High-power planar waveguide visible-lasers.

激光已经在我们的日常生活中变得无处不在，支撑着我们依赖技术的社会的大部分。激光不再是寻找问题的解决方案；激光本身就是一种工具。自从激光器问世以来，已经发展了许多不同的固体激光器结构，其中大多数是基于稀土离子，并在近红外产生相干辐射。在某些情况下，可以提供数千瓦的功率级别，可以在几秒钟内切断几厘米厚的钢材。这些激光器的光发射始于稀土离子的低位亚稳定激发态；然而，存在许多应用，如显示技术、生命科学界面的诊断工具，或利用海水的传输窗口进行海底传感和通信，这需要更高能量的光子，即可见光。这样的波长可以通过红外激光的非线性频率上转换或直接通过来自更高位置的稀土离子激发态的受激发射来获得。基于这些较高激发态发射的固态可见光激光仍然是一种研究实验室现象，通常功率和效率都很低，波长范围有限。制约这些器件的主要技术挑战是有效的泵浦周期，以避免寄生上转换和光变暗等损耗产生机制，例如，这些机制迄今阻碍了上转换泵浦的可见光光纤激光器的商业化。我们提出了一种从稀土离子产生可见输出的新方法，这将扩展激光用户的工具包。凭借我们的开创性研究和专业知识以及最新和关键的技术进步，即超低损耗稀土掺杂晶体波导和窄线宽高功率二极管激光泵浦光源，我们现在首次能够产生正确的泵浦激励参数，使该激光器架构能够高效地高功率运行。我们的愿景是将固态可见光激光简化为只有一个振荡器，同时通过利用位于较高位置的激发态的丰富光谱特性来产生不同的颜色，以及它们独特的能量存储能力来扩大其功能。一种功率可扩展的架构将被实现，展示了在连续波(CW)和脉冲操作模式下的高功率操作的适用性，具有与替代固态系统相比无与伦比的特性。该项目里程碑的成功演示将使英国处于高功率可见光固态激光器领域的国际研究前沿，并有极好的机会通过我们的工业合作伙伴将该技术商业化。

Lasers have become ubiquitous in our daily lives, underpinning much of our technology dependent society. No longer a solution looking for a problem ; lasers are a tool in their own right. Many different solid-state laser configurations have evolved since the inception of the laser, the majority are based on rare-earth (RE) ions and produce coherent radiation in the near-IR. In some cases, multi-kW power levels that can cut through centimetres of steel in seconds are available. The light emission from these lasers starts from low-lying meta-stable excited states of the RE ions; however, many applications exist, such as display technologies, diagnostic tools at the life-science interface, or capitalising on the transmission window of seawater for sub maritime sensing and communications, which require higher-energy photons, that is, visible light. Such wavelengths can be obtained through non-linear frequency upconversion of IR lasers or directly through stimulated emission originating from higher-lying RE-ion excited-states. Solid-state visible lasers based on emission from these higher-lying excited states are still a research laboratory phenomenon, typically with low powers and low efficiencies and a limited range of wavelengths. The principle technical challenge restraining these devices is an effective pumping cycle that avoids loss generating mechanisms such as parasitic upconversion and photo-darkening, which, for example, have so far foiled the commercialisation of upconversion-pumped visible fibre lasers. We present a new approach for generating visible output from RE ions that will expand the toolkit of the laser user. Drawing upon our pioneering research and expertise with recent and critical technological advancements, namely ultra-low-loss rare-earth-doped crystalline waveguides and narrow-linewidth high-power diode-laser pump sources, we can now for the first time generate the right pump excitation parameters that will enable efficient high-power operation of this laser architecture. Our vision is to simplify the solid-state visible laser to just a single oscillator, while simultaneously broadening its capabilities through exploiting the rich spectroscopic properties of the higher-lying excited-states for generating different colours, and, their unique energy storage capacity. A power-scalable architecture will be realised, demonstrating applicability to high-power operation in both continuous wave (cw) and pulsed modes of operation, with unrivalled characteristics compared to alternative solid-state systems. Successful demonstration of the milestones in this project will place the UK at the forefront of international research in the field of high-power visible solid-state lasers, with an excellent opportunity to commercialise the technology through our industrial partners.