PathLengthMatching

PathLengthMatching(
    nets=(),
    *,
    target=None,
    offsets=None,
    objective='length',
    index=None,
    frequency=None,
    tolerance=None,
    bends='free',
    min_gap=None,
    strict=False,
)

Path-length matching specification for one group of nets.

Nets in a group are matched to each other (or to explicit targets) by inserting displacement-neutral meanders in the routes. Groups are independent: each carries its own objective, targets, and contracts.

Args

• nets (Sequence[int]): Net indices in this group. An empty sequence matches every net.
• target (float | Sequence[float] | None): None matches every net to the longest in the group. A single value is an absolute target shared by the group. A sequence sets one target per net (delay ladders, specified ΔL).
• offsets (Sequence[float] | None): Upstream length credit per net. Matching equalizes offset + routed length; with an absolute target, each route ends at target - offset.
• objective (Literal[“length”, “phase”, “group_delay”]): Quantity to equalize: "length" (geometric), "phase" (∫n_eff·ds), or "group_delay" (∫n_g·ds, pulse arrival).
• index (Interpolator | None): Modal index over curvature, and over width and propagation angle where the geometry and the media call for it. One of index or frequency is required by the optical objectives: n_eff values for "phase", n_group values for "group_delay".
• frequency (float | None): Frequency at which to mode-solve the index for the routes’ own cross-section when index is not given.
• tolerance (float | None): Matching tolerance in μm of (effective) length. Defaults to 1e-3 for "length", 5e-3 for "phase", and 1e-2 for "group_delay", because the layout grid quantizes achievable optical length.
• bends (Literal[“free”, “equal_added”, “equal”]): Constraint on the groups bends. "free" lets them differ; "equal_added" gives every net the same number of added bends, for process-corner tracking; "equal" leaves every net with the same bend counts, for a broadband match with equal bend loss.
• min_gap (float | None): Minimal edge-to-edge spacing between group members.
• strict (bool): Raise instead of reporting a refusal. Geometry is left untouched by a refusal either way.

Example

>>> m = pf.PathLengthMatching([0, 1, 2], bends="equal", min_gap=10)

See Also

• parametric.route_auto
• match_path_lengths

Methods

Method	Description
copy	Create a copy of this specification.

copy

copy(self)

Create a copy of this specification.

Returns

PathLengthMatching: New copy.

Attributes

Attribute	Description
bends	str: Bend contract: ‘free’, ‘equal_added’, or ‘equal’.
frequency	float | None: Frequency at which to solve the index, when none is given.
index	Interpolator | None: Modal index for the optical objectives.
min_gap	float | None: Edge-to-edge spacing floor between group members, in μm.
nets	tuple[int, …]: Net indices in the group; empty means every net.
objective	str: Quantity equalized: ‘length’, ‘phase’, or ‘group_delay’.
offsets	tuple[float, …] | None: Upstream length credit per net.
properties	Properties: Object properties.
strict	bool: Raise instead of reporting a refusal.
target	float | tuple[float, …] | None: Group target; None matches the longest net.
tolerance	float: Matching tolerance in μm; reports the objective default when unset.

bends

str: Bend contract: ‘free’, ‘equal_added’, or ‘equal’.

frequency

float | None: Frequency at which to solve the index, when none is given.

index

Interpolator | None: Modal index for the optical objectives.

min_gap

float | None: Edge-to-edge spacing floor between group members, in μm.

nets

tuple[int, …]: Net indices in the group; empty means every net.

objective

str: Quantity equalized: ‘length’, ‘phase’, or ‘group_delay’.

offsets

tuple[float, …] | None: Upstream length credit per net.

properties

Properties: Object properties.

strict

bool: Raise instead of reporting a refusal.

target

float | tuple[float, …] | None: Group target; None matches the longest net.

tolerance

float: Matching tolerance in μm; reports the objective default when unset.