Experimental demonstration of pre-electronic dispersion compensation in IM/DD systems using an iterative algorithm.
Optics Express
|October 7, 2021
Summary
An iterative pre-electronic dispersion compensation (pre-EDC) algorithm effectively combats chromatic dispersion in intensity modulation and direct detection systems. This method enables high-capacity optical communication by achieving near forward error correction thresholds for various signal types and distances.
Area of Science:
- Optical Communications
- Signal Processing
- Photonics
Background:
- Chromatic dispersion (CD) significantly limits data rates in intensity modulation and direct detection (IM/DD) systems.
- Effective dispersion compensation is crucial for achieving high-capacity optical transmission over single mode fiber (SMF).
Purpose of the Study:
- To demonstrate chirp-free optical signal transmission using an iterative pre-electronic dispersion compensation (pre-EDC) algorithm.
- To evaluate the performance of the pre-EDC algorithm in IM/DD systems with different modulation formats and distances.
Main Methods:
- Experimental implementation of an iterative pre-EDC algorithm based on the Gerchberg-Saxton (GS) algorithm at the transmitter.
- Utilizing a linear fractionally-spaced (T/2) post-feed-forward equalizer (post-FFE) at the receiver to mitigate residual inter-symbol interference (ISI).
- Testing the system with 28 GBaud NRZ-OOK, 56 GBaud NRZ-OOK, and 28 GBaud PAM-4 signals over 100 km, 50 km, and 40 km of SMF, respectively.
Main Results:
- Successful chirp-free transmission achieved for all three demonstrations.
- Bit error rate (BER) thresholds close to the forward error correction (FEC) limit of 3.8 × 10-3 were reached with optimized pre-EDC iterations and post-FFE taps.
- Specific iteration and tap counts for each demonstration: (15 pre-EDC, 5-tap post-FFE), (30 pre-EDC, 15-tap post-FFE), and (10 pre-EDC, 25-tap post-FFE).
Conclusions:
- The iterative pre-EDC algorithm is a viable solution for mitigating chromatic dispersion in high-capacity IM/DD systems.
- The algorithm demonstrates applicability for SMF transmission distances up to 100 km.
- The combination of pre-EDC and a simple post-FFE enables robust optical data transmission.
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