Abstract：Strong and controllable light-matter interaction at room temperature requires quantum emitters with large, tunable dipole moments and photonic modes with high quality factors in integration-friendly platforms. In the first part of this talk, I will briefly give an overview of light-matter interactions. In the second part, I will discuss the recent development by our group on this topic, through co-engineering the “matter” and “photon” degrees of freedom across van der Waals (vdW) semiconductors and molecular systems.

Part 1 Giant-dipole interlayer excitons as a reconfigurable matter platform

We establish multilayer WS₂/InSe vdW heterostructures as a layer-engineered platform for giant interlayer exciton dipoles. Dual-gate quantum-confined Stark spectroscopy shows that the out-of-plane dipole moment increases monotonically with the thickness of either InSe or WS₂, reaching 3.18 e·nm, the largest value reported in vdW heterostructures. The giant dipole produces enhanced Stark shifts and strengthened dipole-dipole repulsion, evidenced by power-dependent photoluminescence. Ab initio calculations attribute this behavior to progressive delocalization of the excitonic wave function across multiple layers, providing microscopic support for the experiments. Thus, layer engineering offers a practical knob to tune exciton dipole moment, transition energy, and many-body interactions, yielding a highly configurable “matter platform” for strong-coupling and quantum-photonic experiments.

Part 2 Etch-free vdW metasurfaces for intrinsic exciton–photon hybridization.

We then realize an etch-free vdW metasurface architecture that generates high-Q resonances directly in vdW layers while leaving the 2D crystals pristine. A low-index photoresist nanostructure patterned on top of various vdW materials suppresses scattering losses and supports quasi-BIC resonances with Q factors up to 348. On this universal platform we demonstrate room-temperature exciton polaritons in WS₂, MoS₂, WSe₂, and MoSe₂, with clear anticrossing and Rabi splittings of ~80 meV (WS₂) and ~72 meV (MoSe₂) that exceed the intrinsic excitonic linewidths. The metasurface also enables polarization-dependent emission modulation, including control over phonon-assisted indirect transitions in bulk WS₂ and bright exciton emission in encapsulated monolayer MoSe₂, thereby providing the “photon-side” counterpart to engineered excitonic media.

Part 3 Extending high-Q metasurfaces to molecular J-aggregate crystals.

Finally, we extend this high-Q metasurface strategy to molecular emitters by integrating a TiO₂ dielectric metasurface with monolayer J-aggregate crystals. The hybrid supports strong coupling with a 78 meV Rabi splitting and Q factors up to 239, and achieves uniform, macroscale emission control with 94% emission polarization and a reduction of the non-radiative recombination ratio from 34% to 2%.

Together, these works define a unified route toward room-temperature strong light-matter interaction based on joint design of giant-dipole excitons and high-Q metasurfaces, establishing a versatile platform for tunable polariton physics and many-body phenomena in both vdW and molecular systems. Future directions include integrating layer-engineered interlayer excitons with vdW-compatible metasurfaces to combine strong coupling with strong exciton-exciton interactions, and incorporating chiral or topological metasurface designs to achieve multidimensional control over spin, valley, and polarization for advanced quantum-photonic and optoelectronic devices.

主讲人简介：

许建斌，本科及硕士毕业于南京大学。尔后赴德国康斯坦茨大学深造，从事纳米科学研究，并获博士学位。随后加入香港中文大学电子工程学系，2002年夏晋升为教授。 现任香港中文大学工程学院副院长，卓敏电子工程学讲席教授，材料研究中心主任, 中国科学院深圳先进技术研究院学术副院长。主要从事纳米电子及光子材料与器件、二维材料、微纳扫描探针表征、能源科技等领域的研究。曾先后获得国家自然科学基金委员会"海外及港澳学者合作研究基金（原海外杰出青年基金）"、教育部"高等学校科学研究优秀成果奖（自然科学奖）二等奖"、香港中文大学“卓越研究奖”和“工程学院杰出学人奖”，科睿唯安（Clarivate）高被引学者，并获得教育部高层次人才称号。现任欧洲科学院外籍院士（Foreign Fellow of European Academy of Sciences），国际电气暨电子工程师学会会士（IEEE Fellow），国际光学学会会士，《IEEE Transactions on Electron Devices国际电子器件汇刊》编辑，《ACS Nano》期刊编委，中国真空学会理事，香港材料研究学会常务副理事长。参与多个国际及国家研发资助机构和奖项评审工作.