RSoft Enewsletter

October 2015

RSoft Webinar Mixed-Level Simulation: Using RSoft Products to Model Sub-Wavelength Features in LightTools

RSoft Webinar

Wednesday, October 28, 2015
11:00 am PDT (2:00 pm EDT) 
Duration: 30 minutes

You are invited to attend an RSoft™ webinar to learn about a mixed-level methodology that unifies the use of EM wave-level (RSoft) and ray-level (LightTools®) tools. The approach uses the RSoft products to characterize micro/nano-structured surfaces and include coherent effects in a LightTools simulation. Effects such as scattering due to sub-wavelength structures, diffraction, and polarization can be included.

This webinar is useful for optical engineers who design and simulate LEDs/OLEDs, Diffractive Optical Elements (DOEs), color filters, structured color, wire-grid polarizers, and other applications in which it is necessary to include sub-wavelength scattering effects in a LightTools simulation.

Using WinPLOT to Create High-Quality Graphics for Publications and Presentations: Part 1, Line Plots

High-quality graphics are required to accurately present simulation results in publications and presentations. WinPLOT, the plotting program included with all RSoft products, has a complete set of options that can be used to customize how you display data. In this tip from RSoft Tech Support, we will use a representative example to illustrate some of the options that can be used to customize line plots. Future tips will discuss other types of plots.

In the following example, we customize the reflection spectra plots of an angle-insensitive plasmonic-based nano-resonantor color filter. Such structured color devices are inspired by the natural coloring of many butterflies and birds. One such design1 uses silver deposited on a fused grating with a pitch, depth, and width of P, D, and W. These parameters can be varied to tune the resonant wavelength.  

RSoft CAD Environment™

Fig. 1 (a) SEM picture of the structure2, and 
(b) view of a single period of the structure in The RSoft CAD Environment™

Original simulation plot and Modified plot

Fig. 2 (a) Original simulation plot, and (b) Modified plot using WinPLOT options

The reflection spectra shown in Fig. 2(a) were calculated using DiffractMOD™, RSoft’s RCWA-based simulation tool. This line plot represents the default output for a scan over wavelength and the grating depth D. For illustration purposes, we will modify this plot to change several options, including scaling the data, changing line colors, and adding another line for measured data.

View Editor and View Plot buttons

Fig. 3: The View Editor and View Plot buttons in the top WinPLOT toolbar

Most RSoft product output consists of two ASCII data files: a raw data file and a WinPLOT plot file. Modifying or creating a new plot is as simple as editing the WinPLOT file. The plot can be saved as a new plot file for later use. The simplest way to modify the plot file is to open it in WinPLOT and then click the View Editor button in the top WinPLOT toolbar to display the current plotting commands. To return to the plot after editing, click the View Plot button.

The original commands used to produce Fig. 2(a) are shown in Table 1. The new commands used to produce Fig. 2(b) are shown in Table 2.

Table 1: Original WinPLOT commands

/tkm2 Use tick marks on both sides of plot
/tt"Meas. dm\_de\_r\_total\_vs\_wavelength" Set plot title; ‘\’ is used as an escape character, without them the ‘_’ characters would be interpreted as subscripts
/xl"wavelength" Sets x axis label
/yl"y" Sets y axis label
/w0.38,0.82,0.019919,0.982811 Sets x/y plot window
/l/lh"" Enable legend and set legend title
/ls1 Set line style (1 = solid)
Fig1d_ dm_de_r_total_vs_wavelength.dat Original data file with three spectra
/lc9  /lt"D=0.11" Set legend text and color of first line (9 = blue) and legend text
/lc10 /lt"D=0.13" Set legend text and color of second line (10 = green) and legend text
/lc11 /lt"D=0.17" Set legend text and color of third line (11 = cyan) and legend text


Table 2: Modified WinPLOT commands

The modified commands are:

/tkm1 Use tick mark at left/bottom
/suby1 Specify the number of subdivisions for y axis
/subx2 Specify the number of subdivisions for x axis
!/tt"Meas. dm\_de\_r\_total\_vs\_wavelength" ‘!’ comments out this line, removing original plot title
/xl"Wavelength(nm)" Set x axis label
/yl"Reflectance(%)" Set y axis label
/w400,800,0,100 Set x/y axis plot window
/l:700,70 Set legend location
/lts1.2 Set legend text size
/l/lh"" Enable legend and set legend title
/ls1 Define line style (1 = solid)
/lw2 Define line width
/aspect0.3 Set plot aspect ratio
fig1d_dm_de_r_total_vs_wavelength.dat/sx1000/sy100 Original data file with three spectra. The /sx command scales the data along x by 1000 (converts to nm); the /xy command scales the y data by 100 so it is in ‘percent’ units
/lc9 /lt"D=110nm" Set legend text and color of first line (9 = blue) and legend text
/lc10 /lt"D=130nm" Set legend text and color of second line (10 = green) and legend text
/lc12 /lt"D=170nm" Set legend text and color of third line (12 = red) and legend text
meas.txt/sy0.1/lc12/ls2/lt"Experiment\nD=170nm" Data file that contains measured data for D=170. The scale commands can be used as appropriate to scale the data, the /ls2 command sets the line style (2 = dashed), and the /lt command sets the legend text. Note that the ‘Add Data File’ button in the bottom WinPLOT toolbar can be used to easily add additional data to a line plot

This is just one example of using WinPLOT to create and modify high-quality graphics. There are many more WinPLOT script options that can be used to modify plots; consult the WinPLOT user guide or contact our Tech Support team at rsoft_support@synopsys.com for more information.


References

[1,2]  Yi-Kuei Ryan Wu et al, “Angle-Insensitive Structural Colours based on Metallic Nanocavities and Coloured Pixels beyond the Diffraction Limit,” Scientific Reports, 3 (2013).