1. Surface-enhanced Infrared Absorption Spectroscopy


We are developing a novel class of plasmonic structures for Surface-enhanced infrared absorption (SEIRA) spectroscopy. Extremely high near-field enhancement and enhanced sensing area formed at various plasmonic metamaterial structures may provide a promising sensing platform for future applications of ultrasensitive biological and chemical sensing and detection.
Applications: Biological and chemical sensors, Gas sensors, Pharmacy, and Food safety.

1. I. Hwang et al., “Ultrasensitive molecule detection based on infrared metamaterial absorber with vertical nanogap” Small Methods, 5, 2100277 (2021).[Link]
2. I. Hwang et al., “Plasmon-Enhanced Infrared Spectroscopy Based on Metamaterial Absorbers with Dielectric Nanopedestals” ACS Photonics, 5(9), 3492-3498 (2018).[Link]
3. Y. Jung et al., “Fano metamaterials on nanopedestals for plasmon-enhanced infrared spectroscopy” Scientific Reports, 9, 7834 (2019).[Link]

2. Reconfigurable metasurfaces


We are developing ultra-fast electrically-tunable plasmonic metasurfaces based on coupling of plasmonic resonances in metallic nanostructures with intersubband transitions in multiple-quantum-well (MQW) structures. The MQW structure is designed to have a diagonal transition in real space, allowing for voltage-tunable intersubband transition energies through the Quantum-confined Stark effect. In this configuration, the absorption spectra of the metasurface under normal incidence of light can be changed according to the voltage bias.
Applications: Multi-color night-vision, Free-space optical communications, Active IR light filters, Active meta-lens, and Active beam-steering.

1. J. Lee et al., “Ultrafast electrically-tunable polaritonic metasurfaces” Advanced Optical Materials, 2, 1057, (2014). [pdf]
2. N. Dabidian et al., “Experimental demonstration of phase modulation and motion sensing using graphene-integrated metasurfaces” Nano Letters, 16, 3607, (2016).

3. Nonlinear metasurfaces


We are developing highly-nonlinear metasurfaces based on coupling of electromagnetically-engineered plasmonic nanoresonators with quantum-engineered intersubband nonlinearities. This approach allows us to create large-area meatasurfaces in which virtually any element of the effective nonlinear susceptibility tensor may be engineered to have a giant nonlinear response for the free-space optical applications. From recent experiment, we achieved 1.2um/V of the effective nonlinear susceptibility which is the highest nonlinear response in any condensed matter systems in visible/infrared optical spectra.
Applications: Nonlinear light source for broadband laser-based spectroscopy, Room-temperature THz light sources, Nonlinear spectroscopy.

1. D. Kim et al., “Giant nonlinear circular dichroism from intersubband polaritonic metasurfaces” Nano Letters, 20, 8032-8039, (2020). [Link]
2. J. Yu et al., “Third-harmonic generation from plasmonic metasurfaces coupled to intersubband transitions” Adv. Opt. Mat., 7, 1801510, (2019). [Link]
3. J. Lee et al., “Ultrathin second-harmonic metasurfaces with record-high nonlinear optical response” Adv. Opt. Mat., 4, 664, (2016). [pdf]
4. J. Lee et al., “Giant nonlinear response from plasmonic metasurfaces coupled to intersubband transitions” Nature, 511, 65, (2014).[pdf]

4. Orbital Angular Momentum generation and detection


We are developing metasurfaces that can generate and detect vortex beam carrying orbital angular momentum (OAM). Based on the orthogonality condition of the OAM beams, we can use them as data carrying orthogonal channels for high capacity free-space or fiber-based communication systems. Currently we are working on OAM multiplexing and demultiplexing at E-band frequency for 6G front- or back-haul communications
Applications: High capacity communications, Optical tweezer, Quantum optics

1. H. Chung et al., “Generation of E-band metasurface-based vortex beam with reduced divergence angle” Scientific Reports, 10, 8289, (2020).[Link]