Nonlinear polariton phenomena in GaN-based slab waveguides at temperatures up to 300 K

温度高达 300 K 时 GaN 基平板波导中的非线性极化子现象

• 批准号: EP/R007977/1
• 负责人: Dmtriy Krizhanovskii
• 金额: $ 56.24万
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FR007977%2F1
• 关键词: Nonlinear; polariton; phenomena; GaN; based

Novel quasi-particles, so-called polaritons, can be formed in an optically active semiconductor material due to mixing of photons and excitons (an exciton is an analogue of hydrogen in condensed matter). While two photons colliding in free space do not interact, polaritons strongly repel due to the exciton component in their wavefunctions. The Sheffield group has demonstrated that polariton-polariton interactions are several orders of magnitude stronger than effective photon-photon interactions in any other ultrafast photonic materials, where light is weakly coupled to matter. The efficient polariton-polariton scattering can be utilised for development of novel ultrafast light sources, frequency mixers and converters as well as scalable and compact devices performing control of light by light on a very fast timescale and at very low signal intensities (potentially at a single photon level). Potentially, this may have a strong impact on development of novel photonic signal processing and quantum technology hardware. The polariton platform is also well suited to the study of fundamental many-body phenomena ranging from Bose-Einstein condensation, superfluidity and solitons to quantum correlated phases in important physical systems, such as photonic analogues of topological insulators or quantum Hall systems. So-far phenomena due to polariton interactions have been explored in GaAs microresonators only at 4-50 K. Our proposal capitalises on the recent demonstration of ultraviolet polaritons in waveguides based on AlGaN/GaN material, where polaritons are robust at 300 K given the large exciton binding energy and highly efficient exciton-photon coupling; this provides an opportunity to explore the novel room temperature physics of interacting polaritons and to bring polariton applications to reality. In order to explore the fundamental physics of interacting GaN polaritons we will address polariton solitons, i.e non-spreading wavepackets stabilised by the nonlinearity. These interactions depend on many factors, such as the exciton Bohr radius, binding energy and the exciton fraction in the polariton wavefunction. A weak light pulse propagating in a polariton waveguide broadens with time, as different frequency components propagate with different velocities. By contrast, by increasing the pulse intensity polariton interactions are expected to cancel the spreading leading to formation of a soliton. Given the giant polariton nonlinearities solitons are expected to form at ultra-low thresholds and on a very short length-scale of ~10 micrometers.Another advantage of GaN-based waveguides over GaAs counterparts is that exciton-photon hybridisation occurs over a broad range of frequencies enabling polariton-polariton scattering from a spectrally narrow pulse to a broad quasi-continuum of states. As a result very short UV polariton soliton pulses with a duration down to 10's femtoseconds are anticipated. The outcome of this research would also enable realisation of novel ultraviolet broadband pulsed sources and frequency converters operating at very low thresholds, which are important for many spectroscopy applications in biophotonics and molecular photochemistry. Finally, we will demonstrate a prototype of a compact ultrafast all-optical polariton switch by exploiting nonlinear interactions between the polariton pulses with different central frequencies propagating in a photonic circuit based on coupled waveguides. These interactions induce nonlinear phase shifts in the optical signals enabling routing and switching of the ultrafast optical pulses. Given the very fast response of polariton system such a switch is expected to operate at THz rates. We note that exciton-polaritons in GaN-based nanostructures are also very robust against screening by hot electron-hole carriers, enabling study of the amplification of propagating polaritons in the presence of optical gain. This is essential for scalability of polariton devices.

由于光子和激子（激子是凝聚态物质中氢的类似物）的混合，可以在光学活性半导体材料中形成新的准粒子，即所谓的极化激元。虽然两个光子在自由空间中碰撞不相互作用，但极化激元由于其波函数中的激子分量而强烈排斥。谢菲尔德小组已经证明，极化子-极化子相互作用比任何其他超快光子材料中的有效光子-光子相互作用强几个数量级，其中光与物质弱耦合。有效的极化激元-极化激元散射可用于开发新型超快光源、混频器和转换器以及可扩展的紧凑型设备，这些设备在非常快的时间尺度上和在非常低的信号强度下（可能在单光子水平下）通过光执行光控制。潜在地，这可能对新型光子信号处理和量子技术硬件的开发产生强烈影响。极化子平台也非常适合研究基本的多体现象，从玻色-爱因斯坦凝聚，超流和孤子到重要物理系统中的量子相关相，例如拓扑绝缘体或量子霍尔系统的光子类似物。到目前为止，由于极化激元相互作用的现象已被探索的GaAs微谐振器仅在4-50 K。我们的建议利用了最近的示范紫外极化激元在波导的AlGaN/GaN材料的基础上，其中极化激元是强大的在300 K给定的大激子结合能和高效的激子-光子耦合;这提供了一个机会，探索新的室温物理相互作用的极化激元，并使极化激元应用到现实。为了探索相互作用的GaN极化激元的基本物理，我们将解决极化激元孤子，即非扩展波包稳定的非线性。这些相互作用依赖于许多因素，如激子玻尔半径，结合能和激子分数的极化激子波函数。在极化激元波导中传播的弱光脉冲随时间变宽，因为不同的频率分量以不同的速度传播。相比之下，通过增加脉冲强度，预期极化激元相互作用将抵消导致形成孤子的扩展。考虑到巨大的极化激元非线性，孤子有望在超低阈值和~10 μ m的非常短的长度尺度上形成。GaN基波导相对于GaAs波导的另一个优点是激子-光子杂化发生在宽的频率范围内，使得极化激元-极化激元散射从光谱窄脉冲到宽的准连续态。因此，非常短的紫外偏振孤子脉冲的持续时间下降到10飞秒的预期。这项研究的结果也将使实现新的紫外线宽带脉冲源和频率转换器在非常低的阈值，这是重要的许多光谱应用在生物光子学和分子光化学。最后，我们将展示一个紧凑的超快全光极化激元开关的原型，利用不同的中心频率的极化激元脉冲之间的非线性相互作用，在基于耦合波导的光子电路中传播。这些相互作用在光信号中引起非线性相移，从而实现超快光脉冲的路由和切换。考虑到极化激元系统的非常快的响应，期望这样的开关在THz速率下操作。我们注意到，GaN基纳米结构中的激子极化激元也非常强大，可以抵抗热电子空穴载流子的屏蔽，从而可以研究在光增益存在下传播极化激元的放大。这对于极化激元设备的可扩展性至关重要。

项目成果

Few-photon all-optical phase rotation in a quantum-well micropillar cavity

量子阱微柱腔中的少光子全光相位旋转

• DOI: 10.1038/s41566-022-01019-6
• 发表时间: 2022
• 期刊: Nature Photonics
• 影响因子: 35
• 作者: Kuriakose T

Polariton lasing in AlGaN microring with GaN/AlGaN quantum wells

具有 GaN/AlGaN 量子阱的 AlGaN 微环中的极化子激光

• DOI: 10.1063/5.0132170
• 发表时间: 2023
• 期刊: APL Photonics
• 影响因子: 5.6
• 作者: Delphan A

Ultrafast-nonlinear ultraviolet pulse modulation in an AlInGaN polariton waveguide operating up to room temperature.

• DOI: 10.1038/s41467-021-23635-6
• 发表时间: 2021-06-09
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Di Paola DM;Walker PM;Emmanuele RPA;Yulin AV;Ciers J;Zaidi Z;Carlin JF;Grandjean N;Shelykh I;Skolnick MS;Butté R;Krizhanovskii DN
• 通讯作者: Krizhanovskii DN