Source code for finesse.detectors.field_detector

"""Single-frequency array of complex amplitudes detector."""

import logging

import numpy as np

from finesse.env import warn
from finesse.components.node import Node, NodeType
from finesse.detectors.general import Detector
from finesse.parameter import float_parameter
from finesse.detectors.workspace import DetectorWorkspace
from finesse.warnings import FinesseWarning

LOGGER = logging.getLogger(__name__)


[docs]class FDWorkspace(DetectorWorkspace): def __init__(self, owner, sim): needs_carrier = False needs_signal = False self.lower_audio = False self.is_f_changing = owner.f.is_changing if owner.f.eval() is None: raise ValueError( f"{owner.f}: frequency value is `None`, check values have been set correctly." ) fval = float(owner.f) fs = [] if sim.carrier: f = sim.carrier.get_frequency_object(fval, owner.node) if f is not None: needs_carrier = True fs.append((f, sim.carrier)) if sim.signal: f = sim.signal.get_frequency_object(fval, owner.node) if f is not None: needs_signal = True self.lower_audio = f.audio_order < 0 fs.append((f, sim.signal)) if len(fs) == 0: raise Exception( f"Error in amplitude detector {owner.name}:\n" f" Could not find a frequency bin at {owner.f}" ) elif len(fs) > 1: raise Exception( f"Error in amplitude detector {owner.name}:\n" f" Found multiple frequency bins at {owner.f}" ) super().__init__( owner, sim, needs_carrier=needs_carrier, needs_signal=needs_signal ) freq, self.mtx = fs[0] self.fidx = freq.index self.node_idx = int(self.mtx.node_id(owner.node)) self.set_output_fn(self.__output) @staticmethod def __output(ws): if ws.sim.is_modal: z = np.asarray(ws.mtx.node_field_vector(ws.node_idx, ws.fidx)) / np.sqrt(2) if ws.lower_audio: return z.conj() else: return z else: return np.nan
[docs]@float_parameter("f", "Frequency", units="Hz") # IMPORTANT: renaming this class impacts the katscript spec and should be avoided! class FieldDetector(Detector): """Outputs an array of the higher order modes amplitudes at a particular node and frequency. The mode ordering is given by `Model.homs`. This detector can only be used on optical nodes. Parameters ---------- name : str Name of newly created detector. node : :class:`.Node` Node to read output from. f : float Frequency of light to detect (in Hz). Examples -------- >>> import finesse >>> model = finesse.Model() >>> model.parse(''' laser l1 gauss g1 l1.p1.o w0=1m z=0 m m1 R=1 T=0 xbeta=1e-9 ybeta=3e-8 link(l1, m1) modes(maxtem=1) fd fd1 m1.p1.o 0 ''') >>> out = model.run('noxaxis()') >>> print(out['fd1']) array([ 0.99999998+0.00000000e+00j, 0+1.77157478e-04j, 0+5.90524926e-06j ]) """ def __init__(self, name, node: Node, f): if node.type is not NodeType.OPTICAL: raise Exception(f"Must be an optical node used for FieldDetector {name}") Detector.__init__(self, name, node, dtype=np.complex128, label="HOM Amplitudes") self.f = f def _get_workspace(self, sim): if not sim.is_modal: warn( f"FieldDetector {self} needs higher order modes to be enabled.", FinesseWarning, ) # Need to update the shape of this output depending on how many HOMs there are self._update_dtype_shape((sim.model_settings.num_HOMs,)) return FDWorkspace(self, sim)