Joseph M. Kahn

Joseph M. Kahn received A.B., M.A. and Ph.D. degrees in Physics from the University of California, Berkeley in 1981, 1983 and 1986. In 1987-1990, Kahn was at AT&T Bell Laboratories. In 1989, he demonstrated the first successful synchronous (i.e., coherent) detection in optical fiber systems, achieving record receiver sensitivity. In 1990-2003, Kahn was on the Electrical Engineering and Computer Sciences faculty at Berkeley. He demonstrated coherent detection of QPSK in 1992. In 1999, D.-S. Shiu and Kahn published the first work on shaping and nonequiprobable signaling for optical communications. In the 1990s and early 2000s, Kahn and collaborators performed seminal work on indoor and outdoor free-space optical communications and multi-input multi-output wireless communications. In 2000, Kahn and K.-P. Ho founded StrataLight Communications, whose 40 Gb/s-per-wavelength long-haul fiber transmission systems were deployed widely by AT&T, Deutsche Telekom, and other carriers. In 2002, Ho and Kahn applied to patent the first electronic compensation of fiber Kerr nonlinearity. StrataLight was acquired by Opnext in 2009. In 2003, Kahn became a Professor of Electrical Engineering in the E. L. Ginzton Laboratory at Stanford University. Kahn and collaborators have extensively studied rate-adaptive coding and modulation, as well as digital signal processing for mitigating linear and nonlinear impairments in coherent systems. In 2008, E. Ip and Kahn (and G. Li independently) invented simplified digital backpropagation for compensating fiber Kerr nonlinearity and dispersion. Since 2004, Kahn and collaborators have studied propagation, modal statistics, spatial multiplexing and imaging in multi-mode fibers, elucidating principal modes and demonstrating transmission beyond the traditional bandwidth-distance limit in 2005, deriving the statistics of coupled modal group delays and gains in 2011, and deriving resolution limits for imaging in 2013. Kahnís current research addresses optical frequency comb generators, coherent data center links, rate-adaptive access networks, fiber Kerr nonlinearity mitigation, ultra-long-haul submarine links, and optimal free-space transmission through atmospheric turbulence. Kahn received the National Science Foundation Presidential Young Investigator Award in 1991. In 2000, he became a Fellow of the IEEE.


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Last modified: February 20, 2020.