Integrated Solid-State Steerable Lasers (I-STEER)

激光是现代社会无数领域的关键使能技术，在无处不在的连接、数据存储、医疗保健、安全、环境监测等方面触及我们的生活。例如，电信，它们被用来产生携带光信号的信息，这些光信号通过细玻璃光纤传输；制造，它们被用来焊接和切割材料；医学，它们被用来检测血氧水平，并精确地切除组织。对于几乎所有的激光应用，必须将激光光源与另一种将激光引导到所需方向的技术结合使用。在某些情况下，这种技术可以是“被动的”，电信中使用的玻璃光纤就是这种情况。在其他情况下，操控技术必须是主动的，才能及时改变激光光束的方向，就像一些激光切割和激光成像系统中使用的快速移动的反射镜系统一样。传统的主动激光操控技术往往昂贵、笨重和脆弱。这些缺点中的一个或多个使其不适合许多重要应用，包括汽车应用的激光成像系统、基于空间的激光通信系统和基于无人机的遥感系统。为了解决这一问题，目前全球都在推动开发完全集成的固态光束操纵技术，在这种技术中，激光无需使用任何物理上移动的部件就可以进行操纵。然而，目前，即使是最先进的固态激光光束控制系统的功能也是有限的，不能满足许多现实世界应用的要求。在这个项目中，我们将利用两项关键集成光学技术-相干光子晶体表面发射激光器(PCSEL)二极管阵列和被称为“集成光子灯笼”的三维光波导器件的最新进展，开发能够在二维提供灵活的光束控制并且原则上可以在任何二极管激光波长下工作的全集成固态可控激光器(I-Steer)。I-Steer的一个关键目标是实现更密集的PCSEL阵列，其中激光模式直径减少到20微米(~20个波长)，中心到中心的间隔减少到~50微米(~50个波长)-当前的PCSEL阵列展示了50微米直径的激光模式，中心到中心的间隔为400微米。不幸的是，即使我们的目标是雄心勃勃的空间尺度，也意味着PCSEL阵列仍然不适合直接用作光学相控阵(OPA)，因为光学相控阵需要非常紧凑的广角发射器来实现大角度/波瓣自由波束控制。为了解决这个问题，i-steer引入了一个新的想法，即使用被称为集成光子灯笼的三维集成光波导跃迁来绝热地将PCSEL模式组合成单个高度多模的光图案，其空间相位和幅度特性可以通过PCSEL驱动电子设备直接控制光束方向。通过i-steer项目，我们的目标是将激光二极管重新定义为一种全电子集成可控光源，使其能够在无数应用中实现新的功能，包括自由空间光通信和LiDAR。这一领域的知识产权和能力的产生将使英国在这一强劲增长的学术领域处于领先地位，通过创建许可和/或衍生产品来创造财富，并尽早采用这一新技术的英国原始设备制造商。

Lasers are a key enabling technology in countless areas of modern society, touching on our lives in terms of ubiquitous connectivity, data storage, healthcare, security, environmental monitoring, etc. Examples include telecommunications, where they are used to generate the information carrying optical signals that are transmitted along thin glass optical fibres, manufacturing, where they are used for welding and cutting materials, and medicine, where they are used for sensing blood oxygen levels, and precisely resecting tissues.For almost all laser applications, it is necessary to use the laser source in combination with another technology that directs or "steers" the laser light in the desired direction. In some cases, this technology can be "passive", as is the case with the glass optical fibres used in telecommunications. In other cases, the steering technology must be "active" to change the direction of the laser beam in time, as is the case with the rapidly moving mirror systems used in some laser cutting and laser imaging systems.Conventional active laser steering technologies are often costly, bulky, and fragile. One or more of these disadvantages makes them sub-optimal for many important applications, including laser imaging systems for automotive applications, space-based laser communications systems, and drone-based remote sensing systems. To address this, there is currently a global drive to develop fully integrated solid-state beam-steering technologies, where the laser light is steered without the use of any physically moving components. Currently, however, even state-of-the-art solid-state laser beam steering systems have limited functionality, and do not meet the requirements of many real-world applications. In this project, we will exploit recent advances in two key integrated optical technologies - coherent Photonic Crystal Surface Emitting Laser (PCSEL) diode arrays and three-dimensional optical waveguide devices known as "integrated photonic lanterns" - to develop fully Integrated Solid-State Steerable Lasers (I-STEER) that can deliver agile beam steering in two dimensions and can, in principle, function at any diode laser wavelength.I-STEER will target the development of 900-mode PCSEL arrays, but will deliver the technological advances necessary to enable future PCSEL arrays (using commercial manufacturing facilities) that generate 10's of thousands of independently phase and ampltiude controllable coherent laser modes. A key aim of I-STEER is to enable denser PCSEL arrays, where the laser mode diameter is reduced to 20 microns (~20 wavelengths) and the centre-to-centre separation is reduced to ~50 microns (~50 wavelengths) - current PCSEL arrays exhibit 50 micron diameter laser modes with centre-to-centre separations of 400 microns. Unfortunately, even the ambitious spatial scales we are targeting mean that the PCSEL array will still be unsuitable for direct use as an optical phased array (OPA), since OPAs require very tightly packed wide angle emitters to achieve large angle/lobe free beam-steering. To address this, I-STEER introduces the fresh idea of using three-dimensional integrated optical waveguide transitions known as "integrated photonic lanterns" to adiabatically combine the PCSEL modes into a single highly multimode pattern of light, the spatial phase and amplitude properties of which can be directly controlled for beam steering via the PCSEL drive electronics.Through the I-STEER project, we aim to redefine the laser diode as an all-electronic integrated steerable light source enabling new functionally in countless applications including free-space optical communications and LiDAR. The generation of intellectual property and capability in this area will place the UK in a leading position with regards this strongly growing academic field, wealth generation through the creation of licensing and/or spin-outs, and in early adoption of UK based OEMs of this new technology.