Figure 4 Relative power distribution for the TE αTE waveguide 02 01 Ε½ . mode converter with the improved radius form 7 and the spurious input mode mixture mode TE are s 0.05305, s 0.00338, β¦ s 0.13081, and 02 1 2 the total length is 0.6677 m.
The conversion efficiency for TE is s 99.32%. Suppose that the input mode is changed 01 0 to mode mixtures of TE , TE , TE , and TE , whose 02 01 03 04 relative power levelΠphase difference are 0.95618Π0Π, 0.00049Π44.0Π, 0.04331Π y 174.2Π, and 0.00012Π59.7Π. Now, the conversion efficiency for TE is decreased to 92.22%. 01 Ε½ . The new radius perturbation form 7 is used to transform this input mode mixture into TE , except that produces 01 3 the coupling between TE and TE . The final optimized 03 01 parameters are s 0.05190, s 0.00652, s 0.00592, 1 2 3 and β¦ s 0.15820. The total length is 0.6636 m, and the conversion efficiency for TE , is s 98.38%. The relative 01 βΊ
power distributions for the final case are shown in Figure 4.
IV. CONCLUSION
In this letter, the influence of an input mode mixture in HPM waveguide mode converters with varying radius is studied numerically. The TM αTM and TE αTE , waveguide 02 01 02 01 mode converters are taken as examples, each assuming a spurious input mode mixture. The results show that they do not simply superimpose when such spurious input modes exist, and in some cases, they may degrade the conversion efficiency of the main output mode. The spurious input mode mixture can be transformed into the main output mode simultaneously by superimposing some perturbation terms in the waveguide radius form. Finally, it is recommended that the mode content of the HPM source should be recognized and used in the design of the succeeding waveguide mode converter.