Laboratory of Nanophotonics & Metamaterials  (NanoMeta Lab)

  Over the last few decades, we have witnessed revolutionary developments in photonics technology, such as optical fiber communication, optical disc storage, lasers, LEDs, solar cells, etc. This photonics revolution has brought enormous beneficial impacts to society. More recently, dramatic developments in nanofabrication and numerical modeling techniques have enabled patterning of deep subwavelength photonic nanostructures. Many new opportunities are opening in this field, called nano-optics. These opportunities can lead to dramatic developments in all areas of optical science and technologies. Nano-optics will be a key research field for resolving many critical problems in the 21st century, such as large scale information processing, efficient energy harvesting/conversion, ultra-sensitive environmental sensing, etc.

  Most subwavelength structures involve nanometallic (or plasmonic) elements that can enable extreme light concentration and manipulation. Although resistive heating losses in metals are relatively high at optical frequencies, many useful functionalities can still be realized. Deep subwavelength plasmonic structures also form the basis for an entirely new class of optical materials. Photonic metamaterials are artificially tailored electromagnetic structures that allow the realization of many new, unusual optical properties. There have been a plethora of new ideas in this field, and large opportunities are still awaiting us.

Nanophotonics: Light-Matter interactions at the nanoscale

  We study light-matter interactions at the nanoscale, using novel nanomaterials (e.g. graphene and related 2D materials) and nanostructures (e.g. metallic or semiconductor resonators). Photonic nanostructures can enhance light-matter interactions by orders of magnitude, and often exhibit highly exceptional, unusual optical properties. Leveraged by these properties, we also design, fabricate, and demonstrate novel optical and optoelectronic devices.

Figure: Vertical collimation of colloidal quantum dot emission

Figure: Optical magnetic mirror made of resonant semiconductor cubes

  Mid-infared (Mid-IR) wavelengths refer to the region of 3~20 μm and are important for a number of applications, including chemical/biological sensing and thermal emission/detection. Properly designed plasmonic nanostructures can enhance infrared absorption by several orders of magnitude by giant light field enhancement in resonant metal nanostructures. Moreover, the resonance characteristics of plasmonic structures can be tailored to cover a wide range of infrared absorption. We design, fabricate, and test novel plasmonic structures (such as coupled plasmonic resonators and singular optic structures) to enhance sensitivity to an unprecedented level. We also explore compact, optoelectronic device structures for integrated sensing. 

Figure: Mid-infrared absorbance for several molecules which are important for industrial, environmental, and medical sensing applications (From Nanophotonics, DOI:10.1515/nanoph-2012-0027)

Optical Metamaterials: Artificially tailored electromagnetic structures

  Artificially tailored electromagnetic structures, called metamaterials, can exhibit exotic optical properties, and there has been significant interest in developing such structures in wide frequency ranges. Active tuning of metamaterials is emerging as a natural next step in this burgeoning field. We investigate various tuning mechanisms for this purpose. Especially, in the mid-IR, graphene or doped semiconductors (as well as typical noble metals, such as gold and silver) can be used as plasmonic materials. In these materials, plasmon resonance frequencies can be tuned by doping levels as well as geometric dimensions. Graphene and semiconductors are also easier to dynamically control optical properties by electric gating.  Using novel materials and structural designs, we perform exciting, new research at both fundamental and applied levels.

Figure: Active metamaterial devices based on semiconductor structures

Research Interests

Nanophotonics with novel nanomaterials and nanostructures

Plasmonics and Metamaterials
Semiconductor Optoelectronic devices, Integrated optics, and Sensors
Optical physics and devices in general
4D Printing and Programmable Matter