EDUCATION:

Stanford University, Stanford, USA | Sept, 2015 – June, 2021

PhD Major: Electrical Engineering

Research area: Photonics

Thesis title: Photonic Design of Dielectric Laser Accelerators and Quantum Features of Free Electrons

PhD Minor: Physics

Tsinghua University, Beijing, China | Aug, 2011 – July, 2015

Bachelor of Electronic Engineering

University of California, Los Angeles, USA | July, 2014 – Sept, 2014

Student researcher in Cross-disciplinary Scholars in Science and Technology program

Monash University, Melbourne, Australia | July, 2013 – Nov, 2013

      Exchange student in the Department of Information Technology

PROFESSIONAL EXPERIENCE:

Reality Labs Research, Meta

Research Scientist in Optics and Display Research | July, 2021 – August, 2023

• Optics and waveguide design for transparent eyewear in Augmented Reality                    

IMEC

Integrated photonic circuit design internship | June, 2019 – Sept, 2019

• Designed and simulated integrated photonic transceiver components (e.g., grating couplers, echelle gratings) and circuits

• Contributed to the device library development of process design kits on silicon-nitride technology

• Developed a design toolbox for echelle gratings

RESEARCH EXPERIENCE:

Friedrich-Alexander-Universität Erlangen-Nürnberg, Department of Physics

Postdoctoral Researcher | Oct, 2023 – Present

          Advisor: Professor Peter Hommelhoff

• Free-electron light-matter interaction

Stanford University, Ginzton Lab and Department of Electrical Engineering

On-chip dielectric laser accelerator design and applications | Sept, 2016 – June, 2021

   Advisor: Professor Shanhui Fan, Professor Robert L. Byer

• Studied the quantum interaction between a free electron and a two-level atom and showed that resonantly modulating the free electron with optical field can enhance the electron-atom interaction

• Proposed an all-optical electron pulse compressor using optical beat notes

• Designed a multi-channel photonic crystal dielectric laser accelerator to increase electron throughput

• Designed a tapered slot waveguide dielectric laser accelerator for sub-relativistic electrons

• Contributed to the design and analysis of a fractal ‘tree-branch’ waveguide network functioning as an on-chip optical power delivery system for dielectric laser accelerators

• Analyzed the nonlinear effects in silicon-nitride weakly guided waveguides based on experimental measurements and nonlinear Schrodinger equation simulations

Theoretical study of the temporal coupled-mode theory for a resonant optical system | June, 2018 – Feb, 2019

   Advisor: Professor Shanhui Fan

• Developed the connection between the coupled-mode descriptions of a physical system and its time-reversal conjugate

• Systematically investigated the separate constraint by energy conservation, time-reversal symmetry, and reciprocity

Study the absorption and emission directivities for dipoles coupled with optical antennas | June, 2017 – June 2018

   Advisor: Professor Shanhui Fan

• Provided a proof of identical absorption and emission directivities for a reciprocal optical antenna coupled with a single dipole, based on the Green’s function approach

• Discussed unequal absorption and emission directivities for a reciprocal optical antenna coupled with multiple dipoles

Multi-function Electrodes in Solar Cells | Sept, 2015 – Dec, 2016

   Advisor: Professor Shanhui Fan

• Designed micro-structure conductive electrode to achieve anti-reflection simultaneously

• Introduced a generalized Fabry-Perot interference model to interpret numerical results of anti-reflection

University of California, Los Angeles, Integrated NanoMaterials Core Lab

Investigating optical properties of InAs/AlAsSb quantum dots for Intermediate Band Solar Cells | July – Oct, 2014

         CSST student, Mentor: Professor Diana L. Huffaker

• Experimentally studied temperature dependent photoluminescence of InAs/AlAsSb quantum dots

• Verified effects of strain compensation and stacking on InAs/AlAsSb quantum dots to demonstrate their potential for future intermediate band solar cells with high efficiency

HONORS AND AWARDS:

Robert H. Siemann Fellowship, Stanford University (2020)

Stanford Graduate Fellowship, Stanford University (2016)

Graduation with honors, Tsinghua University (2015) 

National Scholarship, Tsinghua University (2014)

First prize in the Challenge Cup, Tsinghua University (2013)

First prize, National Undergraduate Physics Competition (2012)

VOLUNTEER AND ACTIVITIES:

Stanford Splash volunteer teacher, Stanford University (2019)

Member of Outreach team, Stanford Optical Society, Stanford University (2019)

Co-President, Chinese Woman Collective at Stanford, Stanford University (2017 - 2018)

Vice president, Association of Charity, Tsinghua University (2013 - 2014)

PEER-REVIEWED PUBLICATION:

[30] Karnieli, Aviv, Shai Tsesses, Renwen Yu, Nicholas Rivera, Zhexin Zhao, Ady Arie, Shanhui Fan, and Ido Kaminer. "Quantum sensing of strongly coupled light-matter systems using free electrons." Science Advances 9, no. 1 (2023): eadd2349.

[29] Shiloh, Roy, Norbert Schönenberger, Yuval Adiv, Ron Ruimy, Aviv Karnieli, Tyler Hughes, R. Joel England, Kenneth J. Leedle, Dylan S. Black, Zhexin Zhao, Pietro Musumeci, Robert L. Byer, Ady Arie, Ido Kaminer, and Peter Hommelhoff. "Miniature light-driven nanophotonic electron acceleration and control." Advances in Optics and Photonics 14, no. 4 (2022): 862-932.

[28] Fan, Lingling, Zhexin Zhao, Kai Wang, Avik Dutt, Jiahui Wang, Siddharth Buddhiraju, Casey C. Wojcik, and Shanhui Fan. "Multidimensional Convolution Operation with Synthetic Frequency Dimensions in Photonics." Physical Review Applied 18, no. 3 (2022): 034088.

[27] Guo, Cheng, Zhexin Zhao, and Shanhui Fan. "Internal transformations and internal symmetries in linear photonic systems." Physical Review A 105, no. 2 (2022): 023509.

[26] Fan, Lingling, Zhexin Zhao, Weiliang Jin, Meir Orenstein, and Shanhui Fan. "Lineshape study of optical force spectra on resonant structures." Optics Express 30, no. 4 (2022): 6142-6160.

[25] Zhao, Zhexin, Kenneth J. Leedle, Dylan S. Black, Olav Solgaard, Robert L. Byer, and Shanhui Fan. "Electron pulse compression with optical beat note." Physical Review Letters 127, no. 16 (2021): 164802.

[24] Zhao, Zhexin, Xiao-Qi Sun, and Shanhui Fan. "Quantum entanglement and modulation enhancement of free-electron–bound-electron interaction." Physical Review Letters 126, no. 23 (2021): 233402.

[23] Zhao, Bo, Jiahui Wang, Zhexin Zhao, Cheng Guo, Zongfu Yu, and Shanhui Fan. "Nonreciprocal Thermal Emitters Using Metasurfaces with Multiple Diffraction Channels." Physical Review Applied 16, no. 6 (2021): 064001.

[22] Black, Dylan S., Zhexin Zhao, Kenneth J. Leedle, Yu Miao, Robert L. Byer, Shanhui Fan, and Olav Solgaard. "Operating modes of dual-grating dielectric laser accelerators." Physical Review Accelerators and Beams 23, no. 11 (2020): 114001.

[21] Zhao, Zhexin, and Shanhui Fan. "Design principles of apodized grating couplers." Journal of Lightwave Technology 38, no. 16 (2020): 4435-4446.

[20] Zhao, Zhexin, Dylan S. Black, Tyler W. Hughes, Yu Miao, Olav Solgaard, Robert L. Byer, and Shanhui Fan. "Design of a multi-channel photonic crystal dielectric laser accelerator." Photonics Research 8, no. 10 (2020): 1586-1598.

[19] Tan, Si, Huiyang Deng, Karel E. Urbanek, Yu Miao, Zhexin Zhao, James S. Harris, and Robert L. Byer. "Low-loss GaOx-core/SiO2-cladding planar waveguides on Si substrate." Optics Express 28, no. 8 (2020): 12475-12486.

[18] Fan, Lingling, Yu Guo, Georgia T. Papadakis, Bo Zhao, Zhexin Zhao, Siddharth Buddhiraju, Meir Orenstein, and Shanhui Fan. "Nonreciprocal radiative heat transfer between two planar bodies." Physical Review B 101, no. 8 (2020): 085407.

[17] Papadakis, Georgia T., Siddharth Buddhiraju, Zhexin Zhao, Bo Zhao, and Shanhui Fan. "Broadening near-field emission for performance enhancement in thermophotovoltaics." Nano Letters 20, no. 3 (2020): 1654-1661.

[16] Wang, Haiwen, Cheng Guo, Zhexin Zhao, and Shanhui Fan. "Compact incoherent image differentiation with nanophotonic structures." ACS Photonics 7, no. 2 (2020): 338-343.

[15] Miao, Yu, Dylan S. Black, Kenneth J. Leedle, Zhexin Zhao, Huiyang Deng, Andrew Ceballos, Robert L. Byer, James S. Harris, and Olav Solgaard. "Surface treatments of dielectric laser accelerators for increased laser-induced damage threshold." Optics Letters 45, no. 2 (2020): 391-394.

[14] Black, Dylan S., Uwe Niedermayer, Yu Miao, Zhexin Zhao, Olav Solgaard, Robert L. Byer, and Kenneth J. Leedle. "Net Acceleration and Direct Measurement of Attosecond Electron Pulses in a Silicon Dielectric Laser Accelerator." Physical Review Letters 123, no. 26 (2019): 264802.

[13] Chang, Chun-Chieh, Zhexin Zhao, Dongfang Li, Antoinette J. Taylor, Shanhui Fan, and Hou-Tong Chen. "Broadband Linear-to-Circular Polarization Conversion Enabled by Birefringent Off-Resonance Reflective Metasurfaces." Physical Review Letters 123, no. 23 (2019): 237401.

[12] Zhao, Bo, Yu Shi, Jiahui Wang, Zhexin Zhao, Nathan Zhao, and Shanhui Fan. "Near-complete violation of Kirchhoff’s law of thermal radiation with a 0.3 T magnetic field." Optics Letters 44, no. 17 (2019): 4203-4206.

[11] Zhao, Nathan Z., Ian AD Williamson, Zhexin Zhao, Salim Boutami, and Shanhui Fan. "Penetration depth reduction with plasmonic metafilms." ACS Photonics 6, no. 8 (2019): 2049-2055.

[10] Zhao, Zhexin, Cheng Guo, and Shanhui Fan. "Connection of temporal coupled-mode-theory formalisms for a resonant optical system and its time-reversal conjugate." Physical Review A 99, no. 3 (2019): 033839.

[9] Zhao, Nathan, Zhexin Zhao, Ian AD Williamson, Salim Boutami, Bo Zhao, and Shanhui Fan. "High reflection from a one-dimensional array of graphene nanoribbons." ACS Photonics 6, no. 2 (2019): 339-344.

[8] Tan, Si, Zhexin Zhao, Karel Urbanek, Tyler Hughes, Yun Jo Lee, Shanhui Fan, James S. Harris, and Robert L. Byer. "Silicon nitride waveguide as a power delivery component for on-chip dielectric laser accelerators." Optics Letters 44, no. 2 (2019): 335-338.

[7] Niedermayer, Uwe, Andreas Adelmann, S Bettoni, M Calvi, M Dehler, E Ferrari, F Frei, D Hauenstein, B Hermann, N Hiller, R Ischebeck, C Lombosi, E Prat, S Reiche, L Rivkin, R Aßmann, U Dorda, I Hartl, W Kuropka, F Lemery, B Marchetti, F Mayet, H Xuan, J Zhu, DS Black, PN Broaddus, RL Byer, A Ceballos, H Deng, S Fan, J Harris, T Hirano, TW Hughes, Y Jiang, T Langenstein, K Leedle, Y Miao, A Ody, A Pigott, N Sapra, O Solgaard, L Su, S Tan, J Vuckovic, K Yang, Z Zhao, O Boine-Frankenheim, T Egenolf, E Skär, D Cesar, P Musumeci, B Naranjo, J Rosenzweig, X Shen, B Cowan, RJ England, Z Huang, H Cankaya, M Fakhari, A Fallahi, FX Kärtner, T Feurer, P Hommelhoff, J Illmer, A Li, A Mittelbach, J McNeur, N Schönenberger, R Shiloh, A Tafel, P Yousefi, M Kozak, M Qi, YJ Lee, Y-C Huang, E Simakov. "Challenges in simulating beam dynamics of dielectric laser acceleration." International Journal of Modern Physics A 34, no. 36 (2019): 1942031.

[6] Zhao, Zhexin, Yu Shi, Kaifeng Chen, and Shanhui Fan. "Relation between absorption and emission directivities for dipoles coupled with optical antennas." Physical Review A 98, no. 1 (2018): 013845.

[5] Zhao, Zhexin, Tyler W. Hughes, Si Tan, Huiyang Deng, Neil Sapra, R. Joel England, Jelena Vuckovic, James S. Harris, Robert L. Byer, and Shanhui Fan. "Design of a tapered slot waveguide dielectric laser accelerator for sub-relativistic electrons." Optics Express 26, no. 18 (2018): 22801-22815.

[4] Hughes, Tyler W., Si Tan, Zhexin Zhao, Neil V. Sapra, Kenneth J. Leedle, Huiyang Deng, Yu Miao et al. "On-chip laser-power delivery system for dielectric laser accelerators." Physical Review Applied 9, no. 5 (2018): 054017.

[3] Wang, Jiahui, Yu Shi, Tyler Hughes, Zhexin Zhao, and Shanhui Fan. "Adjoint-based optimization of active nanophotonic devices." Optics Express 26, no. 3 (2018): 3236-3248.

[2] Zhao, Zhexin, Ken Xingze Wang, and Shanhui Fan. "Analysis of an anti-reflecting nanowire transparent electrode for solar cells." Journal of Applied Physics 121, no. 11 (2017): 113109.

[1] Zhao, Zhexin, Ramesh B Laghumavarapu, Paul J Simmonds, Haiming Ji, Diana L Huffaker, 'Photoluminescence study of the effect of strain compensation on InAs/AlAsSb quantum dots', Journal of Crystal Growth 425 (2015): 312-315.

CONFERENCE PROCEEDINGS:

[18] Z. Zhao, K. J. Leedle, D. S. Black, O. Solgaard, R. L. Byer, and S. Fan, "Electron Pulse Compression with Optical Beat Note," in Conference on Lasers and Electro-Optics, Technical Digest Series (Optica Publishing Group, 2022), paper SS2A.7.

[17] Fan, Lingling, Zhexin Zhao, Kai Wang, Avik Dutt, Jiahui Wang, Siddharth Buddhiraju, Casey C. Wojcik, and Shanhui Fan. "Achieving multi-dimensional convolutions in photonic frequency synthetic dimensions." In Frontiers in Optics, pp. JTu5B-40. Optica Publishing Group, 2022.

[16] Karnieli, Aviv, Shai Tsesses, Renwen Yu, Nicholas Rivera, Zhexin Zhao, Ady Arie, Shanhui Fan, and Ido Kaminer. "Probing strongly coupled light-matter interactions using quantum free electrons." In 2022 Conference on Lasers and Electro-Optics (CLEO), pp. 1-2. IEEE, 2022.

[15] Z. Zhao, X. Sun, and S. Fan, "Quantum entanglement and modulation enhancement of free-electron–bound-electron interaction," in Conference on Lasers and Electro-Optics, J. Kang, S. Tomasulo, I. Ilev, D. Müller, N. Litchinitser, S. Polyakov, V. Podolskiy, J. Nunn, C. Dorrer, T. Fortier, Q. Gan, and C. Saraceno, eds., OSA Technical Digest (Optica Publishing Group, 2021), paper FM3N.6.

[14] Z. Zhao and S. Fan, "Design principles of apodized grating couplers," in Conference on Lasers and Electro-Optics, J. Kang, S. Tomasulo, I. Ilev, D. Müller, N. Litchinitser, S. Polyakov, V. Podolskiy, J. Nunn, C. Dorrer, T. Fortier, Q. Gan, and C. Saraceno, eds., OSA Technical Digest (Optica Publishing Group, 2021), paper SM4C.1.

[13] Fan, Lingling, Zhexin Zhao, Weiliang Jin, Meir Orenstein, and Shanhui Fan. "Temporal coupled-mode theory for the line shape of the optical force spectrum." In Laser Science, pp. JW7A-104. Optical Society of America, 2021.

[12] Tan, Si, Huiyang Deng, Karel Urbanek, Yu Miao, Zhexin Zhao, James S. Harris, and Robert L. Byer. "Low loss Gallium Oxide core/Silica cladding planar waveguide." In CLEO: Science and Innovations, pp. STh2H-8. Optical Society of America, 2021.

[11] Z. Zhao, S. Tan, K. Urbanek, T. Hughes, Y. J. Lee, S. Fan, J. S. Harris, and R. L. Byer, "Silicon nitride waveguide as a power delivery component for dielectric laser accelerators," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optica Publishing Group, 2020), paper STu4O.6.

[10] Z. Zhao, D. S. Black, R. J. England, T. W. Hughes, Y. Miao, O. Solgaard, R. L. Byer, and S. Fan, "Design of a multi-channel photonic crystal dielectric laser accelerator," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optica Publishing Group, 2020), paper SM3J.4.

[9] Wang, Haiwen, Cheng Guo, Zhexin Zhao, and Shanhui Fan. "Compact incoherent image differentiation with nanophotonic structures." In Metamaterials, Metadevices, and Metasystems 2020, vol. 11460, p. 114602E. SPIE, 2020.

[8] Zhao, Nathan, Ian AD Williamson, Zhexin Zhao, Salim Boutami, and Shanhui Fan. "Penetration Depth Engineering in Plasmonic Metafilms for Enhanced Reflection and Confinement." In 2020 Conference on Lasers and Electro-Optics (CLEO), pp. 1-2. IEEE, 2020.

[7] Li, Dongfang, Chun-Chieh Chang, Zhexin Zhao, Antoinette J. Taylor, Shanhui Fan, and Hou-Tong Chen. "Broadband linear-to-circular polarization conversion enabled by birefringent reflective metasurfaces." In 2020 Conference on Lasers and Electro-Optics (CLEO), pp. 1-2. IEEE, 2020.

[6] Li, Dongfang, Chun-Chieh Chang, Zhexin Zhao, Antoinette Taylor, Shanhui Fan, and Hou-Tong Chen. "Broadband Linear-to-Circular Polarization Conversion Enabled by Birefringent Off-Resonance Reflective Metasurfaces." Bulletin of the American Physical Society 65 (2020).

[5] Fan, Lingling, Yu Guo, Georgia T. Papadakis, Bo Zhao, Zhexin Zhao, Siddharth Buddhiraju, Meir Orenstein, and Shanhui Fan. "Nonreciprocal radiative heat transfer between two planar bodies." In CLEO: QELS_Fundamental Science, pp. FF1F-3. Optical Society of America, 2020.

[4] Z. Zhao, T. W. Hughes, S. Tan, H. Deng, N. Sapra, R. J. England, J. Vuckovic, J. S. Harris, R. L. Byer, and S. Fan, "Design of a tapered slot waveguide dielectric laser accelerator for sub-relativistic electrons," in Conference on Lasers and Electro-Optics, OSA Technical Digest (Optica Publishing Group, 2019), paper SF2H.7.

[3] Wang, Jiahui, Yu Shi, Tyler Hughes, Zhexin Zhao, and Shanhui Fan. "Adjoint-based optimization of active nanophotonic devices." In CLEO: Science and Innovations, pp. SW4J-5. Optical Society of America, 2019.

[2] Zhao, Nathan, Zhexin Zhao, Ian AD Williamson, Salim Boutami, Bo Zhao, and Shanhui Fan. "High Reflection from a One-Dimensional Array of Graphene Nanoribbons." In CLEO: QELS_Fundamental Science, pp. FF2A-1. Optica Publishing Group, 2019.

[1] Z. Zhao, K. X. Wang, and S. Fan, "Analysis of an Anti-reflecting Nanowire Transparent Electrode for Solar Cells," in Conference on Lasers and Electro-Optics, OSA Technical Digest (online) (Optica Publishing Group, 2018), paper AW3O.6.