In-band optical signal-to-noise ratio monitoring method based on high-resolution polarization analysis and induced differential group delay.
We report on an in-band optical signal-to-noise ratio monitoring technique for wavelength division multiplexed channels. Our proposal relies on the different degree of polarization between the signal (highly polarized) and the noise (not polarized). Using this principle, we divide the signal under test into two orthogonal polarization components and induce a differential group delay via a controlled birefringence apparatus that produces a wavelength-dependent shift of the polarization state of the signal. After a linear polarizing filter, high-resolution spectral analysis allows measurement of the amplified spontaneous emission noise level. The method is tested by experimental measurements of a 40 Gbit/s differential phase-shift keying channel showing very good performance.
Photonics Technology Group (GTF), Aragon Institute for Engineering Research (I3A), University of Zaragoza, PT Walqa, Cuarte, Huesca 22197, Spain. jjosemar@unizar.es
Juan José
JJ
Martínez
Asier
A
Villafranca
Carlos D
CD
Heras
Maria I
MI
Roche
Jesús M
JM
Subias
Javier
J
Pelayo
Enrique
E
Pellejer
Pilar
P
Blasco
Juan I
JI
Garcés