Dispersion control of frequency conversion processes with photonic crystal fibers 

 

Contacts:         

Morten Bache, DTU Fotonik, 4525-3775 (moba@fotonik.dtu.dk)

Ole Bang, DTU Fotonik, 4525-6373 (oban@fotonik.dtu.dk)

http://www.fotonik.dtu.dk/staff/bache/

 

Index-guiding PCF: the holes in the cladding help trapping the light in the core. The dispersion of light guided in the core can be manipulated by changing the hole diameter and the hole pitch.

Index-guiding photonic crystal fibers (PCFs) have many advantages over standard step-index fibers. They are made of a single material, they can be single mode for all wavelengths, and they can confine the light in a very small core resulting in very high nonlinear interaction. Last but not least they have the ability to control the dispersive properties of the light in a striking way. In fact, by merely playing with the hole size and arrangement in the cladding it is possible to design the fiber to have very specialized dispersion properties. This is extremely relevant for nonlinear interaction of ultra-short femtosecond pulses.

 

In the current project you will look for an optimal PCF design for second-harmonic generation (SHG) of femtosecond pulses. The relevant dispersion issues concern phase-matching (0. order dispersion), group-velocity matching (1. order dispersion) and group-velocity dispersion (2. order dispersion). You will use freeware software for advanced numerical solutions of Maxwell’s equations to find the modes allowed in the PCF. The goal is to design a PCF with a very low group-velocity mismatch and at the same time keeping the phase mismatch low.