Very high-capacity short-reach VCSEL systems exploiting multicarrier intensity modulation and direct detection

Area of Science:

• Optical communications
• Photonics
• Signal processing

Background:

• Bandwidth limitations in Vertical-Cavity Surface-Emitting Lasers (VCSELs) hinder high-capacity short-reach optical systems.
• Direct detection systems often face challenges with non-uniform frequency responses in optical fiber transmission.

Purpose of the Study:

• To develop a high-capacity, simple optical communication system for short-reach applications.
• To overcome the inherent bandwidth limitations of VCSELs and fiber optic channels.

Main Methods:

• Exploiting multicarrier intensity modulation with a bandwidth-limited long-wavelength VCSEL.
• Employing direct detection and tailored Frequency Division Multiplexing (FDM) subcarrier modulation and allocation.
• Compensating for non-uniform system frequency response caused by direct modulation, detection, and Single-Mode Fiber (SMF) propagation.

Main Results:

• Demonstrated a whole transported throughput ranging from 34 Gb/s to 25 Gb/s.
• Achieved these data rates over Single-Mode Fiber (SMF) propagation distances from a few hundred meters to 20 km.
• Successfully utilized a 5-GHz band VCSEL source, overcoming its bandwidth limitations.

Conclusions:

• Multicarrier intensity modulation combined with direct detection offers a viable solution for high-capacity short-reach optical systems.
• Tailored FDM strategies effectively compensate for system impairments, enabling high data rates even with limited VCSEL bandwidth.
• The experimental results validate the proposed system's performance for practical short-reach optical communication applications.