Geun Ho Ahn (안근호)

I am a postdoctoral researcher at Stanford University, specializing in integrated photonics, material sciences, and computational optimization to develop innovative photonic-electronic systems for optical interconnects, metrology, and quantum science.

I earned my Ph.D. in Electrical Engineering from Stanford University, where I worked with Professor Jelena Vuckovic as a SGF fellow and FMA fellow on integrated photonics system through heterogeneous integration and photonic inverse design.

I completed my B.S. in EECS from UC Berkeley, where I worked with Professor Ali Javey as a Haas Scholar on optoelectronics and optical material synthesis.

I have served as a teaching assistant/co-lecturer in EE and MSE Departments at Stanford University. For this, I was awarded James F. Gibbons Award, (EE departmental teaching award).

I was born in Ulsan, South Korea, and I spent my formative years in Prague, Czechia.

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  News
Selected Publications
sym Unified laser stabilization and isolation on a silicon chip
Alexander D. White*, Geun Ho Ahn*, Richard Luhtaru, Joel Guo, Theodore J. Morin, Abhi Saxena, Lin Chang, Arka Majumdar, Kasper Van Gasse, John E. Bowers, Jelena Vučković. [*] equal contributions.
arXiv, 2024.

A fully passive and unified approach to simultaneously isolate and stabilize on-chip laser systems through nonlinear integrated photonics.

sym Platform-agnostic waveguide integration of high-speed photodetectors with evaporated tellurium thin films
Geun Ho Ahn*, Alexander D. White*, Hyungjin Kim*, Naoki Higashitarumizu, Felix M. Mayor, Jason F. Herrmann, Wentao Jiang, Kevin K. S. Multani, Amir H. Safavi-Naeini, Ali Javey, Jelena Vučković. [*] equal contributions.
Optica, 2023.

A simple lithographically defined, thermal evaporation of semiconducting tellurium thin film allows for high-speed integrated photodetectors (> 40GHz) on novel photonic platforms that otherwise lack electrical readouts without any complex fabrication processes.

sym Integrated Passive Nonlinear Optical Isolators
Alexander D. White*, Geun Ho Ahn*, Kasper Van Gasse, Ki Youl Yang, Lin Chang, John E. Bowers, Jelena Vučković. [*] equal contributions.
Nature Photonics, 2022.

Highlighted by Stanford News / Stanford Engineering / Phys.org / optics.org

Integrated optical isolator without any external drive can be made to protect on-chip laser systems using optical nonlinear Kerr-effect in CMOS-ready thin film silicon nitride platforms
sym Photonic Inverse Design of On-Chip Microresonators
Geun Ho Ahn, Ki Youl Yang, Rahul Trivedi, Alexander D. White, Logan Su, Jinhie Skarda, Jelena Vučković
ACS Photonics, 2022.

Computational optimization aided design approach can generalize on-chip resonator design processes to enable new functionalities such as wide dispersion engineering, high optical quality factor, and more.

sym Synthetic WSe2 monolayers with high photoluminescence quantum yield
Hyungjin Kim*, Geun Ho Ahn*, Joy Cho, Matin Amani, James P. Mastandre, Catherine K. Groschner, Der-Hsien Lien, Yingbo Zhao, Joel W. Ager III, Mary C. Scott, Daryl C. Chrzan, & Ali Javey.
Science Advances, 2019.

Large scale synthetic monolayer films can demonstrate much higher quantum yield than mechanically exfoliated counterparts, if grown properly.

sym Strain-engineered growth of two-dimensional materials
Geun Ho Ahn*, Matin Amani*, Haider Rasool, Der-Hsien Lien, James P. Mastandrea, Joel W. Ager III, Madan Dubey, Daryl C. Chrzan, Andrew M. Minor & Ali Javey.
Nature Communications, 2017.

Highlighted by U.S. Department of Energy / Lawrence Berkeley Laboratory / phys.org

Engineering the intrinsic van der waal interaction between the electronic substrate and two dimentional materials for built-in strain tunability via large scale growth.

Full Publication List
  1. G. H. Ahn*, A. D. White*, H. Kim*, N. Higashitarumizu, F. M. Mayor, J. F. Herrmann, W. Jiang, K. KS Multani, A. H. Safavi-Naeini, A. Javey, J. Vuckovic. "Platform-agnostic waveguide integration of high-speed photodetectors with evaporated tellurium thin films", arXiv:2209.04034. 2022. [*] These authors contribute equally to this work
  2. A. D. White*, G. H. Ahn*, K. V. Gasse, K. Y. Yang, L. Chang, J. E. Bowers, J. Vuckovic. "Integrated Passive Nonlinear Optical Isolators", Nature Photonics in press [*] These authors contribute equally to this work
  3. H. Batiz, J. Guo, G. H. Ahn, H. Kim, A. Javey, J. W. Ager, D. C. Chrzan"Theory of liquid-mediated strain release in two-dimensional materials", Physical Review Materials 6 (5), 054005, 2022.
  4. G. H. Ahn, K. Y. Yang, R. Trivedi, A. D. White, L. Su, J. Skarda, J. Vuckovic. "Photonic Inverse Design of On-Chip Microresonators ", ACS Photonics 2022.
  5. J. Skarda, G. H. Ahn, R. Trivedi, T. Wu, S. Mitra, J. Vuckovic. "Inverse-Design for High-Performance Computing Photonics in Silicon Photonics for High-Performance Computing and Beyond", CRC Press. 159-176, 2021.
  6. K. Y. Yang, J. Skarda, M. Cotrufo, A. Dutt, G. H. Ahn, M. Sawaby, D. Vercruysse, A. Arbabian, S. Fan, A. Alu, J. Vuckovic. "Inverse-designed non-reciprocal pulse router for chip-based LiDAR", Nature Photonics 14 (6), 369-374, 2020.
  7. A. J. Goodman, D.-H. Lien, G. H. Ahn, L.L. Spiegel, M. Amani, A.P. Willard, A. Javey, W. A. Tisdale. "Substrate-Dependent Exciton Diffusion and Annihilation in Chemically Treated MoS2 and WS2", The Journal of Physical Chemistry C, 2020.
  8. D. M. Lukin, C. Dory, M. A. Guidry, K. Y. Yang, S. D. Mishra, R. Trivedi, M. Radulaski, S. Sun, D. Vercruysse, G. H. Ahn, J. Vuckovic "4H-silicon-carbide-on- insulator for integrated quantum and nonlinear photonics", Nature Photonic 14 (5), 330-334, 2020
  9. A. Y. Piggott, E. Y. Ma, L. Su, G. H. Ahn, N. V. Sapra, D. Vercruysse, A. M. Netherton, A. Khope, J. E. Bowers, J. Vuckovic "Inverse-designed photonics for semiconductor foundries", ACS Photonics 7 (3), 569-575, 2020
  10. P. Zhao, R. Wang, D.-H. Lien, Y. Zhao, H. Kim, J. Cho, G. H. Ahn, A. Javey, "Scanning probe lithography patterning of monolayer semiconductors and application in quantifying edge recombination", Advanced Materials, 31 (48), 1900136, 2019
  11. J. Pak, I. Lee, K. Cho, J. K. Kim, H. Jeong, W. T. Hwang, G. H. Ahn, K. Kang, W. J. Yu, A. Javey, S. Chung, T. Lee, "Intrinsic optoelectronic Characteristics of MoS2 Phototransistors via Fully Transparent van der Waals Heterostructure", ACS Nano, 13 (8), 9638-9646, 2019
  12. K. Han, G. H. Ahn, J. Cho, D.-H. Lien, M. Amani, S. B. Desai, G. Zhang, H. Kim, N. Gupta, A. Javey, M. C. Wu, "Bright electroluminescence in ambient conditions from WSe2 p-n diodes using pulsed injection", Applied Physics Letters, 115, 011103, 2019.
  13. H. Kim*, G. H. Ahn*, J. Cho, M. Amani, J. P. Mastandrea, C. K. Groschner, D.-H. Lien, Y.Zhao, J. W. Ager, M. C. Scott, D. C. Chrzan, A. Javey, "Synthetic WSe2 monolayers with high photoluminescence quantum yield”, Science Advances, 5, eaau4728, 2019. [*] These authors contribute equally to this work
  14. D. Yoo, Y. Kim, M. Min, G. H. Ahn, D.-H. Lien, J. Jang, H. Jeong, Y. Song, S. Chung, A. Javey, T. Lee, "Highly reliable superhydrophobic protection for organic field-effect transistors by fluoroalkylsilane-coated TiO2 nanoparticles", ACS Nano, 12, 11062-11069, 2018.
  15. J. Bullock, M. Amani, J. Cho, Y.-Z. Chen, G. H. Ahn, V. Adinolfi, V. R. Shrestha, Y. Gao, K. B. Crozier, Y.-L. Chueh, A. Javey, "Polarization-resolved black phosphorus/molybdenum disulfide mid-wave infrared photodiodes with high detectivity at room temperature", Nature Photonics, 12, 601–607, 2018.
  16. D.-H. Lien, M. Amani, S. B. Desai, G. H. Ahn, K. Han, J.-H. He, J. W. Ager III, M. C. Wu, A. Javey, "Large-area and bright pulsed electroluminescence in monolayer semiconductor", Nature Communications, 9, 1229, 2018.
  17. M. Amani, E. Regan, J. Bullock, G. H. Ahn, A. Javey, "Mid-Wave Infrared Photoconductors Based on Black Phosphorous-Arsenic Alloys", ACS Nano, 11 (11), 11724–11731, 2017.
  18. G. H. Ahn*, M. Amani*, H. Rasool, D.-H. Lien, J. P. Mastandrea, J. W. Ager, M. Dubey, D. C. Chrzan, A. M. Minor, A. Javey, "Strain-engineered growth of two-dimensional materials”, Nature Communications, 8, 608, 2017. [*] These authors contribute equally to this work.
  19. P. Zhao, M. Amani, D.-H. Lien, G. H. Ahn, D. Kiriya, J. P. Mastandrea, J. W. Ager III, E. Yablonovitch, D. C. Chrzan, A. Javey, "Measuring the Edge Recombination Velocity of Monolayer Semiconductors", Nano Letters, 17, 5356–5360, 2017
  20. T.-Y. Kim, Y. Song, K. Cho, M. Amani, G. H. Ahn, J. Pak, J.-K. Kim, S. Chung, A. Javey, T. Lee, "Analysis on the interface characteristics of CVD-grown monolayer MoS2 by noise measurements”, Nanotechnology, 28 (14), 145702, 2017.
  21. J. Pak, M. Min, K. Cho, D.-H. Lien, G. H. Ahn, J. Jang, D. Yoo, S. Chung, A. Javey, and T. Lee, "Improved photoswitching response times of MoS2 field-effect transistors by stacking p-type copper phthalocyanine layer", Appl. Phys. Lett., 109, 183502, 2016.
  22. S. B. Desai, S. R. Madhvapathy, A. B. Sachid, J. P. Llinas, Q. Wang, G. H. Ahn, G. Pitner, M. J. Kim, J. Bokor, C. Hu, H.-S. P. Wong, A. Javey, "MoS2 transistors with 1-nanometer gate lengths", Science, 354, 99-102, 2016.
  23. Y. Song, H. Jeong, S. Chung, G. H. Ahn, T.-Y. Kim, J. Jang, D. Yoo, H. Jeong, A. Javey, T. Lee, "Origin of multi-level switching and telegraphic noise in organic nanocomposite memory devices", Scientific Reports, 6, 33967, 2016.
  24. M. Amani, R. A. Burke, X. Ji, P. Zhao, D.-H. Lien, P. Taheri, G. H. Ahn, D. Kirya, J. W. Ager III, E. Yablonovitch, J. Kong, M. Dubey, A. Javey, "High Luminescence Efficiency in MoS2 Grown by Chemical Vapor Deposition", ACS Nano, 10, 6535– 6541, 2016.
  25. M. Tosun, L. Chan, M. Amani, T. Roy, G. H. Ahn, P. Taheri, C. Carraro, J. Ager, R. Maboudian, A. Javey, "Air Stable n-Doping of WSe2 by Anion Vacancy Formation with Mild Plasma Treatment", ACS Nano, 10, 6853–6860, 2016.
  26. M. Amani, P. Taheri, R. Addou, G. H. Ahn, D. Kiriya, D.-H. Lien, J. W. Ager III, R. M. Wallace, A. Javey, "Recombination Kinetics and Effects of Superacid Treatment in Sulfur- and Selenium-Based Transition Metal Dichalcogenides", Nano Letters, 16 (4), 2786–2791, 2016.
  27. T.-Y. Kim, M. Amani, G. H. Ahn, Y. Song, A. Javey, S. Chung, T. Lee, "Electrical Properties of Synthesized Large-Area MoS2 Field-Effect Transistors Fabricated with Inkjet-Printed Contacts", ACS Nano, 10, 2819 (2016).
  28. T. Roy, M. Tosun, M. Hettick, G. H. Ahn, C. Hu, and A. Javey, "2D-2D tunneling field-effect transistors using WSe2/SnSe2 heterostructures", Appl. Phys. Lett., 108, 083111, 2016.
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Service

Active Reviewer in Nature Nanotechnology, Nature Photonics, ACS Photonics, Optics Express, Applied Physics Letters

EE 340: Quantum Photonics : Teaching Assistant, Spring 2024

MATSCI 199/209: Electronic and Optical Properties of Solids : Teaching Assistant, Spring 2023

EE 340: Optical Micro- and Nano-Cavities : Grader, Spring 2020

EE 222: Applied Quantum Mechanics I : Grader, Fall 2019

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