Prof. Dr. Yasha Yi
ECE and Energy Institute, University of Michigan, Dearborn&Ann Arbor, MI, USA
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Academic Career Length
13Years (2014-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications13 September 2016 in Nano-Micro Letters
Journal Article
ZYZhi Yang
Zhi YangZLZhaohui Li
Zhaohui Li
XLXuxing Lu
Xuxing Lu
FHFengjiao He
Fengjiao He
XZXingzhong Zhu
Xingzhong ZhuYasha Yi +4
Biosynthesis of gold nanostructures has drawn increasing concerns because of its green and sustainable synthetic process. However, biosynthesis of gold nan
5 January 2015 in Optics Express
Journal Article
Linhan LinYasha YiHeight induced coupling behavior between the plasmonic modes and diffraction orders were studied in the core-shell SiO2/Au nanocylinder arrays (NCAs) using finite difference time domain (FDTD) simulations. New lattice plasmon modes (LPMs) are observed in the structures with high aspect ratio. Specifically, parallel coupling between the plasmonic modes and diffraction orders is obtained here, which shows different coupling behavior from orthogonal LPMs. Electromagnetic (EM) field distributions indicate that horizontal propagation of the magnetic or electric field component is responsible for the generation of these orthogonal and parallel LPMs, respectively. Radiative loss could be effectively suppressed when the height increases. This is important for the applications of fluorescence enhancement and nano laser. Further studies confirm that the LPMs associated with the superstrate diffraction orders could be well maintained even when the Au coating is imperfect. The interference from the substrate associated LPMs could be eliminated by cutting off the corresponding diffraction waves by inducing a Si3N4 substrate. This study of coupling behavior in the core-shell NCAs enables a novel route to design and optimize the LPMs for applications of bio-sensing and nano laser.
Journal Article
Yasha YiDWDachuan Wu
Dachuan WuVKVenus Kakdarvishi
Venus KakdarvishiBYBowen Yu
Bowen YuYZYating Zhuang
Yating Zhuang
AKAlireza Khalilian
Alireza KhalilianOptical phased arrays (OPAs) are renowned for their exceptional ability to manipulate and direct light beams, positioning them as an ideal choice for solid-state light detection and ranging (LiDAR) technologies. This review provides a comprehensive examination of the current research landscape for photonic integrated circuit (PIC)-based OPAs. It begins by addressing the critical design elements at the component level necessary for optimal functionality. This review then delves into phase calibration techniques and the overarching architecture of OPAs. It concludes by emphasizing the innovative 3-D OPA design, which stands out for its enhanced optical efficiency.
14 February 2019 in Optical Materials Express
Journal Article
In this work, high performance subwavelength grating metalens is demonstrated with high-refractive-index silicon-rich silicon nitride material compatible with CMOS fabrication processes. Conventional metalens materials namely TiO2 and GaN require expensive and time-consuming deposition processes such as atomic layer deposition (ALD) and metal-organic chemical vapor deposition (MOCVD). In order to improve the cost efficiency of metalens and its performance, the trade-offs between refractive index, fabrication difficulty and metalens performance is studied. We propose a feasible approach that is silicon-rich nitride (SiNx) as metalens material, which balance the trade-offs between refractive index and fabrication difficulty to large extent. With the advantage of ultra-high refractive index SiNx (n = 2.74) at 685 nm incidence, we are able to shrink the pitch size to unprecedented 220 nm. A propagation-phase-based grating metalens is fabricated and characterized for proof of concept. In addition, the optical parameters (n & k) can easily be adjusted through the deposition process. Our work has also promised a new degree of freedom for future optimization of metalens.
9 April 2018 in IEEE Photonics Technology Letters
Journal Article
One of the major challenges for emerging planar subwavelength micro lens is the significant chromatic behavior due to phase mismatch of subwavelength phase shifters. In this letter, the achromatic micro grating lens covering the whole visible wavelength is demonstrated by utilizing relatively low index contrast gratings. Based on the unique chromatic phase shift behavior of polymer nanostructure, we have designed and fabricated a broadband subwavelength achromatic microlens that can cover 250 nm of visible bandwidths (from 435 to 685 nm) with focal shift less than 5%. Our works also represent the first time to design, fabricate, and characterize micrograting lens ($7~\mu$ m in size) promising for compact integrated nanophotonic devices on chip. In addition, there are more advantages of using a polymer-based microlens, such as easy fabrication on flexible substrate and potential applications, including imaging, spectroscopy, lithography, laser fabrication, and future integrated wearable devices.
4 March 2020 in Applied Optics
Journal Article
Beam-steering devices such as optical phased arrays (OPAs) are key components in the applications of solid-state Lidar and wireless communication. The traditional single-layer OPA results in a significant energy loss due to substrate leakage caused by the downward coupling from the grating coupler structure. In this work, we have investigated a structure based on a multi-layer platform that can form a 3D OPA to emit light from the edge of the device with high efficiency; a 2D converged out-coupling beam will be end-fired to the air. High efficiency and wide horizontal beam steering are demonstrated numerically, and the influence of vertical crosstalk, delay length, and number of waveguide layers are discussed, as well as the fabrication feasibility.
About Me
Yasha Yi (Fellow of the Optical Society of America and Full Professor). Dr. Yi is currently a Fellow of the Optical Society of America and a Full Professor of Electrical Engineering. He was the Founding EECE PhD program chair at the University of Michigan, Dearborn campus and Energy Institute, University of Michigan, Ann Arbor campus. He received a Ph.D. degree from the Massachusetts Institute of Technology (MIT), Cambridge, MA, USA, and was a Post-Doctoral Associate with the MicroPhotonics Center, Massachusetts Institute of Technology, Cambridge, MA, USA, where he was involved in research on integrated nano optoelectronic devices and systems. He has extensive research experience with the Los Alamos National Laboratory and the 3M Corporate Research Laboratory. He is also a Professor Affiliate with the Microsystems Technology Laboratory at MIT. He has authored more than hundreds of top journal papers, edited four book/book chapters, and holds 31 issued patents (15 U.S. patents and 16 international patents). He has led several government/industry-funded projects, has been on review panels for NSF, DOE, and DOD, and has been a reviewer for leading journals. His research interests are silicon photonics chip, artificial intelligence chips; renewable energy; smart chip sensors; VR/AR display chips; chip-scale lidar for autonomous driving/UAVs/robotics; telecommunications; solid-state lighting; integrated quantum photonics.