2DmixSP_h.txt

2D-mix-SP models single-pass mixing with diffraction, birefringent walkoff, group velocity walk off, and group velocity dispersion. This is a slow memory hog so try to select the best values for the time and spatial grids using the faster functions PW-mix-SP, PW-mix-LP, and 2D-mix-LP before running it.  The maximum sizes of the spatial and temporal grids depend on the amount of memory available to SNLO. For help in setting input values, right-click on the input edit box. Help text appears in the lower text box.

The calculation is based on integrating Maxwell's equations using split-step FFT methods to give accurate diffractive and dispersive simulations.  Methods are described in papers "Numerical models of broad bandwidth nanosecond optical parametric oscillators" JOSA B vol. 16 p. 609 (1999); "Phase distortions in sum- and difference-frequency mixing in crystals" JOSA B vol. 12 p. 49 (1995); and "Comparison of a numerical model with measured performance of a seeded, nanosecond KTP optical parametric oscillator," JOSA B vol. 12 p. 2253 (1995). These papers are available online at http://www.as-photonics.com/Publications.html

The phase velocity mismatch (k_3-k_1-k_2) refers to the carrier waves, ie the central frequencies and forward k vectors. The group velocity and group delay dispersion terms then account for phase mismatches at all other frequencies, while the walk off angle accounts for the phase mismatches for all other k-vector directions. This is automatic, you do not have to worry about how all the frequency and tilts are phase matching among themselves.

To specify temporal profiles, use an optional second argument in the pulse duration input box (with the two arguments separated by a space). The second argument should be an integer 0-10, where 0 represents a hyperbolic secant temporal shape, and 1-10 are super Gaussian temporal shapes of order specified (1 for normal Gaussian temporal profile).

Outputs include fluences at the detector and in the farfield, tilts in the walkoff direction, M-squared values in the walkoff direction and perpendicular to it (M-w and M-p buttons), integrated M-squared values (written at top of M-squared plots), and radius of curvature or wavefront curvature at the detector (Focus-w and Focus-p).  Negative values of curvature indicate a beam is diverging. These are calculated vs time or vs spectrum. You should make sure these results are converged by increasing the grid densities by factors of two until the answers stabilize. The Chirp of the output pulses is calculated by computing the chirp at each time and position and performing a spatial irradiance-weighted average over x and y to find chirp as a function of time.

On completion of a run the following ascii files are written: BEAM_3TS.DAT, BEAM_3TI.DAT, BEAM_3TP.DAT with columns in order time in seconds, power in watts for red1/red2/blue beam in file with S/I/P in its name. BEAM_3WS.DAT, BEAM_3WI.DAT, BEAM_3WP.DAT with columns in order frequency shift in Hz, and spectral power in arbitary units for red1/red2/blue beam in file with S/I/P in its name. BEAM_3C.DAT with columns containing time in seconds, red1 chirp in Hz, red2 chirp in Hz, blue chirp in Hz. FLUENCE3.DAT with columns x, y, red1 fluence in W/sq m, red2 fluence in W/sq m, blue fluence in W/sq m. FLUENCE3F.DAT with columns k_x in 1/m, k_y in 1/m, red1 fluence in arbitrary units, red2 fluence in arbitrary units, blue fluence in arbitrary units. These distributions are the x- and y-Fourier transforms of the fields at the detector.


Clicking the Analyze button computes beam parameters and adds the following columns to BEAM_3TS.DAT, BEAM_3TI.DAT, BEAM_3TP.DAT Mx^2, <Mx^2>, My^2, <My^2>, X-curvature, Y-curvature, and x tilt (x is the walkoff direction). Clicking the Analyze button also adds the following columns to BEAM_3WS.DAT, BEAM_3WI.DAT, BEAM_3WP.DAT, Mx^2, <Mx^2>, My^2, <My^2>, X-curvature, Y-curvature, and x tilt (x is the walkoff direction). The units are the same as in the plots displayed by clicking the M-w, etc. buttons.

The last used input set is saved in mix.mat so if you would like to save those settings for later recall, copy (do not simply rename) mix.mat to another file name to store. Copy the file back to mix.mat to restore.

If you are running mlSNLO under MATLAB (not the standalone compiled version), this function can be called from a MATLAB script to automate parametric studies. See the 'SNLO' help tab for details.

2D-mix-SP examples: 63, 66. See file Examples with exercises and descriptions.pdf in mlSNLO folder, or on our website at as-photonics.com/examples

Detailed discussions of crystal nonlinear optics and SNLO examples are presented in the book "Crystal nonlinear optics: with SNLO examples," advertised on the SNLO download page or at as-photonics.com/book