optics-2017-scientifictracks-abstracts

65 / 99

Page 111
Notes:
conferenceseries .com
Volume 4, Issue 4 (Suppl) J Laser Opt Photonics, an open access journal
ISSN: 2469-410X Optics 2017
November 15-17, 2017
November 15-17, 2017 | Las Vegas, USA
8th International Conference and Exhibition on
Lasers, Optics & Photonics
Improvement of optical transmission capacity by data compression and amplitude/phase/frequency
3-dimentional modulation
Dongsun Seo
Myongji University, Korea
In this talk, we discuss novel schemes that improve significantly the spectral efficiency (i.e., channel capacity) of an optical access
link. Firstly, an optical orthogonal frequency division multiplexing (OFDM) signal, which is encoded by multilevel quadrature
amplitude modulation (QAM), is compressed using the proposed sampling scheme sampled at a lower than conventional Nyquist
rate. At the receiver, the OFDM signal is recovered by a Bayesian compressive sensing (CS) technique. We show experimentally the
spectral efficiency improvement (i.e., data compression) up to <40% and <20% for 4-QAM and 16-QAM encoded OFDMwaveforms,
respectively. Secondly, we discuss channel capacity improvement by simultaneous modulation of amplitude, phase and frequency i.e.,
by combining frequency shift keying (FSK) and QAM. This 3-dimensional modulation so called NOFQAM, increases the modulation
order dramatically by multiplying both the FSK and QAM orders. Unlike a conventional orthogonal FSK modulation, the FSK
channels are overlapped in our non-orthogonal (NO) FSK modulation. Therefore, the NO-FSK modulation increases the channel
capacity at a fixed channel bandwidth. For experimental verification, we implement a 20-km optical access link, which transmits a
64-NOFQAM signal formed by combining both 4-FSK and 16-QAM. The symbol rate and FSK channel spacing are 200 M-symbol/s
and 45 MHz, respectively. Comparing to a 200 M-symbol/s 16-QAM transmission, the suggested 64-NOFQAM transmission shows
negligible increase in the occupied channel bandwidth and very small power penalty less than 0.5 dB. Finally, we apply the CS based
data compression technique to the 64-NOFQAM signal and show greater than 50% of data compression.
Biography
Dongsun Seo has received his PhD degree in Electrical Engineering (Optoelectronics) from the University of New Mexico in 1989. In 1990, he has joined the Faculty of
Myongji University, Korea, where he is currently a Professor in the Department of Electronics. From 2002 to 2004, he was with Purdue University, as a Visiting Research
Professor in the School of Electrical and Computer Engineering. He has published over 70 journal articles and over 100 conference papers. His current research interests
are in the areas of optical pulse sources, ultrafast optics, high-capacity optical communications, optical processing and photonics.
Dongsun Seo, J Laser Opt Photonics 2017, 4:4 (Suppl)
DOI: 10.4172/2469-410X-C1-017