Erlangen,Germany

Gas,Glass&Light:25+yearsofphotoniccrystal�ibres

PhilipRussell

©2016PhilipRussell

©2016PhilipRussell

26 years ago at CLEO-US ©2016PhilipRussell

©2016PhilipRussell

2D photonic bandgaps in silica/air PCF

β

Birksetal,Electron.Lett.31,1941(1995)no

rmal

ised

freq

uenc

y ωΛ

/c

normalised wavevector along fibre βΛ 6 7 8 9 10 11 12

6

7

8

9

10

11

12

full photonic band gaps

45% air filling fraction index contrast 1:1.46

©2016PhilipRussell

Solid core photonic crystal fibre (1995)

~100 µm

ncore > ncladding

Knightetal:Opt.Lett.21,1547(1996)

Guidance by modified total internal reflection silica

glass

hollow channels

©2016PhilipRussell

Hollow core PCF (1999)

~100 µm

Creganetal:Science285,1537(1999)

silica glass

hollow channels

ncore < ncladding

Guidance by anti-resonant reflection or a 2D photonic bandgap in cladding

©2016PhilipRussell

MAKING PCF

©2016PhilipRussell

PCF fabrication: Stacking & drawing

©2016PhilipRussell

~1 cm

stack of glass capillaries

©2016PhilipRussell

University of Bath 12th October 2004

University of Bath Group in 2004

©2016PhilipRussell

THE FIRST PCF

©2016PhilipRussell

The first guiding photonic crystal fibre… Knightetal:Opt.Lett.21,1547(1996)

2.3 µm

far-field pattern when carrying green & red light

©2016PhilipRussell

Modified total internal reflection

β

Knightetal,Electron.Lett.31,1941(1995)no

rmal

ised

freq

uenc

y ωΛ

/c

normalised wavevector along fibre βΛ 6 7 8 9 10 11 12

6

7

8

9

10

11

12

45% air filling fraction index contrast 1:1.46

dispersionofPCFcladdingdependsonphotoniccrystaldesign

©2016PhilipRussell

…was endlessly single-mode

  fundamental mode cannot squeeze between air-holes

  higher-order modes can escape into cladding

evanescence anti-resonant

unit cell resonant unit cell

Birksetal:Opt.Lett.22,961(1997)

©2016PhilipRussell

10,000 TIMES BRIGHTER THAN THE SUN

©2016PhilipRussell

Chromatic dispersion in waveguides

optical modes of hollow waveguides always have

anomalous dispersion (geometrical effect)

hollow core

bulk glass or gas typically has

normal dispersion (material response)

bulk material + filled

core

dispersion of filled core combination is

the balance of the two

=

bluer faster bluer slower depends

©2016PhilipRussell

Wavelength (µm)

0.5 0.6 0.7 0.8 0.9 1.0 –300

–200

–100

0

100

200

300 D

ispe

rsio

n (p

s/nm

.km

)

anomalous

normal

Chromatic dispersion of 800 nm core PCF

PCF (measured)

bulk silica

zzeerroo cchhrroommaattiicc ddiissppeerrssiioonn ((556600 nnmm))

Chromatic dispersion of pure silica Knightetal,PhotTechLett,12,807(2000)

zero at ~1300 nm

800 nm

zzeerroo ddiissppeerrssiioonn ccaann bbee ddeessiiggnneedd ttoo lliiee aannyywwhheerree iinn tthhiiss rraannggee

bluer = slower

bluer = faster

©2016PhilipRussell

White-light generation in solid-core PCF

4.5 mW/nm 450-800 nm

Nd:fibre laser & amplifier (1064 nm, 5 ps, 10-11 W launched)

Repetition rate 50 MHz, total SC power 6.5 W

Fianium Ltd

6 µm

extreme nonlinear optics

Rankaetal:Opt.Lett.25,25(2000)Dudleyetal:Rev.Mod.Phys.78,1135(2006)

©2016PhilipRussell

Deep-UV supercontinuum in ZBLAN PCF

core diameter ~3 µm 1042 nm, 140 fs, 75 MHz, 13 nJ

Jiangetal:Nat.Phot.9,133(2015)

Brightstablespectrumdownto200nmwavelength

©2016PhilipRussell

FIBRES WITH NO CORE

©2016PhilipRussell

Excerpt from a talk (by me) in late 1990s

2 µm pitch

November 1995

“The�irstphotoniccrystal�ibrewasuseless……becauseitneededdefects”

©2016PhilipRussell

Coreless PCF guides light when helically twisted

π rad/mm 2.86 rad/mm 1.26 rad/mm

expe

rimen

t si

mul

atio

n

hole diameter 2.2 µm spacing 5.7 µm wavelength 818 nm

Beravatetal:ScienceAdv.2,e1601421(2016)

©2016PhilipRussell

Untwisted coreless PCF

axis

effe

ctiv

e ax

ial i

ndex

nsilica

n = 1

passband of fundamental space-filling

modes

Beravatetal:ScienceAdv.2,e1601421(2016)

©2016PhilipRussell

Twisted coreless PCF

passband in twisted

cladding

naxial ∝ radius2

axis

effe

ctiv

e ax

ial i

ndex

NB: Apparent increase in bulk material refractive

index is purely topological

Geometrical increase in path-length with radius:

Beravatetal:ScienceAdv.2,e1601421(2016)

©2016PhilipRussell

Mode is guided on-axis at bottom of passband

radius

axial refractive index

photonic band-gap

0

cut-off band field-lobes in-phase

anti-guiding

guiding

field-lobes out-of-phase

A gravitational “wormhole” for light in helically curved periodic space

Beravatetal:ScienceAdv.2,e1601421(2016)

©2016PhilipRussell

HOLLOW CORE PCF

©2016PhilipRussell

Guidance by 2D bandgap possible in air

β

Birksetal,Electron.Lett.31,1941(1995)Creganetal:Science285,1537(1999)

norm

alis

ed fr

eque

ncy ωΛ

/c

normalised wavevector along fibre βΛ 6 7 8 9 10 11 12

6

7

8

9

10

11

12

full photonic band gaps

45% air filling fraction index contrast 1:1.46

dispersionofPCFcladdingdependsonphotoniccrystaldesign

NEW AGE CRYSTALS

The Economist November 21st 1999

~25 mm of photonic crystal fibre

microscope

lamp

Creganetal:Science285,1537(1999)©2016PhilipRussell

©2016PhilipRussell

Anti-resonant reflecting (ARR) hollow-core PCFs

  nonlinear gas-light interactions enhanced >10,000 times c.f. focused Gaussian beam

  Benabidetal:Science298,399(2002)  Pryamikovetal:Opt.Exp.19,1441(2011)  Yuetal:Opt.Exp.20,11153(2012)

  Debordetal:Opt.Lett.39,6245(2014)  Uebeletal:Opt.Lett.41,1961(2016)  Froszetal:Phot.Res.5,88(2017)

kagome

~30 µm core

  higher loss (~1 dB/m)   ultra-broadband (1000s of nm)   design of first layer critical

2002 2012

d

D

2016

©2016PhilipRussell

Guidance by antiresonant reflection in air

β

norm

alis

ed fr

eque

ncy ωΛ

/c

normalised wavevector along fibre βΛ 6 7 8 9 10 11 12

6

7

8

9

10

11

12

guidance by anti-resonant

reflection

45% air filling fraction index contrast 1:1.46

coremodeisanti-resonantwithmodesofcapillariesinthering

©2016PhilipRussell

ARR HC-PCFs are not usually single-mode Traboldetal:Opt.Lett.39,3736(2014)

  Prism-coupling through the cladding

  Absence of PBG means that light can pass into core resonance

  Allows accurate measurement of modal phase indices and loss

  Modal field patterns can be imaged

  How to suppress higher order modes?

©2016PhilipRussell

Suppressing HOMs in single-ring ARR-PCF Uebeletal:,Opt.Lett.41,1961(2016)

(nlm

– 1

)×10

−4

α lm [d

B/m

]

FOM×10

–2 FOM11 =α11 −α 01

α 01

dcap /Dcore ≈ z1(J0 ) / z1(J1) = 0.68

thick sheath

thin-wall capillaries

©2016PhilipRussell

Bend loss in single-ring PCFs

Rcr01

D= D2

λ 2

π 2

u012

π 2(d / D)2

1− d / Dcosθ

Froszetal:Phot.Res.5,88(2017)

©2016PhilipRussell

www.ultralumina.com

BRIGHT ULTRAVIOLET LIGHT

Por�olioofultralumina’sproducts&services

§  Design§  Fabrica�on§  Characteriza�on§  Hollow-core

Photoniccrystalfibres

Op�calFibres

LightSources

Services

§  DeepUVsupercon�nuum§  TunabledeepUV§  MHzrepe��onrate,µJ

energy,sub-50fslasers

§  Consul�ng§  Developmentprojects

§  High-powerbeamdelivery§  fsbeamdelivery§  Lowlatency§  Gas-filledfibre-based

lightsources

§  Semiconductormetrology§  Time-resolvedna�ve

fluorescencedetec�on§  Advancedmaterial

processing

§  Deep-levelmarket&applica�onunderstanding

§  Evalua�onofHC-PCFrelatedbusinesscases

§  Fibredevelopment&systemintegra�on

Whatwedo Applica�ons

Asupercon�nuumlightsourceforthedeepUV

§  180–1600nmspectralrange§  BeamqualityM2<1.3§  mW/nmpowerspectraldensity§  Wlevelaveragepower

Keyspecifica�ons

§  Spectralpulsebroadeningingas-filledhollow-corePCF

Technology

§  Semiconductormetrology§  Adv.materialcharacteriza�on§  Time-resolvedfluorescencedetec�on

Applica�ons

©2016PhilipRussell

Pressure-tunable dispersion in ARR-PCF

  long well-controlled path-lengths   broadband guidance (for few-cycle pulses)   low light-glass overlap (high damage threshold)   tunable low anomalous/normal dispersion

400 600 800 1000 1200 1400

1.0

0

0.5

−0.5

−1.0

Dis

pers

ion

(ps2

/km

)

600 900 450 300 200 wavelength (nm)

frequency (THz)

0 bar

2 bar

5 bar 10 bar 20 bar 30 bar

pump laser

argon-filled PCF core diameter 29.6 µm

bluer = faster bluer = slow

er Reviews:PRetal:Nat.Phot.8,278(2014)Traversetal:JOSAB28,A11-A26(2011)kagome

©2016PhilipRussell

Ultrashort pulses of DUV/VUV light

0.4

0.8

1.2

1.6

frequ

ency

(PH

z)

5 10 0 length (cm)

zero GVD SPM-driven broadening

pulse 30 fs, 1 µJ; 5 bar of Ar core diameter 26 µm

−10

0

20

10

time

(fs)

soliton compression

N ~ 7 soliton

Jolyetal:Phys.Rev.Lett.106,203901(2011)

temporal focus

deep UV dispersive wave

soliton fission

deep UV

©2016PhilipRussell

Maketal:Opt.Exp.21,10942(2013)

0.6 0.8 1.0 1.2 1.4 1.6 1.8

frequency (PHz)

inte

nsity

(a.u

.)

0.5

1.0

0.0

500 400 300 200 wavelength (nm)

vacuum-UV deep-UV near-UV visible

Xe Kr Ar Ne

Tunability by varying pulse, fibre & gas

1% to 8% conversion from near-IR to vacuum-UV

©2016PhilipRussell

28 bar 3.5 µJ 28.2 bar

5 µJ

Tunable VUV dispersive wave emission

Coherent ultrashort DW pulses of VUV light generated in Ne-filled HC-PCF (35 fs, 4 µJ pump at 800 nm)

He-filled HC-PCF: VUV portion of the supercontinuum spectrum (linear scale)

Ermolovetal:Phys.Rev.A.,92,033821(2015)

Compressible to 500 attoseconds (theory)

26 bar

21 bar

21 bar

numerical simulation

©2016PhilipRussell

IMPOSING MOLECULAR ORDER

©2016PhilipRussell

Phase-matching in the vicinity of the ZDP

β – β0

ω – ω0

Cw

ΩR = Raman frequency

Δβ = 2π/Λcoh

zero dispersion point

Bauerschmidtetal:Optica2,536–539(2015)

curvature changes sign at ZDP

Raman coherence wave Cw

Cw

©2016PhilipRussell

Pressure-tunable from UV to IR Bauerschmidtetal:Optica2,536–539(2015)

0.37

0.43

0.50

0.60

0.75

1.00

1.50

3.00

800

700

600

500

400

300

200

100 0 1 2 1 10 100

(βref – β) [mm–1] pressure [bar]

wavelength [µm

] frequ

ency

[TH

z]

W0

W–1

zero dispersion wavelength

12 bar

30 bar

3 bar

read

write

read

write

read

write

core diameter ~40 µm

©2016PhilipRussell

1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 wavelength (µm)

300 400 500 600 frequency (THz)

phot

on ra

te (d

B)

0

–10

–30

–40

–50

–20

27.6 bar signal to be up-shifted

Broad-band spectral up-conversion Bauerschmidtetal:Optica2,536–539(2015)

532 nm writing signal

up-shifted signal

©2016PhilipRussell

LIGHT-DRIVEN MECHANICAL MOTION

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camera

guiding beam

particle loading beam

white light source

dichroic mirror

low NA high NA

Particle launching in hollow-core PCF

lack of diffraction means that particle experiences constant acceleration

laser tweezers pioneer Arthur Ashkin (1922-)

hollow core PCF

dichroic mirror

�������������� ����������������������

���� ��������������

©2016PhilipRussell

Flying (charged) particle microphone

At the keyboard: Maria Bykova Recording engineer: Dmitry Bykov

  noise caused by Brownian motion   quality: not quite as good as a wax cylinder

Bykovetal:Nat.Phot.9,461(2015)

©2016PhilipRussell

Acknowledgements Ringberg Castle, June 2017

www.pcfibre.com

©2016PhilipRussell

©2016PhilipRussell

Introduction

Glass syrup

Solid core PCF

10,000 times brighter than the sun

Hollow core PCF

Bright ultraviolet light

Imposing molecular

order

Light-driven mechanical

motion

ultralumina GmbH

Fibres with no core

©2016PhilipRussell