2013/08/08 by Joachim Knittel, Jon D. Swaim, Knittel, Joachim +8
Engineering · Physics and Astronomy · #Biological Physics (physics.bio-ph) #FOS: Physical sciences #Force Microscopy Techniques and Applications #Instrumentation and Detectors (physics.ins-det) #Mechanical and Optical Resonators #Optics (physics.optics) #Photonic and Optical Devices #Quantum Physics (quant-ph) #physics.bio-ph #physics.ins-det #physics.optics #quant-ph
paper · pdf · doi:10.48550/arxiv.1308.1777
5 pages, plus supplementary information
arxiv created 2013/08/08 · openalex publication_date 2013/08/08 · arxiv updated 2013/08/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive realtime observation of motor molecule motion. However, to date technical noise sources, most particularly low frequency laser noise, have constrained such applications. Here we introduce a new technique for whispering gallery mode sensing based on direct detection of back-scattered light. This experimentally straightforward technique is immune to frequency noise in principle, and further, acts to suppress thermorefractive noise. We demonstrate 27 dB of frequency noise suppression, eliminating frequency noise as a source of sensitivity degradation and allowing an absolute frequency shift sensitivity of 76 kHz. Our results open a new pathway towards single molecule biophysics experiments and ultrasensitive biosensors.