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27 January 2004 High-speed large-area surface-normal multiple quantum well modulators
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Since 1998, the Naval Research Laboratory has been developing modulating retro-reflectors (MRR) for free-space optical (FSO) communication links. Using an MRR is beneficial for asymmetric links containing one node with weight or power constraints, such as ground-to-air links. An MRR configuration shifts most of the power, weight, and pointing requirements onto one node. To close an MRR link at any significant distance, the area of the modulator must be fairly large. Using a large area limits the data rate, since capacitance is proportional to area. Resistance also depends on device size, although not in the same manner. To increase the data rate, we designed a top metal contact that diminishes the effect of the semiconductor resistivity. Using this new top contact design decreases the rise time from approximately 2.6 μs to 60 ns using the same wafer structure. However, increasing the data rate increases the power input and results in self-heating, which changes the optimal operating wavelength of MQW modulators. Accordingly, a new coupled quantum well structure is designed. The new design lowers the required drive voltage, which in turn lowers the power consumption, increases yield, and simplifies drive circuitry. The lower power input also reduces the modulation rate dependence of the wavelength.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Peter G. Goetz, Rita Mahon, Todd H. Stievater, William S. Rabinovich, and Steven C. Binari "High-speed large-area surface-normal multiple quantum well modulators", Proc. SPIE 5160, Free-Space Laser Communication and Active Laser Illumination III, (27 January 2004);

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