Multi-beam laser interference lithography (LIL) has become one of the most important techniquesand shown significant advantages in the fabrication of micro- and nano-structures. Controlling intensityratio of optical distributions is a key issue in LIL for fabricating micro- and nano-structures. Thispaper presents an asymmetrical three-beam LIL system which effectively improves the intensity ratioof optical distributions. Comparing with the symmetrical three-beam interference, the asymmetricalthree-beam LIL achieved the high intensity ratio of optical distribution when producing the similarinterference pattern. In addition, this system also avoids modulation patterns in multi-beam LIL systemsand reduces the difficulty of actual LIL processing. A fast Fourier transform (FFT) analysis thatwas used to study the pattern distributions of the asymmetrical three-beam interference from frequencyspectra shows the pattern with a high-intensity array can be obtained by adjusting the parametersettings of incident laser beams. The asymmetrical three-beam LIL system was verified throughfabricating patterns. The experimental results are in good agreement with the theoretical analysis.
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