Why laser accelerator
Download
1 / 16

Why Laser Accelerator? - PowerPoint PPT Presentation


  • 101 Views
  • Uploaded on

Why Laser Accelerator?. High power: ~ petawatts High intensity (field): 10 22 W/cm 2 ~ 2.7x10 12 V/cm Accelerator gradient: limited by materials damage threshold ~ 1GV/m (fused silica) Low loss in guiding structure: 0.2dB/km. losses ~ 0.2 dB/km at l =1.55µm (amplifiers every

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Why Laser Accelerator?' - brenda-keith


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Why laser accelerator
Why Laser Accelerator?

  • High power: ~ petawatts

  • High intensity (field): 1022 W/cm2 ~ 2.7x1012 V/cm

  • Accelerator gradient: limited by materials damage threshold ~ 1GV/m (fused silica)

  • Low loss in guiding structure: 0.2dB/km


Optical fibers today

losses ~ 0.2 dB/km

at l=1.55µm

(amplifiers every

50–100km)

more complex profiles

to tune dispersion

“high” index

doped-silica core

n ~ 1.46

“LP01”

confined mode

field diameter ~ 8µm

protective

polymer

sheath

Optical Fibers Today

silica cladding

n ~ 1.45


Solid core holey fibers
Solid-core Holey Fibers

solid core

holey cladding forms

effective

low-index material

Can have much higher contrast

than doped silica…

strong confinement = enhanced

nonlinearities, birefringence, …

[ J. C. Knight et al., Opt. Lett.21, 1547 (1996) ]


Hollow core bandgap fibers

1000x better

loss/nonlinear limits

(from density)

Hollow-core Bandgap Fibers

Bragg fiber

[ Yeh et al., 1978 ]

1d

crystal

+ omnidirectional

= OmniGuides

2d

crystal

Photonic Crystal

PCF

[ Knight et al., 1998 ]


Experimental air guiding pcf
Experimental Air-guiding PCF

[ R. F. Cregan et al., Science285, 1537 (1999) ]

10µm

5µm


Fabrication air guiding pcf

silica glass tube (cm’s)

(outer

cladding)

~50 µm

fiber

draw

fuse &

draw

~1 mm

Fabrication: Air-guiding PCF


Fabrication bragg fiber

3

1

compatible materials

Thermal evaporation

2

Make pre-form

(“scale model”)

chalcogenide glass, n ~ 2.8

+ polymer (or oxide), n ~ 1.5

fiber drawing

Fabrication: Bragg Fiber

[Y. Fink et al., MIT ]


A drawn bandgap fiber

white/grey

= chalco/polymer

A Drawn Bandgap Fiber

[Y. Fink et al., MIT ]


Acceleration mode in bragg fiber
Acceleration Mode in Bragg Fiber

  • b=k0=2p/l

  • a/l=1

  • nhigh=2.6

  • nlow=1.6

  • Er=-jp r/l Ez

  • Radiation loss: 0.2dB/km

  • 20-pair of layers


Small surface field structure
Small Surface Field Structure

  • b=0.79253k0

  • a/l=1

  • nhigh=2.6

  • nlow=1.6

  • Er=0 at r0=a


Dispersion relation tm 01
Dispersion Relation: TM01

1mm

No perturbation


Dispersion relation tm 011

1mm

Dispersion Relation: TM01


Surface field
Surface Field

Perturbation in Cladding (Metal)

Perturbation in Core

pa/l=2.2

pa/l=3.14


Summery
Summery

  • Hollow core fiber is able to confine acceleration mode (TM01, vp=c)

  • Uniform light wave guiding does not reduce Er (pr/aEz)

  • Looking for structures that can be made for acceleration (polymer microstructured fiber, tapered fiber)


Other challenges
Other Challenges

  • light coupling, (evanescent coupling)

  • mode excitation,

  • imperfection vs. mode mixing


ad