Miniaturization: The Next Wave in Astronomical Instrumentation

光谱仪是一种天文仪器，它将星光分成颜色，并对它们进行精确的定量测量。它对于广泛的天文观测是必不可少的，但它复杂、笨重且昂贵。本项目采用来自电信行业的光子学技术，研制出一种新型的天文光谱仪。光子学技术提供了以数量级缩小尺寸的潜力，同时也降低了成本。Veilleux和他的合作者正在开发这样一种微型光子光谱仪，用于部署在望远镜上。这种演示仪器有可能将传统的光谱仪--任何天文台的主力--转变为灵活的21世纪发现引擎。这些研究人员借鉴了电信行业的几项创新，将光谱仪微型化。最基本的一种是光子灯笼，它是一种将来自多模光纤的光有效地耦合到单模光纤的方法。多模光纤是唯一可以在天文焦平面上使用的类型。然而，耦合到单模光纤可以使用其他光子学创新：光纤布拉格光栅和复杂的波导布拉格光栅，它们过滤掉特定波长并抑制不需要的噪声。噪声来自水蒸气/OH天空发射，是天文红外光谱仪中不需要的背景的主要来源。最后一项创新是阵列波导光栅，这是一种在硅上制造的光波电路，构成了色散元件。这些单独的部件中的每一个都是由调查人员利用他们对制造设施的机构准入来开发和测试的。该项目将完成该仪器，并将其部署在4.3米探索频道望远镜上。为该仪器确定的科学目标包括对伽马射线爆发余辉的后续调查。这一领域在过去20年中取得了巨大进展，并将在未来几年发挥重要作用。

A spectrograph is an astronomical instrument that divides starlight into colors and makes precise, quantitative measurements of them. It is essential for a broad range of astronomical observations; but it is complex, bulky, and expensive. This project uses photonics technology adapted from the telecommunications industry to develop a novel kind of astronomical spectrograph. Photonics technology offers the potential to reduce the size by orders of magnitude while also lowering cost. Veilleux and collaborators are developing such a miniaturized, photonic spectrograph for deployment on a telescope. This demonstration instrument has the potential to transform the traditional spectrograph, workhorse of any astronomical observatory, into a lithe 21st century discovery engine.These investigators borrow several innovations from the telecommunications industry to miniaturize a spectrograph. The essential one is a photonic lantern, which is a method of efficiently coupling light from a multi-mode fiber into a single mode fiber. Multi-mode fibers are the only type that can be used at an astronomical focal plane. However, coupling to single mode fibers enable using other photonics innovations: fiber Bragg gratings and complex waveguide Bragg gratings, which filter out specific wavelengths and suppress unwanted noise. Noise arises from water vapor / OH sky emission and is the major source of unwanted background in an astronomical IR spectrograph. The final innovation is an arrayed waveguide grating -- a lightwave circuit fabricated on silicon that forms the dispersive element. Each of these individual components has been developed and tested by the investigators using their institutional access to fabrication facilities. This project will complete the instrument and deploy it at the 4.3 m Discovery Channel Telescope. The science goals identified for the instrument included follow-up investigations of gamma-ray burst afterglows. This field has seen tremendous advance over the past two decades and will be relevant for years to come.