Micro- and nanoscale photonic structures and devices play important roles in the development of advanced biophotonic systems, in particular, implantable light sources for optogenetic stimulations. In this paper, we numerically investigate silicon (Si) photonics based microprobes that can achieve multi-site, multi-spectral optical excitation in the deep animal brain. On Si substrates, silicon nitride (Si3N4) based planar waveguides can deliver visible light in the deep tissue with low losses, and couple to grating emitters diffracting light in targeted brain regions. In our model, we combine near-field wave optic and far-field ray tracing simulations, showing that the designed photonic structures spectrally split blue, green and red photons into different locations in the tissue. Furthermore, by introducing dual grating components, photons at different wavelengths can be spatially separated at different depths. Therefore, these photonic probes can be used to selectively activate or inhibit specific neurons and nuclei, when expressing various corresponding light sensitive opsins. We anticipate that such device strategies can find wide applications in the design of advanced implantable photonic systems for neuroscience and neuroengineering.

中文翻译：

---

用于大脑深部多位点、多光谱光遗传学的硅光子结构设计

微米级和纳米级光子结构和器件在先进生物光子系统的开发中发挥着重要作用，特别是用于光遗传学刺激的可植入光源。在本文中，我们对基于硅 (Si) 光子学的微探针进行了数值研究，该微探针可以在深部动物大脑中实现多位点、多光谱的光学激发。在 Si 衬底上，基于氮化硅 (Si3N4) 的平面波导可以在深层组织中以低损耗传输可见光，并耦合到光栅发射器，在目标大脑区域衍射光。在我们的模型中，我们结合了近场波光学和远场光线追踪模拟，表明设计的光子结构在光谱上将蓝色、绿色和红色光子分裂到组织中的不同位置。此外，通过引入双光栅元件，不同波长的光子可以在不同深度空间分离。因此，当表达各种相应的光敏视蛋白时，这些光子探针可用于选择性激活或抑制特定的神经元和细胞核。我们预计这种设备策略可以在用于神经科学和神经工程的先进植入式光子系统的设计中得到广泛应用。