1. Photonic Crystal Fibers (PCFs)
Laura Rossi
Photon Physics final presentation

2. OUTLINE INTRODUCTION --> what are PCFs? FABRICATION METHODS
PRINCIPLE OF LIGHT GUIDANCE
APPLICATIONS
WHY U SELECTED THE TOPIC - HOW U’VE USED THE MATERIAL OF THE
COURSE FOR THE PRESENTATION+QUESTION ABOUT AN ISSUE U DID NOT
UNDERSTAND TO START A DISCUSSION ON THE PRESENTATION

3. What are PCFs? new class of optical fibers hollow or solid core
surrounded by an array
of air-holes
(photonic crystal)

4. Fabrication methods 1) EXTRUSION through a die 2) TUBE-STACKING
Fiber drowing tower
2) TUBE-STACKING
technique
Most of them are made of silica extrusion used with other glasses materials
J.C. Knight, Nature 424 (2003)
W.H. Reeves et al., Nature 424 (2003)

5. Two main types… Index guiding or Solid core PCFs Bandgap guiding or
hollow-core
PCFs
CORE with
lower refractive
index
CORE with
higher refractive
index
Modified Total Internal Reflection (MTIR)
Photonic Bandgap (PBG)

6. Light guidance INDEX GUIDING FIBERS TIR
Modified Total Internal Reflection
Solid
core!
PCF

7. Light guidance INDEX GUIDING FIBERS
a) Foundamental mode “trapped” inside the core
b,c) Higher order modes can “escape” from the core
b) Because of their transverse effective wavelenght is smaller
d= hole diameter = interhole spacing
SINGLE MODE GUIDING PCFs d/‹0.4 !!!
P.Russel, Science 299 (2003)

8. Light guidance HOLLOW-CORE FIBERS Hollow Photonic Bandgap effect core!
PCF

9. Light guidance HOLLOW-CORE FIBERS
Periodic nanostructure designed to affect the
propagation of electromagnetic waves
Photonic Crystal
Stop gap = interval of frequencies in which the light cannot
propagate in a specific direction PC I0
I=I0
Band gap ≝
stop gap overlapping
in all directions

10. Light guidance HOLLOW-CORE FIBERS PC LESS ABSORPTION
LESS LOSS!!!
Light traveling in air:

11. { Applications amplifiers and lasers applications
high power experiments on gases
transport of atoms and particles {
Ph.Roy et al.,C.R.Physique 7 (2006)
B.Cowan et al.,Photonic crystal laser
Accelerator structures, Stanford USA (2006)
HOLLOW CORE PCF
PARTICLE TRAPPING AND GUIDANCE IN A HOLLOW-CORE PCF. The van der Waals forces between the um-sized polystyrene particles (c) are broken by making them dance on a vibrating plate (a). The laser beam (b) captures them and entrains them into the hollow-core PCF
The optical dipole forces of a laser beam prevent adhesion to the glass surface in order to obtain acceleration needed to overcome viscosity.
VIBRATING PLATE THAT BREAKS VAN DER
WAALS FORCES BETWEEN THE PARTICLES
LASER BEAM
P.Russel, Science 299 (2003)

12. SUPERCONTINUUM GENERATION
Applications
- nonlinear optics
SUPERCONTINUUM GENERATION
Light generators with high output power, broad and flat spectrum, tight focusing
Ultrashort (femtosecond) laser pulses are coupled into the fiber, through standard microscope objectives, where the non-linear effects influence the pulse by broaden the narrow band laser radiation into a continuous spectrum (Fig.5).---In some applications, like interferometry or spettroscopy, these sources can, in addition to widen the spectral range over which measurements can be made, improve the signal-to-noise ratio and reduce the measurement time.
Applied for:
Optical coherence tomografy
Optical frequency metrology and spettroscopy
P.Russel, Science 299 (2003)

13. Comments and questions…