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Modified low-bandwidth sub-Nyquist sampling receiving scheme in an IM/DD OFDM system enabled by improved optical
Optics Express
|October 15, 2022
Summary
This study introduces a novel optical shaping technique for low-bandwidth sub-Nyquist sampling in intensity modulation/direct detection (IM/DD) orthogonal frequency-division multiplexing (OFDM) systems. The method reduces analog-to-digital converter (ADC) requirements and improves receiver sensitivity for high-capacity networks.
Area of Science:
- Optical Communications
- Signal Processing
- Next-Generation Networks
Background:
- Current intensity modulation/direct detection (IM/DD) orthogonal frequency-division multiplexing (OFDM) systems face challenges with high analog-to-digital converter (ADC) bandwidth requirements.
- Sub-Nyquist sampling offers a potential solution but requires advanced signal processing techniques.
Purpose of the Study:
- To investigate a modified low-bandwidth sub-Nyquist sampling receiving scheme using optical shaping for IM/DD OFDM systems.
- To reduce the sampling rate and analog bandwidth of the ADC.
- To enhance receiver sensitivity and system feasibility.
Main Methods:
- Implementation of a modified low-bandwidth sub-Nyquist sampling scheme enabled by optical shaping.
- Utilizing a phase matrix for data group distinction via shaping module delay.
- Employing an RF sharing architecture for cost reduction and feasibility.
- Applying arcsine digital pre-distortion (DPD) for optical pulse shaping and improved spectrum aliasing control.
Main Results:
- Experimental demonstration of a 12.5-GHz/44.45-Gbit/s IM/DD OFDM system with a low-bandwidth (3.125 GHz) and sub-Nyquist sampling rate (6.25 GSa/s) ADC.
- Achieved effective low-bandwidth reception.
- Demonstrated approximately 0.4 dB receiver sensitivity improvement at a bit error rate (BER) of 3.8×10⁻³.
- Successful transmission over 10.2 km of standard single-mode fiber.
Conclusions:
- The proposed optical shaping scheme effectively enables low-bandwidth reception in IM/DD OFDM systems.
- The scheme offers improved receiver sensitivity and reduced ADC requirements.
- This approach is a promising low-cost solution for achieving high transmission capacity in next-generation networks.
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