Research Accomplishments

06/2010 - 07/2014:
Yale Nanodevices Laboratory (Supervisor: Prof. Hong Tang), Department of Electrical Engineering, Yale University

• Cavity nano-optomechanics
  • proposal and first experimental demonstration of a wavelength-sized optomechanical disk resonator embedded in a surrounding photonic crystal. This structure holds three world records: high vibrational frequency of its fundamental mechanical mode (2.2 GHz), high optical quality factor (~1 million, which is near an order of magnitude higher than prior best demonstrations), and high displacement sensitivity (~6 am/√Hz)
  • first demonstration of a "NEMS-in-cavity," the world's smallest optomechanical system operating at 1.0 GHz with a record low mechanical modal mass ~20 fg
  • first development of wheel- and disk-shaped Si integrated optomechanical resonators operating up to 1.8 GHz with record high mechanical Q factors (~4000) in air at room temperature
  • first development of AlN optomechanical resonators and demonstration of high mechanical Q at microwave frequencies in air at room temperature
• Nonlinear photonics
  • development of AlN photonics on Si substrates and demonstration of efficient electro-optic modulation and second-harmonic generation with AlN's second-order nonlinearities
  • first experimental investigation of optical nonlinear effects in ultrahigh-Q Si nanocavities in superfluid helium environment and investigation of the exotic blue-shifted bistability phenomenon
• Applications of photonic crystals in cavity optomechanics
  • invention and optimization of a high-Q photonic crystal nanocavity with incorporated nanosized mechanical resonator, leading to the first demonstration of a "NEMS-in-cavity"
  • first demonstration of optomechanical transduction and multiplexing of femtogram-mass nanocantilevers by high-Q bandedge states of a slow-light photonic crystal waveguide
  • first realization of a piezo-acousto-photonic crystal nanocavity in AlN where the photonic and acoustic modes are highly colocalized for strong interaction
• Micro/nanoelectromechanical systems (MEMS/NEMS)
  • first development of microwave nano-optoelectromechanical systems where the mechanical modes with frequencies up to 4.2 GHz are efficiently actuated by electrocapacitive or piezoelectric drive and read out by sensitive optical transduction
• Cryogenic nanophotonics and nano-optomechanics
  • first experimental investigation of the exotic optical and mechanical properties of nanophotonic cavities and nano-optomechanical resonators in superfluid helium environment

09/2004 - 06/2010:
Optical & Quantum Electronics Laboratory (Advisor: Prof. Amnon Yariv), Department of Applied Physics, California Institute of Technology

• Hybrid Si/III-V integrated optoelectronic devices and circuits
  • development of a hybrid integration platform of Si and InGaAsP for Si-based active photonics and demonstration of electrically pumped, low-threshold, high-power Si/InGaAsP hybrid lasers on Si substrates
  • proposal and demonstration of a modal control scheme to significantly enhance the modal gain and boost the operation efficiency of the Si/III-V integrated photonic circuitry
  • first theoretical investigation of the shortest adiabatic taper (mode transformer) in a coupled-waveguide system
• Electrically pumped, large-area, single-mode, two-dimensional photonic crystal Bragg lasers
  • first demonstration of room-temperature, continuous-wave lasing operation with single-mode, high-power edge emission
  • spatial and spectral modal control of two-dimensional photonic crystal Bragg lasers
• Theoretical analysis and calculation of surface-emitting chirped circular grating lasers
  • analytical calculation of threshold, output power, mode profiles and proposal of optimal designs
  • unification of theoretical treatment of several types of circular grating lasers: circular DFB, disk-, and ring- Bragg resonator lasers
  • above-threshold analysis: nonuniform pumping, far-field patterns, modal selectivity, gain saturation effects, and design considerations
• Ultralow-loss integrated photonic delay
  • theoretical modeling and analysis of scattering losses of step- and parabolic-index waveguides
  • theoretical derivation and numerical simulation of losses in waveguide bends
  • ultralow-loss curved waveguide path design

09/2002 - 07/2004:
ZnO Lab Group (Advisor: Prof. Zhuxi Fu), Department of Physics, University of Science and Technology of China

• Growth, characterization, and device fabrication of heteroepitaxial ZnO films on Si substrates
  • MOCVD growth and characterization of high-quality ZnO films on Si substrates with SiC buffer layers
  • sol-gel preparation and properties of ZnO films on Si substrates
  • bachelor thesis: Studies on the strain and optical properties of heteroepitaxial ZnO films prepared by low-pressure MOCVD (awarded Outstanding Bachelor Thesis of USTC in 2004)