Astrocomb development for the ELT: enhancing capability with a modern laser platform

该提案旨在确保资金支持赫瑞瓦特大学持续发展激光频率梳（LFC）技术所需的资金，该技术需要在下一代新望远镜（如ELT）中对光谱仪进行超精确校准。具体来说，该设备将支持E-ELT PPRP拨款ST/S001328/1（“英国ELT计划”）和财团拨款ST/V000403/1（“使用单模光子技术的精密天文光谱仪”）的研究。赫瑞瓦特的LFC架构是基于一个超快的钛蓝宝石激光器。这种激光器产生的“超快”激光脉冲持续时间约为30飞秒，重复频率为1千兆赫。这些脉冲作为一些波束线的泵浦源，用于波长下转换、可见光和近红外宽带超连续谱产生、法布里-帕姆氏梳状滤波和梳状计量/传输。近十年来，我们的天文梳的发展一直基于一个开箱Ti：蓝宝石激光器，输出功率有限，现在需要耗时的维护和调整。由于这些原因，它现在不太适合我们正在开发的日益复杂的下游系统，作为英国ELT计划的B阶段试点，以及其他更广泛的研究，探索新的，强大的天文梳结构。这个单项目设备投标是一个现代化的替代激光器，在一个密封的零维护单元中提供50%的功率（允许光束在更多的光束线上分裂）。这种激光器不仅可以通过避免累积数周的维护来显着提高我们的生产力，而且它与目前我们在ELT-HIRES校准单元中选择的激光平台相同，后者需要密封，零维护和完全自动化的激光源。我们的提案在以下方面符合评估标准：(A) STFC计划的战略价值所要求的激光器将直接加强基本天文梳技术的研究和开发，这些技术必须在大约10年的时间内部署在像ELT这样的望远镜上。英国（剑桥，达勒姆，UKATC，赫瑞瓦特）在意大利领导的ELT-HIRES光谱仪开发中发挥着重要的战略作用，该光谱仪需要一个天文梳来进行超精确的波长校准。该设备请求将确保英国继续在ELT-HIRES光谱仪校准的硬件开发中发挥重要作用。(B)及时性激光量子公司（Novanta）的支持信证实，该设备可以在2022年3月31日之前按照拨款条件的要求投入使用。值得注意的是，ST/S001328/1和ST/V000403/1项目的寿命将在一到三年之间，因此这些设备将有可能加强和加速这些资助支持的研究计划。

This proposal aims to secure capital funding needed to support the continued development of laser frequency comb (LFC) technologies at Heriot-Watt University, which are needed for ultra-precise calibration of spectrographs in the next generation of new telescopes, such as the ELT. Specifically, the equipment will support research on E-ELT PPRP grant ST/S001328/1 ("The UK ELT Programme") and consortium grant ST/V000403/1 ("Precision Astronomical Spectrographs using Single-Mode Photonic Technologies"). Heriot-Watt's LFC architecture is based around a single ultrafast Ti:sapphire laser. This laser produces "ultrafast" laser pulses with durations of around 30 femtoseconds and with a repetition frequency of 1 GHz. These pulses serve as the pump source for a number of beamlines for wavelength down-conversion, visible- and near-infrared broadband supercontinuum generation, Fabry-Pérot étalon comb filtering and comb metrology / delivery. For nearly ten years, our astrocomb development has been based around an open-box Ti:sapphire laser, with limited output power, and now requiring time-consuming maintenance and realignment. For these reasons it is now poorly suited to the increasingly complex downstream systems that we are developing as a Phase B pilot for the UK ELT programme and in other wider research exploring new, robust astrocomb configurations.This single-item equipment bid is for a modern replacement laser offering 50% greater power (allowing the beam to be split across a greater number of beamlines) in a sealed zero-maintenance unit. Not only will this laser dramatically increase our productivity by avoiding many cumulative weeks of maintenance, but it is identical to the unit which is currently our laser platform of choice for adoption in the ELT-HIRES calibration unit, which requires a sealed, zero-maintenance and fully automatable laser source.Our proposal meets the assessment criteria in the following ways:(A) Strategic value within the STFC programmeThe requested laser will directly enhance research and development of basic astrocomb technologies, that must be deployed in around 10 years' time on telescopes such as the ELT. The UK (Cambridge, Durham, UKATC, Heriot-Watt) has a significant strategic role in the Italian-led ELT-HIRES spectrograph development, on which an astrocomb is needed for ultra-precise wavelength calibration. This equipment request will ensure that the UK continues to play an important role in the hardware development for the calibration of the ELT-HIRES spectrograph.(B) TimelinessAs the letter of support from Laser Quantum (Novanta) confirms, the equipment can be commissioned by 31 March 2022 as required in the conditions of the grant. Notably, projects ST/S001328/1 and ST/V000403/1 will have lifetimes of between one and three years from this date, and so the equipment will have the potential to enhance and accelerate the research programmes supported by these grants.