Constellation diagram analysis of DPSK signal regeneration in a saturated parametric amplifier.
The regeneration of 10 Gbit/s differential phase shift keying (DPSK) signals in a saturated fiber optic parametric amplifier (FOPA) acting as an optical intensity regenerator is investigated. The regeneration properties are investigated in amplitude and phase separately by means of coherent detection and constellation diagram analysis. A significant reduction of the amplitude fluctuations is observed and the measured signal-to-noise ratio (SNR) after DPSK demodulation is increased up to 10 dB. However, from the constellation analysis it is found that the FOPA introduces phase noise to the signal. The FOPA induced phase noise originates from pump amplitude fluctuations that are transferred to the signal through cross-phase modulation.
Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Göteborg, Sweden. mats.skold@chalmers.se
Mats
M
Sköld
Jiang
J
Yang
Henrik
H
Sunnerud
Magnus
M
Karlsson
Shoichiro
S
Oda
Peter A
PA
Andrekson
D000669:Amplifiers, Electronic; D012815:Signal Processing, Computer-Assisted