Terence S.-Y. Chen
Latitude Design Systems
Abstract
Opto-electronic co-packaging and integration are enabling technologies for next-generation high-speed and high-capacity optical interconnects. This paper reviews the benefits of co-packaging photonic integrated circuits with electronic integrated circuits as well as monolithic integration approaches. Key benefits include increased bandwidth density, reduced power consumption, smaller footprint, and lower costs. These benefits are driving adoption in data center, telecom, and consumer device applications. Co-simulation tools like PIC Studio pSim empower designers to optimize integrated opto-electronic systems.
Introduction
The exponential growth in data traffic is driving demand for higher capacity optical interconnects. However, electrical interfaces are struggling to keep pace due to bandwidth limitations, power constraints, and costs. Opto-electronic co-packaging and integration promises to overcome these challenges by bringing optics closer to electronics.
In co-packaging, photonic and electronic dies are assembled into a single package, providing tight integration while leveraging existing manufacturing infrastructures. Monolithic integration fabricates photonic and electronic components on the same semiconductor substrate for maximum integration. Both approaches offer benefits over traditional discrete packaging and assembly.
This paper reviews the benefits of co-packaging and monolithic integration for optical interconnects. Applications in data centers, telecommunication networks, and consumer devices are discussed. The capabilities of pSim for co-simulation of integrated opto-electronic systems are also highlighted.
Increased Bandwidth Density
A key benefit of opto-electronic integration is increased aggregate bandwidth density, defined as total throughput per unit area. Bringing photonics into close proximity with electronics reduces the length of electrical connections. Shorter connections have higher usable bandwidth, allowing more data channels to be aggregated.
For example, a silicon photonics chip flip-chipped to a CMOS electronic chip achieves much higher connection density compared to wiring to a separate optical engine. This density advantage allows single co-packaged modules to reach multi-Terabit/s throughput.
Reduced Power Consumption
In addition to bandwidth gains, co-packaging and integration also reduce module power consumption. Eliminating power-hungry electrical interfaces and long printed circuit board traces cuts static power draw. Dynamic power also decreases since shorter connections require less driving power for high-speed signals. Co-design and co-simulation can optimize power-saving techniques like selectively turning off laser drivers during idle periods. This is especially impactful as bandwidth scales up. Overall, integrated modules can achieve over 50% power savings compared to discrete alternatives with equivalent throughput.
Smaller Footprint
Integration also dramatically reduces the physical footprint of optical interconnect modules. A silicon photonics transceiver chip is typically just a few millimeters squared, while a discrete optical engine often occupies >100 cm2. By eliminating inter-chip connections and combining multiple dies into a single package, the aggregate footprint decreases by 10x or more. This size reduction is critical for fitting more capacity into space-constrained systems like hyperscale data centers.
Lower Costs
In addition to physical footprint reduction, co-packaging and integration also lower costs by improving manufacturability and economies of scale. Established semiconductor assembly and packaging factories can leverage existing high-volume manufacturing capacity.
Optical testing and active alignment of components - expensive steps for disaggregated discrete modules - are minimized by accurate passive alignment during co-packaging. Overall, costs can be reduced by 2-3x versus traditional optical modules.
Key Applications
Data Centers Hyperscale data centers are deploying integrated optics to meet bandwidth demand driven by high-speed Ethernet, artificial intelligence, and cloud computing. Co-packaged optical engines provide 400+ Gb/s throughput in QSFP-DD and OSFP modules. Silicon photonics-based optical switch chips and co-packaged optics will enable highly efficient data center networks.
Telecom Networks In telecom, coherent optics are achieving over 1 Tb/s transmission in pluggable CFP2 modules by leveraging co-packaging. 5G wireless and fiber-to-the-home broadband require integrated PON ONU/ONT transceivers. Co-packaging also enables efficient microring modulators for next-gen dense wavelength division multiplexing (DWDM).
Consumer Devices Co-packaged optics will help satisfy the need for high-bandwidth in consumer devices like phones, laptops, AR/VR headsets, and gaming systems. already vendors like Intel and Lightelligence have demonstrated co-packaged optical I/O for laptops and tablets. Integration will be key to achieving cost targets for mass adoption.
pSim for Co-Simulation
To accelerate development of these types of integrated opto-electronic systems, designers need co-simulation tools. pSim enables schematic-driven co-simulation of photonic circuits, electronic circuits, and system environments. Advanced models, analyses, and post-processing empower designers to optimize designs without time-consuming fabrication cycles. Integrated opto-electronics requires a platform like pSim that unifies photonic, electronic, and systems modeling.
Conclusion
The benefits of opto-electronic co-packaging and integration are compelling: increased bandwidth density, reduced power consumption, smaller footprint, and lower costs. These advantages are driving adoption across datacom, telecom, and consumer applications. Co-simulation tools like pSim facilitate rapid design optimization. Continued development of packaging assembly, interconnect integration, and co-design methodologies will further unlock the potential of integrated optics.
Comments