6. JOSA-B Tutorial Paper¶
6.1. Introduction¶
Dr Christian Wolff and colleagues have used NumBAT throughout their 2021 SBS tutorial paper Brillouin scattering—theory and experiment: tutorial published in J. Opt. Soc. Am. B. This set of examples works through their discussions of backward SBS, forward Brillouin scattering, and intermodal forward Brillouin scattering.
As the calculations in this paper used NumBAT with essentially the same code in these tutorials, we do not bother to include the original figures.
6.1.1. Example 1 – Backward SBS in a circular silica waveguide¶
Figure 15 in the paper shows the fundamental optical field of a silica 1 micron waveguide, with the gain and other parameters shown in Table 2.
The corresponding results generated with sim-josab-01.py
are as follows:
6.1.2. Example 2 – Backward SBS in a rectangular silicon waveguide¶
Figure 14 in the paper calculates the backwards SBS properties of a
rectangular \(450x200\) nm silicon waveguide.
The corresponding results generated with sim-josab-02.py
are as follows:
The fields and gain parameters are as follows:
We can reproduce Fig. 13 showing the elastic dispersion of this waveguide
silicon waveguide using sim-josab-02b-acdisp.py
.
6.1.3. Example 3 – Forward Brillouin scattering in a circular silica waveguide¶
Figure 16 and Table 3 examine the same waveguides in the case of forward Brillouin scattering.
These results can be generated with sim-josab-03.py
and sim-josab-04.py
.
Let’s see the results for the silica cylinder first:
6.1.4. Example 4 – Forward Brillouin scattering in a rectangular silicon waveguide¶
The corresponding results for the silicon waveguide can be generated with sim-josab-04.py
:
6.1.5. Example 5 – Intermodal Forward Brillouin scattering in a circular silica waveguide¶
For the problem of intermodal FBS, the paper considers coupling between the two lowest optical modes. The elastic mode of highest gain is actually a degenerate pair:
6.1.6. Example 6 – Intermodal Forward Brillouin scattering in a rectangular silicon waveguide¶
Finally, the silicon waveguide generates extraordinarily high gain when operated in an intermodal configuration: