Ultra-coherent semiconductor lasers for metrology

该项目涉及开发紧凑而坚固的激光源，具有计量和量子技术应用所需的高性能，并通过混合半导体激光器的独特特性实现：具有极高精细度腔和超窄基本线宽的波长可工程激光器。与其他激光器相比，这种激光器具有非常低的强度和频率噪声，只要光子寿命超过载流子寿命;然而，在传统格式中，这意味着外腔必须有几厘米长，因此会受到环境噪声的影响。低于几kHz的线宽通常通过对外部基准的主动稳定来实现，最常见的是Fabry-Perot。我们最近报道了半导体盘激光器与亚kHz线宽在新的波长原子冷却应用，这是记录这种激光器类型的性能;然而，到目前为止，我们已经使用相对标准的自由空间激光谐振器，外部频率参考，和标准的锁定方案。这些增加了紧凑型半导体激光器系统的体积和复杂性，并且易于漂移。已经证明了这些激光器的冷原子计量的潜力，我们现在将利用其低的固有噪声和独特的腔内动力学更紧凑的频率锁定schemes.Aim：应用一系列的半导体和光学工程技术结合新颖的激光器架构，以显着减少体积和提高超相干半导体激光系统的计量稳定性。

This project involves the development of compact and robust laser sources with the high performance required for metrology and quantum technology applications, enabled by the unique properties of hybrid semiconductor lasers: wavelength engineerable lasers with very high finesse cavities and ultra-narrow fundamental linewidth. Such lasers have very low intensity and frequency noise compared to other lasers so long as the photon lifetime exceeds the carrier lifetime; however, in conventional formats this means that the external cavity must be a few cm long and therefore subject to environmental noise. Linewidths below a few kHz are usually achieved via active stabilisation to an external reference, most often a Fabry-Perot. We have recently reported semiconductor disk lasers with sub-kHz linewidths at novel wavelengths for atom cooling applications, which is record performance for this laser type; however, to date we have used relatively standard free-space laser resonators, external frequency references, and standard locking schemes. These add bulk and complexity to a compact semiconductor laser system and are subject to drift. Having demonstrated the potential of these lasers for cold-atom metrology we will now take advantage of their low intrinsic noise and unique intracavity dynamics for much more compact frequency locking schemes.Aim: to apply a range of semiconductor and optical engineering techniques combined with novel laser architectures to significantly reduce the volume and improve the stability of ultra-coherent semiconductor laser systems for metrology.