Focus_h.txt

FOCUS helps calculate the curvature of a Gaussian beam at a specific location that will give a certain waist size at a certain location.  This information is needed in 2D-mix-LP and 2D-mix-SP if the beams are focusing (have curved wavefronts). To run this function simply change any of the input values and the output values are automatically updated.  For example, if you want the beam to focus at the center of the crystal, use half the crystal length in the Dist. to focus input.  Filling in the Waist input will then give the radius of curvature in air at the crystal input face and the beam diameter at the crystal input face that are necessary to focus at the crystal center with the specified beam waist.

CAVITY helps design stable cavities in support of function 2D-cav-LP which can model cavities with curved mirrors. In order to mode match an input beam to a stable cavity, 2D-cav-LP needs as inputs the size and radius of curvature of the input beams just inside the left or right curved mirror. This information listed in the output boxes labeled "left in size" and "left input rad of curv" and another pair for the right inputs. If an input beam in 2D-cav-LP is to resonant with the cavity, you must also specify the round trip Gouy phase shift due to focusing within the cavity. For example, for a ring cavity you can set the value of the input parameter 'Phase R-L' equal to the negative of the value of Cavity function output 'Roundtrip phase shift'.  This makes the wave resonant in the cavity, maximizing the cavity enhancement of the field. When this is set correctly the spectrum of the resonated wave will peak at a frequency shift of zero. Click the Spectrum button after a run to check this. Note that the Leg1 length refers to the distance between curved mirrors on the leg containing the crystal while Leg2 refers to the distance between curved mirrors on the other leg. Function executes when you change an input. It displays the 1/e^2 width through the length of the cavity with the crystal highlighted in blue.

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