Crawford Hill, NJ, USA

Chandrasekhar Sethumadhavan

Distinguished Member of Technical Staff


        S. Chandrasekhar received the B.Sc., M.Sc., and Ph.D. degrees in physics from the University of Bombay, Bombay, India, in 1973, 1975, and 1985, respectively.

        He was at the Tata Institute of Fundamental Research, Bombay, India, from 1975 to 1985 and at AT&T Bell Laboratories (later called Lucent Technologies, Bell Laboratories and more recently called Bell Labs, Alcatel-Lucent), Crawford Hill Laboratory, Holmdel, NJ, from 1986 to the present. He initially worked on compound semiconductor devices and high-speed optoelectronic integrated circuits (OEIC's). Since January 1999, he has been responsible for forward looking research in WDM Optical Networking at 40Gb/s, 100Gb/s and beyond 100Gb/s. His current interests include coherent optical transmission systems for high spectral efficiency transport and networking beyond 100Gb/s, multi-carrier superchannels, and software-defined transponders for efficient end-to-end optical netwroking.    

He is a Fellow, Bell Labs, a Fellow of the IEEE, a Fellow of the Optical Society of America, a member of the IEEE Photonics Society and the OSA. He served as an Associate Editor of IEEE Photonics Technology Letters for over ten years. He has been member of the technical program committees of the IEDM, the DRC, the ACP, and the OFC conferences. He holds twenty five US patents, has published over 200 peer-reviewed journal articles, and given several invited talks at international conferences. He was awarded the IEEE LEOS Engineering Achievement Award in 2000 and the OSA Engineering Excellence Award in 2004 for his contributions to OEICs and WDM systems research. Recently he was recognized as a member of the “100Gb/s Coherent (Long Haul – High Capacity WDM Interface) Team” that was awarded the 2010 Bell Labs President’s Award.


Degree    Year              University                       Subject


Ph.D      1985      Bombay University, India          Physics

M.Sc.     1975       Bombay University, India         Physics 

B.Sc.     1973       Bombay University, India          Physics 


Ph.D. Thesis title : " Studies on Laser Recrystallised Polycrystalline Silicon ".

Professional activites

1. Associate Editor, Optics Express, OSA, 2015-2017.

2.       Chair, Optical Communications, OSA’s Technical Groups, 2013-2015.

3.       Nominated Member, Australian Research Council Project Proposal Evaluations, 2013-2015.

4. Member, Technical Program Sub-Committee S5 (Digital Transmission Systems), Optical Fiber Communications Conference (OFC) 2016.

5.       Member, Technical Program Sub-Committee 3 (Optical Transmission and Subsystems), Asia Photonics Conference (ACP), 2010, 2011, 2012, 2013, & 2014.

6.       Reviewer, journal manuscripts: IEEE Photonics Technology Letters, IEEE Journal of Lightwave Technology, IEEE Photonics Journal, OSA’s Optics Express, OSA’s Optics Letters, OSA’s Chinese Optics Letters, OSA’s Optical Communications and Optical Fiber Technology.

6.       Mentor, summer interns at Bell Labs ( Wenjun Gu, 2015; Changyu Lin, 2014; Echo Chen, 2013; Xi Vivian Chen, 2011)

7.       General Co-Chair, “Photonic Networks and Devices”, under OSA’s Advanced Photonics Summer Topicals, Rio Grande, Peurto Rico, July 14-17, 2013.

Selected articles and publications

1. Transmission of a 1.2-Tb/s 24-carrier no-guard-interval coherent OFDM superchannel over 7200-km of ultra-large-area fiber
S Chandrasekhar, X Liu, B Zhu, DW Peckham
ECOC 2009, PD2.6

2. Experimental investigation on the performance of closely spaced multi-carrier PDM-QPSK with digital coherent detection
S Chandrasekhar, X Liu
Optics express 17 (24), 21350-21361

3. Transmission of a 448-Gb/s reduced-guard-interval CO-OFDM signal with a 60-GHz optical bandwidth over 2000 km of ULAF and five 80-GHz-Grid ROADMs
X Liu, S Chandrasekhar, B Zhu, PJ Winzer, AH Gnauck, DW Peckham
Optical Fiber Communication Conference, PDPC2

4. WDM/SDM Transmission of 10 x 128-Gb/s PDM-QPSK over 2688-km 7-Core Fiber with a per-Fiber Net Aggregate Spectral-Efficiency Distance Product of 40,320 km. b/s/Hz
S Chandrasekhar, A Gnauck, X Liu, P Winzer, Y Pan, EC Burrows, B Zhu, ...
European Conference and Exposition on Optical Communications, Th. 13. C. 4

5. High-speed monolithic pin/HBT and HPT/HBT photoreceivers implemented with simple phototransistor structure
S Chandrasekhar, LM Lunardi, AH Gnauck, RA Hamm, GJ Qua
Photonics Technology Letters, IEEE 5 (11), 1316-1318

6. Multiplication noise of wide-bandwidth InP/InGaAsP/InGaAs avalanche photodiodes
JC Campbell, S Chandrasekhar, WT Tsang, GJ Qua, BC Johnson
Lightwave Technology, Journal of 7 (3), 473-478


  1. 9,203,682 "Frequency-dependent I/Q-signal imbalance correction coherent optical transceivers"
  2. 9,160,456 "Dispersion management for inhomogeneous fiber-optic links"
  3. 8,953,949 "Method And Apparatus For Transmitting High-Level QAM optical Signals with Binary Drive Signals"
  4. 8,923,706 "Frequency equalization for an optical transmitter"
  5. 8,842,997 "Apparatus and method for generating interleaved return-to-zero (IRZ) polarization-division multiplexed (PDM) signals"
  6. 8,660,433       “Pilot-assisted data transmission in a coherent optical-communication system”
  7. 8,611,751       “System, apparatus and method for communicating data via polarization multiplexing”
  8. 8,594,515       “Digital phase conjugation for fiber-optic links”
  9. 8,515,286       “Coherent optical receiver for pilot-assisted data transmission”
  10. 8,483,575       “Apparatus and method for generating frequency-locked optical comb sources”
  11. 8,180,227       “Digital coherent detection of multi-carrier optical signal”
  12. 8,121,494       “System and method for receiving high spectral efficiency optical DPSK signals”
  13. 7,782,520       “Duobinary modulation with a lumped-element Mach-Zehnder device”
  14. 7,477,852       “Optical receiver apparatus and method”
  15. 7,333,553       “Tunable duobinary transmitter”
  16. 7,308,169       “Optical equalizer for intersymbol interference mitigation”
  17. 6,996,307       “Variable-bandwidth multi-granularity optical add/drop network”
  18. 6,804,434       “Multi-channel optical equalizer for intersymbol interference mitigation”
  19. 6,785,446       “Multi-channel optical equalizer for intersymbol interference mitigation”
  20. 6,498,873       “Photo detector assembly”
  21. 6,437,891       “Integrated dual-wavelength transceiver”
  22. 6,400,860       “Wavelength selective polarization beam splitter/combiner”
  23. 6,294,821       “Single-chip wavelength converter”
  24. 6,262,411       “Direct detection receiver”
  25. 5,689,122       “InP/InGaAs monolithic integrated demultiplexer, photodetector, and heterojunction bipolar transistor”
  26. 5,656,515       “Method of making high-speed double-heterostructure bipolar transistor devices”
  27. 5,625,206       “High-speed double-heterostructure bipolar transistor devices”
  28. 5,577,139       “Integrated-circuit optical network unit”
  29. 5,577,138       “Integrated-circuit optical network unit”
  30. 5,063,426       “InP/InGaAs monolithic integrated photodetector and heterojunction bipolar transistor”

Honors & Awards

1.       Distinguished Member of Technical Staff (DMTS), Bell Labs, 1999.

2.       IEEE LEOS Engineering Achievement Award, 2000.

3.       Fellow, IEEE, 2001, for “contributions to the design and development of 155 um opto-electronic integrated circuits for wide-spectrum application in optical communications

4.       Member, RZ-DPSK Team, Central Bell Labs Teamwork Award 2002.

5.       OSA Paul F. Foreman Engineering Excellence Award, 2004.

6.       Member, 100Gb/s Coherent (Long Haul – High Capacity WDM Interface) Team, Bell Labs President’s Award 2010.

7.       Fellow, OSA, 2012, for “seminal contributions to high-performance opto-electronic integrated circuits, wavelength division multiplexed transmission and high-capacity coherent optical transmission”.

8. 2015 Outstanding Reviewer Recognition, OSA, 2015.

9. Fellow, Bell Labs, Alcatel-Lucent, December 2015.