Substrate-Integrated Hollow Waveguide for High-Speed Optical Interconnects
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Solution Overview
Problem
Traditional optical interconnects face challenges in achieving high density, low cost, and integration with electrical routing while maintaining efficient signal transmission over long distances, as they suffer from resistance losses and higher refractive indices that hinder signal propagation speed.
Innovation Solution
The development of substrate-integrated hollow metal waveguides using a sacrificial metal template and selective etching processes allows for the creation of waveguides with tight pitches and high transmission efficiency, integrating optical and electrical routing on a substrate, and coating with metals like silver for total internal reflectance, reducing signal attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional optical interconnects are used, then bandwidth and transmission efficiency are improved, but resistance losses and higher refractive indices hinder signal propagation speed
Solution Approach 1:
The patent changes the refractive index parameter by using a hollow core structure filled with air or vacuum (refractive index ≈1) instead of traditional dielectric materials with higher refractive indices. This parameter change enables faster signal propagation speed while reducing resistance losses, as light travels faster in air/vacuum and experiences minimal attenuation.
Solution Approach 2:
The waveguide employs a composite structure combining metal walls (for mechanical support and confinement) with a hollow core (for low-loss optical transmission). This composite design leverages the strengths of both materials: the metal provides structural integrity while the hollow core enables low-loss, high-speed optical signal propagation.
2Ease of manufacture
If metal interconnects are used, then cost and performance benefits are achieved at smaller distances, but bandwidth and loss performance deteriorate over large distances
Solution Approach 1:
The patent segments the interconnect system into two parts: metal interconnects for short-distance routing (where they provide cost and performance benefits) and hollow-core waveguides for long-distance transmission (where low loss is critical). This segmentation allows each technology to operate in its optimal performance range.
Solution Approach 2:
The hollow-core waveguide acts as an intermediary component that bridges the gap between metal interconnects and optical fibers. It receives optical signals from transmitters, transmits them over long distances with minimal loss, and delivers them to detectors, thereby enabling cost-effective integration of metal interconnects with long-range optical transmission.
3Productivity
If high density integration is achieved, then bandwidth and interconnect density are improved, but manufacturing complexity and assembly steps increase
Solution Approach 1:
The patent merges the optical waveguide fabrication process with existing semiconductor manufacturing techniques, including photolithography, etching, and deposition. By integrating waveguide creation into the standard CMOS fabrication flow, the method achieves high interconnect density without significantly increasing manufacturing complexity or assembly steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in faster signal propagation (up to 30% faster than fiber-optic cables) with increased density and bandwidth, lower costs, and integration with existing semiconductor processing techniques, enabling efficient long-range optical signal transmission with minimal assembly steps.
Implementation Method 1
coating with metals like silver for total internal reflectance, reducing signal attenuation
Data Source
AI summary
This document discusses, among other things, a waveguide including a first metal having an outer surface proximate a dielectric material and an inner surface defining a path of the waveguide, a method of receiving an optical signal at the inner surface of the waveguide and transmitting the optical signal along at least a portion of the path of the waveguide. A method of integrating a waveguide in a substrate includes depositing sacrificial metal on a first surface of a carrier substrate to form a core of the waveguide, depositing a first metal over the sacrificial metal and at least a portion of the first surface of the carrier substrate, forming an outer surface of the waveguide and a conductor separate from the sacrificial metal, and depositing dielectric material over the first surface of the carrier substrate about the conductor.