Competition among the two-plasmon decay (TPD) of backscattered light of stimulated Raman scattering (SRS), filamentation of the electron-plasma wave (EPW) and forward side SRS is investigated by two-dimensional particle-in-cell simulations. Our previous work [K. Q. Pan et al., Nucl. Fusion 58, 096035 (2018)] showed that in a plasma with the density near 1/10 of the critical density, the backscattered light would excite the TPD, which results in suppression of the backward SRS. However, this work further shows that when the laser intensity is so high ( $>{10}^{16}$ W/cm²) that the backward SRS cannot be totally suppressed, filamentation of the EPW and forward side SRS will be excited. Then the TPD of the backscattered light only occurs in the early stage and is suppressed in the latter stage. Electron distribution functions further show that trapped-particle-modulation instability should be responsible for filamentation of the EPW. This research can promote the understanding of hot-electron generation and SRS saturation in inertial confinement fusion experiments.

宽谱响应光电探测器在图像传感和光通信等领域应用前景广阔。金属微纳结构通过激发表面等离激元共振效应可高效产生热载流子，将它们与宽带隙半导体构成异质结构，便可利用热载流子开发出低成本宽谱响应光电探测器。研究设计了一种基于Au/TiO₂复合纳米结构的热电子光电探测器。其中TiO₂层经退火后形成尺度约为百纳米的凹凸结构，Au纳米颗粒层与用作电极的保形Au膜共同组成了激发表面等离激元共振的纳米结构。由于Au/TiO₂复合纳米结构的协同作用，该器件在400~900 nm范围内具有宽谱光吸收性能，器件的平均光吸收效率为33.84%。在此基础上，该器件能够探测TiO₂本征吸收波段以外的入射光子。例如，在600 nm波长处，器件的响应率为9.67 μA/W，线性动态范围为60 dB，器件的上升/下降响应速度分别为1.6 ms和1.5 ms。此外，利用有限元法进行了仿真计算，通过电场分布图验证了Au/TiO₂复合纳米结构中所激发的丰富表面等离激元共振效应是其实现宽谱高效探测的原因所在。

提出了一种实现高性能宽带近红外热电子光电探测器的多层薄膜器件结构，该结构基于TiN/TiO₂肖特基势垒和TiN/分布式布拉格反射器形成的塔姆等离激元。通过光学传输矩阵和热电子发射理论模拟计算结果表明，高折射率比介质层构成的分布式布拉格反射器有效扩展了TiN薄膜吸收光谱和器件响应光谱，同时增强了TiN薄膜的吸收率和器件响应度。通过调控分布式布拉格反射器结构参数、TiN薄膜厚度和MgF减反射层厚度，可获得高达29.2 mA/W的响应度，响应光谱半峰全宽约为900 nm，为高性能宽带近红外热电子器件的实现提供了新的途径，有利于拓展热电子光电探测器的应用领域。

Stimulated Raman scattering (SRS) in plasma in a non-eigenmode regime is studied theoretically and numerically. Different from normal SRS with the eigen electrostatic mode excited, the non-eigenmode SRS is developed at plasma density $n_{e}>0.25n_{c}$ when the laser amplitude is larger than a certain threshold. To satisfy the phase-matching conditions of frequency and wavenumber, the excited electrostatic mode has a constant frequency around half of the incident light frequency $\unicode[STIX]{x1D714}_{0}/2$, which is no longer the eigenmode of electron plasma wave $\unicode[STIX]{x1D714}_{pe}$. Both the scattered light and the electrostatic wave are trapped in plasma with their group velocities being zero. Super-hot electrons are produced by the non-eigen electrostatic wave. Our theoretical model is validated by particle-in-cell simulations. The SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than $10^{15}~\text{W}/\text{cm}^{2}$.