Anomalous dispersion phase matching

Fig. 1. (a) Phase matched second harmonic generation (2cJ = 0.49 fiTo) at cj = 0.98 where = refractive index by ordinary rays and = by extraordinary rays, (b) Hypothetical anomalous dispersion phase matching at 850 nm in similar a crystal having a Lorent2ian absorption centered at 650... 

Chemistry of Anomalous-Dispersion Phase-Matched Second Harmonic Generation... 

Our recent report(1) on ADPM SHG (Anomalous-Dispersion Phase-Matched Second-Harmonic Generation) addressed the physics of ADPM, a... 

TABLE 3 Comparison of Waveguide SHG Devices Using Birefringent and Anomalous Dispersion Phase Matching Reported in Organic and Some Inorganic Materials ... 

H3uasi-phase matching (QPM), modal dispersion phase matching (MDPM), anomalous dispersion phase matching (ADP), and birefringent phase matching (BPM). 

Kowaiczyk, T. C., Singer, K. D., and Cahill, P. A., Anomalous dispersion phase-matched second-harmonic generation in a polymer waveguide. Opt. Lett., 20, 2273-2275 (1995). 

Fig. 10. An example of anomalous dispersion phase-matching in which the dopant molecule exhibits a strong absorption at frequency a>o between the fundamental (< ) and harmonic (2a>), leading to a lower index of refraction at the harmonic. The dopant is added to a polymer exhibiting normal dispersion resulting in a composite with equal refractive indices at the fundamental and harmonic, no.

A further improvement and more freedom in the choice of laser wavelengths can be expected with the use of dye vapors. In liquids, the phase-matching concentration is set by the requirement that the anomalous dispersion of the dye compensates for the normal dispersion of the solvent. The latter is a new parameter that can be varied at will in the gas phase by changing the nature and partial pressure of the buffer gas. The broader resonances of dyes as opposed to metal vapors, which are sometimes used for this purpose, is an advantage for tunable frequency tripling of dye lasers. Another advantage results from the possibility of working at much lower temperatures than with metal vapors. 

Fig.4. Schematic representation of the different common phase-matching techniques in the k space representation. (ADM) anomalous dispersion (WBM) waveguide birefringence (MD) modal dispersion (QPM) quasi-phase-matching (C) Cerenkov and (CP) counter propagating Cerenkov...

Figure 7.37 is a schematic diagram for the refractive indices n(w) for Xe and rubidium vapor. Choosing the proper density ratio N(Xe)/N(Rb), phase matching is obtained for n(w) = n(3to) where the refractive index n = n(Xe) + n(Rb) is determined by the rubidium and Xe densities. Figure 7.37 illustrates that this method utilizes the compensation of the normal dispersion in Xe by the anomalous dispersion for rubidium [7.83]. 

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