这种光纤的纤芯折射率比包层基质折射率小，所以短波长时基模损耗迅速增大，使得光传输截止。

The index of the core is a little smaller than that of the cladding base material, so the fundamental mode loss of short wavelength increases rapidly and leads to the mode cutoff.

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实验结果发现：电子辐照后器件响应光谱在短波处有变窄的趋势，但响应峰值波长和截止波长基本无变化；

It's been observed that after irradiation, the response spectra of detectors become narrower at shot wavelength while the peak and cut-off wavelength have no noticeable change.

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