finesse.components.cavity.Cavity

Overview

class finesse.components.cavity.Cavity(name, *args, **kwargs)

Bases: TraceDependency

Represents a cavity in an interferometer configuration.

This class stores the shortest round-trip path from the start node of the cavity (via a given node) back to the same node, and holds symbolic expressions for each physical attribute of the cavity. Numeric values corresponding to these attributes are obtained through the relevant properties.

Adding a Cavity to a Model results in the beam parameters of all nodes in the cavity path being set according to the cavity eigenmode (Cavity.q) when a beam trace is performed (e.g. at the start of a modal based simulation). The mode of the cavity is then also used as a trace starting point when setting beam parameters at nodes outside of the cavity - see Tracing the beam for details on the beam tracing algorithm.

Parameters

namestr

Name of newly created cavity.

sourceOpticalNode or Port

Node / Port that the cavity path starts from. If no via node is specified, then the cavity path will be given by the shortest path from source back to the component that owns source.

If a port is given then the output optical node of that port will be used as the source.

viaOpticalNode, optional

Node that the cavity path must traverse via; defaults to None.

Note that, unlike source, this cannot be a Port object as this would be ambiguous for beamsplitter type components - i.e. determination of which node to use cannot be assumed automatically.

prioritynumber, optional; default: 0

Priority value for beam tracing. Beam tracing dependencies are sorted in descending order of priority - i.e. higher priority value dependencies will be traced first. Any dependency with a priority value of zero will be traced, after non-zero priority dependencies, in alphabetic order of the dependency names.

Properties

Cavity.ABCD	The round-trip ABCD matrix of the cavity in both planes.
Cavity.ABCDx	The tangential round-trip ABCD matrix of the cavity.
Cavity.ABCDy	The sagittal round-trip ABCD matrix of the cavity.
Cavity.FSR	The free-spectral-range (FSR) of the cavity.
Cavity.FWHM	The cavity full-width-half-maximum (FWHM).
Cavity.S	The resolution of the cavity in both planes.
Cavity.Sx	The resolution of cavity in the tangential plane.
Cavity.Sy	The resolution of cavity in the sagittal plane.
Cavity.finesse	The finesse of the cavity.
Cavity.g	The stability of the cavity, in both planes, given by the \(g\)-factor:
Cavity.gouy	The accumulated round-trip Gouy phase of the cavity in both planes (in degrees).
Cavity.gouy_x	The round-trip Gouy phase in the tangential plane (in degrees).
Cavity.gouy_y	The round-trip Gouy phase in the sagittal plane (in degrees).
Cavity.gx	The stability, g, of the cavity in the tangential plane.
Cavity.gy	The stability, g, of the cavity in the sagittal plane.
Cavity.is_changing	Flag indicating whether any geometric parameter inside the cavity is changing.
Cavity.is_critical	Flag indicating whether the cavity is critically stable.
Cavity.is_critical_x	Flag indicating whether the cavity is critically stable in the tangential plane.
Cavity.is_critical_y	Flag indicating whether the cavity is critically stable in the sagittal plane.
Cavity.is_fabry_perot	Flag indicating whether the cavity is a Fabry-Perot cavity.
Cavity.is_stable	Flag indicating whether the cavity is stable.
Cavity.is_stable_x	Flag indicating whether cavity is stable in the tangential plane.
Cavity.is_stable_y	Flag indicating whether cavity is stable in the sagittal plane.
Cavity.loss	The round-trip loss of the cavity as a fraction of the incoming power.
Cavity.m	The stability of the cavity, in both planes, given by the \(m\)-factor:
Cavity.mode_separation	The mode separation frequency of the cavity in both planes.
Cavity.mode_separation_x	The mode separation frequency in the tangential plane.
Cavity.mode_separation_y	The mode separation frequency in the sagittal plane.
Cavity.mx	The stability, m, of the cavity in the tangential plane.
Cavity.my	The stability, m, of the cavity in the sagittal plane.
Cavity.path	The OpticalPath instance of the cavity.
Cavity.pole	The pole-frequency of the cavity.
Cavity.q	The eigenmode of the cavity in both planes.
Cavity.qx	The eigenmode of the cavity in the tangential plane.
Cavity.qy	The eigenmode of the cavity in the sagittal plane.
Cavity.round_trip_optical_length	The round-trip optical path length of the cavity (in metres).
Cavity.source	Starting node of the cavity.
Cavity.storage_time	The cavity storage time (\(\tau\)).
Cavity.via	Via node of the cavity.
Cavity.w0	The waist size of the cavity in both planes.
Cavity.w0x	The waist size of the cavity in the tangential plane.
Cavity.w0y	The waist size of the cavity in the sagittal plane.
Cavity.waistpos	The position of the cavity waist in both planes.
Cavity.waistpos_x	The waist position of the cavity in the tangential plane.
Cavity.waistpos_y	The waist position of the cavity in the sagittal plane.

Methods

Cavity.__init__(name, source[, via, priority])
Cavity.any_changing_params([geometric])	Determines whether any parameter of any component inside the cavity is changing.
Cavity.draw()	A string representation of the cavity route.
Cavity.generate_abcd_str()	Generates a string representation of the cavity round-trip ABCD matrix operations.
Cavity.get_exit_nodes()	Obtains a dictionary of source: target mappings where source -> target and target is an exit node of the cavity.
Cavity.initialise()	Initialises the symbolic equations of the cavity and calculates the cavity path from the associated model.
Cavity.plot([direction])	Plots the beam representing the cavity eigenmode over the path of the cavity.
Cavity.trace_beam()	Traces the cavity eigenmode through the cavity path.