II-VI’s VCSEL approach for co-packaged optics

Co-packaged optics was a central theme at this year’s OFC show, held in San Diego. But the solutions detailed were primarily using single-mode lasers and fibre.

Vipul Bhatt

The firm II-VI is beating a co-packaged optics path using vertical-cavity surface-emitting lasers (VCSELs) and multi-mode fibre while also pursuing single-mode, silicon photonics-based co-packaged optics.   

For multi-mode, VCSEL-based co-packaging, II-VI is working with IBM, a collaboration that started as part of a U.S. Advanced Research Projects Agency-Energy (ARPA-E) project to promote energy-saving technologies.

II-VI claims there are significant system benefits using VCSEL-based co-packaged optics. The benefits include lower power, cost and latency when compared with pluggable optics.

The two key design decisions that achieved power savings are the elimination of the retimer chip - also known as a direct-drive or linear interface - and the use of VCSELs.

The approach - what II-VI calls shortwave co-packaged optics - integrates the VCSELs, chip and optics in the same package.

Click to read more ...

Broadcom discusses its co-packaged optics plans

If electrical interfaces are becoming an impediment, is co-packaged optics the answer? Broadcom certainly thinks so.

One reason for the growing interest in co-packaged optics is the input-output (I/O) demands of switch chips. If the packet processing capacity of such chips is doubling every two years, their I/O must double too.

Alexis BjörlinRepeatedly doubling the data throughput of a switch chip is a challenge.

Each new generation of switch chip must either double the number of serialiser-deserialiser (serdes) circuits or double their speed.

A higher serdes count - the latest 25.6-terabit switch ICs have 256, 100 gigabit-per-second serdes - requires more silicon area while both approaches - a higher count and higher speed - increase the chip's power consumption.

Faster electrical interfaces also complicate the system design since moving the data between the chip and the optical modules on the switch's front panel becomes more challenging.

Click to read more ...