Fail to find a bandgap for 1-d PC cavity


#1

Hi,
I am a really new beginner for FDTD. I am trying to simulate 1D PC cavity follow this paper(https://arxiv.org/abs/1108.2675). When I try to simulate figure 2 (b), I encounter some problems I get a band diagram which has no band gap. I guess maybe I misunderstand something. This is my simulation. helper.fsp (4.0 MB)
and some results derived from my simulation.


Power coupling from one fiber to another
#2

Dear @iambud

Thank you for reaching out. Linked paper is one of my favourite papers for designing 1D PC cavities and I will be happy to be of a help.

Since you are new to the software, you can start with some of KB application examples linked below:
https://kb.lumerical.com/en/index.html?diffractive_optics_waveguide_pcbandstructure.html
https://kb.lumerical.com/en/index.html?diffractive_optics_waveguide_pc_line_defect.html
https://kb.lumerical.com/en/index.html?diffractive_optics_pc_bandstructure.html
https://kb.lumerical.com/en/index.html?diffractive_optics_pc_bandstructure_2d.html

To calculate the bandgap, you will need only one unit cell. Since your cavity is 1D, the y and z boundary conditions need to be PML. Also, you need to define the width (thickness) of PC cavity and increase FDTD y-span (z-span) so that there is at least half wavelength between PML and PC cavity. You will also need a finer mesh to make sure that you are resolving holes properly.

Please keep me updated with modified simulation file and results and I will be happy to be of a help.

Thanks


#3

A post was split to a new topic: Power coupling from one fiber to another