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www.esi.comLaser Business Division
Very high power picosecond and nanosecond
fiber lasers
François SALIN, Julien SABY, Pierre Jean DEVILDER, Anthony MEUNIER, Damien SANGLA, Alexandra RAPAPORT
EOLITE Systems ‐ PESSAC, France
www.eolite.com
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Yb doped Rod type fiberYb doped Rod type fiber
(Patented design)
200 µm 80 µm
Air clad
Pump clad area
Active core area
2 mm fused silica‐rod (whole diameter hidden)
Very large mode area: > 7000 µm2
Very high absorption: up to 30 dB/mNo photodarkening
SINGLE MODE
• 40-100 µm core
• 100-200 µm clad
• 1-2 mm outer diameter
Photonic Crystal Fiber
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Rod type fiber variety
Photonic Crystal Rod type fiber Distributed-Mode-Filtering (NKTP) Large Pitch Fiber (IAP)
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I. High Average Power nanosecond lasers
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Average power of Rod type fiber Q‐switched lasers at EOLITE
IR
Green
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• Fiber length ≈ 50 cm
• Pump diode @ 976 nm
• AOM for Q‐Switching
Laser ConfigurationLaser ConfigurationSingle stage oscillator
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Amplifier set-up
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• Pulse duration down to 8 ns• Beam Quality M2 < 1.1• Spectral width < 400 pm
Common characteristicsCommon characteristics
M2<1.1
0.4 nm
10 ns
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IR Q-switched laser familly
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310 W @ 300 kHz
< 25 ns pulsesM2 < 1.2Linear polarization 100:1
High power Q-switched rod type fiber laser
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Power independent beam profile 1030nm
Beam quality independent of pump power level
No adjusment, close-loop needed
75W 100W 150W 191W 241W 282W 310W
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Toward kW class, 10 nanosecond lasers
issue: beam instabilities at high power in LMA fibers. Fundamental physics
Multiplexing high power lasers
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Wavelength multiplexing
Laser 1
Laser 2
Laser 3
λ1
λ2
λ3
Transmission Volume Bragg Grating
3 lasers 340 W 1 kWMain issue is the thermal load in the VBG
LEADERSHIP IN FIBRE LASER TECHNOLOGY (EC funded)
AIM : Demonstrate a 1 kW nanosecond system 1 kW 10 ns 10mJ @ 100 kHz M²<1.3
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300 W @ 100 kHz10 ns 20 – 500 kHz
M2<1.3
Toward higher powers: polarization beam combining
Temporal synchronization: < 3 ns jitter Spatial beam overlapping
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Laser1
Laser2Grating
Wavelength multiplexing2 lasers 1030 nm & 1047 nm
2x 210 W -> 400 W
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GREEN 515 nmUV 343 nm
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SHG Q-switched lasers @ different pump powerSHG Q-switched lasers @ different pump power
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150 W @
515 nm
HIGHEST diffraction limited green power
on the market
M2= 1.07
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Third Harmonic Generation47 W @ 343 nmType II LBO 20x3x3 mm
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High Power Picosecond Fiber Lasers
High Repetition rate: 30 – 80 MHz SIROCCOHigh Peak Power: 0-5 MHz HEGOA
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2
Laser Architecture
Pre-Amp
Main-Amplifier
Pulse picker
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• Output Power = 291W
• 3.7µJ / 90kW
1030nm
Sirocco IR250
80 MHz
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1030nmM² Measurement @ 291W
Mx² = 1,21My² = 1,17
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2
THG Results
• 63W @ 343nm / 80MHz• THG Efficiency = 25% (for improved UV lifetime)
343nm63W
Sirocco UV50
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High energy picosecond fiber laser
Rod type fibers opens the road for MW peak powerpicosecond pulses
at low cost
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1.5 MW peak power HEGOA IR60
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SummaryRod Type Fibers offer an unique opportunity to get very high
average and very high peak powers with diffraction limited beams
Kilowatt class industrial short pulses lasers are coming
10 nanoseconds300 W (400W) @ 1030 nm
150 W @ 515 nm47 W @ 343 nm
15-50 ps300 W @ 1030 nm
65 W @ 343 nm1.5 MW peak power
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