finesse.knm.maps.scattering_coefficients_to_KnmMatrix¶
- finesse.knm.maps.scattering_coefficients_to_KnmMatrix(modes, K)¶
Converts a 4-D scattering coefficient array into a 2D KnmMatrix object to be used in simulations.
- Parameters
- modestuple, array
Array of 2D modes indicies (n,m) to specify the order in which they appear in the returned matrix.
- Karray
4D array of coefficients indexed with [in_x, out_x, in_y, out_y]
- Returns
- KnmKnmMatrix
A KnmMatrix class representing a 2D scattering matrix for the requested modes.
Examples
Compute KNM matrix from a previously calculated 4-D scattering coefficient array:
import finesse from finesse.knm.maps import ( map_scattering_coefficients, scattering_coefficients_to_KnmMatrix ) import numpy as np # compute all scatterings up to maximum TEM order maxtem = 3 q = finesse.BeamParam(w0=1e-3, z=0) x = np.linspace(-4*q.w, 4*q.w, 201) y = np.linspace(-4*q.w, 4*q.w, 200) X, Y = np.meshgrid(x, y) # Mix of liner and quadratic phase terms to compute scattering # coefficients for Z = np.exp(1j * 1e-6 * 2 * np.pi * X / 1064e-9) K = map_scattering_coefficients(q, maxtem, x, y, Z) # Generate specific ordering of coefficients into a 2D matrix that can # be used in simulations for propagating and array of modes. modes = ( (0,0), (1,0), (2,1), ) Knm = scattering_coefficients_to_KnmMatrix(modes, K) # Propagate some mode amplitudes Knm.data @ [1, 0.1, 0] >>> array([9.99995641e-01+2.95261180e-04j, 9.99986923e-02+2.95261180e-03j, 4.23516474e-22+2.16840434e-20j])