Power-Efficient Coherent Optical Transceiver for Data Centers

Background

Intra-datacenter traffic has increased significantly in the past few years, placing increasingly stringent cost and power consumption requirements on optical transceivers. As both the start and end point in fiber-optic communications, optoelectronic transceivers have the potential to increase the efficiency of fiber-optic communications; however, current optoelectronic transmitters have limitations imposed by fabrication. Many optoelectronic transmitters are fabricated based on narrow-band ring-resonator modulators, which can be very sensitive to process and temperature variations compared to Mach-Zehnder modulators (MZMs). There is a need for optical transceivers that are power-efficient and can provide high-speed data transfer over long distances.

Description

Researchers at the University of California, Santa Barbara have developed a scalable optoelectronic transceiver that combines tunable traveling-wave modulation and analog coherent reception to support power-efficient, high-speed optical links. This technology integrates traveling-wave Mach-Zehnder modulators, driver biasing, optical amplification, and wavelength and polarization multiplexing with analog coherent receivers. The receiver separates polarization channels and uses local-oscillator detection and feedback-based control to recover transmitted signals, supporting wavelength-multiplexed communication for data-center networks.

• Patent application: https://patents.google.com/patent/US20240089001A1/en
• Publication: https://ieeexplore.ieee.org/document/9606026

Advantages

• Enables high-speed, power-efficient data transmission over optical links
• Coherent detection provides greater link margin than conventional intensity-modulation direct detection
• Tunable modulator biasing offers flexibility to balance bandwidth, modulation efficiency, and optical loss
• Supports polarization and wavelength multiplexing to increase link capacity
• O-band operation near the fiber dispersion minimum can reduce digital signal-processing requirements
• Analog coherent detection can avoid the need for highly linear electronics, helping reduce power consumption

Applications

• Intra-datacenter optical interconnects and network switches
• Short-reach optical links, including links under 2 km
• High-capacity wavelength-division and polarization-multiplexed networks
• Silicon photonics transceivers for scalable data-center infrastructure
• Optical communication systems requiring low energy per bit and high-speed transmission

Patent Status