In-band OSNR monitoring using a pair of Michelson fiber interferometers

Abstract

Two polarization-independent Michelson fiber interferometers with different optical delays were used to measure the in-band OSNR of an optical signal from 5 to 30dB within an accuracy of 0.5dB. Using an expansion of the amplitude autocorrelation function of the signal around zero delay, it was possible to perform measurements without any prior knowledge of the signal. The system is shown to be immune to the effects of modulation frequency (up to 10G), partially and fully polarized noise, chromatic dispersion and poorly biased modulators.

Towards Large-Scale Fast Reprogrammable SOA-Based Photonic Integrated Switch Circuits

“…In particular, the optical signal-to-noise ratio (OSNR) monitoring can provide information on the intra-chip signal transmission quality. Intra-chip OSNR measurement has been demonstrated through both discrete [37] and integrated [38][39][40] solutions, but has never been integrated within a switching circuit. However, the most advanced circuits do already contain the essential components.…”

In-band OSNR monitor based on Mach Zehnder DLI interferometer for polarization multiplexed signals

“…It is also possible to use a Mach Zehnder interferometer to calculate the OSNR based on coherence difference between signal and noise [6][7][8][9], but for all these methods when applied to the real network environment with polarization multiplexed signals, it imposes constraints on its applicability. Although [8] describes an interferometric OSNR estimation method for polarization multiplexed signals, this method does not have precision to monitor signals filtered at 50GHz and with bit rate beyond 100Gbps and modulation format such as DP-QPSK (dual polarization quadrature phase shift keyed) and N-QAM (quadrature amplitude modulation).…”

“…This interference pattern in the photodetector can be expressed in terms of the autocorrelation function of the signal and noise, as described by the voltage on the equation 1 [8], which comes from the electrical current with a unitary trans impedance gain.…”

A Fully-integrated In-band OSNR Monitor using a Wavelength-tunable Silicon Microring Resonator and Photodiode

“…However, this technique may not be accurate when the noise is partially polarized or in the presence of polarization-mode dispersion (PMD), and it is difficult to realize in integrated optics. Another method, based on mach-zehnder interferometry [4][5][6], requires the prior knowledge of the signal amplitude autocorrelation function and therefore typically requires system calibration by turning off the noise and scanning signal interference [6]. Recently several efforts [7][8][9] have been made to realize OSNR monitoring in an integrated fashion, however these demonstrations still require discrete and bulky off-chip components such as power meters.…”