Optical 90-Degree Hybrid Circuit Wavelength-Independent Phase Control
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Solution Overview
Problem
Conventional optical 90-degree hybrid circuits face challenges in maintaining accurate phase difference between in-phase and quadrature outputs across different wavelengths, leading to degradation in demodulation performance and increased power consumption due to the need for precise phase shift control.
Innovation Solution
The optical 90-degree hybrid circuit employs a directional coupler or MMI coupler as the second optical splitter to achieve a 90-degree phase difference between split light beams independently of wavelengths, eliminating the need for a 90-degree phase shifter and ensuring wavelength-independence of the IQ phase difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical 90-degree hybrid circuit uses a 90-degree phase shifter to maintain phase difference, then the phase difference between in-phase and quadrature outputs can be controlled, but the circuit becomes dependent on wavelength and requires continuous power consumption for phase monitoring and adjustment
Solution Approach 1:
The patent removes the 90-degree phase shifter component from the optical hybrid circuit. Instead of actively controlling phase with a phase shifter, the invention extracts only the necessary splitting function and relies on the inherent phase characteristics of directional couplers or MMI couplers to provide the required 90-degree phase difference between output ports, thereby eliminating wavelength dependence and the need for active phase control
Solution Approach 2:
The directional coupler or MMI coupler inherently provides the 90-degree phase difference between its output ports without requiring external phase control mechanisms. The circuit serves itself by utilizing the natural phase characteristics of the coupler structure, eliminating the need for separate phase shifters and continuous phase monitoring systems
2Reliability
If a 90-degree phase shifter is used to maintain accurate phase difference, then demodulation performance can be improved, but power consumption increases due to continuous phase shift control
Solution Approach 1:
The patent removes the power-consuming 90-degree phase shifter component while preserving the essential function of generating accurate 90-degree phase difference between in-phase and quadrature outputs. The directional coupler or MMI coupler inherently provides this phase difference without requiring external power input for phase control, thereby improving power efficiency while maintaining demodulation performance
Solution Approach 2:
The coupler structure provides the required phase difference function autonomously without needing external power input for phase adjustment. The circuit utilizes the inherent physical characteristics of the coupler to self-generate the 90-degree phase difference, eliminating continuous power consumption associated with active phase control mechanisms
3Ease of manufacture
If conventional optical splitting means are used, then the circuit can be constructed, but it requires additional 90-degree phase shift control mechanisms increasing device complexity
Solution Approach 1:
The patent combines the optical splitting function with the phase difference generation function into a single component. The directional coupler or MMI coupler simultaneously performs both the splitting of input optical signals and the generation of 90-degree phase difference between output ports, eliminating the need for separate phase shifter components and reducing overall device complexity
Solution Approach 2:
The directional coupler or MMI coupler serves multiple functions: it acts as an optical splitter and simultaneously provides the required 90-degree phase difference between output ports. This multi-functional component replaces what would traditionally require separate dedicated components for splitting and phase control, simplifying the overall circuit architecture
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 maintains a consistent 90-degree phase difference across various wavelengths, enhancing reception characteristics and reducing power consumption by eliminating the requirement for continuous phase shift monitoring and adjustment.
Implementation Method 1
second optical splitting means including an optical coupler configured to receive the second light beam and to output two light beams having a phase difference of 90 degrees
Data Source
AI summary
An optical 90-degree hybrid circuit includes: first and second optical splitters for receiving and splitting a first and second light beam into two, respectively; a first optical coupler for generating an interfering light beam by multiplexing one of the light beams split by the first optical splitter and the second optical splitter; and a second optical coupler for generating an interfering light beam by multiplexing another one of the light beams split by the first optical splitter and the second optical splitter. The first optical splitter includes an optical coupler configured to output two light beams having equal phases, and the second optical splitter includes an optical coupler configured to output two light beams having a phase difference of 90 degrees.