Surface plasmon resonance (SPR) sensor has been studied for high sensitivity optical biosensor as a single molecule detection, virus detection, DNA sequencing etc. SPR sensor requires an ultra-small signal detection system that measures very small intensity variation of reflected light along with the change of a refractive index near the sensor surface. In this reason, lock-in detection method which is able to detect small signal buried in noise has been applied to SPR sensor. In general lock-in detection method using multiplier and low pass filter measures DC value of output, and its sensitivity is determined by 1/f noise at DC. Unlike the DC measurement we have proposed 2ω harmonic lock-in detection method using multiplier and band pass filter. Sensitivity of the proposed lock-in detection method is much lower than 1/f noise at DC. In this paper we will show that 2ω harmonic lock-in detection method for SPR sensor system providing the sensitivity enhanced.

Date Published: 13 March 2015
PDF: 6 pages
Proc. SPIE 9369, Photonic Instrumentation Engineering II, 93690C (13 March 2015); doi: 10.1117/12.2079043

Published in SPIE Proceedings Vol. 9369:
Photonic Instrumentation Engineering II
Yakov G. Soskind; Craig Olson, Editor(s)