Over more than two decades, we have performed seminal research on coherent optical detection. In the late 1980s, we demonstrated the first optical phase-locked loop using semiconductor lasers, and built BPSK homodyne transmission systems that achieved record receiver sensitivities (as low as 38 photons/bit). In 1992, we demonstrated coherent detection of QPSK, a technique offering high spectral efficiency and high receiver sensitivity.
More recently, we have been studying digital signal processing techniques for carrier recovery and compensation of transmission impairments. These include linear effects, such as chromatic dispersion and polarization-mode dispersion, as well as nonlinear effects arising from the Kerr nonlinearity in silica glass. We have studied important practical issues, for example, using polyphase digital filters to reduce receiver sampling rates well below 2 samples/symbol (which was widely believed to be the minimum required). At the same time, we have addressed fundamental issues, for example, using digital backpropagation to cancel fiber nonlinearity (which was widely believed to pose insuperable performance limitations). We have also performed extensive research on fundamental limits to spectral efficiency dictated by information theory.
We are now studying bandwidth-scalable transmission based on orthogonal frequency-division multiplexing (OFDM) and rate-adaptive transmission based on low-density parity-check (LDPC) codes. These will help enable 400 Gbit/s-per-channel and 1 Tbit/s-per-channel long-haul systems to become a practical reality. With the goal of exploiting spatial dimensions to further increase transmission capacity, we are also performing research on coherent mode-division multiplexing in multi-mode fiber, a form of multi-input, multi-output (MIMO) transmission.
E. Ip and J. M. Kahn, "Fiber Impairment Compensation using Coherent Detection and Digital Signal Processing", J. of Lightwave Technol., vol. 28, no. 4, pp. 502-519, February 15, 2010 (Invited Paper). PDF
G.-H. Gho and J. M. Kahn, "Rate-Adaptive Modulation and Coding for Optical Fiber Transmission Systems", to be published in J. of Lightwave Technol. PDF
G.-H. Gho, L. Klak and J. M. Kahn, "Rate-Adaptive Coding for Optical Fiber Transmission Systems", J. of Lightwave Technol., vol. 29, no. 2, pp. 222-233, January 15, 2011. PDF
E. Ip and J. M. Kahn, "Compensation of Dispersion and Nonlinear Effects using Digital Backpropagation", J. of Lightwave Technol., vol. 26, no. 20, pp. 3416-3425, October 15, 2008. PDF
D. J. F. Barros and J. M. Kahn, "Optical Modulator Optimization for Orthogonal Frequency-Division Multiplexing", J. of Lightwave Technol., vol. 27, no. 13, pp. 2370-2378, July 1, 2009. PDF
D. J. F. Barros and J. M. Kahn, "Optimized Dispersion Compensation Using Orthogonal Frequency-Division Multiplexing", J. of Lightwave Technol., vol. 26, no. 16, pp. 2889-2898, August 15, 2008. PDF
E. Ip and J. M. Kahn, "Digital Equalization of Chromatic Dispersion and Polarization Mode Dispersion", J. of Lightwave Technol., vol. 25, no. 8, pp. 2033-2043, August 2007. PDF
A. P. T. Lau, S. Rabbani and J. M. Kahn, "On the Statistics of Intra-Channel Four-Wave Mixing in Phase-Modulated Optical Communication Systems", J. of Lightwave Technol., vol. 26, no. 14, pp. 2128-2135, July 15, 2008. PDF
A. P. T. Lau and J. M. Kahn, "Signal Design and Detection in Presence of Nonlinear Phase Noise", J. of Lightwave Technol., vol. 25, no. 10, pp. 3008-3016, October 2007. PDF
A. P. T. Lau and J. M. Kahn, "Power Profile Optimization in Phase-Modulated Systems in Presence of Nonlinear Phase Noise", IEEE Photon. Technol. Lett., vol. 18, no. 23, pp. 2514-2516, December 1, 2006. PDF
A. P. T. Lau and J. M. Kahn, "Design of Inline Amplifier Gains and Spacings to Minimize Phase Noise in Optical Transmission Systems", J. of Lightwave Technol., vol. 24, no. 3, pp. 1334-1341, March 2006. PDF
K.-P. Ho and J. M. Kahn, "Electronic Compensation Technique to Mitigate Nonlinear Phase Noise", J. of Lightwave Technol., vol. 22, no. 3, pp. 779-783, March 2004. PDF
E. Ip and J. M. Kahn, "Carrier Synchronization for 3- and 4-bit-per-Symbol Optical Transmission", J. of Lightwave Technol., vol. 23, no. 12, pp. 4110-4124, December 2005. PDF
J. R. Barry and J. M. Kahn, "Carrier Synchronization for Homodyne and Heterodyne Detection of Optical Quadriphase-Shift Keying", J. Lightwave Technol., vol. 10, pp. 1939-1951, 1992. PDF
K.-P. Ho and J. M. Kahn, "Optical Frequency Comb Generator Using Phase Modulation in Amplified Circulating Loop", Photon. Technol. Lett., vol. 5, no. 6, pp. 721-725, June 1993. PDF
J. M. Kahn, A. M. Porter and U. Padan, "Heterodyne Detection of 310-Mb/s Quadriphase-Shift Keying Using Fourth-Power Optical Phase-Locked Loop", IEEE Photon. Technol. Lett., vol. 4, pp. 1397-1400, 1992. PDF
J. M. Kahn, A. H. Gnauck, J. J. Veselka, S. K. Korotky and B. L. Kasper, "4 Gbit/s PSK Homodyne Transmission System Using Phase-Locked Semiconductor Lasers," IEEE Photon. Technol. Lett., vol. 2, pp. 285-287, 1990. PDF
J. M. Kahn, "1 Gbit/s PSK Homodyne Transmission System Using Phase-Locked Semiconductor Lasers," IEEE Photon. Technol. Lett., vol. 1, pp. 340-342, 1989. PDF
J. M. Kahn, C. A. Burrus and G. Raybon, "High-Stability 1.5 Micron External-Cavity Lasers for Phase-Lock Applications," IEEE Photon. Technol. Lett., vol. 1, pp. 159-161, 1989. PDF
J. M. Kahn and B. L. Kasper, "Optical Phaselock Receiver with Multi-Gigahertz Signal Bandwidth", Electron. Lett. vol. 25, pp. 626-627, 1989. PDF
J. Wang and J. M. Kahn, "Accurate Bit-Error Ratio Computation in Nonlinear CRZ-OOK and CRZ-DPSK Systems", IEEE Photon. Technol. Lett., vol. 16, no. 9, pp. 2165-2167, September 2004. PDF
J. Wang and J. M. Kahn, "Conventional DPSK vs. Symmetrical DPSK: Comparison of Dispersion Tolerances", IEEE Photon. Technol. Lett., vol. 16, no. 6, pp. 1585-1587, June 2004. PDF
J. Wang and J. M. Kahn, "Performance of Electrical Equalizers in Optically Amplified OOK and DPSK Systems", IEEE Photon. Technol. Lett., vol. 16, no. 5, pp. 1397-1399, May 2004. PDF
J. Wang and J. M. Kahn, "Impact of Chromatic and Polarization-Mode Dispersions on DPSK Systems using Interferometric Demodulation and Direct Detection", J. of Lightwave Technol., vol. 22, no. 2, pp. 362-371, February 2004. PDF
K.-P. Ho and J. M. Kahn, "Channel Capacity of WDM Systems Using Constant-Intensity Modulation Formats", Proc. of Optical Fiber Commun. Conf., Anaheim, CA, March 17-22, 2002. PDF
J. M. Kahn and K.-P. Ho, "A Bottleneck for Optical Fibres", Nature, vol. 411, pp. 1007-1010, June 28, 2001 (Invited Paper). PDF Also see this related paper by Mitra and Stark: PDF
K.-P. Ho and J. M. Kahn, "Spectrum of Externally Modulated Optical Signals", J. of Lightwave Technol., vol. 22, no. 2, pp. 658-663, February 2004. PDF
W. Mao and J. M. Kahn, "Lattice Codes for Amplified Direct-Detection Optical Systems", IEEE Trans. on Commun., vol. 56, no. 7, pp. 1137-1145, July 2008. PDF
D. Shiu and J. M. Kahn, "Shaping and Non-Equiprobable Signaling for Intensity Modulated Signals", IEEE Trans. on Information Theory, vol. 45, pp. 2661-2668, November 1999. PDF
R. You and J. M. Kahn, "Average Power Reduction Techniques for Multiple-Subcarrier Intensity-Modulated Optical Signals", IEEE Trans. on Commun., vol. 49, pp. 2164-2171, December 2001. PDF
K.-P. Ho and J. M. Kahn, "Optimal Predistortion of Gaussian Inputs for Clipping Channels", IEEE Trans. on Commun., vol. 44, no. 11, pp. 1505-1513, November 1996. PDF
K.-P. Ho and J. M. Kahn, "On Models of Clipping Distortion for Lightwave CATV Systems", IEEE Photon. Technol. Lett., vol. 8, no. 1, pp. 125-126, January 1996. PDF
K.-P Ho and J. M. Kahn, "Equalization Technique to Reduce Laser Clipping-Induced Distortion in Subcarrier-Multiplexed Lightwave Systems", IEEE Photon. Technol. Lett., vol. 5, no. 9, pp. 1100-1103, September 1993. PDF
K.-P. Ho and J. M. Kahn, "Methods for Crosstalk Measurement and Reduction in Dense WDM Systems", J. Lightwave Technol., vol. 14., pp. 1127-1135, June 1996. PDF
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Last modified: April 3, 2012.