Annular Waveguide Isolator for Low Insertion Loss
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Solution Overview
Problem
In isolators with non-reciprocal phase devices, achieving sufficient non-reciprocity to reduce insertion loss while maintaining a smaller size is challenging, as existing configurations result in increased size and insertion loss when non-reciprocity is low.
Innovation Solution
The isolator design incorporates a linear first waveguide and an annular second waveguide with a non-reciprocal member, where the annular shape of the second waveguide enhances non-reciprocity and reduces insertion loss by optimizing the coupling coefficients for electromagnetic wave propagation in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If non-reciprocity is increased to reduce insertion loss, then insertion loss is reduced, but device size increases
Solution Approach 1:
The patent employs asymmetric coupling between waveguides with different geometries (straight waveguide coupled with annular waveguide) to achieve non-reciprocal behavior. The asymmetric structure creates different coupling coefficients for forward and backward propagation directions, enabling insertion loss reduction without requiring large device dimensions. This asymmetry is fundamental to achieving non-reciprocity in a compact footprint.
Solution Approach 2:
The patent introduces curvature by using an annular waveguide instead of a straight waveguide. The curved/annular geometry of the second waveguide creates different optical path lengths and coupling characteristics for waves propagating in opposite directions. This curvature enables enhanced non-reciprocity and insertion loss reduction while maintaining a compact device size, directly addressing the technical contradiction.
2Reliability
If non-reciprocity is increased to improve isolator functionality, then isolator performance is improved, but device complexity increases
Solution Approach 1:
The patent combines the functions of non-reciprocity generation and waveguiding into a single integrated structure. The annular waveguide serves both as the guiding structure and as the element that generates non-reciprocal behavior through its geometry. This merging of functions achieves improved isolator functionality while avoiding the need for separate non-reciprocal components, thereby reducing overall device complexity.
Solution Approach 2:
The annular waveguide structure performs multiple functions simultaneously: it acts as a waveguide for electromagnetic wave propagation, generates non-reciprocal behavior through its geometry, and provides the coupling mechanism between waveguides. This multi-functionality improves isolator performance while minimizing the number of separate components needed, thus reducing device 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 effectively reduces insertion loss and achieves a smaller size by increasing non-reciprocity, allowing for efficient electromagnetic wave propagation in one direction while impeding propagation in the opposite direction, thus improving the isolator's functionality.
Implementation Method 1
an isolator whose transmittance differs depending on the propagation direction of electromagnetic waves includes a non-reciprocal phase device
Data Source
AI summary
An isolator includes a first waveguide with a linear shape and a second waveguide with an annular shape on a substrate including a substrate surface, the first waveguide being positioned along the substrate surface. The first waveguide and the second waveguide each include a core and a cladding. The first waveguide includes a first end, a second end, and a port at each of the first end and the second end for input and output of electromagnetic waves. The core of the second waveguide includes a non-reciprocal member in at least a portion of a cross-section intersecting a direction in which the second waveguide extends.