# AstigmaticGaussianOverlapMonitor

Monitor that records the overlap integral between simulated fields and an astigmatic Gaussian beam profile. The astigmatic Gaussian beam allows both an elliptical intensity profile and different waist locations for the two principal axes of the ellipse. When equal waist sizes and equal waist distances are specified in the two directions, this monitor becomes equivalent to GaussianOverlapMonitor.

# Name

name: Unique name for monitor.

Required field

# Size and Position

Specification of the monitor size and position.

# Center + size

Object definition through a center position and size.

center: Center of the object in x, y, and z-directions.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Default: (0, 0, 0)

size: Size of the object in x, y, and z-directions.

Use Infinity to define a geometry extending to infinity in both directions along an axis.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Constraint: greater than or equal to 0
  • Required field

# Bounds

Object definition through minimum and maximum coordinate bounds.

min: Values of the x, y, and z coordinates defining the object lower corner.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Required field

max: Values of the x, y, and z coordinates defining the object upper corner.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Required field

# Direction

direction: Specifies propagation in the positive or negative direction of the injection axis.

Options:

  • +: Propagate in the positive direction of the injection axis
  • -: Propagate in the negative direction of the injection axis

Required field

# Waist Sizes

waist_sizes: Size of the beam at the waist in the local x and y directions.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Constraint: greater than 0
  • Default: (1, 1)

# Waist Distances

waist_distances: Distance to the beam waist along the propagation direction for the waist sizes in the local x and y directions. When direction is + and waist_distances are positive, the waist is behind the monitor plane. When direction is + and waist_distances are negative, the waist is in front of the monitor plane.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Default: (0, 0)

# Polar Angle

angle_theta: Polar angle of the propagation axis from the injection axis.

Type: floating-point number

  • Unit: rad or degree (default)
  • Default: 0

# Azimuth Angle

angle_phi: Azimuth angle of the propagation axis in the plane orthogonal to the injection axis.

Type: floating-point number

  • Unit: rad or degree (default)
  • Default: 0

# Polarization Angle

pol_angle: Specifies the angle between the electric field polarization and the plane defined by the injection axis and the propagation axis.

  • 0 specifies P polarization (default)
  • 90 degrees or π/2 rad specifies S polarization

Type: floating-point number

  • Unit: rad or degree (default)
  • Default: 0

# Frequencies

Definition of the monitor wavelengths/frequencies.

Options:

  • Wavelengths: Specify monitor wavelengths in units of m, μm (default), or nm.
  • Frequencies: Specify monitor frequencies in units of Hz (default) or THz.

Default: Wavelengths

# Enter wavelength/frequency range

Create an evenly spaced list of wavelength/frequency points between a minimum and a maximum value.

min: Minimum wavelength/frequency value.

  • Required field Default: None

max: Maximum wavelength/frequency value.

  • Required field Default: None

number of points: Number of wavelength/frequency points.

  • Required field Default: None

# Custom wavelength/frequency list

Create a custom list of wavelength/frequency points. Click the Edit list button to include, edit, or exclude wavelength/frequency values from the list.

# Downsampling

interval_space: Number of grid step intervals between monitor recordings.

  • If equal to 1, there will be no downsampling.
  • If greater than 1, fields will be downsampled and automatically colocated.

Type: integer

  • Unit: unitless
  • Constraint: greater than 0
  • Default: (1, 1, 1)

# Colocate Fields

colocate: Toggle whether fields should be colocated to grid cell boundaries (i.e. primal grid nodes).

Options:

  • False: Fields will NOT be colocated to grid cell boundaries.
  • True: Fields will be colocated to grid cell boundaries.

Default: True

# Conjugated Dot Product

conjugated_dot_product: Use conjugated or non-conjugated dot product for the overlap integral computation.

Options:

  • False: Use non-conjugate dot product.
  • True: Use conjugate dot product.

Default: True

# Number of Frequency Points

num_freqs: Number of points used to approximate the frequency dependence of the Gaussian beam profile.

Type: integer

  • Default: 3

# Apodization

Sets parameters of (optional) apodization. Apodization applies a windowing function to the Fourier transform of the time-domain fields into frequency-domain ones, and can be used to truncate the beginning and/or end of the time signal, for example to eliminate the source pulse when studying the eigenmodes of a system.

Note: apodization affects the normalization of the frequency-domain fields.

start: Defines the time at which the start apodization ends.

Type: floating-point number

  • Unit: s (default), ps, or fs
  • Constraint: greater than or equal to 0

Default: None

end: Defines the time at which the end apodization begins.

Type: floating-point number

  • Unit: s (default), ps, or fs
  • Constraint: greater than or equal to 0

Default: None

width: Characteristic decay length of the apodization function.

Type: floating-point number

  • Unit: s (default), ps, or fs
  • Constraint: greater than or equal to 0

Default: None

# Store Fields

store_fields_direction: When Store Fields = True, the astigmatic Gaussian beam field datasets are available in the simulation results. The beam propagation direction is selected using the Direction toggle.

Options:

  • None (default): It means that Store Fields is unchecked and the field datasets will NOT be available in simulation results.
  • +: It means that Store Fields is checked and the field datasets will be available in simulation results for the + (Forward) propagation direction.
  • -: It means that Store Fields is checked and the field datasets will be available in simulation results for the - (Backward) propagation direction.

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