| Abstract: | By means of the weakly guiding approximation, the mode spot sizes Wx and Wy of the fundamental mode along the semimajor (x-direction) and semiminor (y-direction) axes of the fiber core in elliptical core twomode fiber are discussed. The variation of their ratio value Wx/Wy with the operation wavelength λ and the length ratio a/b between the semimajor axis and the semiminor axis of the fiber core is analyzed. Based onthis analysis, the distribution figures of two-lobe interferential mode patterns are evaluated and simulated quantitatively for different phase difference changes between LPo1 and LPeven11 modes. The two-lobeinterferential mode patterns have the same profile and distribute symmetrically when the phase differenceequals π/2. Their central distance S becomes larger when WX/Wy augments gradually. Furthermore,the equation about the central distance S of the two-lobe interferential mode patterns is given when the operation wavelength varies between 0.65 and 1.31 μm, which is important to applications shuch as sensors and coupling devices between different fibers. |
