A requested quantity of the laser can be obtained in terms of normalized propagation constant, which is represented by alpha, belonging to active region. As a new computation procedure this alpha method based on structural property of material contains the computing of the requested quantity for the semiconductor laser theoretically when width of the active region, refractive indices of the regions and wave length are given. In this work, the loss and absorption constants or confinement factors have been analyzed in terms of normalized propagation constants for even and odd fields in a semiconductor single asymmetric step-index laser. Some important parameters, such as propagation constants, effective index of active region, phase constant, phase velocity, absorption constants or confinement factors of the regions, percent of device loss and percent of active region loss, coordinate variables η , ζ for energy eigenvalues for charged carriers in the perpendicular coordinate system ζ − η for single asymmetric step-index laser have been obtained. The validities of found formulas have been tested, numerically. Since effective refractive index belong to active region of the laser is constant, the phase constant and the phase velocity are also constant for each of even and odd field. Key Words: Absorption coefficient, Confinement factor