# PLaSK User Manual

#### Page Contents

- WasiakNewCyl

# WasiakNewCyl

<gain solver="WasiakNewCyl">

  Corresponding Python class: `gain.wasiak.WasiakNewCyl`.

  Simple gain solver based on Fermi Golden Rule for Cylindrical geometry.

  > This solver does not use any mesh by default and the the full gain calculation is performed in each requested point.

  > However, if there is a mesh specified then the gain is computed only in the mesh points and interpolated in-between.

  Attributes:

    - name (`required`) – Solver name.

  Contents:
    <geometry>

      Geometries for use by this solver.

      Attributes:

        - ref (`required`) – Name of the geometry used by the this solver. (cylindrical geometry)

        - mod – Name of the modified geometry for broadening calculation. (cylindrical geometry)

    <mesh>

      Optional Ordered or Regular mesh used by this solver.

      Attributes:

        - ref – Name of the existing Ordered or Regular mesh used by this solver. (mesh)

    <config>

      Some important gain parameters.

      Attributes:

        - lifetime – Average carriers lifetime. This parameter is used for gain spectrum broadening. (float (ps), default 0 ps)

        - matrix-elem – Value of the squared matrix element in gain computations. If it is not set it is estimated automatically. (float ((eV/m0)2))

        - strained – Boolean attribute indicating if the solver should consider strain in the active region. If set to yes then the substrate material must be either explicitly specified of there must a layer with the role “substrate“ in the geometry. The strain is computed by comparing the atomic lattice constants of the substrate and the quantum wells. (bool, default is `no`)

        - substrate – Name of the substrate material. This attribute is used only if the strained attribute is set to yes. If this attribute is not set then the substrate material must be specified by a layer with the role “substrate“. (material)

        - cond-qw-shift – Additional conduction band shift for quantum wells. (float (eV))

        - vale-qw-shift – Additional valence band shift for quantum wells. (float (eV))

        - adjust-layers – Setting this to true, allows to adjust the widths of the gain region layers by few angstroms to improve numerical stability. (bool, default is `yes`)

        - roughness – If there is no modified geometry: roughness of the thicknesses of the quantum wells. With modified geometry present: broadening factor. (float, default 1)

        - fast-levels – Compute levels only once and simply shift for different temperatures? Setting this to True strongly increases computation speed, but makes the results less accurate for high gains.” (bool, default is `yes`)

        - Tref – Reference temperature. If fast-levels is set, this is the temperature used for initial computation of the energy levels. (float (K))