Partial response signaling for improved chromatic dispersion tolerance in intensity modulation optical transmissions

Area of Science:

• Optical Communications
• Signal Processing
• Digital Transmission

Background:

• Direct detection optical systems face limitations in transmission length.
• On-Off-Keying (OOK) is a conventional modulation technique.
• Advanced modulation schemes are needed to enhance optical link performance.

Purpose of the Study:

• To investigate Partial Response Signaling (PRS) for increasing transmission length in direct detection optical systems.
• To evaluate the performance of duobinary and PRS modulations against OOK.
• To assess the impact of equalization on PRS performance.

Main Methods:

• Simulations were used to model and analyze modulation performance.
• Experimental validation was conducted to confirm simulation results.
• Performance was compared across On-Off-Keying (OOK), duobinary, and Partial Response Signaling (PRS) schemes.

Main Results:

• Duobinary modulation increased link distance by up to 1.5 times compared to OOK without signal processing.
• Partial Response Signaling (PRS) increased link distance by up to 3 times compared to OOK without signal processing.
• The performance gains from duobinary and PRS were maintained even when equalization techniques were applied.
• PRS with 4-level pulse-amplitude modulation (PAM-4) also demonstrated a significant improvement, nearly tripling transmission distance.

Conclusions:

• Partial Response Signaling (PRS) is a highly effective technique for extending transmission distances in direct detection optical systems.
• Duobinary modulation offers a moderate increase in link distance.
• The benefits of PRS are robust and persist even with the inclusion of equalization, making it suitable for practical optical communication systems.