The transmission of light waves through a perturbed one-dimensional (1D) photonic band gap structures (PBGS) which was constructed by stacking a number of GaAlAs/AlAs unit cells, has been investigated. Because of the interruption to the stack periodicity of the unit cells, the electromagnetic density of modes (DOM) of the photonic crystals was changed, so that the transmission of the light waves changed. And the DOM and the transmission mode were calculated and simulated by the popular density calculation method and the characteristic matrix. It is found that the asymmetric structures are more profitable compared with symmetric structure in applications. The asymmetric 1D PBGS was realized by the MOCVD method. The full width at half maximum (FWHM) narrowed to 3.1 nm, inspired at 20 mA, which is better than RCLED. And the edge emission was also observed.