# Set calculation parameters

With the option pull-down box set to SET CALCULATION PARAMETERS, the modal analysis tab displays the calculation parameters. Some of the parameters can be set through the script.

The parameters shown include:

- FREQUENCY: The frequency at which the modes are solved
- WAVELENGTH: The wavelength at which the modes are solved
- MESH STRUCTURE: Used to produce a mesh of the structure which can be examined in the visualization window
- NUMBER OF TRIAL MODES: This is the maximum number of modes returned in the Mode List. If there are less modes found, the number of modes in the Mode List will be smaller than this number.
- SEARCH: Define the target effective index value(s) for mode calculations
- NEAR N: Find all of the modes around a value of effective index
- USE MAX INDEX: Checked by default. If checked, search the modes that have the highest possible effective indices, the search results typically include the fundamental modes. Un-check this option to define N and find other modes.
- N: Search around a specific value of effective index. Users can type complex effective index values (ex. 0.5+5i), which is very useful for studying modes with high loss.
- IN RANGE: Find all of the modes within a range of effective index values defined by N1 and N2, with N1 > N2.
- BENT WAVEGUIDE: This checkbox is used to specify whether the waveguide is bent
- BEND RADIUS: The radius of curvature of the bend
- BEND ORIENTATION: The direction in which the waveguide is bent; refer to Bent waveguide calculation in User Guide for more details.
- HELICAL WAVEGUIDE: This checkbox is used to specify whether the waveguide is helical.
- HELICAL CENTER X, Y, Z: This is the center position of the helix, ie, the coordinates of the point around which everything is twisted. This is not user editable at the current release.
- HELIX PERIOD: The pitch of the helix.
- CALCULATE MODES: Starts the calculation
- RESTORE LAST SETTINGS: Resets all the settings in this tab to those that were used to calculate the modes in the mode list.