Recent Research Activities on Specialty Fibers Presentation … · – Erbium-doped fiber: fiber...

Recent Research Activities on Specialty Fibers

Ming-Jun Li

Science and Technology Division, Corning IncorporatedE-mail: [email protected]

WOCC’2007Newark, NJ, April 27-28, 2007

3

Acknowledgement• X. Chen • D. A. Nolan• G. E. Berkey• J. Wang• J. Koh• S. Li• S. Gray• S. R. Bickham

• A.B. Ruffin• D.T. Walton• L. A. Zenteno• J. A. West • K. W. Koch • J. Coon• Kevin W. Bennett

4

Outline• Introduction

• Recent research and development at Corning– Single polarization fiber– High Power Laser Fiber– Nonlinear Fiber– Microstructured Fiber– High Numerical Aperture Fiber

• Conclusions

5



• Conclusions

6

Specialty Fibers and Applications• Specialty optical fiber is modified, usually by design and by doping, for a

specialized function

• Examples of specialty fibers– Attenuating fiber: control attenuation– Ytterbium-doped double-clad fiber: high power fiber lasers– Erbium-doped fiber: fiber amplifiers for telecommunications– High NA fiber: capture more input with low bend-induced loss– Metallized fiber: coated with metals for high temperatures– Photonic crystal fiber: use photonic crystal structure to modify fiber

properties– Mid-infrared fiber: low loss optical transmission in 2 to 10 μm . – Photosensitive fiber: fiber gratings by UV exposure– Polarization maintaining fiber: keep linear polarized light

7

Corning Specialty Fiber’s ProductsCorning Specialty Fiber’s Products

• PM 480• PM 630• PM 850• PM 980• PM 1300• PM 14XX• PM 1550

• PM 480• PM 630• PM 850• PM 980• PM 1300• PM 14XX• PM 1550

Corning Specialty Fiber

Polarization Control Erbium Power Delivery

Polarization MaintainingSingle Polarization

• SP 1060 (NEW)• SP 1310 (NEW)• SP 1550 (NEW)• SP 850 (Development)

• SP 1060 (NEW)• SP 1310 (NEW)• SP 1550 (NEW)• SP 850 (Development)

•RC PM 1550•RC PM 14XX•RC PM 1300•RC PM 980•Low Birefringence Fibers•High NA•PM 400 Visible (NEW)

Other Capabilities

Special Single-mode Fibers

High Index /Bend

Insensitive

• SMF-28e Photonic Fiber(NEW)

• RGB 400 (NEW)• RC Std SMF Fiber

• SMF-28e Photonic Fiber(NEW)

• RGB 400 (NEW)• RC Std SMF Fiber

•HI 780•HI 980•HI 1060•HI 1060 FLEX•RC HI 980•RC HI 1060•RC HI 1060 FLEX•RC 1300•RC 1550

•ER 1550C•ER 1550C3•ER 1550C3 LC (NEW)•ER 1600L3•RC ER 1550C3•RC ER 1600L3

• Yb Double Clad (NEW)• Polymer Clad Silica

(NEW)• High NA Silica Core

In Development

• Yb Double Clad (NEW)• Polymer Clad Silica

(NEW)• High NA Silica Core

In Development

• Hermetic Coatings• Polyimide Coatings• Reduced Cladding Fibers• Photonic Band Gap Fibers

In Development

8



• Conclusions

9

What is Single Polarization (SP) Fiber?• Fiber in which only one polarization mode propagates, while

the other polarization mode is attenuated• Difference between SP and PM fiber

SP fiber PM fiber

x

y

Delayx (fast)

y (slow)

– Guide one polarization only– No PMD, PDL

– Guide two polarizations– For long fiber, mode coupling

can cause PMD, PDL

10

Applications of Single Polarization Fiber• Medical and military application

– High power single polarization fiber lasers• Long haul networks

– Eliminates the need to deal with PMD, PDL, etc.• Coherent communication

– Eliminate polarization instability • Optical interconnection

– Reduce component costs • Fiber sensors

11

Design Concepts of SP Fiber • High birefringence to separate the two polarization modes

• Fiber structure to let one polarization propagate, the other polarization be cutoff

• Two design approaches:– Using stress birefringence– Using geometry birefringence

yx nnB −=

claddingycladdingx nnnn <> ,

12

Corning Patented Design with Dual Air Holes

• Use air holes to create geometry birefringence • The air holes are also used to achieve differential cutoff

wavelengths

CoreAir hole

Cladding

13

1550 nm SP FiberPower distribution along minor axis

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00

Radius (μm)

Pow

er (a

.u)

Pow

er distribution along major axis

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9 1-10.00-8.00

-6.00-4.00

-2.000.00

2.004.00

6.008.00

10.00

Radius (μm

)

Power (a.u)

Mode field diameter (μm)

Minor Major2.8 10.2

Wavelength (nm)1500 1520 1540 1560 1580 1600

Spe

ctra

l Sig

nal (

dB)

-100

-95

-90

-85

-80

-75

-70

-65

1550 window

14


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00

Radius (μm)

Pow

er (a

.u)

Power distribution along m

ajor axis

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9 1-10.00-8.00

-6.00-4.00

-2.000.00

2.004.00

6.008.00

10.00

Radius ( μm

)

Power (a.u)


Minor Major2.4 8.7

Wavelength (nm)

1250 1270 1290 1310 1330 1350

Spe

ctra

l Sig

nal (

dB)

-100

-95

-90

-85

-80

-75

-70

-65

1310 window

15


0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00

Radius (μm)

Pow

er (a

.u)

Pow

er distribution along major axis

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9 1-10.00-8.00

-6.00-4.00

-2.000.00

2.004.00

6.008.00

10.00

Radius ( μm

)

Power (a.u)


Minor Major2.7 9.6

Wavelength (nm)1020 1040 1060 1080 1100

Spe

ctra

l Sig

nal (

dB)

-85

-80

-75

-70

-65

-60

1060 window

16

Polarization Dependent Loss

Wavelength (nm)1420 1440 1460 1480 1500 1520 1540

PDL

(dB

)

01020304050607080

L = 101.3 cmL = 53.9cmL = 27.8 cm

17

Application of SPF in High Power LasersBuilt in Single Polarization Double Clad Fiber

18



• Conclusions

19

High Power Narrow-linewidth Fiber LaserHigh Power Narrow-linewidth Fiber Laser• Many applications require

•• A major limiting factorA major limiting factor

SBS threshold in LMA fiber ~ 100 W

High PowerHigh Power & Narrow Narrow linewidthlinewidth

SBSSBSStimulated Stimulated BrillouinBrillouin ScatteringScattering

20

Corning’s allall--glassglass,, LMA double-clad fiber

LMA fiber crossLMA fiber cross--sectionsection

LMA core

1st clad

2nd clad

LMA Core: Yb/Al/Ge/SiO2

Inner clad: Ge-SiO2

Outer clad: B/F-SiO2

Core: 30Core: 30--60 um, core NA: 0.0460 um, core NA: 0.04--0.060.06Pump NA (1Pump NA (1stst clad to 2clad to 2ndnd clad): clad): ≥≥ 0.30.3

Index

LMA index profileLMA index profile

SiO2

21

Advantages of OVD LMA fiber makingAdvantages of OVD LMA fiber making

• All-glass double-clad structure – no polymer in optical path, ideal for high-power

• Lowest fiber background loss & high Yb QE– all vapor-phase doping, warranted hi-purity & low-defect

• SBS mitigation, gain guiding etc – Dopants (Al, Yb) profile capability

• High-NA for pump– Up- and down-dope capability

• low-NA for Yb-doped core with high Yb/Al content – Core compositional flexibility

• All-glass double-clad structure – no polymer in optical path, ideal for high-power

• Lowest fiber background loss & high Yb QE– all vapor-phase doping, warranted hi-purity & low-defect

• SBS mitigation, gain guiding etc – Dopants (Al, Yb) profile capability

• High-NA for pump– Up- and down-dope capability

• low-NA for Yb-doped core with high Yb/Al content – Core compositional flexibility

22

Reducing the interaction length:- Increase Yb doping concentration

•• Corning has the highest YbCorning has the highest Yb--doping (1doping (1--2wt%) concentration with 2wt%) concentration with uncompromised quantum yield/background loss in the worlduncompromised quantum yield/background loss in the world

23

High-Yb fiber with the lowest background loss

Loss in core region Loss in MM pump region

Low-loss characteristics of Yb-doped OVD fibers

0

1

23

4

5

6

78

9

10

1050 1100 1150 1200 1250 1300 1350 1400Wavelength (nm)

Loss

(dB

/km

)

Low-loss characteristics of Yb-doped OVD fibers

0

1

23

4

5

6

78

9

10

1050 1100 1150 1200 1250 1300 1350 1400Wavelength (nm)

Loss

(dB

/km

)

Pumping (innerclad) region Attenuation (141-0383)

0

10

20

30

40

50

60

70

80

90

100

600 800 1000 1200 1400 1600

Wavelength (nm)Lo

ss (d

B/k

m)

MCVD solution-doping data

24

Stimulated Brillouin Scattering

• Intense pump-light creates acoustic wave, via ‘electrostrictive effect’• Acoustic wave creates an index grating • Light is scattered by the grating in the backward direction• Frequency of scattered light is downshifted in due to the Doppler shift

Incident Light ω

Scattered Light ω−Ω

Acoustic Wave Ω

Index Grating

25

A New Comprehensive SBS Analysis• SBS Threshold: input power at which the SBS power starts to

rise exponentially

: fiber optical effective area: overlap integral

K: polarization factorg(νmax): maximum effective gain coefficient

αu: acoustic mode lossLeff : effective length

aouI

Optical Profile DesignPolarization control

Brillouin Frequency change

effA

Optical Profile DesignAcoustic Profile design

aoueff

ueffth ILLg

KAP

),( maxνα

∝

26

Reduce Optical/Acoustic Overlap by Fiber DesignReduce Optical/Acoustic Overlap by Fiber Design

• Overlap integral gives us a new criterion for designing high SBS threshold fibers

• Minimize acousto-optic overlap– index profiles to modify optical/acoustic modes– choose dopants to modify acoustic velocity

• Overlap integral gives us a new criterion for designing high SBS threshold fibers

• Minimize acousto-optic overlap– index profiles to modify optical/acoustic modes– choose dopants to modify acoustic velocity

↓↓↑↑↑↑↑Acoustic refractive index

↑↑↓↓↑↑↑Optical refractive index

AlAl22OO33F2B2O3TiO2P2O5GeO2Dopant

27

Fiber Profile for Reduced SBSFiber Profile for Reduced SBS

Radius (μm)0 5 10 15 20 25 30

Aco

ustic

Del

ta (%

)

-0.6-0.4-0.20.00.20.40.60.8

Acoustic Delta ProfileRefractive index/

Dopant concentration

Radius (μm)0 5 10 15 20 25 30

Fiel

d A

mpl

itude

-1.0

-0.5

0.0

0.5

1.0LP01L01L02

• Triangular acoustic index profile pushes acoustic waves to edge of core

• Acousto-optic overlap integral is reduced

• Predicted SBS threshold increase of ~7dB

Al

Ge Ge B/FYb

LMA Profile Schematic

coreinner

cladding

outercladding

28

Measured SBS Thresholds in Large Mode Area Fibers

0

5

10

15

20

25

30

35

0.0 50.0 100.0 150.0 200.0 250.0 300.0Output power (Watts)

Bac

kwar

d po

wer

mon

itor (

mW

)

Step Index

Low SBS

SBS threshold is improved by 6 dB

Dual pump configuration

30 μm core12 m long

29



• Conclusions

30

Nonlinear Fiber Design Considerations• Small effective area - High nonlinearity

Nonlinear coefficient

• Low loss – High figure of merit• Right amount chromatic dispersion• Cutoff below the operating window-Single mode• Low polarization mode dispersion• High SBS threshold for non-Brillouin applications

effAn22

λπγ =

31

Figure of Merit• Conventional figure of merit

• New figure of merit considering SBS

αγ

=0F γ: nonlinear coefficient, α: attenuation

BgPF γα

γ== 0 gB: Brillouin gain

32

Profile Designs

Step Index Profile W-profile

33

Typical Fiber CharacteristicsParameter

Effective areaDispersionDispersion slopeCutoff wavelengthAttenuation

Typical Value

15-25 μm2

0-20 ps/nm/km0-0.06 ps/nm2/km1200-1500 nm0.4-0.7 dB/km

34

Reducing SBS in Nonlinear Fibers• SBS Threshold:

: fiber optical effective area: overlap integral

K: polarization factorg(νmax): maximum effective gain coefficient

αu: acoustic mode lossLeff : effective length

aouI

Optical Profile DesignPolarization control

Brillouin Frequency change

effA

Optical Profile DesignAcoustic Profile design

aoueff

ueffth ILLg

KAP

),( maxνα

∝

35

Profile Design

• Ring profile design to reduce overlap between optical and acoustic fields

• SBS threshold is similar to standard single mode fiber

-0.5

0

0.5

1

1.5

2

0 2 4 6 8

Radius (microns)

% D

elta

DDC fiber DS fiber

-25

-20

-15

-10

-5

0

5

10

15

5 7 9 11 13 15

Input power (dBm)

Ref

lect

ed p

ower

(dB

m)

13 km ring profile10 km graded-index

36

Decrease Dopant Level Along the Fiber

• Broaden the Brillouin spectrum and reduce the gain• SBS improvement of 7 dB demonstrated

CoreClad

Ge dopant decreases along the fiber (a)

-40

-30

-20

-10

0

10

20

30

-8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26

Input Power (dBm)

Bac

k-sc

atte

ring

pow

er (d

Bm

)

(a)

(b)

(d)

(c)

(a) Conventional CDF. (b) Conventional DDF. (c) SBS-DDF launched at high dispersion side. (d) SBS_DDF lunched at low dispersion side.

37



• Conclusions

38

Photonic band-gap fiberPBGF

Photonic band-gap fiberPBGF

Bragg fiber Bragg fiber

Photonic crystal fiberPCF or “holey” fiber

Photonic crystal fiberPCF or “holey” fiber

Micro-structured air/silica or highly nonlinear fiber

Micro-structured air/silica or highly nonlinear fiber

Solid- & Hollow-Core Photonic Crystal Fibers

39

Why Photonic Crystal Fiber?Air-Silica Fiber

High Index Contrast Microstructured Cladding

Band-Gap EffectsSmall Core

High Birefringence

Endless Single Mode

High Nonlinearity

High NA

Fiber lasers

Components

Low loss transmission

UV and NIR guides

Unique sources

Large SM guides

40

Potential for Low Loss

PROPERTY CONVENTIONAL FIBER

HOLLOW-COREPBGF

(POTENTIAL)

HOLLOW-COREPBGF

(CURRENT) Loss

(dB/km)

Surface modes

0.15-0.17 < 0.1 13

Lowest-loss, small-core PBGF

41

Comparison of Effective Nonlinearity of PBGF0.15

0.10

0.05

0 Δ

λ/L

(nm

/cm

)

0.12 4 6 8

12 4 6 8

102

Peak power (MW)

Corning fiber HC-1550-01

γ =

2πn2

λ Aeff γ Blaze = 2.5×10−8(W ⋅cm)−1

γ Corning = 2.4 ×10−9 (W ⋅cm)−1 γ SMF = 3×10−5(W ⋅cm)−1

Nonlinearityparameter

Spectral broadening

measurement at zero-

dispersion point

42

High Birefringent PBGF

Wavelength (nm)1550 1570 1590 1610 1630

Bea

tleng

th (m

m)

0.06

0.07

0.08

0.09

0.10

0.11

Bire

frin

genc

e

0.015

0.017

0.019

0.021

0.023

0.025

0.027BeatlengthBirefringence

(b)

Birefringence is 0.016-0.025, highest values reported on PBGF

43



• Conclusions

44

High NA Fiber Applications• Laser Power Delivery• Illumination• Industrial Sensors • Medical• Interferometers• Short-Haul Data and Video

45

Polymer Clad Silica Fibers

0

10

20

30

40

50

60

70

400 500 600 700 800 900 1000 1100 1200 1300Wavelength (nm)

Atte

nuat

ion

(dB/

km)

ETFEBuffer

Fluorinatedpolymer Cladding

Silica Core

Typical AttenuationCOR-400-VIS39 (Low OH)

• Features:– High Numerical Aperture (0.39)– Low attenuation– High Purity Silica Core

• Low OH and High OH available– Excellent Epoxy Adhesion for

Connectorization– Variety of Core Sizes available

(200, 400µm)– OVD Manufactured Fiber

Consistency– Other Geometries, NA, and

Buffers Possible by Special Request

46

All Glass High NA Fibers• Features:

– OVD high purity glass technology • Glass core• Glass cladding

– High Numerical Aperture • 0.3-0.4 depending on wavelength

window– High temperature operating range

• Up to 125 oC with polymer coating • Higher temperatures special

coating– Low attenuation

• Prototypes are being developed

Coating

Silica Cladding

Silica Core

47

Conclusions• Corning offers a broad product portfolio

• World-class research capability– Advanced fiber design– Leading fiber making technology

• New specialty fibers are being developed– Offer unique features for different applications

Recent Research Activities on Specialty Fibers Presentation … · – Erbium-doped fiber: fiber...

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