paraxial_wave.xmds

<?xml version="1.0"?>
<simulation>
  
<!-- $Id: paraxial_wave_body.part 999 2004-08-03 05:42:47Z cochrane $ -->

<!--  Copyright (C) 2000-2004                                           -->
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<!--  Code contributed by Greg Collecutt, Joseph Hope and Paul Cochrane -->
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<!--  This file is part of xmds.                                        -->
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  <name> paraxial_wave </name>      <!-- the name of the simulation -->
  
  <author> Paul Cochrane </author>  <!-- the author of the simulation -->
  <description>
    Solves the paraxial wave equation for various input fields using
    one transverse dimension.  This is an example of double slit interference.
    Script adapted from equation in "Fundamentals of Photonics", 
    B.E.A. Saleh and M.C. Teich (1991)
  </description>
  
  <!-- Global system parameters and functionality -->
  <prop_dim> z </prop_dim>    <!-- name of main propagation dim -->
  
  <error_check> no </error_check>   <!-- defaults to yes -->
  <use_wisdom> yes </use_wisdom>     <!-- defaults to no -->
  <benchmark> yes </benchmark>       <!-- defaults to no -->
  <use_prefs> yes </use_prefs>       <!-- defaults to yes -->
  
  <!-- Global variables for the simulation -->
  <globals>
  <![CDATA[
      const double lambda = 628e-9;   // red He-Ne laser
      const double k = 2*M_PI/lambda;

      // double slit
      const double d = 0.5e-3;   // slit separation
      const double w = 0.1e-3;  // slit width

      // single slit
      //const double d = 0.0;
      //const double w = 0.5e-3;   // slit width
  ]]>
  </globals>
  
  <!-- Field to be integrated over -->
  <field>
    <name> main </name>
    <dimensions> x </dimensions> <!-- transverse dims -->
    <lattice> 10000 </lattice>       <!-- no. of points for each dim -->
    <domains> (-5e-2,5e-2) </domains> <!-- domain of each dimension -->
    <samples> 1 </samples>       <!-- sample 1st point of dim? -->
    
    <vector>
      <name> main </name>
      <type> complex </type>           <!-- data type of vector -->
      <components> A </components>       <!-- names of components -->
      <fourier_space> no </fourier_space> <!-- defined in k-space? -->
      <![CDATA[
          A = fabs(x) > d ? ((fabs(x)-d) > w ? 0.0 : 1.0) : 0.0; // double slit
	  //A = fabs(x) < w ? 1.0 : 0.0; // single slit
      ]]>
    </vector>
  </field>
  
  <!-- The sequence of integrations to perform -->
  <sequence>
    <integrate>
      <algorithm> RK4IP </algorithm> <!-- RK4EX, RK4IP, SIEX, SIIP -->
      <interval> 1.0 </interval>   <!-- how far in main dim? -->
      <lattice> 1 </lattice>     <!-- no. points in main dim -->
      <samples> 1 </samples> <!-- no. pts in output moment group -->
      
      <k_operators>
        <constant> yes </constant>         <!-- yes/no -->
        <operator_names> L </operator_names>
        <![CDATA[
          L = rcomplex(0.0,kx*kx/(k*2.0));
        ]]>
      </k_operators>
      
      <vectors> main </vectors>     <!-- vector names -->
      <![CDATA[
        dA_dz = L[A];
      ]]>
    </integrate>
  </sequence>
  
  <!-- The output to generate -->
  <output format="ascii">
    <filename>paraxial_wave.xsil</filename>
    <group>
      <sampling>
        <fourier_space> no </fourier_space> <!-- sample in k-space? -->
        <lattice> 10000 </lattice>           <!-- no. points to sample -->
        <moments> A2 </moments>           <!-- names of moments -->
        <![CDATA[
          A2 = mod2(A);  // find the modulus squared
        ]]>
      </sampling>
    </group>
  </output>
  
</simulation>