Photonic crystal nanocavity assists upconversion IR detection

June 1, 2015
A near-infrared upconversion photodetector has responsivity of 0.81 A/W for 1 W of coupled power.
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By coupling a strong, cavity-enhanced second-harmonic signal from a gallium phosphide (GaP) planar photonic-crystal (PPC) nanocavity to a commercial silicon photodiode, researchers at Northwestern Polytechnical University (Xían, China), Columbia University (New York, NY), Massachusetts Institute of Technology (MIT; Cambridge, MA), and Humboldt-Universität zu Berlin (Berlin, Germany) have demonstrated a near-infrared (NIR) upconversion photodetector with a responsivity of 0.81 A/W for 1 W of coupled power.

To fabricate the detector, air holes (and a central solid region of three missing air holes) are lithographically patterned in photoresist and transferred to the GaP substrate using chemical etching processes. The resultant PPC structure is then positioned over a silicon detector separated by an air gap or low-refractive-index material layer. Coupled NIR light is then upconverted by strongly confined resonant modes in the PPC cavity to submicron wavelengths that illuminate the silicon detector below for photocurrent generation. The PPC-assisted upconversion detector has higher responsivity and a smaller form factor than bulk-optic lithium niobate-based upconversion detectors and is more responsive than comparably sized indium gallium arsenide detectors. In addition, the detector can function as an efficient and compact autocorrelator for ultrafast optical pulse characterization with sub-picosecond resolution. Reference: X. Gan et al., Opt. Express, 23, 10, 12998–13004 (2015).

About the Author

Gail Overton | Senior Editor (2004-2020)

Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.

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