Advanced waveguide laser source development using ultrafast laser inscription

大多数激光系统发出连续的光波，但如果激光器设计正确，可以使用一种称为锁模的技术来诱导它发射非常短的光脉冲。目前，在从生物光子学到计量学的各个领域，对紧凑型锁模激光光源有着广泛的需求。这一拟议项目的目的是利用两种创新技术来开发这种来源：超快激光刻字和碳纳米管，如下所述。该项目将利用赫里奥特·瓦特大学和剑桥大学在这些领域的国际领先专业知识。如果成功，该项目将导致当前技术的范式转变。超快激光是一种发射极短脉冲光的激光，通常小于100飞秒。由于这种脉冲的持续时间很短，由现代桌面系统提供的峰值功率通常可以达到GW制度。通过将超快激光脉冲聚焦在透明材料内，放置在焦点上的材料的结构可能会永久改变。如果材料随后通过焦点进行平移，则可以在材料中刻入三维结构修改。诱导的结构修饰可以以各种方式表现出来，例如增加的蚀刻速率或折射率的变化。通过仔细控制刻写参数，结构变化可以用于直接刻写光子元件，如光波导管(其引导光的方式类似于通过金属线引导电流)和微通道(可用于引导流体或气体)。在这个项目中，我们将利用超快激光刻字提供的前所未有的灵活性来制造一些以前不可能或难以制造的用于波导激光应用的元件。碳纳米管是圆柱形的碳分子，直径通常只有几个纳米，长度可达几个厘米，它们是纳米技术研究的中心。与传统的块体材料相比，碳纳米管的电学和光学性质可以通过其物理尺寸和结构来控制。如果将正确制造的碳纳米管放置在激光器内，就可以在不需要复杂电子设备的情况下诱导锁模。该项目的很大一部分将集中在为波导激光锁模应用开发具有正确性质的碳纳米管，以及使用超快激光刻字来构建将这些碳纳米管集成到最终设备中的波导激光元件。

Most laser systems emit a continuous wave of light, but if the laser is designed correctly it can be induced to emit very short pulses of light using a technique known as mode-locking . There is currently a wide spread requirement for compact, mode-locked laser sources in areas ranging from bio-photonics to metrology. The aim of this proposed project is to develop such sources using two innovative technologies: ultrafast laser inscription and carbon nanotubes as described briefly below. The project will utilise the internationally leading expertise in each of these areas at Heriot Watt University and Cambridge University. If successful, the project will result in a paradigm shift in the current technology. Ultrafast lasers are lasers that emit extremely short pulses of light, routinely less than 100 fs. Due to the short durations of such pulses, the peak powers supplied by modern table top systems can often reach the GW regime. By focusing ultrafast laser pulses inside a transparent material, the structure of the material placed at the focus may be permanently altered. If the material is then translated through the focus, three-dimensional structural modifications can be inscribed in the material. The induced structural modification may manifest itself in a variety of ways, examples of which include an increased etch rate or refractive index change. Through careful control of the inscription parameters, the structural changes can be used to directly inscribe photonic components such as optical waveguides (that guide light in an analogous way to the guiding of electrical current by a metal wire) and micro-channels (that can be used to guide fluids or gases). During this project, we will utilise the unprecedented flexibility offered by ultrafast laser inscription to fabricate a number of previously impossible, or hard to fabricate elements for waveguide laser applications.Carbon nanotubes are cylindrical carbon molecules with diameters of typically only a few nanometers and lengths of up to a few cm, they are at the centre of nanotechnology research. In contrast to conventional bulk materials, the electronic and optical properties of carbon nanotubes can be controlled through their physical size and structure. If correctly fabricated carbon nanotubes are placed inside a laser, mode-locking can be induced without the need for complex electronics. A large part of the project will focus on developing carbon nanotubes with the correct properties for waveguide laser mode-locking applications, and on using ultrafast laser inscription to construct a waveguide laser element that will integrate these carbon nanotubes into the final device.