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Unformatted text preview: Lecture 9 Phase-Matching Considerations (PMC) For SFG the intensity of the generated field varies with wave vector mismatch. is difficult to achieve because the refractive index of materials that are lossless in the range (where ) have normal dispersion (i.e. refractive index increases with frequency. As a result: ( 29 ( 29 2 3 3 2 sin k 2 (max) k 2 L I I L ∆ = ∆ k ∆ = 1 2 to ϖ ϖ 1 2 3 ϖ ϖ ϖ ≤ ≤ 1 2 2 3 3 n n n ϖ ϖ ϖ + = 1 where cannot be achieved. For SHG PMC: which is impossible when increases monotonically with frequency. The most common procedure for achieving PM is to use birefringent crystals. Birefringence is the dependence of the refractive index on the polarization of the optical radiation (cubic crystals are optically isotropic, i.e. no birefringence). 1 1 2 2 3 3 ϖ ϖ ϖ 1 2 3 ϖ ϖ ϖ + = 1 1 ( ) (2 ) n n ϖ ϖ = ( ) n ϖ To achieve PM using birefringent crystals, the highest-frequency wave Is polarized in the direction that gives it the lower refractive index....
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This note was uploaded on 01/10/2011 for the course ECE 615 taught by Professor Shalaev during the Fall '10 term at Purdue.
- Fall '10