Good morning

Silicon photonics is a promising technology to realize low-cost and energy-effcient optical links for emerging short-reach intra-rack and rack-to-rack interconnects in data-center and high-performance computing applications.

This technology also enables high-radix network switches, scalable interconnect fabric for future memory systems, and core-to-core crossbars once it is integrated with the large-scale electronic system-on-chips.

The high performance in all of the above mentioned applications requires tightly integrated electronic-photonic circuits. Various integration strategies have been utilized to meet these demands including hybrid, heterogeneous via 3D-stacking, and monolithic integration. Among these, monolithic integration has the potential for reliable, low-cost, and large-scale integration, while being most promising in terms of energy-effciency and bandwidth density.

Optical Interconnects

Light-based data transfer and communication have been firstly deployed about 30 years ago in transatlantic links connecting Europe and America. The low loss of fiber optics (0.2 dB/km at 1550nm wavelength) compared with copper wires was the main attraction for optical links. As the demand for higher-data rates grew, the copper channel losses (which are frequency dependent) drastically increased even at short distances and this caused considerable energy penalties in electrical transceivers.

As an example, a 5m copper cable with 50 dB loss has been deployed for 28Gb/s data communication and the transceiver energy-effciency of 15 pJ/b.

Just to compare with optical links, with almost the same energy-effciency and data-rate, we can communicate data over more than 2 km. Furthermore, more advanced CMOS nodes could not alleviate this issue as the limit is imposed by the channel loss mechanisms. Today, even on-board electrical signaling for distances of 12-inch traces is facing serious challenges as demand for data-rates increases above 25Gb/s typically consuming around 10 pJ/b.

Optical interconnects achieving high energy-effciency and bandwidth density can break the electrical signaling barriers and empower future computing and communication systems. Designing energy-effcient photonic transceivers with high-bandwidth density can revolutionize the interconnection paradigms in applications where copper wires cannot reach. Additionally, achieving ultra-high energy effciencies of sub-1 pJ/b for shortreach links such as on-board signaling can also brings the new opportunities for optical links as well.

Itching to find out whats next with poet: modulator implementation !

Cheers