A hybrid grism lens, which integrates an off-axis diffractive grating and an on-axis refractive lens onto a prism structure, is developed. The proposed grism lens can simplify the setup of grating-based wavelength-division multiplexing (WDM) device owing to the dual-functional characters combined within only one element. The 100-GHz dense WDM (DWDM) device based on the grism lens is designed with an insertion loss of 2.91+-0.53 dB and a crosstalk of 58.02 dB. The tolerance analysis, the allowable grating tilt angle of +-0.5 deg and fiber displacement of +-1 (mu)m, shows that the proposed structure could be practically applied to the grating-based demultiplexers.
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