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Memory-based pulse amplitude modulation for short-reach fiber communications with intensity modulation and direct
Optics Express
|July 14, 2016
Summary
This study introduces memory-based Pulse Amplitude Modulation (PAM) to enhance fiber optic communication systems. Memory-based PAM improves tolerance to fiber dispersion, extending transmission distances for high-speed data.
Area of Science:
- Optical Communications
- Signal Processing
Background:
- Intensity modulation and direct detection systems are cost-effective for short-reach fiber communications.
- High-order Pulse Amplitude Modulation (PAM) combined with Maximum Likelihood Sequence Estimation (MLSE) extends transmission length.
- Fiber dispersion limits transmission distance in optical systems.
Purpose of the Study:
- To improve the performance of PAM systems in dispersive fiber channels.
- To propose a memory-based PAM technique for spectrum compression.
- To enhance the achievable fiber transmission length.
Main Methods:
- Introduced memory into PAM for spectrum compression.
- Implemented memory-based PAM using simple pre-coding at the transmitter.
- Evaluated system performance using theoretical analysis and simulations.
Main Results:
- Memory-based PAM exhibits a smaller mainlobe bandwidth, increasing tolerance to fiber dispersion.
- Memory-based PAM-4 extends maximum transmission length from 60km to 70km compared to memory-less PAM-4.
- An optimized memory-based PAM further extends achievable fiber transmission length.
Conclusions:
- Memory-based PAM is an effective technique for improving optical communication system performance in dispersive channels.
- The proposed method enhances transmission distance without additional receiver complexity.
- Further optimization of memory-based PAM can lead to even greater transmission length extensions.
