Background:
Discussing the upcoming transition from 400 gig to 800 gig optics and 1.6 terabit optics. Driven by the increasing speed of SIRDIS IO technology on switch silicon.

Current Landscape:
Current switched silicon primarily uses 25-gig NRZ or 50-gig PEM4 electrical lanes. Transition to 100-gig CERDIS starting in 2023, expected to dominate bandwidth shipments by then.

800 Gig Optics:
100 gig CERDIS speed enables 800 gig optics in 800 gig eight lane optical formats. Initial focus on dual 400-gig and octal 100-gig breakout applications. 800-gig Ethernet spec completed in April 2020, incorporation in switch silicon from 2023. Unique situation where 800 gig optics may be ready before 800 gig Ethernet availability.

Transition Timeline:
400 gig optics expected to peak in 2023, followed by a rise in 800-gig optics shipments. 800-gig optics projected to become the majority by 2024.

Advantages of 800 Gig Optics:
Lower cost, lower power, and higher density compared to 400 gig optics.

Expected 800 Geek Optics Modules in 2023:
800-gig CR (100km reach with 16-QAM modulation), 800-gig LR (10km version), 100-gig FR4 and DR4 (using 200-gig PAM4 optical lambda). FR8-LR8 (single fiber with eight channels of 100-gig lambda), dual FR4, dual LR4 (400-gig breakout), DR8 (eight channels of 100-gig), and SR8 (eight SR channels based on Vixels).

Breakout Applications and Industry Standard Connectors:
Many initial uses of 800-gig modules will be for breakout applications. Optics modules must support industry standard connectors, such as dual LC, dual mini-LC, dual MPO, and octal SN/MDC.

OSFP Module with Breakout Connectors:
OSFP modules with dual LC, dual mini-LC, and dual MPO connectors for breakout applications. Octal SN/MDC connectors also supported on the front surface of the OSFP module.

Availability of Breakout Modules:
Multiple vendors have modules with breakout capabilities in the lab. Modules expected to be available in the market by the end of 2022.

Next-Generation Switch:
51.2 terabit switch with 64 800 gig OSFP modules, supporting up to 128 400 gig ports.

200 Gig Lambda Optics:
Significant interest in increasing the speed of lambda for power and cost reductions. Potential cost reduction between 100G and 200G generations. Early development stage, technical feasibility established with EML and silicon photonics. Complete lambda specification needed for industry to tape out and deliver components. First modules expected in late 2023, gaining momentum in 2024, and reaching higher volumes from 2025 onwards.

1.6T Pluggable Optics Modules:
Achievable with minor adjustments in mechanical dimensions, fully backwards compatible with 800G OSFP. Tied to 200G SIRTUS switch silicon, expected in production in 2025. OSFP-XD introduced with 1600G lanes to deliver 1.6T module in 2023 with 51.2T switch silicon. Fits into 1U line card or 1U fixed chassis with 51.2T density. 16 electrical lanes of 100G, up to 3.2T with 200G service interface, power up to 33 watts. Footprint of OSFP-XT identical to stacked Ethernet Geek OSFP, enabling single motherboard design. Module types: 1.6T CR, LR with 10km reach, CWM8 (8 channels of 200G PAM4 over duplex fiber), dual FR4 (two 800G EFNETs), and DR8 (eight channels of 200G lambda breakout). Advantages: Densest pluggable optic solution, matches density of future switch silicon on a 1U front panel basis.

Power Reduction Challenges:
Cloud bandwidth growth at 50-60% annually, while power reduction on the optical side is at 25-30% per year. Overall network power is increasing.

Process Technology:
Advanced process technology offers predictable power reduction. From 7nm to 5nm to 3nm, power reduction is nearly halved. Applies to switch chip, DSP, and optics.

Power Projections:
25.6T switch in 7nm, 51.2T switch in 5nm, and future 102.4T switch in 3nm. Total system power, including switch chip, fan power, and optics, shows significant reduction.

Optics Power Reduction:
Phonak Geek DR4 (1st generation) had high power per bit without integrated TIAs and drivers. Ethernet Geek DR8 with 5nm DSP and integrated drivers offers significant power reduction. Further reduction expected with 1.6T generation in 3nm.

Power per Bit vs. Power per Module:
Power per bit declining, but power per module increasing due to doubled/quadrupled bandwidth per module. Current estimates for 1.6Tbps data center modules range from 20-25 watts; coherent DCO modules up to 30 watts.

Future Power Reduction Strategies:
3nm and beyond (2nm) DSPs for significant power reduction on the digital side, including coherent DSPs. Lower-power service design optimization. Optics technologies with lower-power modulating technologies to reduce laser power requirements.

Industry Innovations:
The industry is focusing on innovations for developing efficient optics and reducing power consumption. Significant improvements are anticipated in laser sources, coupling losses, and modulators to achieve power efficiency.

Power Reduction Targets:
Industry experts predict a power consumption of five to six picojoules per bit in five years through DSP technology advancements along with enhancements in other components. Power reduction benefits all aspects of optics, regardless of form factor.

Pluggable Optics Advantages:
Pluggable optics modules enable immediate delivery of low-power optics to high-volume platforms. Pluggable modules allow for ongoing power reduction without waiting for co-packaged platform releases.

Co-Packaged Optics:
Co-packaged optics is still in development with progress made in prototyping and understanding challenges. Initial driving force was power reduction on a switch chip basis, targeting a 20% power reduction. Challenges include laser power, optical losses, connectors, manufacturability, repairability, and serviceability.

Power Reduction Challenges in Co-Packaged Optics:
Current solutions use external light sources and flyover cables, resulting in additional optical coupling losses. Multiple connectors in co-packaged solutions increase insertion losses. The net effect is an increase in laser power, leading to higher CPU power consumption compared to pluggable modules.

Potential Solutions for Power Reduction:
Direct drive modulation completely eliminates the DSP, using the service of the switch chip to drive the optics, leading to significant power reduction. Innovations in reducing coupling losses for ELS. Alternative modulation technologies to reduce insertion loss of silicon photonics.

Comparison of Pluggable and Co-Packaged Optics:
Pluggable optics for 51.2T and 102.4T switch divisions require no co-packaged optics because the problem has been solved with pluggable optics. Pluggable optics offer advantages in design, serviceability, and manufacturability compared to co-packaged optics.

Summary of Key Points:
800-gig optics modules are in development for lab testing, targeting dual 400-gig and octal 100-gig applications. 1.6-terabit modules based on the 16 by 100-gig electrical interface are next, targeting the 51.2T switch generation with production estimated in 2023. 1.6-terabit modules using 8 by 200-gig electrical interface will follow, targeting the 102.4T switch with 200-gig service, with an estimated production timeline of 2025. Decoupling optics transitions from switch silicon enables innovation and delivery of new components to the installed base.