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Search Publications by: Alexander Yulaev (Assoc)

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Displaying 1 - 19 of 19

Scalable and robust beam shaping using apodized fish-bone grating couplers

November 20, 2023
Author(s)
Chad Ropp, Dhriti Maurya, Alexander Yulaev, Daron Westly, Gregory Simelgor, Vladimir Aksyuk
Efficient power coupling between guided and free-space optical modes requires precision spatial mode matching with apodized Bragg gratings. Yet, grating apodizations are often limited by the minimum feature size realizable by the fabrication approach

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

Exceptional points in lossy media lead to deep polynomial wave penetration with spatially uniform power loss

April 21, 2022
Author(s)
Alexander Yulaev, Sangsik Kim, Qing Li, Daron Westly, Brian Roxworthy, Kartik Srinivasan, Vladimir Aksyuk
Waves entering a spatially uniform lossy medium typically undergo exponential decay, arising from either the energy loss of the Beer–Lambert–Bouguer transmission law or the evanescent penetration during reflection. Recently, exceptional point singularities

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

Meta-grating outcouplers for optimized beam shaping in the visible

May 10, 2021
Author(s)
Chad Ropp, Alexander Yulaev, Daron Westly, Gregory Simelgor, Vladimir Aksyuk
Accurate coupling between optical modes at the interface between photonic chips and free space is required for the development of many on-chip devices. This control is critical in quantum technologies where large-diameter beams with designed mode profiles

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

Probing Electrified Liquid-Solid Interfaces with Scanning Electron Microscopy

December 2, 2020
Author(s)
Hongxuan Guo, Alexander Yulaev, Evgheni Strelcov, Alexander Tselev, Christopher M. Arble, Andras Vladar, John S. Villarrubia, Andrei Kolmakov
The mean free path of secondary electrons in aqueous solutions is on the order of a nanometer, making them a suitable probe of ultrathin electrical double layers at solid-liquid electrolyte interfaces. Employing graphene as an electron-transparent

Nanoscale mapping of the double layer potential at the graphene-electrolyte interface

January 28, 2020
Author(s)
Evgheni Strelcov, Christopher M. Arble, Hongxuan Guo, Brian D. Hoskins, Alexander Yulaev, Ivan Vlassiouk, Nikolai B. Zhitenev, Alexander Tselev, Andrei A. Kolmakov
The structure and potential drop across the electrical double layer (EDL) govern the operation of multiple electrochemical devices, determine reaction potentials and condition ion transport through the cellular membranes in living organisms. Despite more

In aqua electrochemistry probed by XPEEM: experimental setup, examples, and challenges

November 10, 2018
Author(s)
Slavomir Nemsak, Evgheni Strelcov, Hongxuan Guo, Brian Hoskins, Tomas Duchon, D Muller, Alexander Yulaev, Ivan Vlassiouk, Alexander Tselev, Andrei Kolmakov
Recent developments in environmental and liquid cells equipped with electron transparent graphene windows have enabled traditional surface science spectromicroscopy tools, such as XPS, PEEM, and SEM to be applied to study solid-liquid and liquid-gas

Photonic waveguide to free-space Gaussian beam extreme mode converter

October 10, 2018
Author(s)
Sangsik Kim, Daron Westly, Brian J. Roxworthy, Qing Li, Alexander Yulaev, Kartik Srinivasan, Vladimir Aksyuk
Integration of photonic chips with atomic, micromechanical, chemical and biological systems can advance science and open many possibilities in chip-scale devices and technology. Compact photonic structures for direct coupling of light between high-index

From Microparticles to Nanowires and Back: Radical Transformations in Plated Li Metal Morphology Revealed via in situ scanning electron microscopy

February 3, 2018
Author(s)
Alexander Yulaev, Vladimir P. Oleshko, Paul M. Haney, Jialin Liu, Yue Qi, Talin Alec, Leite Marina, Andrei A. Kolmakov
Li metal is the preferred anode material for all-solid-state Li batteries due to its high theoretical capacity and low voltage vs. standard hydrogen electrode. However, stable plating and stripping of Li metal in contact with a solid electrolyte at high

Interfacial Electrochemistry in Liquids Probed with Photoemission Electron Microscopy

December 20, 2017
Author(s)
Slavomir Nemsak, Evgheni Strelcov, Tomas Duchon, Hongxuan Guo, Johanna Hackl, Alexander Yulaev, Ivan Vlassiouk, David Mueller, Andrei Kolmakov
Studies of the electrified solid-liquid interfaces are crucial for understanding of the biological and electrochemical systems. Until recently, the use of photoemission electron microscopy (PEEM) for such purposes has been hampered by the in-compatibility

Graphene microcapsule arrays for combinatorial electron microscopy and spectroscopy in liquids

April 27, 2017
Author(s)
Alexander Yulaev, Hongxuan Guo, Evgheni Strelcov, Lei Chen, Ivan Vlasssiouk, Andrei Kolmakov
An atomic-scale thickness, molecular impermeability, low atomic number, and mechanical strength make graphene an ideal electron transparent membrane for scanning electron microscopy and spectroscopy in liquids. Here, we present a novel sample platform made

Enabling photoemission electron microscopy in liquids via graphene-capped microchannel arrays

February 8, 2017
Author(s)
Hongxuan Guo, Evgheni Strelcov, Alexander Yulaev, Jian Wang, Narayana Appathurai, Stephen Urquhart, John Vinson, Subin Sahu, Michael P. Zwolak, Andrei Kolmakov
Photoelectron emission microscopy (PEEM) is a powerful tool to spectroscopically access dynamic surface processes at the nanoscale but is traditionally limited to ultra-high or moderate vacuum conditions. Here, we develop a novel graphene-capped

Imaging and Analysis of Encapsulated Objects through Self-Assembled Electron and Optically Transparent Graphene Oxide Membrane

January 23, 2017
Author(s)
Alexander Yulaev, Alexey Lipatov, Annie Xi Lu, Alexander Sinitskii, Leite Marina, Andrei Kolmakov
We demonstrate a technique for facile adhesion and encapsulation of micro- and nano objects on arbitrary substrates, stencils, and micro structured surfaces by ultrathin graphene oxide membranes via a simple drop casting of graphene oxide solution. A

Toward Clean Suspended CVD Graphene

August 26, 2016
Author(s)
Alexander Yulaev, Guangjun Cheng, Angela R. Hight Walker, Ivan Vlassiouk, Alline Myers, Marina S. Leite, Andrei Kolmakov
The application of suspended graphene as electron transparent supporting media in electron microscopy, vacuum electronics, and micromechanical devices requires the least destructive and maximally clean transfer from their original growth substrate to the