Ultra-sensitive Nanoparticle Detection using a Portable Whispering Gallery Mode Biosensor driven by a PPLN doubled DFB laser
S. I. Shopova, R. Rajmangal, Y. Nishida, S. Arnold
Review Of Scientific Instruments (Dec 2009).

Abstract: We demonstrate a significant reduction in the limit of label-free detection of individual viral-sized nanoparticles in aqueous solution through the use of a frequency doubled telecom laser constructed from a DFB-PPLN union. By driving a Whispering Gallery Mode Biosensor near a wavelength of 650 nm with this device we have detected real-time adsorption steps for particles 36 nm in radius with a signal to noise ratio of 8. The noise equivalent detection limit is ~ 20 attograms (17 nm radius). This new lower limit is attributed to the ultra-low resonance wavelength noise associated with the use of the DFB-PPLN device.