DBPSK and DQPSK crosstalk in single-span WDM systems using DRA

Area of Science:

• Optical communications
• Nonlinear optics
• Fiber optics

Background:

• Wavelength-division multiplexing (WDM) systems are susceptible to nonlinear crosstalk.
• Self-phase modulation (SPM) and cross-phase modulation (XPM) significantly degrade signal quality.
• Differential phase-shift keying (DPSK) schemes are commonly used in optical systems.

Purpose of the Study:

• To derive a closed-loop formula for nonlinear crosstalk in WDM systems.
• To analyze crosstalk in differential binary phase-shift keying (DBPSK) and differential quadrature phase-shift keying (DQPSK) schemes.
• To evaluate system performance using standard single-mode fiber and distributed Raman amplifiers.

Main Methods:

• Derivation of a closed-loop formula for nonlinear crosstalk.
• Investigation of crosstalk effects in DBPSK and DQPSK modulation formats.
• Simulation and analysis of a single-span fiber system with distributed Raman amplification.

Main Results:

• A closed-loop formula accurately models nonlinear crosstalk.
• Backward DBPSK exhibits better crosstalk performance than backward DQPSK.
• Minimum crosstalk performance reached 71% for backward DBPSK.

Conclusions:

• The derived formula provides a valuable tool for analyzing nonlinear crosstalk in WDM systems.
• Backward DBPSK is a more robust modulation scheme against nonlinear crosstalk in this configuration.
• System design should consider modulation format choice for optimal performance in the presence of nonlinear effects.