Optical Transmission Apparatus Using Phase-Shifted Clock Modulation
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Solution Overview
Problem
Conventional optical transmission systems face limitations in increasing transmission speed without the use of high-speed electronic circuits, primarily due to the constraints of dual division multiplexing techniques.
Innovation Solution
The optical transmission apparatus generates multiple clock signals with specific phase differences and uses these signals to modulate light beams, allowing for quad-division or octa-division multiplexing without the need for high-speed electronic circuits by adjusting the interference conditions in optical modulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If dual division multiplexing is used to increase transmission speed, then transmission speed is improved, but the system is limited by the need for high-speed electronic circuits
Solution Approach 1:
The patent replaces electronic division multiplexing with optical division multiplexing using Mach-Zehnder modulators. The optical modulators directly divide the optical signal into multiple time slots using optical interference, eliminating the need for high-speed electronic switches and circuits. This substitution of optical domain operations for electronic domain operations resolves the contradiction by achieving high transmission speed without corresponding electronic circuit complexity
Solution Approach 2:
The patent changes the operating parameters by using multiple clock signals with specific phase relationships (e.g., 90-degree phase differences) to control the optical modulators. By adjusting the phase and timing parameters of the clock signals, the system achieves quad-division or octa-division multiplexing ratios, thereby increasing transmission speed while maintaining manageable device complexity through optical rather than electronic means
2Speed
If higher division multiplexing ratios are achieved, then transmission speed increases, but the requirement for high-speed electronic circuits becomes more stringent
Solution Approach 1:
The patent achieves higher division multiplexing ratios (quad-division, octa-division) by cascading multiple optical modulators in series, where each modulator performs optical switching based on clock signals. This optical cascading approach avoids the exponential increase in electronic circuit complexity that would be required for higher division ratios, thereby maintaining system feasibility while achieving higher transmission speeds
Solution Approach 2:
The patent segments the optical signal division function across multiple independent optical modulators rather than requiring a single complex electronic switch. Each modulator handles a portion of the division task, and their combined effect achieves the overall high division ratio. This segmentation distributes the complexity across multiple simpler optical components, improving reliability while achieving high transmission speed
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 enables the generation of high-speed optical signals through quad-division or octa-division multiplexing, enhancing transmission speed without relying on high-speed electronic circuits, thereby overcoming the limitations of conventional systems.
Implementation Method 1
changes a phase difference of resulting light beams according to the first clock signal
Implementation Method 2
causes interference of the light beams having the changed phase difference
Data Source
AI summary
A first clock modulator branches a light beam, varies a phase difference of the resulting light beams according to a first clock, and causes interference of the light beams. A second clock modulator branches a light beam from the first clock modulator and synchronized with the first clock, varies a phase difference of the resulting light beams according to a second clock, and causes interference of the light beams. A third clock modulator branches a light beam from the first clock modulator and inversely synchronized with the first clock, varies a phase difference of the resulting light beams according to a third clock, and causes interference of the light beams. The second clock and the first clock have identical cycles and differing phases. The third clock and the second clock have phases that differ by a 1/2 cycle. Four data modulators modulate the light beams from the clock modulators.