Laser Focus World: What is Broadcom doing within the optical interconnect realm?
Natarajan Ramachandran: Leveraging our depth of expertise in digital signal processors (DSPs) and fiber optics, Broadcom provides optical interconnect solutions for high-performance networking and computing applications. Multiple business units of Broadcom, including our Physical Layer Products Division (PLP) and Optical Systems Division (OSD), supply a wide range of semiconductor devices and optical components for this market.
LFW: Can you describe Broadcom’s basic design work involved?
Ramachandran: Optical interconnects, specifically pluggable, are already widely used within data center networks and now for artificial intelligence (AI)/machine learning (ML) clusters. Each of our pluggables has an optical DSP (from the PLP BU) and optical subcomponents like lasers and pin diodes (from OSD BU). Optical DSPs are the heart of a pluggable and help compensate for much of the copper and optical impairments that exist in an end-to-end link.
LFW: How is Broadcom differentiating itself within this space?
Ramachandran: Broadcom provides services for the 1.6T market in the following ways:
For the short reach market (<50 m), Broadcom has an optical DSP product called Sian2M in 5-nm TSMC node to enable 200G/lane vertical-cavity surface-emitting lasers (VCSELs). Traditionally, VCSELs were the go-to solutions for short reach market at 25G/50G/100G per lane. But at 200G/lane, VCSELs are constrained by bandwidth limitations. Sian2M was custom built with highly sophisticated signal-processing techniques to enable 200G/lane VCSELs by compensating for inherent bandwidth limitations. It allows us to extend the life of VCSELs by at least one generation, which enables cheaper and lower-power short reach optics.
For the longer reach market (<10 km), Broadcom has an optical DSP product called Sian3 in 3-nm TSMC node, which will bring down the power of 1.6T optical modules to sub-23W. Lowering the power is a very critical industry ask, because it opens up more rack power for computation.
LFW: Anything surprising about Broadcom’s optical interconnects?
Ramachandran: Enabling the short reach (multimode) optics with a 200G/lane VCSEL was a major milestone for us. The ecosystem was writing off this technology, but Broadcom once again showed that one thing that you should never bet against is our engineering expertise and innovation. The single-mode optics will enable the industry with its lower power/bit, and cost/bit solutions will continue to be our focus. We believe we can enable a 23-W 1.6T module in 2025, but we want to continue driving more innovation to sub-20W.
LFW: Any challenges to overcome?
Ramachandran: AI clusters are part compute and part connectivity, so the goal for us is always to reduce the power footprint and cost footprint of connectivity to make more available for compute. These challenges will become more severe as the industry transitions to 400G/lane.
LFW: Applications/timeline to use?
Ramachandran: Applications are in AI/ML clusters and traditional data center networks. All hyperscalers—whether located in the U.S. or China—are currently investing billions in capex spending to deploy larger clusters with more sophisticated learning models. These clusters need optical connectivity to push data in and out, and it’s where Broadcom comes in!
LFW: What’s next?
Ramachandran: Market research firm LightCounting is projecting ~$1B for the 1.6T PAM4 DSP market and the total PAM4 (pulse amplitude modulation 4-level) DSP market to grow to $7B by 2030. There continues to be an insatiable need for compute power, which in turn is dependent on connectivity speed. To service this growing market, Broadcom and ecosystem partners need to continue to innovate to help drive the picojoule/bit and the cost/bit down!