tailieunhanh - Wave Propagation Part 3

Tham khảo tài liệu 'wave propagation part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 62 Wave Propagation õ2max 2Z K ne. 107 Substituting 107 into 106 we find the absolute maximum of the excitation factor 0 p0 noZ max Keo Keo smax KoY eno 2 n 0 2 z 108 which is inversely proportional to the small parameter z this guarantees the efficiency of the resonance especially in the infrared region. According to 87 and 58 the numerator in 108 is expressed as Ex. V1 - 1 - Y c2 109 This shows that the coefficient Kmoax can be additionally increased by choosing a crystal with high anisotropy factor 1 - Y and the orientation of the optical axis in the yz plane c1 0 corresponding to the maximum possible component c2 1. As a result we obtain p0 1 Y -1 and instead of 108 we have the optimized value K max eo 1 leo - e z N o e 110 Below we will assume that c1 0 in all numerical estimates and figures. In terms of the ratios Keo Km ax s2 smax and Aao Aamax the sections of the peak 104 for a fixed value of the parameter Aao Aam x 105 or s2 smax 107 are given by Fig. 9. Two sections of the surfaces Keo s2 Aao and roo s2 Aao Ỷ shown in Fig. 8 when a Aao An m or b s2 s2max A0 pm and K Electromagnetic Waves in Crystals with Metallized Boundaries 63 Figure 9a curve 1 shows that the section of the peak for Aao Aa2 x rapidly reaches a maximum and then slowly decreases as the parameter s increases. Of course this is advantageous for applications but restricts at least in the visible range the applicability of the approximation based on the inequality S2 1. The half-width of this peak is A52 i 2 W0 2ax zz Kn0 . 112 Away from the section Aao Aá the coordinate of the maximum and the half-width of the peak with respect to s noticeably increase which is clearly shown in the threedimensional picture of the peak in Fig. 8. Another section of the same peak for Õ2 Ổ22ax is shown in Fig. 9b curve 1 . According to 111 2 its half-width is Aa V 8z Aamax 8z z . 113 Aao 1 2 Aao _ . 113 z KY Compared with 112 this quantity contains an additional small parameter z .