Fiber lasers and amplifiers

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Fiber lasers and amplifiers
by Khanh Kieu
(11/12/2009)
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Outlines

• Introduction
• Fiber optics basics
• Active fibers
• Laser performances
• Cladding pump technology
• Fiber laser research at the College of Optical
  Sciences
• Future directions

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Introduction
Nobel Prize in Physics awarded for contribution
related to laser

• 1964 Townes, Basov and Prokhorov
• 1971 Gabor
• 1981 Bloembergen and Schawlow
• 1997 Chu, Cohen-Tannoudji and Phillips
• 2000 Alferov and Kroemer
• 2005 Hänsch an Hall

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Laser market
Laserfocusworld.com
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Laser market
Laserfocusworld.com
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History
First laser was demonstrated in 1960 by T. Maiman
First fiber laser was demonstrated in 1963 E.
Snitzer
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Why are people still doing research in lasers?

• Requirements
• New wavelength bands
• Maximum average output power
• Maximum peak output power
• Minimum output pulse duration
• Maximum power efficiency
• Minimum cost

The physics of laser operation is
well understood. But there is always need for
better and cheaper lasers. Also, there are still
a lot of applications requirements that current
technology can not satisfy.
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Fiber optics Basics
(http//en.wikipedia.org/)

• NA
• V number
• Core size, MFD
• Polarization maintaining or not polarization
  maintaining
• Dispersion

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Fiber optics Basics

• Types of fiber by construction
• step index
• graded index
• PM fiber
• photonic crystal fiber
• multi-core fiber

• Types of fiber by functionality
• passive fibers
• active fibers

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Fabrication methods
Modified chemical vapor deposition method
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Fabrication methods active fibers
Nano-particle vapor deposition (Liekki)
MCVD process
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Fabrication methods active fibers
Rod-in-tube method UoA
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Active fibers
Nd3, Yb3
Er3
Pr3 (491nm,520nm,605nm,695nm)
Tm3, Ho3
Er3, ZBLAN
Bi3
Pr3
3?m
1?m
2?m
1.5?m
0.5?m
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Advantages of fiber format

• High efficiency
• Direct diode pumping
• Compact
• Alignment free
• Reliable
• Low cost
• Performance

Fiber format removes the strict requirement of
heat management which is normally very critical
in solid-state lasers

• But there are also disadvantages
• Long gain media
• High nonlinearity
• Polarization stability

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Laser design
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Fiber laser performance
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mJ energy femtosecond fiber laser gt 1GW peak
power!
Tünnermanns group
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What can fiber laser do?
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Cladding pump technology
http//www.rp-photonics.com/double_clad_fibers.htm
l
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Cladding pump technology
(Goldberg, Opt. Lett. 1999)
(US patent 5,864,644)
GTWave technology (credit D. Payne)
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Beam combination
(credit D. Payne)
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Fiber laser research at the College of Optical
Sciences
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Fiber laser research at the College of Optical
Sciences
Highly doped Yb-Er phosphate fiber
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Fiber laser research at the College of Optical
Sciences
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Cladding pump technology
Polynkin, 2004
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Reflector with ultra-narrow bandwidth
Allow single-frequency operation even when
the cavity is long.
Kieu, Opt. Lett., 2007
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Understanding the reflectivity of microsphere
resonator
HR mirrors
Microsphere
Reflection
Scattering
Transmission
Reflection
Transmission
Taper
Input
Microsphere resonator
Fabry-Perot resonator
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Femtosecond pulse generation with carbon nanotubes
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Femtosecond pulse generation with carbon nanotubes
Kieu, Opt. Lett., 2007
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Femtosecond pulse generation with carbon nanotubes
Old technology
New technology
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Future directions

• New fiber design with increased MFD to reduce
  nonlinear effects
• New doped fibers operating at other spectral
  regions
• Generation of new frequencies
• Pulsed source with ultra-high peak power
• Compact lasers for precision
• measurement and sensing

(Credit Nufern.com)
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Thank you!