OSNR Measurement Using Comparative Signal Spectra
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Solution Overview
Problem
Existing online in-band optical signal-to-noise ratio (OSNR) measurement methods are inadequate for quick and accurate measurement of arbitrary signals, particularly those with polarization-multiplexed signals, as they rely on assumptions about signal and noise polarization that do not apply universally, and are not suitable for signals with overlapping signal and noise spectra.
Innovation Solution
A method and device that measure OSNR by obtaining the spectrum of a signal of interest and a comparative signal with the same spectrum characteristics but different OSNR, using a splitter, optical processing device, and optical spectrum analyzer to calculate OSNR without additional polarization control or modulation devices, allowing for online measurement of arbitrary signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional online OSNR measurement methods are used, then measurement speed is improved, but measurement accuracy deteriorates for arbitrary signals including polarization-multiplexed signals
Solution Approach 1:
The patent changes the measurement approach by transforming the OSNR measurement problem into a spectrum analysis problem. Instead of relying on polarization assumptions or signal turning-off, the method uses spectral characteristics and power spectrum density distribution to calculate OSNR, enabling accurate measurement of arbitrary signals including polarization-multiplexed signals at high speeds
Solution Approach 2:
The patent creates a comparative signal that has the same spectrum characteristics as the signal of interest but with known OSNR. By comparing the spectrum of the signal of interest with the spectrum of the comparative signal, the system calculates the OSNR without needing to turn off the signal or make polarization assumptions, thus achieving both speed and accuracy
2Productivity
If polarization-based measurement methods are used, then online measurement capability is improved, but adaptability to arbitrary signals deteriorates
Solution Approach 1:
The patent develops a universal measurement method that works for any signal type including single-polarization, polarization-multiplexed, and arbitrary modulation formats. The method uses spectral characteristics that are common to all signals, making the measurement system universally applicable without requiring signal-specific adjustments or polarization assumptions
Solution Approach 2:
The patent shifts the measurement basis from polarization properties to spectral properties. By using power spectrum density distribution and comparing signals with known spectral characteristics, the system achieves online measurement capability while maintaining universal adaptability to any signal type regardless of polarization or modulation characteristics
3Measurement precision
If signal turning-off method is used, then in-band OSNR measurement accuracy is improved, but online measurement capability deteriorates
Solution Approach 1:
The patent uses a comparative signal that replicates the spectral characteristics of the signal of interest but with known OSNR. By comparing the two signals' spectra, the system can calculate the OSNR of the signal of interest without turning it off, thus maintaining online measurement capability while achieving accurate in-band OSNR measurement
Solution Approach 2:
The comparative signal acts as an intermediary reference that enables OSNR measurement without directly measuring the signal of interest in isolation. The comparative signal with known OSNR serves as a reference standard, allowing the system to calculate the OSNR of the signal of interest through spectral comparison while both signals remain active
4Productivity
If existing online measurement methods are used, then measurement speed is improved, but measurement precision for signals with overlapping spectra deteriorates
Solution Approach 1:
The patent changes the measurement approach by using power spectrum density distribution analysis instead of traditional power level measurement. This spectral analysis approach allows the system to distinguish between signal and noise components even when their spectra overlap, enabling both fast and accurate measurement for signals with overlapping spectra
Solution Approach 2:
The patent segments the measurement process into spectral characteristic analysis and power calculation steps. By analyzing the power spectrum density distribution and comparing spectral characteristics, the system can separate signal and noise components in the frequency domain, enabling accurate OSNR measurement even when time-domain signals overlap
Data Source
AI summary
Embodiments of the present invention relate to method and device for measuring optical signal-to-noise ratio (OSNR). A method for measuring an OSNR of a signal of interest may comprise: obtaining spectrum of the signal of interest, the spectrum including power spectrum density distribution of the signal of interest in a channel bandwidth B; obtaining spectrum of a comparative signal that has the same spectrum characteristics as but different OSNR than the signal of interest, the spectrum including power spectrum density distribution of the comparative signal in the channel bandwidth B; and calculating the OSNR of the signal of interest by using the spectrum of the signal of interest and the spectrum of a comparative signal.