@article{CHEN2026, 
author = {Qiming CHEN and Weixin LIU and You’an YANG and Jiawei KANG and Zhonglin LI and Yingying WANG and Weiyan JIAO and Guanghua FAN and Renxi GAO},
title = {Ultrasensitive Hemoglobin Photothermal Detection Using Stimulated Raman Frequency-Shift Feedback in a Whispering-Gallery-Mode Microbottle},
year = {2026},
journal = {Photonic Sensors},
volume = {16},
number = {3},
pages = {9560026},
keywords = {Hemoglobin detection, photothermal sensing, stimulated Raman scattering, frequency-shift feedback, whispering-gallery-mode microcavity},
url = {https://www.sciopen.com/article/10.26599/PhoS.2026.9560026},
doi = {10.26599/PhoS.2026.9560026},
abstract = {Precise quantification of hemoglobin is critical for clinical diagnostics and biomedical analysis. We present an ultra-sensitive photothermal sensor enhanced by a frequency-shift feedback mechanism based on stimulated Raman scattering. A whispering-gallery-mode (WGM) hollow microbottle serves as a microfluidic channel while simultaneously exciting the Raman signal. The generated Raman signal is frequency-modulated outside the cavity and subsequently reinjected, where it coherently interferes with the intrinsic Raman mode. A photothermal response is induced within the cavity by a 405 nm laser, leading to a shift in the relaxation oscillation frequency of the intrinsic Raman mode. When this frequency approaches the modulation frequency, feedback-induced optical gain yields substantial signal amplification. The system enables rapid, label-free, and ultra-high sensitivity detection, achieving a limit of hemoglobin detection of 9.35×10−6 g/dL – nearly two orders of magnitude lower than that of wavelength-shift-based photothermal detection methods. It provides a compact and scalable platform for integrated biomedical sensing.}
}