Model-based spectral shaping technique for WSSs with insertion loss and ripple penalties consideration

Area of Science:

• Optical communication systems
• Photonics and optoelectronics
• Signal processing in optical networks

Background:

• Cascaded wavelength-selective switches (WSSs) cause bandwidth narrowing, limiting high-baud rate communication performance.
• Spectral shaping via WSS attenuation control enhances channel bandwidth but faces challenges in optimal profile determination due to optical overlap and lack of physical models.
• The trade-off between bandwidth enhancement and penalties like insertion loss (IL) and ripple in WSS spectral shaping is not well understood.

Purpose of the Study:

• To develop a novel WSS filtering model for optimizing spectral shaping.
• To determine the optimal attenuation profile for enhanced channel bandwidth under IL and ripple constraints.
• To systematically investigate and quantify the trade-offs between bandwidth enhancement, IL, and ripple penalties.

Main Methods:

• A novel WSS filtering model was developed.
• The model was integrated into a gradient descent algorithm for iterative optimization of attenuation profiles.
• Simulations and experiments were conducted to quantify the relationship between bandwidth enhancement, IL, and ripple penalties.

Main Results:

• A practical strategy was identified, trading 0.5 dB IL and 0.3 dB ripple for bandwidth enhancement.
• Experimental validation showed mean bandwidth enhancements of 1.9 GHz (0.5-dB) and 0.76 GHz (3-dB) under the defined constraints.
• Close agreement was observed between simulation and experimental results.

Conclusions:

• The proposed WSS filtering model and optimization approach effectively enhance channel bandwidth.
• The study quantifies the achievable bandwidth enhancement against acceptable IL and ripple penalties.
• Findings provide valuable guidance for designing practical and high-performance optical communication systems using WSS spectral shaping.