Two-Photon-Absorption Scheme for Optical Beam Tracking

TBMG-10601

01/01/2011

Abstract
Content

A new optical beam tracking approach for free-space optical communication links using two-photon absorption (TPA) in a high-bandgap detector material was demonstrated. This tracking scheme is part of the canonical architecture described in the preceding article. TPA is used to track a long-wavelength transmit laser while direct absorption on the same sensor simultaneously tracks a shorter-wavelength beacon. The TPA responsivity was measured for silicon using a PIN photodiode at a laser beacon wavelength of 1,550 nm. As expected, the responsivity shows a linear dependence with incident power level. The responsivity slope is 4.5 × 10–7 A/W2. Also, optical beam spots from the 1,550-nm laser beacon were characterized on commercial charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) imagers with as little as 13.7 μW of optical power (see figure). This new tracker technology offers an innovative solution to reduce system complexity, improve transmit/receive isolation, improve optical efficiency, improve signal-to-noise ratio (SNR), and reduce cost for free-space optical communications transceivers.

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Citation
"Two-Photon-Absorption Scheme for Optical Beam Tracking," Mobility Engineering, January 1, 2011.
Additional Details
Publisher
Published
Jan 1, 2011
Product Code
TBMG-10601
Content Type
Magazine Article
Language
English