U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by:

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 1 - 25 of 53

Impact of fin aspect ratio on enhancement of external quantum efficiency in single AlGaN fin light-emitting diodes pixels

June 26, 2023
Author(s)
Babak Nikoobakht, Yuqin Zong, Okan Koksal, Amit Agrawal, Christopher B. Montgomery, Jacob Leach, Michael Shur
Previously, we showed within a sub-micron fin shape heterojunction, as current density increases, the non-radiative Auger recombination saturates mediated by the extension of the depletion region into the fin, resulting in a droop-free behavior. In this

Integrating planar photonics for multi-beam generation and atomic clock packaging on chip

April 3, 2023
Author(s)
Chad Ropp, Wenqi Zhu, Alexander Yulaev, Daron Westly, Gregory Simelgor, Akash Rakholia, William Lunden, Dan Sheredy, Martin Boyd, Scott Papp, Amit Agrawal, Vladimir Aksyuk
The commercialization of atomic technologies requires replacing laboratory-scale laser setups with compact and manufacturable optical platforms. Complex arrangements of free-space beams can be generated on chip through a combination of integrated photonics

Synthesizing ultrafast optical pulses with arbitrary spatiotemporal control

October 26, 2022
Author(s)
Lu Chen, Wenqi Zhu, Pengcheng Huo, Junyeob Song, Henri Lezec, Ting Xu, Amit Agrawal
The ability to control the instantaneous state of light – its phase, amplitude, polarization, or wavefront – of high-energy pulses down to the single-photon level is an indispensable and a necessary requirement in photonics. This has, for example

Broadband Nanoscale Surface-Enhanced Raman Spectroscopy by Multiresonant Nanolaminate Plasmonic Nanocavities on Vertical Nanopillars

August 8, 2022
Author(s)
Meitong Nie, Yuming Zhao, Wonil Nam, Junyeob Song, Wenqi Zhu, Henri Lezec, Amit Agrawal, Wei Zhou
Surface-enhanced Raman spectroscopy (SERS) has become a sensitive detection technique for biochemical analysis. Despite significant research efforts, most SERS substrates consisting of single-resonant plasmonic nanostructures on the planar surface suffer

Single-atom trapping in a metasurface-lens optical tweezer

August 1, 2022
Author(s)
Ting-Wei Hsu, Wenqi Zhu, Tobias Thiele, Mark Brown, Scott Papp, Amit Agrawal, Cindy Regal
Single neutral atoms in optical tweezers have become an important platform for quantum simulation, computing, and metrology [1-3]. With ground-up control similar to trapped ions, individual atoms can be prepared and entangled [2, 4, 5], and the scalability

Metasurface on integrated photonic platform: from mode converters to machine learning

July 20, 2022
Author(s)
Zi Wang, Yahui Xiao, Kun Liao, Tiantian Li, Hao Song, Haoshuo Chen, S M Zia Uddin, Dun Mao, Feifan Wang, Zhiping Zhou, Bo Yuan, Wei Jiang, Nikolas Fontaine, Amit Agrawal, Alan Willner, Xiaoyong Yu, Tingyi Gu
Integrated photonic circuits are created as a small form factor and robust analogue for fiber-based optical systems, from wavelength-division multiplication transceivers to more recent mode-division multiplex-ing components. Silicon nanowire waveguides

ZnO fin optical cavities

June 16, 2022
Author(s)
Babak Nikoobakht, Amit Agrawal, Scott A. Wight, Jonathan Lee, Michael Shur
Nanostructured semiconductors have shown great promise toward miniaturization of electrically driven semiconductor lasers. Previously, we reported on an electrically driven sub-micron size ZnO-GaN fin LED architecture that at high current densities showed

Full-Stokes polarimetry for visible light enabled by an all-dielectric metasurface

February 20, 2022
Author(s)
Yongze Ren, Shihao Guo, Wenqi Zhu, Pengcheng Huo, Sijia Liu, Song Zhang, Peng Chen, Lu Chen, Henri Lezec, Amit Agrawal, Yanqing Lu, Ting Xu
Decoding arbitrary polarization information from an optical field has triggered unprecedented endeavors in polarization imaging, remote sensing and information processing. Therefore, developing a polarization detection device with full on-chip integration

Generation of perfect vortex beams by dielectric geometric metasurface for visible light

October 31, 2021
Author(s)
Qianwei Zhou, Mingze Liu, Wenqi Zhu, Lu Chen, Yongze Ren, Henri Lezec, Yanqing Lu, Ting Xu, Amit Agrawal
Perfect vortex beam (PVB) is a propagating optical field carrying orbital angular momentum (OAM) with a radial intensity profile that is independent of topological charge. PVB can be generated through the Fourier transform of a Bessel-Gaussian beam, which

Interfacing Photonics to Free-Space via Large-area Inverse-designed Diffraction Elements and Metasurfaces

June 6, 2021
Author(s)
Alexander Yulaev, Wenqi Zhu, Chad Ropp, Daron Westly, Gregory Simelgor, Cheng Zhang, Henri Lezec, Amit Agrawal, Vladimir Aksyuk
Large-area inverse-designed photonic gratings and optical metasurfaces directly couple waveguides to wide free-space modes with custom wavefronts and polarizations in the visible and near-infrared. Design, modeling methods and experimental results are

Multifunctional metasurfaces enabled by simultaneous and independent control of phase and amplitude for orthogonal polarization states

May 25, 2021
Author(s)
Mingze Liu, Wenqi Zhu, Pengcheng Huo, Lei Feng, Maowen Song, Cheng Zhang, Lu Chen, Henri Lezec, Yanqing Lu, Amit Agrawal, Ting Xu
Monochromatic light can be characterized by its three fundamental properties: amplitude, phase and polarization. In this work, we propose a versatile, transmission-mode all-dielectric metasurface platform that can independently manipulate the phase and

Broadband generation of perfect Poincare beams via dielectric spin-multiplexed metasurface

April 13, 2021
Author(s)
Mingze Liu, Pengcheng Huo, Wenqi Zhu, Cheng Zhang, Si Zhang, Maowen Song, Song Zhang, Qianwei Zhou, Lu Chen, Henri Lezec, Amit Agrawal, Yanqing Lu, Ting Xu
Poincaré beam, which describes the space-variant polarization of a light beam carrying spin angular momentum (SAM) and orbital angular momentum (OAM), plays an important role in various optical applications. Since the radius of a Poincaré beam depends on

Magneto-optical trapping using planar optics

January 29, 2021
Author(s)
William McGehee, Wenqi Zhu, Daniel Barker, Daron Westly, Alexander Yulaev, Nikolai Klimov, Amit Agrawal, Stephen Eckel, Vladimir Aksyuk, Jabez J. McClelland
Laser-cooled atoms are a key component of many calibration-free measurement platforms— including clocks, gyroscopes, and gravimeters—and are a promising technology for quantum networking and quantum computing. The optics and vacuum hardware required to

Independent Amplitude Control of Arbitrary Orthogonal States of Polarization via Dielectric Metasurfaces

December 23, 2020
Author(s)
Qingbin Fan, Mingze Liu, Cheng Zhang, Wenqi Zhu, Yilin Wang, Peicheng Lin, Feng Yan, Lu Chen, Henri Lezec, Yanqing Lu, Amit Agrawal, Ting Xu
Exquisite polarization control using optical metasurfaces has attracted considerable attention thanks to their ability to manipulate multichannel independent wavefronts with subwavelength resolution. Here we present a new class of metasurface polarization

Endothermic reaction at room temperature enabled by deep-ultraviolet plasmons

November 2, 2020
Author(s)
Canhui Wang, Wei-Chang Yang, David Raciti, Alina Bruma, Ronald Marx, Amit Agrawal, Renu Sharma
Sequestration and conversion of CO2 is a promising method for remedying climate change. However, current technologies remain limited due to infeasible system demands and outputs, such as high-temperature/pressure conditions, use of precious metals, or low

Plasmonic Electronic Raman Scattering as Internal Standard for Spatial and Temporal Calibration in Quantitative Surface-enhanced Raman Spectroscopy

October 28, 2020
Author(s)
Wonil Nam, Yuming Zhao, Junyeob Song, Seied Ali Safiabadi Tali, Seju Kang, Wenqi Zhu, Henri Lezec, Amit Agrawal, Peter J. Vikesland, Wei Zhou
Ultrasensitive surface-enhanced Raman spectroscopy (SERS) still faces difficulties in quantitative analysis because of its susceptibility to local optical field variations at plasmonic hotspots in metallo-dielectric nanostructures. Current SERS calibration

Scalable microresonators for room-temperature detection of electron spin resonance from dilute, sub-nanoliter volume solids

October 28, 2020
Author(s)

Nandita S. Abhyankar, Amit K. Agrawal, Pragya R. Shrestha, Russell A. Maier, Robert D. McMichael, Jason P. Campbell, Veronika A. Szalai

Microresonators used for spin detection in volume-limited samples suffer from poor quality factors, which adversely affect sensitivity and ease of coupling to the microwave source. Here we adapt a metamaterial design with toroidal moment to confine

Photorealistic full-color nanopainting enabled by a low-loss metasurface

September 4, 2020
Author(s)
Pengcheng Huo, Maowen Song, Wenqi Zhu, Cheng Zhang, Lu Chen, Henri Lezec, Yanqing Lu, Amit Agrawal, Ting Xu
We design and experimentally demonstrate a TiO2 metasurface that enables full-color generation and ultrasmooth color brightness variations. The reproduced famous artwork "girl with a pearl earring" features photorealistic color representation and

Plasmon Lasers

August 26, 2020
Author(s)
Wenqi Zhu, Shawn M. Divitt, Matthew S. Davis, Cheng Zhang, Ting Xu, Henri Lezec, Amit Agrawal
Recent advancements in the ability to design, fabricate and characterize optical and optoelectronic devices at the nanometer scale have led to tremendous developments in the miniaturization of optical systems and circuits. Development of wavelength scale