Happy to share our latest paper in Laser & Photonics Reviews.
We demonstrate free-space–coupled, frequency-locked microtoroid resonators for gas sensing—overcoming the long-standing limitation of fragile fiber tapers and moving WGM sensors closer to real-world use.
We accomplished:
• 25 ppt detection limit at room temperature
• >10⁷ Q factors preserved after polymer coating
• 3 orders of magnitude improvement over prior work
• Compact, robust, and capable of long-duration, unattended sensing
Using a mustard gas simulant (2-CEES), we show that ultrahigh sensitivity and real-world robustness can coexist.
This is the first demonstration of free-space–coupled WGM microtoroids for chemical sensing, opening new opportunities in defense, security, and environmental monitoring.
Thanks to our excellent collaborators and generous sponsors.

Free‐Space‐Coupled Frequency‐Locked Microtoroid Resonators With Reactive Polymer Functionalization for Part‐Per‐Trillion Gas Detection – Xu – Laser & Photonics Reviews – Wiley Online Library

I am honored to have been elected as a Fellow of Optica. I would like to express my gratitude for the support of my peers, my sponsors, and the diligent efforts of my talented group.

Optica announces 2026 Fellows class. | Optica

Honored that our work on label-free optical mapping of single 5-nm quantum dots using our photothermal-based FLOWER platform was selected for the cover of Optics & Photonics News’ Year in Optics 2025 issue.

Each year, the December issue of Optics & Photonics News—the monthly magazine of Optica—highlights the most exciting optics research from around the world in the preceding 12 months.

Here is the link to the original paper: Single 5-nm quantum dot detection via microtoroid optical resonator photothermal microscopy | Light: Science & Applications

Optics & Photonics News – December 2025

 

Labels like fluorescent tags are powerful but often perturb the system. Our work highlights FLOWER, a technique that eliminates this need by using frequency-locked optical microcavities for ultra-sensitive, stable, and portable label-free sensing.

I’m happy to share that our Feature Article is featured on the front cover of Chemical Communications as part of the Pioneering Investigators collection.

 

 

Thrilled to share that our team under the leadership of Pri Narang (UCLA) has been selected as a Stage 1 Winner of the NIH Quantum Sensing Technology Challenge.

This recognition highlights the potential of quantum-enabled technologies to transform biomedical research. We’re looking forward to competing in the second stage.

Grateful to NIH for launching this forward-looking initiative.

Read the announcement here: Challenge.gov

Glad to share our latest article which is part of Chemical Communications’ 2025 Pioneering collection. The article focuses on my past and current research and puts it in perspective. I appreciate all my lab members, collaborators, and sponsors who made this possible:

FLOWER: A Frequency-Locked Optical Whispering Evanescent Resonator for Label-Free Molecular Detection – Chemical Communications (RSC Publishing)

Glad to share our latest paper on optical biosensors for diagnosing neurodegenerative diseases: https://www.nature.com/articles/s44328-025-00040-3

Glad that our latest paper has been selected to be featured on Nature Protocol’s website.

Happy to share our latest paper: “Frequency locked whispering evanescent resonator (FLOWER) for biochemical sensing applications” which is now available online in Nature Protocols. Thanks to my diligent lab and generous sponsors who’ve allowed us to continuously improve our platform.

https://www.nature.com/articles/s41596-024-01096-7

Honored to have been elected as a Fellow of SPIE. I would like to express my gratitude for the support of my peers, my sponsors, and the diligent efforts of my talented group.

https://spie.org/news/spie-the-international-society-for-optics-and-photonics-announces-its-2025-fellows