Plotting

PhoXonic.jl provides two plotting paths via package extensions:

Extension	Trigger	Functionality
RecipesBaseExt	`using RecipesBase` (or any backend)	`plot(bs)` recipe for `BandStructure`
PlotsExt	`using Plots`	`plot_bands`, `plot_bands!` (full-featured)
PythonPlotExt	`using PythonPlot`	`savefig_publication` (publication-quality PDF/PNG)

RecipesBase Recipe

The lightweight recipe is activated when any RecipesBase-compatible backend is loaded.

using PhoXonic, Plots   # or CairoMakie, etc.

solver = Solver(TEWave(), geo, (64, 64))
bs = compute_bands(solver, kpath)

plot(bs)

Attribute	Default
xlabel	`"Wave vector"`
ylabel	`"Frequency"`
legend	`false`
grid	`true`
linewidth	2

Override any attribute with standard keyword arguments:

plot(bs, ylabel="ω a / 2πc", title="TE Bands", linewidth=1)

Plots.jl Functions

These functions require using Plots and provide additional features such as high-symmetry point tick labels, scatter mode for 3D, and band gap highlighting.

`plot_bands`

using PhoXonic, Plots

bs = compute_bands(solver, kpath)
p = plot_bands(bs; title="TE Bands", show_gaps=true)
savefig(p, "bands.png")

Scatter mode (recommended for 3D to avoid line artifacts at Γ point):

p = plot_bands(bs; scatter=true, markersize=2)

`plot_bands!`

Add band structure to an existing plot:

p = plot_bands(bs_te; color=:blue, title="TE + TM")
plot_bands!(p, bs_tm; color=:red)

Options

Option	Type	Default	Description
`color`	Symbol	`:blue`	Line/marker color
`linewidth`	Int	2	Line width
`scatter`	Bool	`false`	Use scatter instead of lines
`markersize`	Int	3	Marker size (scatter mode)
`title`	String	`"Band Structure"`	Plot title
`ylabel`	String	`"Frequency"`	Y-axis label
`show_gaps`	Bool	`false`	Highlight band gaps
`gap_color`	Symbol	`:yellow`	Gap highlight color
`gap_alpha`	Float64	0.2	Gap highlight transparency
`normalize`	Float64	1.0	Frequency normalization factor

`band_plot_data`

Extract raw plot data from a BandStructure (backend-independent):

data = band_plot_data(bs; normalize=1.0)
# data.distances, data.frequencies, data.label_positions, data.label_names

PythonPlot — Publication-Quality Figures

Activated when using PythonPlot is loaded. Provides savefig_publication for matplotlib-backed PDF/PNG output with precise axis-size control suitable for journal submissions.

`savefig_publication`

Single BandStructure:

using PhoXonic, PythonPlot

bs = compute_bands(solver, kpath)
savefig_publication(bs, "bands.pdf"; axis_width_cm=8.0, axis_height_cm=6.0,
                    title="TE Bands")

Multiple BandStructure as subplots:

savefig_publication([bs_te, bs_tm], "te_tm.pdf"; layout=(1, 2))

Multiple BandStructure as overlay (single axis):

savefig_publication([bs_te, bs_tm], "te_tm_overlay.pdf"; overlay=true,
                    title="TE vs TM")

Options

Option	Type	Default	Description
`axis_width_cm`	Real	`8.0`	Axis width in centimeters
`axis_height_cm`	Real	`6.0`	Axis height in centimeters
`ylims`	Tuple or `nothing`	`nothing`	Y-axis range (auto if `nothing`)
`title`	String	`""`	Plot title (suppressed if empty)
`show_gaps`	Bool	`false`	Highlight band gaps with `axhspan`
`normalize`	Real	`1.0`	Frequency normalization factor
`layout`	Tuple	`(1, n)`	Subplot grid `(nrows, ncols)`
`overlay`	Bool	`false`	Plot all on a single axis

The output format is inferred from the file extension (.pdf, .png, .svg, etc., as supported by matplotlib).

API Reference

PhoXonic.plot_bands — Function

plot_bands(bs::BandStructure; kwargs...)

Plot a band structure diagram.

Arguments

bs: BandStructure object from compute_bands()

Keyword Arguments

color: Line/marker color (default: :blue)
linewidth: Line width (default: 2)
scatter: Use scatter plot instead of lines (default: false). Recommended for 3D band structures where Γ point anomalies may occur.
markersize: Marker size for scatter plot (default: 3)
markershape: Marker shape for scatter plot (default: :circle)
title: Plot title (default: "Band Structure")
ylabel: Y-axis label (default: "Frequency")
show_gaps: Highlight band gaps (default: false)
gap_color: Color for gap highlighting (default: :yellow)
gap_alpha: Transparency for gap highlighting (default: 0.2)
normalize: Normalization factor for frequency (default: 1.0)

Returns

A Plots.jl plot object.

Example

using PhoXonic, Plots
solver = Solver(TEWave(), geo, (64, 64))
bands = compute_bands(solver, kpath)
p = plot_bands(bands; title="TE Bands", show_gaps=true)
savefig(p, "bands.png")

# For 3D, use scatter to avoid line artifacts at Γ point
p = plot_bands(bands; scatter=true, markersize=2)

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PhoXonic.plot_bands! — Function

plot_bands!(p, bs::BandStructure; kwargs...)

Add band structure to an existing plot.

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PhoXonic.band_plot_data — Function

band_plot_data(bs::BandStructure; normalize=1.0)

Extract data for plotting a band structure.

Returns a NamedTuple with:

distances: K-path distances
frequencies: Normalized frequency matrix
label_positions: Positions of high-symmetry points
label_names: Names of high-symmetry points

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PhoXonic.savefig_publication — Function

savefig_publication(bs::BandStructure, path; kwargs...)
savefig_publication(bss::AbstractVector{<:BandStructure}, path; kwargs...)

Save a publication-quality band structure figure via the PythonPlot extension. Requires using PythonPlot to activate PhoXonicPythonPlotExt.

The output format is inferred from the file extension (.pdf, .png, .svg, ...).

Keyword arguments

axis_width_cm = 8.0, axis_height_cm = 6.0 — Axis size in centimeters.
ylims = nothing — Y-axis range (auto if nothing).
title = "" — Plot title (suppressed if empty).
show_gaps = false — Shade band gaps with axhspan.
normalize = 1.0 — Frequency normalization factor (forwarded to band_plot_data).
layout = (1, length(bss)) — Subplot grid for the vector overload.
overlay = false — Plot all bss on a single axis (vector overload).

See also: plot_bands for interactive plotting with Plots.jl.

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