► Mulitphoton absorption Mulitphoton absorption ► Low thermal and mechanical side effects Low thermal and mechanical side effects ► AblationAblation► Induced structural changesInduced structural changes

Material Ablation

1) Photons generate electrons

e-2) Electron avalanche

3) Plasma expansion

4) Electron-phonon coupling

5) Material is ejected

(Herbert Welling, Laser Zentrum Hannover)

200 fs pulse

2.3 ps pulse

Material ProcessingMaterial Processing

► Variety of materials Variety of materials including dielectrics, including dielectrics, semiconductors, semiconductors, metals, plastics metals, plastics

► Multiphoton absorption Multiphoton absorption allows for processing of allows for processing of materials that are not materials that are not very photosensitive.very photosensitive.

What can we make?What can we make?► Micro gratings and Micro gratings and

periodic periodic nanostructuresnanostructures

► Machined parts for Machined parts for industrial and industrial and medical applicationsmedical applications

► Subsurface wave Subsurface wave guides and all optical guides and all optical componentscomponents

MedicalMedical

► Laser Surgery Laser Surgery ► Medical biopsy Medical biopsy ► Hard tissue processingHard tissue processing

(Gerard Morou, University of Michigan)

Corneal flap removal in LASIK

Applications in dentistryApplications in dentistry

► Alternative to Alternative to mechanical drills and mechanical drills and CW lasersCW lasers

► Reduced thermal stressReduced thermal stress

► And micro cracks in And micro cracks in enamelenamel

Femtosecond X-Ray PulsesFemtosecond X-Ray Pulses

► Femtosecond X-ray pulses Femtosecond X-ray pulses probe core electronic levelsprobe core electronic levels

► Indication of the structural Indication of the structural changes changes

► Femtosecond X-rays can be Femtosecond X-rays can be generated through generated through scattering visible laser scattering visible laser beams by high energy beams by high energy

electronselectrons..

ConclusionConclusion

►Many industrial and research Many industrial and research applicationsapplications High Resolution Imaging High Resolution Imaging Photochemistry And PhotobiologyPhotochemistry And Photobiology Material ProcessingMaterial Processing Medical ApplicationsMedical Applications High Energy PhysicsHigh Energy Physics

►Del Mar Ventures offers a wide variety Del Mar Ventures offers a wide variety of femtosecond productsof femtosecond products

Thank you for comingThank you for coming

Charlie Barnes and Andy Charlie Barnes and Andy CarsonCarson

Del Mar VenturesDel Mar Ventures