Optical LDPC decoders for beyond 100 Gbits/s optical transmission

Area of Science:

• Optical communications engineering
• Information theory
• Digital signal processing

Background:

• High-speed optical communication systems require efficient error correction.
• Existing decoders face limitations in speed and coding gain.
• Low-density parity-check (LDPC) codes offer powerful error correction capabilities.

Purpose of the Study:

• To present a novel optical low-density parity-check (LDPC) decoder.
• To achieve implementation speeds exceeding 100 Gbits/s.
• To demonstrate significant coding gains with large-girth LDPC codes.

Main Methods:

• Implementation of a probabilities multiplier circuit using a Mach-Zehnder interferometer.
• Proposal and simulation of a probabilistic-domain sum-product algorithm (SPA).
• Fully parallel implementation using girth-10 LDPC codes and the proposed SPA.

Main Results:

• The optical LDPC decoder operates above 100 Gbits/s.
• A girth-10 LDPC(24015,19212) code (rate 0.8) demonstrated superior performance.
• Achieved a net effective coding gain of 10.09 dB, outperforming a turbo-product code by 0.91 dB at 100 Gbits/s (BER 10^-9).

Conclusions:

• The proposed optical LDPC decoder enables high-speed, high-performance error correction.
• Mach-Zehnder interferometer-based circuits are suitable for probabilistic computations in decoders.
• This technology offers a significant advancement for future optical communication systems.