S. Ibrahim, A. D. Ellis, F. C. G. Gunning, F. H. Peters,
"Demonstration of CoWDM using DPSK modulator array with injection-locked lasers,"
Electron. Lett. 46, 150-152 (2010).

P. J. Winzer, M. Pfennigbauer, R. J. Essiambre, "Coherent
crosstalk in ultradense WDM systems," IEEE J. Lightw. Technol. 23, 1734-1744
(2010).

A. D. Ellis, J. Zhao, D. Cotter, "Approaching the non-linear
Shaonnon limit," IEEE J. Lightw. Technol. 28, 423-433 (2010).

S. L. Jansen, A. A. Amin, H. Takahashi, I. Morita, H. Tanaka,
"132.2-Gb/s PDM-8QAM-OFDM transmission at 4-b/s/Hz spectral efficiency," IEEE
Photon. Technol. Lett. 21, 802-804 (2009).

A. Sano, E. Yamada, H. Masuda, E. Yamazaki, T. Kobayashi, E.
Yoshida, Y. Miyamoto, R. Kudo, K. Ishihara, Y. Takatori, "No-guard-interval
coherent optical OFDM for 100 Gb/s long-haul WDM transmission," IEEE J. Lightw.
Technol. 27, 3705-3713 (2009).

S. Chandrasekhar, X. Liu, "Experimental investigation on the
performance of closely spaced multi-carrier PDM-QPSK with digital coherent
detection," Opt. Exp. 17, 21350-21361 (2009).

W. Shieh, H. Bao, Y. Tang, "Coherent optical OFDM: Theory and
design," Opt. Exp. 16, 841-859 (2008).

A. J. Lowery, L. B. Du, J. Armstrong, "Performance of optical OFDM
in ultra long-haul WDM lightwave systems," IEEE J. Lightw. Technol. 25, 131-138
(2007).

G. Goldfarb, G. Li, M. G. Taylor, "Orthogonal wavelength division
multiplexing using coherent detection," IEEE Photon. Technol. Lett. 19, 2015-2017
(2007).

F. C. G. Gunning, T. Healy, A. D. Ellis, "Dispersion tolerance of
coherent WDM," IEEE Photon. Technol. Lett. 18, 1338-1340 (2006).

A. D. Ellis, F. C. G. Gunning, "Spectral density enhancement using
coherent WDM," IEEE Photon. Technol. Lett. 17, 504-506 (2005).

S. B. Weinstein, P. M. Ebert, "Data transmission by frequency
division multiplexing using the discrete Fourier transform," IEEE Trans. Commun.
Technol. COM-19, 628-634 (1971).

R. W. Chang, "Synthesis of band-limited orthogonal signals for
multi-channel data transmission," Bell Syst. Tech. J. 45, 1775-1796
(1966).

R. W. Chang, "Synthesis of band-limited orthogonal signals for
multi-channel data transmission," Bell Syst. Tech. J. 45, 1775-1796
(1966).

S. Ibrahim, A. D. Ellis, F. C. G. Gunning, F. H. Peters,
"Demonstration of CoWDM using DPSK modulator array with injection-locked lasers,"
Electron. Lett. 46, 150-152 (2010).

A. Sano, E. Yamada, H. Masuda, E. Yamazaki, T. Kobayashi, E.
Yoshida, Y. Miyamoto, R. Kudo, K. Ishihara, Y. Takatori, "No-guard-interval
coherent optical OFDM for 100 Gb/s long-haul WDM transmission," IEEE J. Lightw.
Technol. 27, 3705-3713 (2009).

P. J. Winzer, M. Pfennigbauer, R. J. Essiambre, "Coherent
crosstalk in ultradense WDM systems," IEEE J. Lightw. Technol. 23, 1734-1744
(2010).

A. J. Lowery, L. B. Du, J. Armstrong, "Performance of optical OFDM
in ultra long-haul WDM lightwave systems," IEEE J. Lightw. Technol. 25, 131-138
(2007).

A. D. Ellis, J. Zhao, D. Cotter, "Approaching the non-linear
Shaonnon limit," IEEE J. Lightw. Technol. 28, 423-433 (2010).

S. L. Jansen, A. A. Amin, H. Takahashi, I. Morita, H. Tanaka,
"132.2-Gb/s PDM-8QAM-OFDM transmission at 4-b/s/Hz spectral efficiency," IEEE
Photon. Technol. Lett. 21, 802-804 (2009).

G. Goldfarb, G. Li, M. G. Taylor, "Orthogonal wavelength division
multiplexing using coherent detection," IEEE Photon. Technol. Lett. 19, 2015-2017
(2007).

A. D. Ellis, F. C. G. Gunning, "Spectral density enhancement using
coherent WDM," IEEE Photon. Technol. Lett. 17, 504-506 (2005).

F. C. G. Gunning, T. Healy, A. D. Ellis, "Dispersion tolerance of
coherent WDM," IEEE Photon. Technol. Lett. 18, 1338-1340 (2006).

S. B. Weinstein, P. M. Ebert, "Data transmission by frequency
division multiplexing using the discrete Fourier transform," IEEE Trans. Commun.
Technol. COM-19, 628-634 (1971).

W. Shieh, H. Bao, Y. Tang, "Coherent optical OFDM: Theory and
design," Opt. Exp. 16, 841-859 (2008).

S. Chandrasekhar, X. Liu, "Experimental investigation on the
performance of closely spaced multi-carrier PDM-QPSK with digital coherent
detection," Opt. Exp. 17, 21350-21361 (2009).

X. Liu, S. Chandrasekhar, B. Zhu, D. W. Peckham, "Efficient
digital coherent detection of a 1.2 Tb/s 24-carrier no-guard-interval Co-OFDM
signal by simultaneously detecting multiple carriers per sampling," Proc. Opt.
Fiber Commun. Conf.OWO2 (2010) pp. 1-3.

H. Sanjoh, E. Yamada, Y. Yoshikuni, "Optical orthogonal frequency
division multiplexing using frequency/time domain filtering for high spectral
efficiency up to 1 bit/s/Hz," Optical Fiber Communication Conf., AnaheimCA (2002)
Paper ThD1.

A. Sano, H. Masuda, E. Yoshida, T. Kobayashi, E. Yamada, Y.
Miyamoto, F. Inuzuka, Y. Hibino, Y. Takatori, K. Hagimoto, T. Yamada, Y. Sakamaki,
"30$\,\times\,$100 Gb/s all-optical OFDM transmission over 1300 km SMF with 10
ROADM nodes," Eur. Conf. Optical Communication BerlinGermany (2007) Paper
PD1.7.

K. Takiguchi, M. Oguma, T. Shibata, H. Takahashi, "Optical OFDM
demultiplexer using silica PLC based optical FFT circuit," Proc. Opt. Fiber
Commun. Conf. (2009) pp. 1-3.

D. O. North, An Analysis of the Factors Which Determine
Signal/Noise Discrimination in Pulse Carrier Systems RCA Tech. Report no. 6,
PTR-6C (1943).

J. Proakis, Digital Communication (McGraw-Hill,
2001).

M. O'Sullivan, K. Roberts, C. Bontu, "Electronic dispersion
compensation techniques for optical communication systems," Proc.Eur. Conf. Opt.
Commun. (2005) pp. 189-190.

X. Zhou, J. Yu, M. F. Huang, Y. Shao, T. Wang, L. Nelson, P.
Magill, M. Birk, P. I. Borel, D. W. Peckham, R. Lingle, "64 Tb/s
(640$\,\times\,$107 Gb/s) PDM-36QAM transmission over 320 km using both pre- and
post-transmission digital equalization," Proc. Opt. Fiber Commun. Conf. (2010) pp.
1-3.

G. Gavioli, E. Torrengo, G. Bosco, A. Carena, V. Curri, V. Miot,
P. Poggiolini, M. Belmonte, F. Forghieri, C. Muzio, S. Piciaccia, A. Brinciotti,
A. L. Porta, C. Lezzi, S. Savory, S. Abrate, "Investigation of the impact of
ultra-narrow carrier spacing on the transmission of a 10-carrier 1 Tb/s
superchannel," Proc. Opt. Fiber Commun. Conf. (2010) pp. 1-3.

J. Zhao, A. D. Ellis, "Electronic signal processing for crosstalk-
and ISI-free operation in all-optical OFDM," Proc. Eur. Conf. Opt. Commun. (2010)
pp. 1-3.

T. Ellermeyer, J. Mullrich, J. Rupeter, H. Langenhagen, A. Bielik,
M. Moller, "DA and AD converters for 25 GS/s and above," Proc. IEEE/LEOS Summer
Top. Meetings (2008) pp. 117-118.

R. I. Killey, P. M. Watts, P. Bayvel, "Electronic pre-compensation
techniques to combat dispersion and nonlinearities in optical transmission," Proc.
Eur. Conf. Opt. Commun. (2005) pp. 251-254.

I. P. Kaminow, T. Li, A. E. Willner, Optical Fiber
Telecommunications V B (Elsevier, 2008).