|
 |
|
|
|
 |
|
|
|
|
|
Home |
|
Research |
|
Publications |
|
People |
|
Links |
|
|
|
|
|
|
Optimal Dimensions for Nonlinearity |
|
|
|
We investigate strong light confinement in high core-cladding index contrast waveguides with dimensions comparable to and smaller than the wavelength of incident light. We consider oval and rectangular cross sections and demonstrate that an optimal core size exists that maximizes the effective nonlinearity. We also determine that waveguides with asymmetrical cross sections provide the maximum possible nonlinearity, although only a small improvement over the symmetric case. Furthermore, we find that for a specified waveguide shape the largest nonlinearity occurs for nearly the same core area in all cases. Calculations of the dispersion for the optimal-size waveguide at a particular wavelength indicate that the group-velocity dispersion is normal. Ultimately, such designs could be used to develop low-power all-optical devices and to produce waveguides for ultra-low threshold nonlinear frequency generation such as supercontinuum generation. |
|
|
|
 |
|
|
|
The effective nonlinearity and mode field diameter (MFD) for a circular glass (ncore = 1.45) waveguide in air (nclad = 1.0).
|
|
|
|
M. A. Foster, K. D. Moll, and A. L. Gaeta, "Optimal waveguide dimensions for nonlinear interactions," Opt. Express 12 2880-2887 (2004). PDF
|
|
|
|
Low Threshold Supercontinuum Generation |
|
|
| We show that optical waveguides with sub-wavelength transverse dimensions optimize the effective nonlinearity and provide desirable dispersive properties for generating supercontinuum with ultra-low threshold power. Using a tapered small-core microstructured fiber with a sub-wavelength diameter core, we generate an octave-spanning supercontinuum with 150 pJ pulses from a femtosecond modelocked Ti:sapphire oscillator. |
|
|
|
 |
|
|
|
Supercontinuum generated in (a) a tapered microstructured fiber, and (b) an untapered microstructured fiber with 2.3 μm core diameter.
|
|
|
|
M. A. Foster and A. L. Gaeta, "Ultra-low threshold supercontinuum generation in sub-wavelength waveguides," Opt. Express 12 3137-3143 (2004). PDF
|
|
|
| 159 Clark Hall |
| Cornell University |
| Ithaca, NY 14853 |
| (607) 255-0657 Lab |
| a.gaeta@cornell.edu |
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|