Fast Spatial Light Modulators for Neuronal Excitation and Imaging

项目摘要：我们建议开发快速空间光调制器(SLM)来解决 需要与当前快速基因编码传感器兼容的光学硬件 执行机构。SLM是一种多功能光学组件，可实现光束控制和全息 任意图案的投影。它们最近被用于图案化的光遗传 兴奋大脑中特定的神经元组。然而，目前的实验受到以下因素的限制 现有的空间光调制器速度较低(~100赫兹)。以满足FAST的需求 我们建议开发一种用于超高速自由空间SLM的技术 在近红外波长(850 nm-1000 nm)下运行的速度超过10 MHz，因此 兼容双光子光生激发和双光子显微镜。我们已经 演示了在电信波长(~1550 nm)下工作的硅中的概念器件 通过热光效应以较慢的速度调制。然而，电信运营 波长不适合神经刺激和成像的大多数应用，而硅可以 也不能用于~1100 nm以下的波长，因为它是吸收的。我们将使用类似的 设计和技术，如我们目前的硅光子学SLM，以开发器件在砷化镓 能够在近红外的自由空间中快速调整光束方向。这项技术是基于 在已经能够使片上光子调制器以高速运行的GaAs纳米光子学上 超过几GHz。 目标1：制定单个SLM像素的概念证明并演示操作 在近红外线下的速度超过10 MHz。为此，我们将把我们已有的 开发了从硅到砷化镓材料的SLM设计。我们将首先演示使用 速度超过1 KHz的热光效应，然后使用载波调制 注入/耗尽速度超过10 MHz。像素大小约为10微米×10微米 目标2：研制一台像素的SLM样机，演示基本光束偏转 功能性。这是最终设备的一个小版本。它将允许我们对任何 设备可能出现的问题，如像素之间的串扰、发热、最大 可操控的光能。 目标3：开发一台具有1000x1000像素的SLM原型，并展示快速光学 波束转向。这是一个SLM原型，将具有所需的大部分功能 演示波束控制和方向图投影的概念验证，速度高于 10 MHz。我们将演示双光子激发显微镜的概念证明。

Project Summary: We propose to develop fast spatial light modulators (SLM) to address the need for optical hardware compatible with the current fast genetically encoded sensors and actuators. SLMs are versatile optical components that enable beam steering and holographic projection of arbitrary patterns. They have recently been used for patterned optogenetic excitation of specific sets of neurons in the brain. However, current experiments are limited by the low speed of available spatial light modulators (~100 Hz). To match the needs of fast neuronal activation we propose to develop a technology for ultra-fast free-space SLMs with speeds exceeding 10 MHz operating at near infrared wavelengths (850nm-1000nm) and thus compatible with two-photon optogenetic excitation and two-photon microscopy. We already demonstrated proof of concept devices in silicon operating at telecom wavelength (~1550nm) modulated at slower speed via the thermo-optic effect. However, operation at telecom wavelengths is not suitable for most applications in neural stimulation and imaging, and Si can nor be used for wavelengths below ~1100nm because it is absorptive. We will use similar designs and techniques as in our current silicon photonics SLMs to develop devices in GaAs capable of fast optical beam steering in free space in the near infrared. The technology is based on GaAs nano-photonics that already enables on-chip photonic modulators operating at speeds exceeding several GHz. Aim 1: Develop proof of concept of a single SLM pixel and demonstrate operation at speeds faster than 10MHz in the near infrared. For this aim we will translate our already developed designs for Si SLMs to the GaAs material. We will show first modulation using the thermo-optic effect with speeds exceeding 1KHz, and then modulation using carrier injection/depletion at speeds exceeding 10MHz. The pixel size will be ~10µmx10µm Aim 2: Develop a prototype SLM with 8x8 pixels and demonstrate basic beam deflection functionality. This is a small version of the final device. It will allow us to troubleshoot any problems that may arise with the device, like cross-talk between pixels, heating, maximum optical power that can be handled. Aim 3: Develop a prototype SLM with >1000x1000 pixels and demonstrate fast optical beam steering. This is a SLM prototype that will have most of the functionality required to demonstrate proof of concept beam steering and pattern projection at speeds greater than 10MHz. We will demonstrate proof of concept two photon excitation microscopy.