"""Detectors for calculating mode mismatches in an optical configuration."""
import numpy as np
from ..components.node import OpticalNode, Port
from .general import Detector
from .compute.gaussian import ModeMismatchDetectorWorkspace
[docs]class ModeMismatchDetector(Detector):
"""Detector for mode mismatch figure-of-merit for a specified node coupling.
The computed quantity is given in :meth:`finesse.gaussian.BeamParam.mismatch` where
:math:`q_1` is the input beam parameter at `node1` propagated via the associated
ABCD matrix to `node2`, and :math:`q_2` is the beam parameter at `node2`.
As mode mismatches cannot occur over spaces in Finesse, `node1` must be an input
node and `node2` must be an output node.
Parameters
----------
name : str
Name of the detector.
node1 : :class:`.OpticalNode` or :class:`.Port`
Input node or port. If a :class:`.Port` instance is given then this
node will be the input node of that port. Note that this node cannot
be an output node.
node2 : :class:`.OpticalNode` or :class:`.Port`
Output node or port. If a :class:`.Port` instance is given then this
node will be the output node of that port. Note that this node cannot
be an input node.
direction : str, optional; default: "x"
Plane of computation, defaults to "x" for the tangential plane. Changing
to "y" will compute the mode mismatch in the sagittal plane.
percent : bool, optional; default: True
Whether to calculate the mode mismatch as a fraction (default behaviour)
or a percentage.
"""
def __init__(self, name, node1, node2, direction="x", percent=False):
if isinstance(node1, Port):
node1 = node1.i
if isinstance(node2, Port):
node2 = node2.o
if not isinstance(node1, OpticalNode):
raise TypeError("Argument node1 must be an OpticalNode.")
if not isinstance(node2, OpticalNode):
raise TypeError("Argument node2 must be an OpticalNode.")
if not node1.is_input:
raise ValueError("Expected node1 to be an input node.")
if node2.is_input:
raise ValueError("Expected node2 to be an output node.")
if node1.component != node2.component:
raise ValueError(
"Expected node1 and node2 to be owned by the same component."
)
label = f"Mode mismatch\n{node1.full_name}->{node2.full_name}"
unit = "%" if percent else ""
super().__init__(name, dtype=np.float64, label=label, unit=unit)
comp = node1.component
comp.check_coupling(node1, node2)
self.__node1 = node1
self.__node2 = node2
self.__direction = direction
self.__percent = percent
@property
def in_node(self):
"""Input node.
:getter: Returns the input node. Read-only.
"""
return self.__node1
@property
def out_node(self):
"""Output node.
:getter: Returns the output node. Read-only.
"""
return self.__node2
@property
def component(self):
"""The component at which the mode mismatch is calculated.
:getter: Returns the associated component. Read-only.
"""
return self.in_node.component
@property
def in_percent(self):
"""Flag indicating whether the mismatch is computed as a percentage.
:getter: Returns the percentage flag.
:setter: Sets the percentage flag.
"""
return self.__percent
@in_percent.setter
def in_percent(self, value):
self.__percent = bool(value)
@property
def direction(self):
"""The plane in which the mode mismatch is calculated.
A value of "x" represents the tangential plane, whilst "y" gives
the sagittal plane.
:getter: Returns the plane of computation as a string representation. Read-only.
"""
return self.__direction
@property
def needs_fields(self):
return False
@property
def needs_trace(self):
return True
def _get_workspace(self, sim):
return ModeMismatchDetectorWorkspace(self, sim)