DocumentCode :
1115992
Title :
Sensitivity enhancement using coherent heterodyne detection
Author :
Lachs, Gerard ; Zaidi, Syed M. ; Singh, Amit K.
Author_Institution :
Dept. of Electr. Eng., Univ. of South Florida, Tampa, FL, USA
Volume :
12
Issue :
6
fYear :
1994
fDate :
6/1/1994 12:00:00 AM
Firstpage :
1036
Lastpage :
1041
Abstract :
This paper focuses on some heretofore overlooked advantages of coherent detection (CD) over direct detection (DD) in optical fiber communication systems. The basis for these sensitivity improvements is the fact that the local laser in coherent fiber optic systems adds a large number of photons to the net received optical signal. Under these conditions, the Bohr correspondence principle enables us to treat the photodiode output signal classically. Specifically, the usual CD environment yields a photodiode output that can be regarded as a classical signal disturbed by Gaussian noise (central limit theorem). This detection process has been studied extensively, and there exist many powerful signal processing techniques that may be used to enhance system sensitivity. In particular, we utilize a sum of digitally modulated subcarriers to frequency modulate an optical carrier along with the aid of coherent detection to achieve 11.1 photons/b sensitivity as determined by computer simulation
Keywords :
correspondence principle; frequency modulation; optical links; optical modulation; photodetectors; photodiodes; random noise; sensitivity; Bohr correspondence principle; CD environment; Gaussian noise; central limit theorem; coherent fiber optic systems; coherent heterodyne detection; computer simulation; digitally modulated subcarriers; frequency modulate; local laser; net received optical signal; optical carrier; optical fiber communication systems; photodiode output; photodiode output signal; sensitivity enhancement; sensitivity improvements; signal processing techniques; system sensitivity; Digital modulation; Frequency modulation; Optical detectors; Optical fiber communication; Optical mixing; Optical modulation; Optical noise; Optical sensors; Optical signal processing; Photodiodes;
fLanguage :
English
Journal_Title :
Lightwave Technology, Journal of
Publisher :
ieee
ISSN :
0733-8724
Type :
jour
DOI :
10.1109/50.296196
Filename :
296196
Link To Document :
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