# PLaSK User Manual

#### Page Contents

- EffectiveIndex2D

# EffectiveIndex2D

<optical solver="EffectiveIndex2D">

  Corresponding Python class: `optical.effective.EffectiveIndex2D`.

  Scalar optical solver based on the effective index method.

  Attributes:

    - name (`required`) – Solver name.

  Contents:
    <geometry>

      Geometry for use by this solver.

      Attributes:

        - ref (`required`) – Name of a Cartesian2D geometry defined in the `<geometry>` section.

    <mesh>

      Optional Rectangular2D, Ordered, Regular mesh used by this solver.

      Attributes:

        - ref (`required`) – Name of a Rectangular2D, Ordered, Regular mesh defined in the `<grids>` section.

    <mode>

      Mode properties

      Attributes:

        - polarization – Longitudinally-propagating mode polarization (TE or TM). (`TE` or `TM`, default is `TE`)

        - wavelength – Mode wavelength. (float (nm))

        - vneff – Initial vertical effective index of the in location in which the vertical solution is calculated; setting this value helps to find models in very long resonators. (float (-))

        - vat – Horizontal position of at which the vertical part of the field is calculated. (float (µm), default 0.0 µm)

        - emission – Direction of the useful light emission. Necessary for the over-threshold model to correctly compute the output power. (`front` or `back`, default is `front`)

    <root>

      Parameters of the horizontal root-finding algorithm.

      Attributes:

        - method – Root finding algorithm. (`muller`, `broyden`, or `brent`, default is `muller`)

        - tolx – Maximum change of the effective frequency parameter which is allowed for convergent solution. (float, default 1e-06)

        - tolf-min – Minimum value of the determinant sufficient to assume convergence. (float, default 1e-07)

        - tolf-max – Maximum value of the determinant required to assume convergence. (float, default 2e-05)

        - maxstep – Maximum step in one iteration of root finding. Significant for the Broyden’s method only. (float, default 0.1)

        - maxiter – Maximum number of root finding iterations. (int, default 500)

        - alpha – Parameter ensuring sufficient decrease of determinant in each step (Broyden method only). (float, default 1e-07)

        - lambda – Minimum decrease ratio of one step (Broyden method only). (float, default 1e-08)

        - initial-range – Initial range size (Muller method only). (complex, default 0.001)

        - stairs – Number of staircase iterations (Brent method only). (int, default 3)

    <stripe-root>

      Parameters of root-finding algorithm for one stripe.

      Attributes:

        - method – Root finding algorithm. (`muller`, `broyden`, or `brent`, default is `muller`)

        - tolx – Maximum change of the effective frequency parameter which is allowed for convergent solution. (float, default 1e-06)

        - tolf-min – Minimum value of the determinant sufficient to assume convergence. (float, default 1e-07)

        - tolf-max – Maximum value of the determinant required to assume convergence. (float, default 1e-05)

        - maxstep – Maximum step in one iteration of root finding. Significant for the Broyden’s method only. (float, default 0.1)

        - maxiter – Maximum number of root finding iterations. (int, default 500)

        - alpha – Parameter ensuring sufficient decrease of determinant in each step (Broyden method only). (float, default 1e-07)

        - lambda – Minimum decrease ratio of one step (Broyden method only). (float, default 1e-08)

        - initial-range – Initial range size (Muller method only). (complex, default 0.001)

        - stairs – Number of staircase iterations (Brent method only). (int, default 3)

    <mirrors>

      Mirror losses.

      Attributes:

        - R1 – Reflectivity of the front mirror. (float)

        - R2 – Reflectivity of the back mirror. (float)