Bo Xu

Technical Skills

Photonics & Optics:

Photonic integrated circuits, waveguides, nonlinear optics, plasmonics, UV/NIR/MIR optical systems, spectroscopy, fiber laser systems, signal modulation, optical alignment

Test & Characterization:

Optical spectroscopy (FTIR, Raman, UV-Vis), SEM, AFM, ellipsometry, signal analysis

Nanofabrication & Cleanroom:

E-beam/photo-lithography, ICP-RIE, CVD, PVD, thin-film deposition, mask design, polymer

Simulation & Software:

Python, COMSOL Multiphysics, Ansys Lumerical, MATLAB, Klayout, Zemax, LabVIEW

Engineering Tools:

SolidWorks, AutoCAD, experimental automation, data processing pipelines

Key Projects

PIC Interconnects & Multi-Platform Chip I/O

I designed and optimized high-efficiency photonic integrated circuit (PIC) couplers to facilitate seamless light injection and extraction across hybrid material platforms. I engineered I/O interfaces that minimize insertion loss and maximize bandwidth for chip-scale optical systems utilizing Lumerical for FDTD mode-matching, COMSOL for multi-physics thermal stability, and Zemax for free-space-to-fiber alignment.

High-Q Chalcogenide Microresonator Development

I led the design and nanofabrication of high-quality factor (Q) Ge-Sb-S and Ge-Sb-Se reflowed wedge and ring resonators optimized for the near- and mid-infrared spectrum. This work involved advanced PIC designm, dispersion engineering and nanofabrication techniques to achieve ultra-low loss components critical for nonlinear optics and on-chip sensing applications.

Nanophotonic Biosensing & Optical Force Systems

I engineered hybrid nanostructures combining upconverting nanoparticles with plasmonic gold nanodisks to create highly sensitive, ratiometric optical force sensors. By modulating luminescence through selective plasmonic enhancement, I developed scalable fabrication methods for robust sensing platforms capable of detecting mechanical and spectroscopic changes at the nanoscale.

Publications

B. Lu, J. W. Erikson, B. Xu, S. Guo, M. Zohrabi, J. T. Gopinath, and W. Park, Ultrahigh-Q chalcogenide micro-racetrack resonators, arXiv, 2025. View Paper
B. Lu, J. W. Erikson, B. Xu, S. Guo, M. Zohrabi, J. T. Gopinath, and W. Park, Chalcogenide Racetrack Resonators With Intrinsic Q Factor Above 5 Million, Optica Laser Congress 2025, 2025. View Paper
B. Xu, B. Lu, M. Topper, M. Zohrabi, J. T. Gopinath, and W. Park, Dispersion Engineered High-quality Ge–Sb–S Reflowed Wedge Resonator, J. Light. Technol., 2025. View Paper
C. Corbella Bagot, T. Ba Tis, B. Xu, C. Sabo, E. Rappeport, and W. Park, Optical Force Sensor Based on Plasmon Modulated Upconversion Luminescence, Adv. Opt. Mater., 2024. View Paper
T. B. Tis, C. Sabo, B. Xu, C. C. Bagot, E. Rappeport, and W. Park, A scalable fabrication method for gold nanodisk-upconverting nanoparticle hybrid nanostructures, Nanoscale, 2024. View Paper
B. Lu, B. Xu, G. Krueper, M. Zohrabi, J. T. Gopinath, and W. Park, High-quality Mid-infrared Chalcogenide Ring Resonator, CLEO 2024, 2024. View Paper
B. Xu, Chalcogenide Microresonators for Near- and Mid-infrared Nonlinear Photonics, Ph.D. Dissertation, University of Colorado at Boulder, 2024. View Paper
B. Xu, M. Grayson, T. Shanavas, J. T. Gopinath, and W. Park, Dispersion Control of High-quality Ge23Sb7S70 Reflowed Wedge Resonators, CLEO 2023, 2023. View Paper
M. Grayson, G. Krueper, B. Xu, M. Zohrabi, D. Hjelme, J. T. Gopinath, and W. Park, On-chip mid-infrared optical sensing with GeSbSe waveguides and resonators, Opt. Express, 2023. View Paper
M. Grayson, B. Xu, T. Shanavas, M. Zohrabi, K. Bae, J. T. Gopinath, and W. Park, Fabrication and characterization of high quality GeSbSe reflowed and etched ring resonators, Opt. Express, 2022. View Paper
T. Shanavas, M. Grayson, B. Xu, M. Zohrabi, W. Park, and J. T. Gopinath, Cascaded forward Brillouin lasing in a chalcogenide whispering gallery mode microresonator, APL Photonics, 2022. View Paper
M. Grayson, G. Krueper, B. Xu, D. Hjelme, J. T. Gopinath, and W. Park, GeSbSe Devices for Mid-Infrared Optical Sensing, Optical Sensors and Sensing Congress 2022, 2022. View Paper
K. Bae, B. Xu, A. Das, C. Wolenski, E. Rappeport, and W. Park, Selective enhancement of upconversion luminescence for enhanced ratiometric sensing, RSC Adv., 2021. View Paper
B. Xu, B. M. Heffernan, K. Bae, M. E. Siemens, J. T. Gopinath, and W. Park, Selective excitation of plasmon resonances with single V-point cylindrical vector beams, Opt. Express, 2021. View Paper
B. Xu, B. M. Heffernan, K. Bae, M. Siemens, J. T. Gopinath, and W. Park, Group Theory Guided Symmetry Coupling between Cylindrical Vector Beams and Localized Surface Plasmon Resonances, CLEO 2021, 2021. View Paper
B. M. Heffernan, B. Xu, K. Bae, M. E. Siemens, W. Park, and J. T. Gopinath, Tailoring the Multipolar Content at Tight focus Using Cylindrical Vector Beams with Orbital Angular Momentum, CLEO 2021, 2021. View Paper
K. Bae, A. Das, B. Xu, and W. Park, A spectroscopic study on the interaction between upconversion nanoparticles and plasmonic nanostructure, Nanoengineering: Fabrication, Properties, Optics, Thin Films, and Devices XVII, 2020. View Paper