Simulation Software for Multilayer Optical Stacks


Structure of the Multilayer Stack

The multilayer's structure is defined by the user, and may have an arbitrary number of layers up to 99. (The maximum allowed number of layers may be extended upon request.) Each layer is identified by its thickness and its dielectric tensor; the program imposes no restrictions on the values of these parameters. The structure may thus represent an arbitrary stack of metallic, dielectric, birefringent, and magneto-optically active  layers. The multilayer stack is sandwiched between a semi-infinite substrate and a semi-infinite medium-of­incidence. The following material types are allowed for the various layers:

     (A) Isotropic with known n and k
     (B) Isotropic with known dielectric constant
     (C) Anisotropic with diagonal dielectric tensor
     (D) Magneto-optical but otherwise isotropic
     (E) Possessing an arbitrary dielectric tensor
     (F) Optical constants tabulated in data-file
     (G) Identical to an existing layer

Type E is the most general type of material, but it requires nine complex constants for full identification of the dielectric tensor. Types A through D have therefore been introduced to simplify the task of data entry by the user.

When a type F material is selected, optical constants are read directly from the tables contained within the subdirectory <DFILES>. These tables contain a list of the optical constants within a certain range of wavelengths. MULTILAYER reads the specified table and extracts the values of the optical constants at the required wavelengths.

By selecting a type G layer the user duplicates an already existing layer without having to re-enter all the necessary parameters. When this option is chosen, the optical constants and the thickness of the two layers become identical. The savings of time and the reduced potential for error during data entry could be substantial, considering that many multilayers of practical interest use a periodic repetition of only a few distinct layers.

Material types C, D, and E, are anisotropic and, therefore, their dielectric tensors may have an arbitrary orientation relative to the coordiante system in which the multilayer stack is defined. If you choose to rotate the coordinates of the dielectric tensor, you will be asked to identify the Euler angles of the rotated coordinate system.

Printout of a structural data file created during a typical run of MULTILAYER is shown below. This text file, which contains the parameters of a quadrilayer magneto-optical stack, may be edited by the user prior to being imported by the program.

!                  @@ MULTILAYER 3.0     File TR01.STK @@                 #
!                  @@ Date: 04/28/1998     Time: 17:43 @@                 #
!                  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@                 #
!                                                                         #
! Notes: Structural parameters of the quadrilayer magneto-optical stack   #
!        used in Test Run 1.                                              #
!                                                                         #
$                                                                         #
        Number of layers:   4                                             #
$                                                                         #
  Substrate index (Nsub):    1.5000000                                    #
$                                                                         #
Layer#01      Type (A-G): A                                               #
                   (n,k):    2.7500000       8.3100000                    #
               Thickness:    500.00000                                    #
$                                                                         #
Layer#02      Type (A-G): A                                               #
                   (n,k):    1.4490000       .00000000                    #
               Thickness:    143.20000                                    #
$                                                                         #
Layer#03      Type (A-G): D                                               #
     Real(Exx),Imag(Exx):   -4.8984000       19.415000                    #
     Real(Exy),Imag(Exy):    .43220000      5.80000000E-03                #
     Real(Exz),Imag(Exz):    .00000000       .00000000                    #
     Real(Eyz),Imag(Eyz):    .00000000       .00000000                    #
               Thickness:    20.000000                                    #
       Euler Eta,Chi,Psi:    .00000000       .00000000       .00000000    #
$                                                                         #
Layer#04      Type (A-G): A                                               #
                   (n,k):    1.4490000       .00000000                    #
               Thickness:    143.20000                                    #
$                                                                         #
 Incidence medium (Ninc):    1.0000000                                    #



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