Bi-directional Signal Interface with Tapered Optical Modulator Isolation
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Solution Overview
Problem
Existing bi-directional signal interfaces struggle to achieve high enough isolation between outgoing and incoming signals, particularly in demanding applications where the strong outgoing signal interferes with the weaker incoming signal, limiting the detection of the incoming signal.
Innovation Solution
The use of a Mach-Zehnder interferometric modulator with a tapered electromagnetic interaction function, which modifies the modulation efficiency and isolation by varying the electromagnetic interaction between the modulation electrodes and optical waveguides, allowing for improved outgoing-to-incoming signal isolation while maintaining efficient conveyance of the incoming signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bi-directional signal interface is used, then the device complexity is low, but the outgoing-to-incoming signal isolation is insufficient
Solution Approach 1:
An optical carrier wave is introduced as an intermediary to transfer the incoming RF signal to the outgoing port. The optical modulator converts the RF signal to optical domain, transmits it through the interaction region, and a photodetector converts it back to RF, achieving high isolation between incoming and outgoing ports while maintaining signal transfer functionality
Solution Approach 2:
The patent replaces direct electrical signal transmission between ports with an optical transmission system. By substituting the electrical domain with optical domain for signal transfer, the system achieves superior isolation characteristics that cannot be obtained with conventional electrical interfaces alone
2Productivity
If the electromagnetic interaction length is increased to improve signal conveyance efficiency, then the incoming signal efficiency improves, but the outgoing-to-incoming signal isolation deteriorates
Solution Approach 1:
The patent transitions the signal transmission from the electrical domain to the optical dimension. By using optical waveguides and an optical carrier wave, the system achieves signal conveyance in a different domain that is isolated from the electrical ports, thereby maintaining high isolation while enabling efficient signal transfer through the interaction region
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 significantly enhances the outgoing-to-incoming signal isolation by a factor of 10,000 with only a minor reduction in incoming signal efficiency, effectively addressing the interference issues in bi-directional signal interfaces.
Implementation Method 1
a Mach-Zehnder interferometric modulator with a tapered electromagnetic interaction function, which modifies the modulation efficiency and isolation by varying the electromagnetic interaction between the modulation electrodes and optical waveguides
Implementation Method 2
The optical modulator conveys the incoming RF signal to an outgoing port with a very high degree of isolation from the incoming RF signal port
Data Source
AI summary
A bi-directional signal interface includes a carrier signal source that generates a carrier traveling wave at an output. A first traveling wave structure includes a first and a second waveguide having an input that is coupled to the output of the carrier signal source. The first and second waveguide propagate the carrier traveling wave. A second traveling wave structure includes an outgoing signal port that receives an outgoing signal and a bi-directional signal port that receives an incoming electrical signal and provides the outgoing signal. The first and second traveling wave structures have an electromagnetic interaction region with a geometry that is chosen for a desired outgoing-to-incoming signal isolation. A detector having an input coupled to the output of the first traveling wave structure generates an electrical signal related to the incoming electrical signal.