Intel Silicon Photonic 100G CWDM4 QFSP28 Transceiver

In just a few short years, Intel has already shipped more than 3M units of its 100G pluggable transceivers. And with its CWDM4 100G technology, Intel is the first in the world to offer a silicon photonic solution up to 10km. The 100G PSM4 and CWDM4 represent the first step, with Intel’s 200G and 400G products expected to enter volume production in the second half of 2020.

The transceiver reuses a part of the PSM4 technology, but many other facets represent new approaches from Intel.

The transceiver comes with two separated lines with several dies. The transmitter silicon photonic die integrates four InP lasers for the four wavelengths, in a different configuration than the PSM4. On the same die, a Mach-Zehnder modulator is added to modulate the signal, but the CWDM MZI is more complex. Light extraction is performed by the edge of the die and not by a mirror. Other components have been added to the system in order to focus or isolate the signal. Data is processed by using a four-channel 25G optical Clock and Data Recovery (CDR) component from MACOM.

The receiver function is performed by four germanium photodiode dies and a TransImpedance Amplifier (TIA) circuit. The Ge photodiodes are manufactured on a dedicated SOI substrate, and an optical demultiplexer is assembled between the SiGe photodiode and the fiber optic.

This report describes Intel’s potential in terms of packaging and photonics. Within a very small form factor, Intel has managed to integrate four lasers, a photonic driver, optical modules, CDR functionality, high-performance photo-diodes, two advanced substrates, and materials for optic. This report shows how the chipset configuration is implemented and describes in detail the transmitter and receiver line.

Also included in this report is an exhaustive analysis of the Intel 100G CWDM4 connector’s main components, including a full analysis of the silicon photonic die, the TIA circuit, the Mach-Zehnder Driver circuit, the MACOM circuit, and the germanium photodiodes. A cost analysis and price estimate are furnished too, along with a description and estimated price for the two fiber optic couplers, the focusing lens, and the isolator. Lastly, a comparison is made with Intel’s PSM4 silicon photonic circuit.

COMPLETE TEARDOWN WITH

• Detailed photos
• Precise measurements
• Materials analysis
• Manufacturing process flow
• Supply chain evaluation
• Manufacturing cost analysis
• Comparison with the Intel 100G PSM4
• Didactic explanation of device operation
• Estimated sales price

Overview/Introduction

Intel Company Profile

Physical Analysis

• CWDM4 Connector – Teardown
• Transmitter Block
  • View, dimensions, light path, cross-section
• MZI Driver Die
• Silicon Photonic Die
  • Die overview and dimensions
  • InP laser, MZI, light extraction, waveguide processes and cross-sections
  • Die process characteristics
• Receiver Block
  • View, dimensions, demultiplexer, cross-sectioN
• Germanium Photodiode
  • Die view and dimensions, process, and cross-section
• TIA Die
• MACOM MG37049G Die

Comparison – Intel’s PSM4 and CWDM4 Dies

Manufacturing Process Flow

• MZI Driver Die – Front-End Process and Fabrication Unit
• Silicon Photonic Die – Process Flow
• Silicon Photonic Die – Front-End Fabrication Unit
• Receiver – Fiber-Optic Coupler, Demultiplexer, Process Flow, and Cost
• Germanium Photodiode Die – Process Flow and Fabrication Unit
• TIA and MACOM M37049G Dies – Front-End Process and Fabrication Unit

Cost Analysis

• Transmitter Block
  • Silicon photonic die
  • Wafer, step and die costs
  • MZI driver die
  • MACOM M37049G
  • Optical elements
  • Assembly
• Receiver Block
  • Germanium photodiode die
  • TIA Die
  • MACOM M37049G
  • Optical element
  • Assembly

Estimated Sales Price Analysis: Transmitter Block and Receiver Block