Modified low CSPR Kramer-Kronig receivers based on a signal-signal beat interference estimation

Area of Science:

• Optical communications
• Signal processing

Background:

• Single-sideband transmission with Kramer-Kronig (KK) receivers is suitable for 80 km data center interconnects due to structural simplicity and robustness.
• Traditional KK receivers require a high carrier signal power ratio (CSPR) to mitigate signal-signal beat interference (SSBI), which compromises receiver sensitivity.

Purpose of the Study:

• To propose and evaluate modified KK receivers capable of estimating and eliminating SSBI.
• To enable signal detection at lower CSPR values, improving receiver sensitivity and reducing system costs.

Main Methods:

• Development of two novel KK receiver architectures designed to address SSBI.
• Experimental transmission over an 80 km optical fiber link to assess performance.

Main Results:

• Modified KK receivers increased receiver sensitivity by 3 dB compared to traditional KK receivers at a reduced CSPR of 6 dB.
• Achieved optical signal-to-noise ratio (OSNR) improvements of 1.16 and 1.60 dB with an 8 dB CSPR reduction.
• Demonstrated successful signal detection with CSPR below 0 dB.

Conclusions:

• The proposed modified KK receivers effectively mitigate SSBI, allowing for lower CSPR operation.
• These advancements significantly enhance receiver sensitivity and OSNR, while reducing the necessary carrier power and overall system cost.