近红外光探测能力强的光电探测器更有利于检测人体心率，而且探测范围覆盖红光与近红外光的宽带响应光电探测器能用于检测血氧饱和度，因此提升宽带响应光电探测器的红光与近红外光探测能力具有重要意义。然而，经典的二元体异质结宽带响应倍增型有机光电探测器通常由于活性层中给体/受体比例差异较大，导致器件对红光与近红外光的响应能力较弱甚至没有响应。本文通过用少量给体材料PCE10替代活性层P3HT∶IEICO?4F（100∶1）中部分P3HT的方法，制备了结构为ITO/PEDOT∶PSS/P3HT∶PCE10∶IEICO?4F（90∶10∶1）/Al的体异质结三元倍增型有机光电探测器。-20 V偏压下，三元器件获得紫外到近红外（330~810 nm）响应较均匀的EQE光谱，并且器件在660 nm和810 nm处的EQEs（134000%和147000%）是相同条件下二元器件的78倍和106倍，相应的探测灵敏度（5.4×10¹³ Jones和7.27×10¹³ Jones）分别提升了26倍和36倍。三元器件的红光和近红外光探测能力得到显著提升，为制备用于人体心率与血氧饱和度检测的高性能光电探测器提供了策略。

We demonstrate a configuration optimization process of an off-axis parabolic mirror to maximize the focused peak intensity based on a precise knowledge of the tight focusing properties by using a full vector-diffraction theory and obtain an optimum configuration scaling rule, which makes it possible to achieve the maximum peak intensity. In addition, we also carry out an assessment analysis of the offset and off-axis angle tolerances corresponding to a 5% drop of the maximum focused peak intensity and present scaling laws for the tolerances of the offset and off-axis angle. Understanding these scaling laws is important to enhance the focusability of a laser beam by an off-axis parabolic mirror in the optimum configuration, in particular, which is valuable for structural design and selection of an off-axis parabolic mirror in ultrashort and ultraintense laser–matter interaction experiments.

A tunable dual-band infrared polarization filter is proposed and investigated. Based on the perfect absorption characteristic of the metal-dielectric-metal sandwich structure, the reflection spectrum performs as a filter. The filter consists of three layers. The top layer is a compound metal nano-structure array comprised of rectangular strips. The middle and bottom layers are a dielectric spacer and metal film, respectively. The calculated results show that the filter properties are closely related to the polarization of the incident light. Different dual-band wavelengths are filtered while the incident light has different polarizations, which are parallel or vertical to the x axis. Moreover, it is found that the resonant wavelength strongly depends on the length of the rectangular strip (which causes the resonant effect) and is independent of other strips. Therefore, the filter wavelengths can be tuned freely by adjusting the length of the corresponding rectangular strip. In addition, the calculated results show that all of the intensities at the filter wavelengths are closed to zero, which implies that the filter exhibits good filtering performance.