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Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Quality parameter for coherent transmissions with Gaussian-distributed nonlinear noise.
Edouard Grellier1, Alberto Bononi
1Alcatel-Lucent, Bell Labs, Centre de Villarceaux, Route de Villejust, 91620, Nozay, France. ard.grellier@alcatel-lucent.com
Optics Express
|July 1, 2011
Summary
This study introduces a new quality parameter for coherent optical communication systems, identifying an optimal power level that balances nonlinear and amplified spontaneous emission noise for maximum signal quality. This nonlinear threshold offers a 1.76 dB signal-to-noise ratio penalty compared to linear propagation.
Area of Science:
- Optical communication systems engineering
- Signal processing in optical networks
- Nonlinear optics in fiber communications
Background:
- Coherent optical systems are susceptible to nonlinear noise and amplified spontaneous emission (ASE).
- Characterizing system performance under combined noise sources is crucial for high-speed data transmission.
- Existing quality parameters may not fully capture performance trade-offs in nonlinear regimes.
Purpose of the Study:
- To introduce and analyze a new quality parameter for coherent receivers, analogous to signal-to-noise ratio (SNR) at the sampling gate.
- To determine the optimal operating power (nonlinear threshold) that maximizes this quality parameter.
- To investigate the relationship between nonlinear noise, ASE noise, and the resulting Q-factor and SNR penalties.
Main Methods:
- Analytical derivation of a new quality parameter assuming signal-independent circular Gaussian nonlinear noise.
- Investigation of the quality parameter's behavior across varying power levels and ASE noise.
- Verification of analytical findings using the polarization-division multiplexing quadrature phase shift keying (PDM-QPSK) modulation format.
Main Results:
- The maximum Q-factor is achieved at the nonlinear threshold, where ASE noise power is twice the nonlinear noise power.
- At the nonlinear threshold, the SNR penalty relative to linear propagation is approximately 1.76 dB.
- SNR and Q-factor maxima exhibit a linear decrease with increasing ASE power, with distinct slopes for SNR (~-2 dB/dB) and Q-factor (~-2.7 dB/dB for PDM-QPSK).
Conclusions:
- The proposed quality parameter provides valuable insights into system performance under nonlinear impairments.
- The identified nonlinear threshold offers a practical operating point for optimizing coherent system performance.
- The study quantifies performance penalties and provides guidance for system design in non-dispersion managed links.
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