AWG Optical Multiplexer With 180-Degree Bent Waveguides
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Solution Overview
Problem
The challenge is to design a miniaturized and cost-effective optical multiplexer/demultiplexer for high-speed Ethernet transceivers that can fit within the compact CFP4 module size, while maintaining efficient multiplexing/demultiplexing capabilities and reducing manufacturing costs, particularly for large channel spacing and wavelength bandwidth requirements.
Innovation Solution
The solution involves an arrayed waveguide grating optical multiplexer/demultiplexer with a unique waveguide configuration where the arrayed waveguides change directions by 180 degrees or more, allowing for a compact footprint and efficient fan-out part arrangement, using waveguides with a refractive index difference of 2% or more to achieve steep bends with minimal loss, and eliminating the need for antireflection coatings by tilting output waveguides, thus reducing chip size and processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AWG design is used, then wavelength demultiplexing characteristics are excellent, but chip size increases for large channel spacing
Solution Approach 1:
The patent applies curvature by designing arrayed waveguides that change direction by 180 degrees or more, forming bent waveguide paths instead of straight lines. This curved configuration allows the waveguides to be compactly arranged on the chip while maintaining the required optical path length differences for wavelength demultiplexing, thereby reducing chip size without compromising demultiplexing characteristics
Solution Approach 2:
The patent utilizes two-dimensional spatial arrangement by having arrayed waveguides extend in different directions and change direction multiple times. This allows efficient packing of waveguides with different path lengths in a compact area, reducing the chip footprint while maintaining the necessary optical path differences for proper wavelength separation
2Ease of manufacture
If waveguides with small refractive index difference are used, then manufacturing is easier, but bending loss increases for steep bends
Solution Approach 1:
The patent changes the refractive index parameter by specifying waveguides with a refractive index difference of 2% or more between core and cladding. This increased refractive index difference raises the critical angle for total internal reflection, allowing the waveguides to sustain steeper bends (180 degrees or more) with acceptable loss, thus enabling compact chip design while controlling bending losses
3Loss of energy
If antireflection coatings are applied, then reflection loss is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of applying antireflection coatings to reduce reflection loss, the patent inverts the approach by tilting the output waveguides at an angle. This geometric modification changes the reflection characteristics, directing reflected light away from the optical path and effectively reducing reflection loss without adding coating processes or increasing manufacturing complexity
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 configuration enables a significant reduction in chip size and manufacturing costs, achieving efficient multiplexing/demultiplexing with a compact footprint and low loss, while allowing for alignment without complex multi-body aligners, thus providing a cost-effective ROSA module.
Implementation Method 1
the arrayed waveguides change extending directions of the arrayed waveguides 180 degrees or more
Implementation Method 2
using waveguides with a refractive index difference of 2% or more to achieve steep bends with minimal loss
Implementation Method 3
eliminating the need for antireflection coatings by tilting output waveguides
Data Source
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AI summary
To provide a multiplexer/demultiplexer that functions as an extremely small AWG optical filter in order to prepare a miniaturized and low-cost transceiver module necessary to realize a high speed transceiver for Ethernet (registered trademark). An optical multiplexer/demultiplexer includes: at least one input waveguide that has an input part at one end; a first slab waveguide of which one end is connected to the other end of the input waveguide; an arrayed waveguide group of which one end is connected to the other end of the first slab waveguide, the arrayed waveguide group having a plurality of waveguides; a second slab waveguide of which one end is connected to the other end of the arrayed waveguide group; and at least one output waveguide of which one ends are connected to the other end of the second slab waveguide and the other ends respectively have output parts, wherein each of the waveguides of the arrayed waveguide group has: a first bent part of which a waveguide extending direction changes 180 degrees or more; and a second bent part of which a waveguide extending direction changes 180 degrees or more in a direction opposite to a direction of the change of the first bent part.