"Integrated Semiconductor Vertical-Cavity Surface-Emitting Lasers and PIN Photodetectors for Biomedical Flourescence Sensing," IEEE Journal of Quantum Electronics
Updated: Aug 12, 2014
Author(s): Evan Thrush, Ofer Levi, Wonill Ha, Glen Carey, Laura J. Cook, Jason Deich, Stephen J. Smith, W.E. Moerner, James S. Harris, Jr.
Vertical-cavity surface-emitting lasers (VCSELs), optical emission filters, and PIN photodetectors were fabricated as part of a monolithically integrated near-infrared flourescence detection system. The integration of these micro-fabricated components with micro-arrays, flow channel arrays, and biochips can drastically reduce cost and enable parallel sensing architectures. An optoelectronic design is presented that integrates VCSELs, optical filters, and photodetectors through a modification to a typical VCSEL structure. System designs were simulated and compared, leading to several innovative approaches for integrated sensors. The laser and detector modules were characterized independently and subsequently integrated to form a complete sensor. VCSELs with oxidation apertures measuring 4, 7, 17, and 20 mm showed a lasing wavelength of 773 nm, threshold current densities from 6400 to 1300 A cm^-2, and maximum output powers of 0.6-4 mW, with transverse single-mode and multimode operation. PIN photodetectors were fabricated with integrated emission filters. Quantum efficiencies above 85% were observed with a dark current of 500 fA/(mm detector diameter). Complete sensor units were tested and near-infrared flourescent molecules (IR-800) were detected. A theoretical detection limit of 10^5 flourophores/mm^2 were determined. The compact parallel architecture, high-power laser, and low-noise photodetector make this sensor a good candidate for biomedical flourescence-based sensing applications.
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