Development of Ultra Intense, High Average Power Lasers Advanced - - PowerPoint PPT Presentation

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Development of Ultra Intense, High Average Power Lasers Advanced - - PowerPoint PPT Presentation

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Intense Lasers: High Average Power talk II Development of Ultra Intense, High Average Power Lasers Advanced Summer School on Laser Driven Sources of High Energy Particles and Radiation Anacapri, Italy July 9-16, 2017 Andy Bayramian, Al

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This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC

Intense Lasers: High Average Power talk II Development of Ultra Intense, High Average Power Lasers

Advanced Summer School on “Laser Driven Sources of High Energy Particles and Radiation” Anacapri, Italy July 9-16, 2017

Andy Bayramian, Al Erlandson, Tom Galvin, Emily Link, Kathleen Schaffers, Craig Siders, Tom Spinka, Constantin Haefner Advanced Photon Technologies, NIF&PS

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Amplification of Multiple Wavelengths (Broadband) typically needed for short pulse operation & secondary sources

Depiction of scientists who must amplify broadband radiation

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Advanced Photon Technologies, 7-2017

High intensity lasers operated at high average power are poised to have far reaching impact on industry, society, and science

X-rays EUV Plasma Fusion Photo Neutron Fission

Advanced Photon Technologies, 7-2017

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Inertial Fusion Energy

Enabling laser fusion power

EUV Litography

Extending Moore’s Law

Medical

PET tracer, tomography

SNM Detection

Nuclear Materials Security

HEDS / Materials Sci

Laboratory Astrophysics

Accelerators

Compact laser based

Industrial Processing

Taylor made properties

Non-Destructive

Quality Assurance

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1. Broadband spectrum (many different colors of laser light) 2. Ability to “line up” all the waves

What do we need to make a short pulse?

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How does a free running broadband oscillator work with bandwidth?

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How does a mode locked broadband oscillator work?

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Amplifying Intense Ultrashort Laser Pulses

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  • Telescope placed between compressor gratings effectively reverses the dispersion

sign

  • A number of stretcher designs developed: all-reflection solutions for pulses <50 fs

Nanosecond pulse stretcher - principle

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Group delay can be written as a Taylor Expansion of the spectral phase

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Goal: Spectral dispersion introduced by Stretcher = spectral dispersion by transmission optical elements + spectral dispersion by reflective layers + spectral dispersion by Compressor Example: Delay introduced by one compressor and 3 different stretchers. Residual delay from summing compressor + stretcher delays

from C.V. Filip, Computers at Work on Ultrafast Laser Design, Optics & Photonics News, May 2012

Dispersion management in broadband laser systems

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Advanced Photon Technologies, 7-2017 E.B. Treacy, Optical Pulse Compression With Diffraction Gratings, IEEE J. Quant. El., Vol QE-5, pp. 454-458 (1969) O.E. Martinez, IEEE J. Quantum Electron. QE-23, 59 (1987)

G1 G2 G3 G4

Grating compressor: ns to fs pulses

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A Typical Ultra-intense Laser Architecture

Oscillator/ Front End Pre-Amplifier Power Amplifier Pump Laser Amplifier Pump Laser Amplifier Final Output Pump Laser Front End Pump Laser Front End

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Advanced Photon Technologies, 7-2017

Ti:sapphire OPCPA

Broadband laser amplifiers

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Remember from talk 1: High-efficiency strategy – still applies with some adjustments

  • Any energy that does not become laser light is ultimately heat that must be removed.
  • Even diode pumped laser systems which have high efficiency operate between 3-20%

efficiency – that is still a lot of heat

  • Minimize decay losses during the pumping process
  • Use cladding and smaller apertures smaller to reduce amplified spontaneous

emission loss

  • Use a pump profile with a high fill factor that gain-shapes the extracting beam
  • Absorb nearly all the pump light
  • Extract nearly all the available stored energy
  • Operate at fluences well above the saturation fluence
  • Multipass the extracting beam
  • Keep passive optical losses low
  • Relay the beam to the middle of each amplifier to minimize edge losses
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New issues specific to short pulse require extremely detailed design and attention during commissioning to meet performance requirements

  • Contrast is important to deliver energy for secondary sources

Example: Assume you have a petawatt laser system which is easily capable of 10^21 W/cm2 for use in secondary source generation.

  • A beam with 10^10:1 contrast (difficult) still has prepulse of 10^12 W/cm2 which is

enough to vaporize solid targets.

  • Need > 10^11:1 – very difficult
  • Gratings, stretcher optics, transmissive optics, mirror surfaces, amplifier

spontaneous emission, and even quantum noise sets the limit on background and prepulse contrast.

  • Every surface, material must be carefully managed to avoid these problems
  • Nonlinear phase accumulation or B-integral:
  • Long pulse limit was ~2 rad.
  • Short pulse system limits more like ~1 radian.
  • Issue is nonlinear phase shifts colors around within the pulse messing up the chirp.
  • Since B is intensity dependent any intensity spatial nonuniformity will result in spatially

non uniform chirp which is not correctable

  • B integral also transfers energy from post pulse to pre-pulse where it becomes a

contrast issue.

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Petawatt discoveries:

  • 1.3-PW = 1,300,000,000,000,000 Watts of power
  • ~1021 W/cm2
  • 10-100-MeV electron beams
  • Laser made proton beams
  • Hard x-rays and gamma-rays
  • Photo-fission

1996: LLNL Demonstrates First Petawatt Laser: 600 J, >1 PW

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Advanced Photon Technologies, 7-2017

Two major high intensity petawatt laser projects at LLNL

Advanced Radiographic Capability (ARC) High repetition-rate Advanced Petawatt Laser System (HAPLS)

World’s most energetic Petawatt laser World’s highest rep-rate Petawatt laser (10 Hz)

1 Petawatt = 1015 Watts = 1,000,000,000,000,000 Watts 30 J in 30 fs, 10 shots/second 12,000 J in 10 ps, 1 shot/2 hours

12000 J 50 ps 1 shot/2h up to 4 PW 1018 W/cm2 2014 >30 J 30 fs 10 Hz >1 PW TBD 2016

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Modifications to the NIF quad (Q35T) are required to protect NIF & ARC components, optimize ARC performance and permit changing from NIF to ARC during automated shots

ARC diagnostic table (ADT) Deformable mirror

Replace Nd slab with polarizer reduces # of slabs on ARC quad to reduce backscatter gain & manage birefringence

Dual Regen Amplifier High Contrast Front End Transport Optics Transport Spatial Filter Power Amp Polarization Switch Main Amplifier Polarizer Fiber Preamp NIF Master Oscillator Compressor Assembly Target Positioner

Triple pulse PEPC to increase 1ω backscatter isolation Wavefront control

  • ptimized for TCC

focus using target in the loop (TIL) software ARC/NIF pick-off mirror switches beams from NIF to ARC final optics High Contrast Front-End (HCAFE) and Dual Regen Table (DRT) produce 2 beamlets that can be independently timed and each match the group delay of the 2 different compressors A half waveplate in the preamp is inserted/removed to switch between ARC & NIF ARC final optics compress chirped pulses and focuses beamlets to TCC

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The High Contrast ARC Front End (HCAFE) uses short pulse OPA technology* to produce high temporal contrast

OPA* “c(2) Cleaner”

Commercial Nd:glass Oscillator Spectral Shaper-B Spectral Shaper-A Pulse Width Controller-B Pulse Width Controller-A Trombone

20 uJ 50 nJ

SP-Regen SHG

Stretcher Oscillator Pulse Control Cleaner

Bulk Stretcher

A B

OPA Trombone

*Based on LLE Omega EP front-end OPA (C. Dorrer, et al., CLEO 2011)

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The dual regens (DRT) & split beam injection (SBI) produce 2 beamlets that can be independently timed

ARC ILS Nearfield Beam

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The High Contrast Front End output meets prepulse contrast requirement of 80 dB for t < -200 ps

1.E-10 1.E-9 1.E-8 1.E-7 1.E-6 1.E-5 1.E-4 1.E-3 1.E-2 1.E-1 1.E+0

  • 500
  • 400
  • 300
  • 200
  • 100

100

ps

Target requirement is 70 dB for T < -200 ps flows down to 80 dB at regen output

Third Order Auto Correlator Pre Pulse Contrast Measurements

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Advanced Photon Technologies, 7-2017 Frontend Alpha Amplifier Beta (Power) Amplifier wideband Multipass Amplifier Stretcher Compressor Beam Conditioning

Pulse shaping and contrast enhancement

Deformable Mirror Target Harmonic converter Pump power amplifier Modified NIF front-end Power amplifier diagnostics 3.2 MW laser diode arrays

ELI Beamlines facility control system Integrated Controls

10 Hz rep rate allows adaptive feedback enabling highest intensities

DPSSL pump lasers

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HAPLS Petawatt System is compact and has a 17m x 4.6 m footprint

Pump laser power amplifier 3.2MW laser diode arrays Pump laser frequency converter and homogenizers Petawatt power amplifier Short pulse laser frontend with high contrast pulse cleaner DPSSL pump 2J green Pump laser frontend Short pulse a-amplifier Compressor

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Rod amplifiers THIN DISK: “active mirror” multislab-face-cooling

Heat can be extracted through the “edge” or the “face”

  • Conductive/convective cooling

with liquid (National Energetics) or Helium gas (LLNL, RAL)

  • Stress parallel to laser beam
  • High energy storage
  • Conductive cooling through

back side

  • Stress parallel to laser beam
  • Low energy storage
  • Conductive cooling through

edges

  • Stress orthogonal to laser

beam

  • High energy storage

Pump light Pump light Laser emission

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Amplifier slabs

Helium

Pump Pump Gas-cooled amplifier prototype HAPLS production Amplifier Assembly

LLNL’s HAPLS Laser slabs are cooled by rapidly flowing, room temperature He-gas

  • Face cooled Nd:Glass slabs
  • Room temperature Helium gas coolant
  • Gas acceleration vanes Mach 0.1
  • Cooled ASE Edge claddings

Advanced Photon Technologies, 7-2017

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Today the HAPLS pump laser delivers continuously >100J at 3.3Hz, energy stability 0.7%RMS, and no optical damage

10 20 30 40 50 60 70 20 40 60 80 100

Energy (J) Time (mins)

Eave = 100.97 rms = 0.72%

Continuous 1hr run delivering 100Joule pulses at 340W Eave=101J

dE=0.7% RMS

Energy stability scales with output

  • energy. Predicted <0.35% @ 200J

Output beam profile

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Today HAPLS delivers 80J of second harmonic light

Pump Profile at Beta Amplifier

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The commercial short pulse front end provides a robust, turn- key stretched-pulse seed to HAPLS short pulse beamline

Robust XPW Pulse Cleaner enables achieving reliably ~109 temporal contrast and 1011 (5ps) in optimized configuration Includes an LLNL-built Offner-triplet stretcher with a 20,000:1 stretch factor The last time the SPFE system required manual alignment was >12months ago

20fs pulse shape

  • ptimized

Day-to-day

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The short pulse laser architecture utilizes dual amplifier zero propagation architecture to achieve high mode-fill and stability

  • Fully relay imaged
  • Only 2 amplifier stages
  • Distributes gain
  • ASE management
  • Minimizes cost
  • Improved stability

Beam size 5x5 cm2 Beam transport all reflective for beam size >1cm2

To compressor 21 x 21 cm2

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The Ti:Sa short pulse power amplifier is pumped with ~1 kW 2w and utilizes the same gas-cooling concept

  • Approx. 50% of the pump incident to Ti:sapphire dissipated into heat
  • ~heat load doubles when unextracted
  • High-speed flow of helium gas between Ti:sapphire slabs removes heat
  • HAPLS uses solid state edge claddings
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Today, the HAPLS delivers 16J of broadband laser pulses at 3.3 Hz and pulse duration 28fs.

Encircled energy in DL spot = ~0.5

500 1000 500 1000 500 1000 500 1000

NF and FF Profiles at energy (first results, adaptive mirror not active) HAPLS output NF Advanced Photon Technologies, 7-2017

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Today, the HAPLS delivers 16J of broadband laser pulses at 3.3 Hz and pulse duration 28fs.

µ = 28.1 fs σ = 1.4fs = 5.0% 1 hour Pulse duration Advanced Photon Technologies, 7-2017

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Contours: compressor output energy Full performance today

The HAPLS final amplifier can deliver up to 45J of pulse energy

Advanced Photon Technologies, 7-2017

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The HAPLS laser runs 200,000 times faster than both ARC and the original 1996 Petawatt

Advanced Photon Technologies, 7-2017

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HAPLS is the first laser system that approaches a performance level consistent with real applications

Advanced Photon Technologies, 7-2017

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