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Next Generation Optical Fiber for IR Applications:
Novel Materials and Nano‐Scale Textures
Axel Schülzgen
College of Optics and Photonics, CREOL & Townes Laser InstituteUniversity of Central Florida, Orlando, FL 32816, USA
Outline
• Impact of fiber optics• What are next generation optical fibers?
• Selected IR fiber research activities at CREOL, Townes Laser Institute
– Single frequency phosphate glass fiber lasers at 1.5 m
– High power cw and short pulse Tm:fiber lasers at 2 m
– Hollow‐core photonic bandgap fiber
– Chalcogenide glass fiber
Nobel Prize in Physics 2009
"for groundbreaking achievements concerning the transmission of light in fibers for optical communication"
Charles K. Kao
Brief history of fiber optics:
1970’s: First low-loss silica glass fiber1990’s: US information superhighway project2000’s: Global fiber-optic network
The internet has changed our way of life. It has• created new industries• given rise to new cultures • influenced politics
Impact of Fiber Optics
Next Generation of Optical Fiber
Low‐losssilica fiber
Transmission of light & data
Fiber‐optic sensing
• High power laser• Low‐noise lasers• Supercontinuum sources• IR light sources
• Environmental• Bio‐Chemical• Long distanceacoustic sensing
Advances in optical fiber technology:
Medical fiber‐optic • Fiber miniaturization• Diagnostics and surgery • Photodynamic therapy
Fiber‐optic light sources• New materials• Micro‐ and nano‐structures
Expansion of application areas
1985 1990 1995 2000 2005 201010-4
10-3
10-2
10-1
100
101
102
103
104
Pow
er (W
atts
)Year
Fiber Lasers – CW Laser Oscillator
Specialty Fiber
Fiber Bragg Grating
Commercially available today:1.5 kW single mode 1 micron fiber laser10 kW multi mode 1 micron fiber laser
2010/2011 Industrial laser PRISM award:YLR‐150, quasi cw fiber laser, IPG Photonics (http://www.ipgphotonics.com)
MM Cladding Pumping
1995 2000 20050.0
0.5
1.0
1.5
2.0
2.5
Out
put P
ower
(W)
Year
Cladding pumpingwith multi modepump diodes
Highly‐doped phosphate glass
fiber
Single‐Frequency Fiber Lasers Oscillator
Photonic crystalhighly‐doped phosphate fiber
FBG 1 FBG 2Active fiber
Short length DBR fiber lasers @ 1.5 m • Long distance interferometric sensing
(acoustic sensing: security, oil exploration)• Doppler LIDAR (wind measurements)• Seed laser, test equipment, …
Major achievements
• Low loss fiber (~ 0.01 dB/cm)
• Microstructuredlarge mode area fiber
• Photonic bandgap fiber
• Multiple core fiber
• Optimized high concentrationEr/Yb doping for efficient fiber lasers
• Photosensitive fiber for Bragg grating fabrication
New Fiber Materials ‐ Phosphate Glass Fibers
Reflection> 92%
fiber Bragg grating in phosphate glass fiber
0 5 10 15 200
1
2
Out
put P
ower
(W)
Pump Power (W)
active MOF (3.8 cm)
step‐index fiber (4 cm)
Single‐Frequency Phosphate Glass Fiber Laser
2 μm Light Sources: Thulium Fiber Lasers
New dopants – Tm doped fiber lasers offer: Wide range of emission wavelength ~1.8 – 2.2 μm Eye‐safe operation >75% slope efficiency via
• pumping at ~1.6 μm• diode pumping at 790 nm
& efficient cross relaxation
Potential applications include:• Materials processing• LIDAR• Medical• Directed energy• Free space communication
Tunable CW Tm:Fiber MOPA Laser System
8 W Tm:fiber laser oscillator
Tm:fiber amplifier
>200 W 1927‐2097 nm
M2 < 1.2
Femtosecond Tm:Fiber Laser and Raman Amplifier
Raman Amplifier:
Pulse energy: 8‐9 nJPulse duration: 150‐170 fsPeak power: ~60 kWλcenter : 1.97 – 2.2 mΔλ (FWHM) : 27‐31 nm
-600 -400 -200 0 200 400 6000
2
4
6
8
10
12
14
16
18
20
Sign
al (A
.U.)
Time (fs)
AC width = 260 fs
1900 2000 2100 2200-70
-60
-50
-40
-30
-20
Sig
nal (
dB)
Wavelength (nm)
Increasing Pump Power
IR ‐ Limits of Silica Fiber
Photonic crystal fiber OmniGuide fiber
Hollow core
Periodic glass/polymer structure
Cladding
• P. Yeh, A. Yariv, & E. Marom, JOSA 68, 1196 (1978).
• Y. Fink et al., J. Lightwave Technol. 17, 2039 (1999).
Periodic glass/air structure
Light guiding in hollow core fibers
• P. St. J. Russell, private papers (1991).
• R. F. Creganet al., Science 285, 1537 (1999).
Hollow Core Photonic Bandgap (HC‐PBG) Fiber
Different HC‐PBG fiber in chronological order.
(a) The first fabricated HC‐PCF: air‐filling fraction ~40%, transmission loss of a few 100 dB m−1.(b) ~60% of air‐filling fraction, transmission loss ~10 dB m−1.(c) Air‐filling fraction >70% with expansion of the core and distortion of the cladding structure).(d) Air‐filling fraction greater than 87% drawn using the modified stack‐draw technique. (e) A HC‐PCF from BlazePhotonics.
“Over the past decade HC‐PBG fibers have been developed from a radical concept to a high performance product.”
F. Benabid, Phil. Trans. R. Soc. A 2006 364, 3439‐3462 (2006).
Evolution of HC‐PBG Fibers
300 nm
wavelength, (nm)
atten
uatio
n, (d
B / k
m)
50 dB / km
Attenuation down to 15 dB / km
Low‐loss Photonic Bandgap Fiber
~96% air‐filling fraction
Nano‐ and Micro‐Structured Optical Fibers
Group
• IR transmission• High power delivery • Femtosecond pulse delivery and compression• Gas‐phase nonlinear optics & lasers• Laser guiding of molecules and atoms
Applications of HC‐PBG fiber
IR ‐ Limits of Silica Fiber
Glass type
Borate 1400Phosphate 1200Silicate 1100Germanate 900Tellurite 700
Fluorozirconate 500Chalcogenide 350
High nonlinearity for IR continuum generation in short fiber segments.
Mid‐Infrared Chalcogenide Glass FibersMulti‐Material
Optical Fiber Devices Group
Multi‐material chalcogenide glass preform
Chalcogenide glass PCF preformFiber‐preform extrusion
Multi‐Material Optical Fiber Devices
Group New Materials ‐ Chalcogenide Glass Fibers
Multi‐Material Optical Fiber Devices
Group Mid‐Infrared Chalcogenide Glass Fibers
Summary
• Advanced functionality of optical fiber can be achieved through the incorporation of novel materials and nano‐scale textures into next‐generation fibers.
• Examples of various research activities at the Townes Laser Institute including novel fiber host and fiber doping materials as well as photonic bandgap fibers have been presented.
• Fiber optics is a fertile ground for research and applications in
– IR light transmission beyond the silica transmission window. – IR light sources.– IR light manipulation.– IR light detectors.