Fast Spatial Light Modulators for Neuronal Excitation and Imaging

项目概述：我们建议开发快速空间光调制器（SLM），以解决 需要与当前快速基因编码传感器兼容的光学硬件， 执行器SLM是多功能光学元件，能够实现光束转向和全息成像。 任意图案的投影。它们最近被用于图案化光遗传学， 大脑中特定神经元的兴奋。然而，目前的实验受到以下限制： 可用空间光调制器的低速（~100 Hz）。为了满足快速 我们建议开发一种用于超快速自由空间SLM的技术， 在近红外波长（850 nm-1000 nm）下工作的速度超过10 MHz， 与双光子光遗传学激发和双光子显微术兼容。我们已经 在电信波长（~ 1550 nm）下工作的硅概念验证器件 通过热光效应以较慢的速度调制。然而，电信运营 波长不适合于神经刺激和成像中的大多数应用，并且Si可以 也不能用于低于~ 1100 nm的波长，因为它是吸收性的。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GaAs器件 能够在近红外的自由空间中进行快速光束转向。该技术基于 GaAs纳米光子学已经使芯片上的光子调制器能够以高速运行， 超过几GHz。 目标1：开发单个SLM像素的概念验证，并演示其在 在近红外线中速度超过10 MHz。为了这个目标，我们将翻译我们已经 开发的设计，硅SLM的砷化镓材料。我们将使用 速度超过1 KHz的热光效应，然后使用载波调制 注入/耗尽的速度超过10 MHz。像素大小约为10µ mx 10 µm 目标2：开发一个8x8像素的SLM原型，并演示基本的光束偏转 功能.这是最终设备的小型版本。它将使我们能够解决任何 设备可能出现的问题，如像素之间的串扰、发热、最大 可以处理的光功率。 目标3：开发一个> 1000 x1000像素的SLM原型，并展示快速的光学性能。 波束控制这是一个SLM原型，将有所需的大部分功能， 演示概念验证光束转向和模式投影，速度大于 10兆赫。我们将证明双光子激发显微镜的概念。

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.