Ultrafast lasers - Introduction | dautreppe.photonique ...dautreppe.photonique.grenoble.cnrs.fr/sites/all/images/presentations... · Laboratoire Temps – Fréquence (LTF) oscillators

Laboratoire Temps – Fréquence (LTF)

Thomas Südmeyer Time/Frequency Laboratory, Physics Institute, University of Neuchatel Grenoble, Dautreppe 2015 Photonique, 7. Dec. 2015

Ultrafast lasers

Laboratoire Temps – Fréquence (LTF) 7.12.2015


What is ULTRAFAST?


Ultrafast laser pulses

Access ultrashort time scales

Broad optical spectrum

Concentrate in time and space


Resolving fast events

Cinema: time between images 124 Hz

= 42 ms


The horse in motion

Baronet, 1794

www.wikipedia.org

George Stubbs (1724-1806): English painter, best known for his paintings of horses.

Whistlejacket, 1762

http://www.wikipedia.org/


Fast mechanical shutter photography E. Muybridge in 1878: understand horse gallop using fast photography in the ms-domain


Fast mechanical shutter photography E. Muybridge in 1878: understand horse gallop using fast photography in the ms-domain


Fast flash photography Harold E. Edgerton (1903-1990): understand fast processes using flash light (limited by duration of flashes to µs-domain)








Femtochemistry by A. H. Zewail in 1994 A. H. Zewail in 1994: understand transition states in chemical reactions using fs-pulses

http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1999/illpres/reaction.html

http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1999/illpres/reaction.html


Femtochemistry by A. H. Zewail in 1994 A. H. Zewail in 1994: understand transition states in chemical reactions using fs-pulses


Scales

picosecond 10–12 s

femtosecond 10–15 s

nanosecond 10–9 s

Time


Scales

The Lunar Laser Ranging Experiment from the Apollo 11 mission

A laser beam from the Apache Point Observatory heads toward the moon

𝟑𝟑𝟑𝟑𝟑𝟑𝟑𝟑𝟑𝟑𝟑𝟑 𝐤𝐤𝐤𝐤𝒄𝒄

= 𝟏𝟏.𝟐𝟐𝟐𝟐 𝒔𝒔


A 5 fs pulse

Electric field 𝐸𝐸𝑥𝑥(𝑟𝑟0, 𝑡𝑡)

Time t

2.7 fs =wavelength

𝑐𝑐=

800nm𝑐𝑐


A 5 fs pulse

speed of light

𝟐𝟐 𝐟𝐟𝐟𝐟 ⋅ 𝒄𝒄 = 𝟏𝟏.𝟐𝟐 µ𝒎𝒎

Distance y

Distance z

Distance x



Observe and use fast dynamics • understand chemical reaction dynamics • fast communication • …


interconnects optical clocking







Key advantage of laser light: coherence

Spatial coherence Propagation over long distances & reduced divergence…

… or extremely small spot & high divergence


Key advantage of laser light: coherence

Long duration and very small spectrum …

… or short pulses and wide spectrum

⇒ Ultrafast lasers and frequency combs!

Spatial coherence Temporal coherence Propagation over long distances & reduced divergence…

… or extremely small spot & high divergence


Continuous-wave laser

Light circulates in resonator

Losses compensated by gain in laser medium (which is externally pumped)

Gain saturates to a level that it compensates the losses

Light emission typically continuous


Passively modelocked laser

Short pulse circulates in cavity (fs-ps)

High repetition rate pulse train at the output (MHz-GHz)

Pulse formation process initiated and stabilized by saturable absorber in the laser cavity

Steady-state pulse parameters: governed by interplay of gain, (saturable) loss, dispersion, Kerr nonlinearity, etc.

Saturable loss


Modelocking and frequency combs

http://www.physik.uni-wuerzburg.de/femto-welt/pulsframe.html

http://www.physik.uni-wuerzburg.de/femto-welt/pulsframe.html


Saturable absorber modelocking

Animation: http://www.rp-photonics.com/mode_locking.html

http://www.rp-photonics.com/mode_locking.html


Time, light, and extreme precision


From: T. Hänsch, „A passion for precision“, Nobel Lecture, Stockholm 2005

𝟏𝟏𝟏𝟏𝟏𝟏 𝐩𝐩𝐟𝐟𝟏𝟏 𝐝𝐝𝐝𝐝𝐝𝐝


≈ 𝟏𝟏𝟏𝟏−𝟏𝟏𝟐𝟐


The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.

http://www.bipm.org/fr/si/si_brochure/chapter2/2-1/2-1-1/second.html www.wikipedia.org http://hyperphysics.phy-astr.gsu.edu/hbase/images/csclock.gif


http://www.bipm.org/fr/si/si_brochure/chapter2/2-1/2-1-1/second.html


http://hyperphysics.phy-astr.gsu.edu/hbase/images/csclock.gif


Scales

http://www.earth-time.org/trollart.html www.wikipedia.org

http://www.earth-time.org/trollart.html






Scales


Formation of moon 𝟑𝟑𝟐𝟐𝟏𝟏𝟏𝟏 𝐤𝐤𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦 𝐝𝐝𝐲𝐲𝐝𝐝𝐲𝐲𝐟𝐟 ∙ 𝟏𝟏𝟏𝟏−𝟏𝟏𝟐𝟐

= 𝟏𝟏𝟑𝟑𝟐𝟐 𝐟𝐟𝐲𝐲𝐬𝐬𝐦𝐦𝐦𝐦𝐝𝐝𝐟𝐟







Scales


Extinction of dinosaurs 65 𝐤𝐤𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦𝐦 𝐝𝐝𝐲𝐲𝐝𝐝𝐲𝐲𝐟𝐟 ∙ 𝟏𝟏𝟏𝟏−𝟏𝟏𝟐𝟐 = 𝟐𝟐 𝐟𝐟





𝟏𝟏𝟏𝟏𝟏𝟏 𝐩𝐩𝐟𝐟𝟏𝟏 𝐝𝐝𝐝𝐝𝐝𝐝


≈ 𝟏𝟏𝟏𝟏−𝟏𝟏𝟐𝟐





Oscillators

Oscillator: repetitive movement

Counter: measure time in practical units

Pendulum: Quartz resonator: Microwave resonator: Typical optical atomic transition:

~ 1 osc/sec ~ 1’000’000 osc/sec

~ 10’000’000’000 osc/sec ~ 100’000’000’000’000 osc/sec


Oscillators

Oscillator: repetitive movement

Counter: measure time in practical units

Pendulum: Quartz resonator: Microwave resonator: Typical optical atomic transition:

~ 1 osc/sec ~ 1’000’000 osc/sec

~ 10’000’000’000 osc/sec ~ 100’000’000’000’000 osc/sec

How to count?


the basic time unit in the SI system

an optical frequency standard

Previous measurements of absolute optical frequencies




a heroic frequency chain





a heroic frequency chain


a single frequency

comb laser


Frequency combs

optical

microwave

Revolution in metrology: stabilization of frequency combs! Allows to compare microwaves with optical frequencies ⇒ Nobel price 2005: T. W. Hänsch, J. L Hall

Phase-stable link between optical and microwave frequencies

Fs-laser based frequency combs

Unknown frequency


H. Telle et al., Appl.Phys. B 69, 327 (1999)

CEOCEOf

tϕ∂

=∂

Carrier Envelope Offset (CEO)

http://www.rp-photonics.com/img/ceo.gif




CEO stabilization


H. Telle et al., Appl.Phys. B 69, 327 (1999)

Octave spanning supercontinuum required (typically achieved by coherent spectral broadening in highly-nonlinear fiber)

Detection of the CEO-phase change No direct measurement possible Indirect f-to-2f-measurement scheme

CEOCEOf

tϕ∂

=∂

CEO detection in the f-2f scheme


Artist’s rendering of JILA’s molecular fingerprinting system

http://patapsco.nist.gov/ImageGallery/details.cfm?imageid=842

Baxley/JILA

http://patapsco.nist.gov/ImageGallery/details.cfm?imageid=842


Dual comb spectroscopy


Astrocomb

http://www2.mpq.mpg.de/~haensch/comb/Astrocomb/english.html

T. Steinmetz, T. Wilken, C. Araujo-Hauck, R. Holzwarth, T. W. Hänsch, L. Pasquini, A. Manescau, S. D’Odorico, M. T. Murphy, T. Kentischer, W. Schmidt, T. Udem, “Laser frequency combs for astronomical observations,” Science 321, 1335–1337 (2008)

http://www2.mpq.mpg.de/%7Ehaensch/comb/Astrocomb/english.html


Yb-lattice atomic clock






Generate ultrastable frequency combs • high precision spectroscopy • optical clocks • …







Concentrate in time and space


Ultrafast lasers: material processing

Picture: Stefan Nolte



https://www.youtube.com/watch?v=S_8nD4OuwX4







https://www.youtube.com/watch?v=AD2Oqg0Pnq0

https://www.youtube.com/watch?v=AD2Oqg0Pnq0



https://www.youtube.com/watch?v=5VfCiqRWbeA

https://www.youtube.com/watch?v=5VfCiqRWbeA


Ultrafast laser market


pulse energy

repetition rate average power ( = Ep frep) pulse duration

peak power ( ∝EP / τP )

Ep

frep Pave

τp Ppeak

𝜆𝜆 Δ𝜆𝜆

time domain TR = 1 / frep

τp

Key parameters of ultrafast lasers

wavelength optical bandwidth


Frontier: average power and pulse energy

High energy and MHz

T. Südmeyer, et al., “Femtosecond laser oscillators for high-field science”, Nature Photonics 2, 559 (2008)

Industrial applications • increase throughput, • reduce costs per item, …

Scientific applications

• reduce measurement time, • increase signal-to-noise, • MHz XUV sources, …

Nolte, et al., Adv. Eng. Mater. 2, 2000


Key for high average power: heat removal ⇒ High surface-to-volume ratio

Fiber Slab Thin disk

High average power ultrafast sources


Key for ultrafast: reduce nonlinearities, avoid damage

High average power ultrafast sources

http://www.amazon.de/Supercontinuum-Generation-Optical-Fibers-Dudley/ http://lidaris.com/glossary-2/laser-induced-damage-morphology/

⇒ Reduce peak intensity ⇒ Reduce interaction volume

http://www.amazon.de/Supercontinuum-Generation-Optical-Fibers-Dudley/










http://lidaris.com/glossary-2/laser-induced-damage-morphology/











A. Giesen, et al., Appl. Phys. B 58, 365 (1994)

- Use in reflection: efficient heat removal through back side

- 1D longitudinal heat flow → reduced thermal lensing

- Power scalable by increase of mode diameter D (constant intensities)

Thin disk laser


Highest average powers and highest energies of any ultrafast oscillator technology

Ep = 80 μJ

τp = 1.07 ps frep = 3 MHz Pav = 242 W

Ep = 17 µJ Pav = 275 W τp = 583 fs frep = 16.3 MHz

C.J. Saraceno, et al., Optics Express 20, 23535 (2012)

SESAM Modelocked Thin Disk Lasers


Modelocked thin disk laser

Animation by Martin Hoffmann


Harnessing intracavity nonlinearities


Key for ultrafast: reduce nonlinearities • Operation at reduced peak intensity • Reduced interaction volume

Chirped Pulse Amplification (CPA)

Dispersion


Chirped Pulse Amplification (CPA)

https://en.wikipedia.org/wiki/Chirped_pulse_amplification

https://en.wikipedia.org/wiki/Chirped_pulse_amplification


Chirped pulse amplification (CPA) in a fiber: 830 W, 640 fs

T. Eidam, et al., Optics Letters 35, 94-96 (2010)


osci

llato

rs

amplifiers

Towards powerful MHz ultrafast laser sources

Chirped pulse amplification 830 W, 640 fs, 78 MHz

Innoslab amplifier 1.1 kW, 615 fs, 20 MHz P. Russbueldt, et al., Opt. Lett. 35 (2010) T. Eidam, et al., Opt. Lett. 35 (2010)

Thin disk multipass amplifier 1.4 kW, 7.7 ps, 300 kHz

Thin disk oscillators 275 W, 580 fs, 17 MHz

J. P. Negel, et al., Opt. Lett. 38 (2013)

C.J. Saraceno, et al., Optics Express 20 (2012)


High energy CPA systems: National Ignition Facility


National Ignition Facility: towards laser-based fusion

https://www.youtube.com/watch?v=yixhyPN0r3g

https://www.youtube.com/watch?v=yixhyPN0r3g


What is ULTRAFAST?


National Ignition Facility: towards laser-based fusion

N I F WARP CORE https://www.youtube.com/watch?v=wdD5M3Vtdh0

https://www.youtube.com/watch?v=wdD5M3Vtdh0







Concentrate in time and space Achieve extremely high intensities • material processing, eye surgery, … • biomedical imaging, …. • high field science, …


Thank you for your

attention !


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Ultrafast lasers - Introduction | dautreppe.photonique ...dautreppe.photonique.grenoble.cnrs.fr/sites/all/images/presentations... · Laboratoire Temps – Fréquence (LTF) oscillators