Waveguide InputΒΆ

Learning targets

  • Transparent boundary conditions in 3D
  • Inhomogeneous exterior domain: waveguides and layered media
  • Boolean Difference

This example describes a computational domain with transparent boundary conditions at all sides. In this case, waveguides are included some of which touch the boundary of the computational domain, and which are modeled to extend also to the exterior domain. Further, a substrate is included which also extends to the exterior domain.

The following figure shows an image of parts of the geometry and mesh:

_images/ex3d_waveguide_input_mesh.png

The waveguides exhibit a sidewall angle for the vertical flanks. This is achieved by a normal displacement of the waveguide structure during the extrusion process. To ease this we use the Boolean difference operator to form the ring resonator, so that we can apply the normal shift on the entire ring composed from the different geometrical primitives. For the straight waveguide adjacent to the ring we only apply the displacements on segments which are not extended to the exterior domain. Here, a SegmentNormalDisplacement is used inplace of the NormalDisplacement.

Input Files

  • layout.jcm [ASCII]

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Layout3D { 
  Name = "TutorialExample3D" 
  UnitOfLength = 1e-06 
  
  MeshOptions {
    MaximumSideLength = 1 
    MinimumMeshAngle = 18 

  }
  Extrusion {
    Objects {
      Parallelogram {  
        DomainId = 10  
        Priority = ComputationalDomain
        Name = "ComputationalDomain"
        Width = 14
        Height = 14
        GlobalPosition = [-5 0]
        Boundary { 
          Class = Transparent 
        } 
      } 
      
      Parallelogram {  
        Name = "Waveguide"  
        DomainId = 20  
        Priority = 1 
        Width = 0.5
        Height = 14
        SegmentNormalDisplacement {           
          Segment = [2 4]
          Value {
            PiecewiseLinear {
              AtInterface {
                Interface = 1              
                Value = 0
              }
              AtInterface {
                Interface = 2
                Value = 0.05
              }
            }
          }
        }       
        MeshOptions {
          MaximumSideLength = 0.45 
        }
      } 
      
      BooleanOperation {
        Operator = Difference
        DomainId = 20
        Name = "Ring"
        A {
          Parallelogram {
            Name = "P"
            Width = 10.5
            Height = 2.5
          }
          CircleSector {
            Radius = 5.25
            RefineAll = 2
            AngleRange = [0 180]
            Alignment {
              Parent {
                Domain = "P"
                Port = North
              }
              Orientation = AntiParallel
            }
          }
          CircleSector {
            AngleRange = [0 180]
            Radius = 5.25
            RefineAll = 2
            Alignment {
              Parent {
                Domain = "P"
                Port = South
              }
              Orientation = AntiParallel
            }
          }
        }
        
        B {
          Parallelogram {
            Name = "P"
            DomainId = 25
            Width = 9.5
            Height = 2.5
          }
          CircleSector {
            Radius = 4.75
            RefineAll = 2
            AngleRange = [0 180]
            
            Alignment {
              Parent {
                Domain = "P"
                Port = North
              }
              Orientation = AntiParallel
            }
          }
          CircleSector {
            Radius = 4.75
            RefineAll = 2
            AngleRange = [0 180]
            Alignment {
              Parent {
                Domain = "P"
                Port = South
              }
              Orientation = AntiParallel
            }
          }
        }
        Alignment {
          Parent {
            Domain = "Waveguide"
            Port = Center
          }
          Orientation = Parallel
          Displacement = [-5.8 0.0]
        }
        NormalDisplacement { 
          PiecewiseLinear {
            AtInterface {
              Interface = 1
              NormalDisplacement = 0
            }
            AtInterface {
              Interface = 2
              NormalDisplacement = 0.05
            }
          }
        }             
      }
    }     
    MultiLayer { 
      Layer {  
        Thickness = 0.225 
        DomainIdMapping = [10 1, 20 1] 
      } 
      LayerInterface {
        GlobalZ = 0.0
      }
      Layer {  
        Thickness = 0.25 
        DomainIdMapping = [10 3, 20 2] 
      } 
      Layer {  
        Thickness = 0.225 
        DomainIdMapping = [10 3, 20 3] 
      } 
    } 
  } 
}