This invention is an optical sensing system for trace detection of mustard gas. It is a method of detecting small quantities of gases (such as mustard gas) using the Frequency-Locked Optical Whispering Evanescent Resonator (FLOWER) technique. Background: Optical microresonators are photonic devices that confine light in tiny volumes with very high-quality factors, enhancing light-matter interactions. By sustaining whispering-gallery modes, they can detect subtle changes in refractive index, absorption, or scattering caused by nearby molecules. This makes them powerful tools for chemical and biological sensing, offering high sensitivity, label-free operation, and real-time monitoring. They are especially valuable for hazardous gas detection at trace levels, where traditional methods like mass spectrometry or ion mobility spectrometry require bulky instruments and sample preparation. Microresonator platforms instead enable compact, high-performance sensors for environmental monitoring, industrial safety, and defense against chemical threats. Applications:
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