# Total-Field Scattered-Field (TFSF)
Total-field scattered-field (TFSF) source that can inject a plane wave in a finite region. The TFSF source injects 1 W/μm² of power along the injection_axis. Note that in the case of angled incidence, 1 W/μm² is still injected along the source's injection_axis, and not the propagation direction, unlike a PlaneWave source. This allows computing scattering and absorption cross sections without the need for additional normalization.
# Name
name: Optional name for the source.
# Source Region
Specification of the source region.
# 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
# Injection Axis
injection_axis: Specifies the injection axis. The plane of incidence is defined via this injection_axis and the direction. The propagation axis is defined with respect to the injection_axis by angle_theta and angle_phi.
Options:
- x (0 in Simulation JSON)
- y (1 in Simulation JSON)
- z (2 in Simulation JSON)
Required field
# Direction
direction: Specifies propagation in the positive or negative direction of the injection axis.
Options:
- +: Propogate in the positive direction of the injection axis
- -: Propogate in the negative direction of the injection axis
Required field
# 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 of the source 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
At normal incidence when S and P are undefined, 0 defines:
- Ey polarization for propagation along x
- Ex polarization for propagation along y
- Ex polarization for propagation along z
Type: floating-point number
- Unit: rad or degree (default)
- Default: 0
# Source Time
source_time: Specification of the source time-dependence.
Options:
Required field
# Number of Frequency Points
num_freqs: Number of points used to approximate the frequency dependence of the injected field.
Type: integer
- Default: 3
Note: For simulations which are not very broadband and the source is very large (e.g. metalens simulations), decreasing the value to 1 may lead to a speed up in the preprocessing.