Optofluidic FRET Lasers and Their Applications in Novel Photonic Devices and Biochemical Sensing

• Published in: IEEE journal of selected topics in quantum electronics Vol. 22; no. 4; pp. 188 - 202
• Main Authors: Aas, Mehdi, Qiushu Chen, Jonas, Alexandr, Kiraz, Alper, Xudong Fan
• Format: Journal Article
• Language: English
• Published: IEEE 01-07-2016
• Subjects: Absorption; Biophotonics; biophysics; biosensors; Cavity resonators; fluorescence; Laser excitation; lasers; Mathematical model; nonlinear optics; optical resonators; Photonics; Sensors; lasers; nonlinear optics; fluorescence; Biophotonics; biosensors; optical resonators; biophysics
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2015.2477397

Incorporating fluorescence resonance energy transfer (FRET) into a laser cavity can increase the sensitivity of FRET-based biochemical sensors due to the nonlinear dependence of the lasing output on the FRET parameters. Here, we carry out a comprehensive theoretical analysis of optofluidic FRET lasers based on a Fabry-Pérot microcavity using a rate equation model. We compare conceptually distinct cases of donor and acceptor molecules diffusing freely in a bulk solution versus molecules connected by a fixed-length linker and show that the latter arrangement is especially well suited for sensing of low-concentration analytes. By comparing FRET lasing-based sensors with conventional FRET sensors, we show that for optimal pump fluence and FRET-pair concentration, FRET lasing can lead to more than 100-fold enhancement in detection sensitivities of conformational changes in the Förster radius range. We also show that for optimal experimental conditions, donor and acceptor emission intensities become over 20-fold more sensitive to FRET-pair concentration changes in the presence of FRET lasing. We study the dependence of the sensitivity enhancement on the cavity Q-factor. We show that the highest enhancements can be obtained for Q-factors between 10 4 -10 6 , and enhancement values decrease for Q-factors above 10 6 due to the radiative energy transfer in the cavity.