PAM-4 transmission up to 160  Gb/s with surface-normal electro-absorption modulators

Area of Science:

• Photonics
• Optical Communications
• Semiconductor Devices

Background:

• Surface-normal electro-absorption modulators (SNEAMs) are crucial for optical interconnects.
• Achieving high-speed, multi-level modulation is essential for increasing data transmission capacity.
• Polarization-independent operation simplifies system design and enhances robustness.

Purpose of the Study:

• To investigate and demonstrate multi-level modulation capabilities in polarization-independent SNEAMs.
• To achieve record-breaking data rates for SNEAM technology.
• To assess the performance of SNEAMs in direct-detection fiber transmission systems.

Main Methods:

• Fabrication and packaging of SNEAM devices with varying active area diameters (15 µm and 30 µm).
• Characterization of electro-optic bandwidth, achieving over 65 GHz for unpackaged devices.
• Demonstration of Four-Level Pulse Amplitude Modulation (PAM-4) at line rates of 44, 112, and 160 Gb/s.
• Direct detection fiber transmission experiments up to 23 km.

Main Results:

• Demonstrated 44 Gb/s PAM-4 on a packaged SNEAM with a 30 µm active area and 14 GHz bandwidth.
• Achieved 112 Gb/s and 160 Gb/s PAM-4 on an unpackaged SNEAM with a 15 µm active area and >65 GHz bandwidth.
• Successful fiber transmission up to 23 km at 44 Gb/s and 2 km at 112/160 Gb/s.

Conclusions:

• Polarization-independent SNEAMs are capable of high-capacity, multi-level modulation.
• The demonstrated SNEAMs achieve the highest multi-level modulation rates reported for this technology.
• These results highlight the potential of SNEAMs for future high-speed optical communication.