High-powEr phosphorous-based DFB Lasers for Cold ATom Systems (HELCATS)

为了推动量子钟的尺寸、重量和成本的减小，对用于量子钟的应用的定制光源的需求日益增长。特别是，我们的项目集中在锶钟的源上，这是正在开发的最有前途的离子系统之一，它提供了大约10^18水平的时钟精度和~10^15/tau1/2的稳定性。该系统需要4个波长范围为~680-710 nm的激光源。在这些波长发射的商用激光器要么不能满足锶时钟系统的严格要求，要么由于含铝增益区而可靠性较差。本项目开发了在GaAs衬底上生长的磷基DFB激光器，以满足这种日益增长的需求。我们的创新在于利用合适的半导体材料(InGaAsP/AlInGaP)来覆盖所需的光谱波段(680-710 nm)。这种方法改善了与现有铝合金方法相关的可靠性和输出功率问题。此外，我们采用低损耗波导方法来实现更窄的发射线宽度和光子集成元件，从而实现DFB和放大器元件的在片制造。该联盟提供了从新外延层结构的生长和制造工艺的开发到用于运行时钟系统的DFB激光器的晶片规模制造的制造供应链。该项目将运行在680至710 nm波长范围内的稳定DFB激光器的技术准备水平提升到后期商用前水平，即TRL&GT；6。

There is a growing need for custom light sources for applications in quantum clocks in order to drive their reduction in size, weight, and cost. In particular, our project concentrates on sources for the Sr+ clock, one of the most promising ion systems being developed, which offers a clock accuracy around the 10^18 level, and stability at ~10^15/tau1/2. This system requires 4 laser sources in the ~680-710 nm wavelength range. The commercially available lasers emitting in these wavelengths either do not meet the stringent requirements for Sr+ clock systems or suffer from poor reliability because of the aluminium-containing gain region.This project develops phosphorous-based DFB lasers on GaAs substrates to address this growing need. Our innovation lies in utilising suitable semiconductor materials (InGaAsP/AlInGaP) that allows coverage of the required spectral bands (680-710nm). This approach ameliorates reliability and output power issues associated with the incumbent aluminium alloy approach. Furthermore, we adopt a low loss waveguide approach to enable narrower emission linewidths and elements of photonic integration to enable on-chip manufacturing of separate DFB and amplifier elements.The consortium provides a manufacturing supply chain from the growth of new epilayer structures and development of fabrication processes through to wafer scale manufacturing of DFB lasers to be deployed in operational clock systems. The project advances the Technological Readiness Level of stable DFB lasers operating in the 680 to 710 nm wavelength range to a late-stage pre-commercial level, i.e. TRL>6.