title: Coupling variation induced ultrasensitive label-free biosensing by using single mode coupled microcavity laser.
abstract: A novel label-free optical biosensing scheme by using a single mode coupled microcavity laser is experimentally realized. We demonstrate that a slight change of the coupling coefficient due to the existence of biosamples leads to sensitive single mode laser hopping to a new frequency that is several nm away from the original mode wavelength. By monitoring the emergence of the hopped laser mode intensity, the lowest detectable concentration of bovine serum albumin (BSA) of approximately 80 pg/mL was obtained, which is comparable to the detection limit of a passive microcavity sensor with Q > 10(7), but with a much simplified experimental setup. With the mode hopping and mode shift combined, the single frequency coupled cavity laser provides a detection range from pg/mL (limit of mode hopping) to microg/mL (limit of mode shift). Our results show the possibility of using a coupled optical microcavity to achieve ultrasensitive optical sensing.
authors.affiliation: State Key Lab for Advanced Photonic Materials and Devices, Department of Optical Science and Engineering, School of Information Science and Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Shang
authors.forename: Xin
authors.initials: X
authors.lastname: Tu
authors.forename: Liying
authors.initials: L
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Xu
mesh_terms: D000818:Animals; D015374:Biosensing Techniques; D002417:Cattle; D007834:Lasers; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine / Q000032:analysis
chemical_list: D012710:Serum Albumin, Bovine