Waveguide module¶

With this module you can easily describe waveguide profiles to be fed in the pynumpm.phasematching module.

Two classes are available:

pynumpm.waveguide.Waveguide, for the simulation of simple, ideal system with translational invariance;
pynumpm.waveguide.RealisticWaveguide, for the simulation of systems with a parameter that varies along their propagation axis.

Waveguide¶

class pynumpm.waveguide.Waveguide(length: float, poling_period: float = inf)[source]¶

Base class for the description of a waveguide object. Initialize the object providing its length (in meter) and, if necessary, its poling period.

Parameters:	length (float) – Length of the waveguide [meter]. poling_period (float) – Poling period of the structure, [meter]. Default: +numpy.infty

The following block of code initialises a 10mm-long waveguide with a poling period of 16 \(\mu\mathrm{m}\):

thiswaveguide = waveguide.Waveguide(length = 10e-3,
                                    poling_period = 16e-6)

poling_period¶: The poling period of the structure, in m.

poling_period_um¶: The poling period of the structure, in \(\mu\mathrm{m}\).

length¶: The length of the structure, in m.

RealisticWaveguide¶

class pynumpm.waveguide.RealisticWaveguide(z: numpy.ndarray, poling_period: float = inf, nominal_parameter: float = 1.0, nominal_parameter_name: str = '')[source]¶

Class for the description of waveguides with variable profiles. It can generate noisy profiles (via the functions in the pynumpm.noise module) and it can load user-defined profiles and/or poling structures (they must be consistent with the user specified mesh).

Initialize the waveguide by providing a z-mesh,a poling and the nominal parameter of the profile. This will automatically generate a uniform profile with the specified nominal parameter.

Parameters:	z (numpy.ndarray) – linearly spaced space mesh [meter]. poling_period (float) – poling period of the structure [meter]. nominal_parameter (float) – nominal parameter of the structure [variable units depending on the Sellmeier used]. nominal_parameter_name (string) – (optional) name of the nominal parameter (used for the axes). LaTeX syntax is allowed.

The following block of code initialises and plots the profile of a 15mm-long, 7 \(\mu\mathrm{m}\)-wide waveguide with a poling period of 9 \(\mu\mathrm{m}\). The waveguide is discretized over a z-mesh with steps of 10 \(\mu\mathrm{m}\). The waveguide width is characeterised by a noise with a 1/f spectrum with amplitude 0.2 \(\mu\mathrm{m}\).

z = np.arange(0, 15e-3, 10e-6)
thiswaveguide = waveguide.RealisticWaveguide(z = z,
                                             poling_period = 9e-6,
                                             nominal_parameter = 7e-6,
                                             nominal_parameter_name = "Width")
thiswaveguide.create_noisy_waveguide(noise_profile = "1/f",
                                     noise_amplitude = 0.2)
thiswaveguide.plot_waveguide_properties()

z¶: Array containing the z-mesh of the structure.

dz¶: Resolution of the z-mesh.

profile¶: Waveguide profile (array). Array containing the values of the waveguide profile to be simulated (e.g., the waveguide width or temperature profile).

nominal_parameter_name¶: Name of the nominal fabrication parameter.

poling_structure_set¶: Boolean to describe if the poling structure is set.

poling_structure¶: Array containing the poling structure.

nominal_parameter¶: Nominal fabrication parameter of the waveguide.

load_waveguide_profile(waveguide_profile: numpy.ndarray = None)[source]¶

Function to load a user-defined waveguide profile.

Parameters:	waveguide_profile (numpy.ndarray) – Array with the waveguide profile, with respect to the parameter under investigation, or None. If None, it will create a uniform waveguide with the a constant waveguide.nominal_parameter. If an array, it must have the same shape as the z-mesh. Default: None
Returns:	The numpy.ndarray containing the waveguide profile.

create_noisy_waveguide(noise_profile: str = '1/f', noise_amplitude: float = 0.2)[source]¶

Function to create a noisy waveguide with a predefined noise spectrum.

Parameters:	noise_profile (str) – String identifying the noise profile. Options are AWGN \| 1/f \| 1/f2. Default: 1/f. noise_amplitude (float) – Range of the noise (in the same units as `nominal_parameter()`). Default: 0.2
Returns:	A `ndarray` containing the generated profile of the waveguide.

load_poling_structure(poling_structure)[source]¶

Function to load the poling structure of the waveguide. This function can be used to create custom poling structures, such as apodized poling, e.g. [1] and [2]. If the poling structure is set via this function, the poling period of the waveguide is automatically set to +`numpy.infty`.

Warning

The correct behaviour of this function is untested.

Parameters:	poling_structure (numpy.ndarray) – Array containing the orientation of the poling. It must have the same dimensions of the z-mesh.
Returns:	The poling structure

plot(ax: matplotlib.axes._axes.Axes = None)[source]¶

Function to plot the waveguide profile. If an axis handle is passed, it will plot in those axes.

Parameters:	ax (matplotlib.axes.Axes) – handle to axis, if you want to plot in specific axes.
Returns:	ax: handle to the axis object

plot_waveguide_properties(fig=None, **plotkwargs)[source]¶

Function to plot the waveguide properties in a figure. This function plots the waveguide profile, the power spectrum, autocorrelation and histogram distribution of the noise. If a Figure handle is passed, it plots in said Figure.

Parameters:	fig (matplotlib.figure.Figure) – Handle of the figure where the plots should be displayed. If None, then opens a new figure. Default is None. plotkwargs (dict) – dictionary to be passed to `matplotlib.pyplot.plot()`