Glossary

Terms specific to PDK authoring. The end-user glossary in the Lumicron API User Guide covers cell, port, pin, route, etc.

Component - A @pcell-decorated factory function in your PDK. Returns a CELL. The naming is colloquial; technically every PDK component is also a PCell.

Continuous stroke - One p.layer(...) band in a route profile. Renders as a FlexRoute along the entire route, including bends.

Datatype - The second integer in a (layer, datatype) pair. Lets multiple semantic layers share one number - drawn (datatype 0), exclusion (1), fill (2), etc.

Default registry - The process-wide TransitionRegistry accessed via lpdk.default_transitions(). PDK transition modules register into it on import.

Factory - A zero-argument function that returns a fresh CELL. Transitions are stored as factories so the router can re-instantiate per use.

LayerSpec - The minimal layer descriptor: (layer, datatype). Layer is a subclass that adds design rules and color.

LayerTable - A named container of Layer objects. End users see it as pdk.LAYER.

Manifest - generated manifest.json inside a .lumpdk archive. Carries nested meta (display name, importable package-name, version) plus layers, stack, profiles, simulation, and component metadata when available.

Periodic feature - A tooth declared via p.tooth(cell, period=...). The cell is tiled along the route at the given arc-length spacing.

PCell - Parametric Cell. Any function decorated with @lm.pcell. Lumicron’s PCells auto-name distinct parameter combinations into distinct GDS cells.

Process Design Kit (PDK) - The package authored by this guide. Contains layers, profiles, components, and (optionally) transitions for one foundry process or in-house technology.

Process-wide registry - See default registry.

Profile - RouteProfile. A cross-section recipe - strokes plus periodic features. Built with @lpdk.route_profile.

RouteProfiles - Container collecting route profiles by name. End users see it as pdk.RP.

Route profile - See Profile.

Sellmeier coefficients - B and C arrays describing material dispersion n²(λ) = 1 + Σ Bᵢ·λ²/(λ² − Cᵢ).

Sibling stroke - A continuous stroke other than the primary core. Cladding rectangles, exclusion zones, slot rails - all sibling strokes.

SOI - Silicon-on-insulator. The substrate type for most photonic PDKs.

StackLayer - One physical layer in a LayerStack: GDS layer reference, thickness, and optical model.

Subwavelength grating (SWG) - A grating with period much smaller than the operating wavelength, behaving as a homogenized effective index. Built using p.tooth() with sub-wavelength period.

Tooth - One periodic feature in a route profile. Declared with p.tooth(cell, period=...).

TransitionRegistry - Maps (layer_a, layer_b) to a factory function. The router reads it to insert bridge PCells on cross-layer routes.

.lumpdk - The packaging format for PDKs the Lumicron Mac app installs. A zip archive with root manifest.json, package-relative Python source, and optional drc.json.