Room Temperature Continuous-Wave Inorganic Maser

直到最近，微波激射器只能用于射电天文学等非常专业的应用。其原因是低温冷却和在较小程度上施加的高磁场，以复杂性和成本为由禁止大规模生产。尽管事实上，微波激射器是在激光之前被发现的，这些问题意味着后者，它不需要应用磁场或冷却，看到了广泛的应用范围从条形码阅读器，激光光盘到激光眼科手术。2013年，帝国理工学院和伦敦大学学院获得了EPSRC资助的研究项目，以生产室温微波激射器。虽然我们有初步的观察，室温聚积是可能的，但我们还没有在不同的实验室环境中验证这一点，我们也不清楚聚积分子是如何与光相互作用的，以及哪种晶体取向或掺杂剂浓度是最佳的。这次合作非常成功，实现了我们设定的所有目标。现在，在另一个世界首创中，该团队建造了一个能够在室温下连续工作的钻石微波激射器。我们以前的研究仅仅集中在有机材料作为凝聚介质上。在这个提议中，我们将探索无机材料在室温下聚积的潜力。这样，我们就可以避免有机物遇到的两个关键问题。问题1 -衰变率：阻碍有机物连续运行的主要障碍是最低三态亚能级的相对较长的寿命，减少了可用于光泵浦的五苯的数量（瓶颈），破坏了种群反转。问题2 -加热：我们首先用来演示室温微波激射器的有机增益介质，对terphenyl中的并五苯不能承受激光的连续照射，因为terphenyl主体的温度会上升到其熔点以上。这两个问题的解决方案：一个彻底但令人兴奋的突破将同时解决这两个问题，那就是探索具有高熔融/分解温度和良好导热性（tc）的无机材料的高自旋态：如金刚石（M.P. 3550C; tc 2000 W/mK）和碳化硅（2730C; tc 120 W/mK）。最近，我们在室温下观察到钻石开采NV中心的聚集。这意味着我们可以在英国和其他地方对钻石NV中心进行大量研究。同样，有很多研究在探索碳化硅的缺陷，我们可以建立在。我们已经开始与w<s:1> rzburg小组的Vladimir Dyakonov教授小组合作，他们目前正在研究SiC。REF. https://arxiv.org/pdf/1709.00052.pdf实现这一目标将毫无疑问地进一步确立英国作为开展室温微波激射器主题基础研究的关键地点。

Until very recently the MASER could only be used in very specialist applications such as radio astronomy. The reason for this is that cryogenic cooling and to a lesser extent, high applied magnetic fields, prohibited mass production on the grounds of both complexity and cost. Despite the fact that the MASER was discovered before the LASER these issues meant that the latter, which does not need applied magnetic fields or cooling, saw widespread adoption in a huge range of applications from bar-code readers, laser discs to laser eye surgery.In 2013 Imperial and UCL were awarded an EPSRC funded research project to produce a room temperature MASER. Although we had preliminary observations that room temperature masing was possible we had not verified this in a different laboratory setting, nor did we have a clear idea of how the masing molecule interacted with light and which crystal orientations or dopant concentrations would be optimal. This collaboration was remarkably successful achieving all the objectives we set.Now, in what is another world first, the team has constructed a diamond MASER capable of continuous-wave operation at room temperature. Our previous research has concentrated solely on organic materials as the masing medium. In this proposal we will explore the potential of masing in inorganic materials at room temperature. In doing so we will obviate two key problems encountered with organics.Problem 1 - Decay rates: The primary obstacle that prevents continuous operation in organics is the relatively long lifetime of the lowest triplet sub-level, reducing the number of pentacenes available for optical pumping (bottleneck) and destroying the population inversion.Problem 2 - Heating: The organic gain medium, pentacene in p-terphenyl we first used to demonstrate a room temperature MASER cannot withstand a continuous illumination by a laser because the temperature of the terphenyl host rises above its melting point. Solution to both problems: a radical but exciting departure which will address both problems simultaneously is to explore high spin states in inorganic materials with high melting/decomposition temperature and favourable thermal conductivities (T.C.): such as diamond (M.P. 3550C; T.C. 2000 W/mK) and silicon carbide (2730C; T.C. 120 W/mK).Very recently we observed masing at room temperature in diamond exploiting NV centres. This means we can build upon a huge wealth of research in the UK and elsewhere on diamond NV centres. Again there is much research exploring defects in SiC that we can build on. We have initiated a collaboration with the group of Prof. Dr. Vladimir Dyakonov at Würzburg group who are currently exploring SiC. REF. https://arxiv.org/pdf/1709.00052.pdf Achieving this would further establish without doubt the UK as the key place to carry out fundamental research on the topic of room temperature MASERs.