Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: S-matrix absolute optimization method for a perfect vertical waveguide
  grating coupler   Vertical coupling using a diffraction grating is a convenient way to couple
light into an optical waveguide. Several optimization approaches have been
suggested in order to design such a coupler; however, most of them are
implemented using algorithm based modelling. In this paper, we suggest an
intuitive method based on S-matrix formalism for analytically optimize 3-port
vertical grating coupler devices. The suggested method is general and can be
applied to any 3-port coupler device in order to achieve an optimal design
based on user constrains. The simplicity of the model allows reduction of the
optimization to two variables and the location of an absolute optimal operation
point in a 2D contour map. Accordingly, in an ideal device near 100 percent
coupling efficiency and insignificant return loss could be achieved. Our model
results show good agreement with numerical FDTD simulations and can predict the
general tendencies and sensitivities of the device behavior to changes in
design parameters. We further apply our model to a previously reported high
contrast uni-directional grating coupler device and show that additional
improvement in the coupling efficiency is achievable for that layout.

7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
1
The categories of this paper are: cs
18
The categories of this paper are: econ
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas