Use the adjustable diameter fiber splicing platform to manufactured coupler, N fibers were put into the appropriate aperture silica capillaries, and then changed the taper model to manufactured fiber coupler [1], and adjusted the taper model and fusion parameters to reduce the fiber transmission loss and reduce the diameter of the fibers to achieve the optical coupling effect. We preferred to the Eisenmann & Weidel in 1988 [2]. It is a low loss of the fusion type equilateral triangle of 3¡Ñ3 fiber coupler. And we will study the asymmetric shape of an 3¡Ñ3 fiber coupler, the research method is the use of arc heating. The fiber has smaller heating area and the heating position which can be controlled. With the parameters which BeamPorp, we cut the fiber coupler and to discuss its cross-section. By the different geometric distribution of fibers, and the core spacing, we discuss the spectra of the OSA to change the coupling site. We changed the interior structure to make the power coupling to a marked effect; if we could control the asymmetric coupler explicitly then we could achieve the transmission power [3], power coupling, and the multiple spectra of light.