Bidirectional Optical Transceiver With T-Band Mode Filtering
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Solution Overview
Problem
Current bidirectional optical transmission systems in 4G mobile networks face challenges with waveform distortion due to higher-order mode conversion in single-mode optical fibers, which affects communication speed and requires costly isolators and complex configurations.
Innovation Solution
The use of a surface-emitting laser with a T-band oscillation wavelength and a planar lightwave circuit with integrated mode filters and a simplified configuration that omits directional couplers and isolators, allowing for low-power, compact, and cost-effective bidirectional optical transceivers with reduced light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an edge-emitting laser is used in the current optical transmission system, then single-mode transmission can be ensured in the 1.3 μm or 1.5 μm band, but the power consumption is high and a cooling mechanism is required
Solution Approach 1:
The patent changes the oscillation wavelength parameter from the conventional 1.5 μm band to the T-band (1.1-1.2 μm), which is shorter than the cutoff wavelength of the optical fiber. This parameter change enables the use of surface-emitting lasers with lower power consumption while maintaining single-mode transmission through the optical fiber
Solution Approach 2:
The patent adopts a surface-emitting laser structure that copies the successful single-mode transmission characteristics of edge-emitting lasers but with improved power efficiency. The surface-emitting laser design achieves similar transmission reliability with reduced power consumption and simplified cooling requirements
2Use of energy by moving object
If a surface emitting laser with T-band wavelength is used, then power consumption is reduced and cooling mechanism can be simplified, but waveform distortion may occur due to higher-order mode conversion in the optical fiber
Solution Approach 1:
The patent extracts and eliminates the higher-order modes from the optical signal using a mode filter. The mode filter is configured to remove higher-order modes that cause waveform distortion while allowing the fundamental mode to pass through, thereby maintaining signal quality in the T-band transmission system
Solution Approach 2:
The patent introduces a mode filter as an intermediary component between the optical fiber and the photodetector. This mode filter acts as a mediator that selectively filters out harmful higher-order modes while preserving the useful fundamental mode, thus protecting the waveform quality without affecting the low-power operation of the surface-emitting laser
3Reliability
If isolators and directional couplers are included in the configuration, then communication reliability can be improved, but device complexity and cost increase
Solution Approach 1:
The patent removes isolators and directional couplers from the conventional optical transmission configuration. By using a surface-emitting laser with T-band wavelength shorter than the fiber cutoff wavelength, the system achieves sufficient isolation and signal directionality without requiring these additional components, thereby simplifying the overall device configuration and reducing cost
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 high-speed communication by suppressing waveform distortion and reducing power consumption and size, while maintaining low light loss and eliminating the need for costly isolators, thus supporting efficient 5G network requirements.
Implementation Method 1
a surface emitting laser employed as a transmitter having a T-band (1.1 μm to 1.2 μm) oscillation wavelength
Implementation Method 2
a photodetector employed as a receiver having a detection sensitivity with respect to the T band
Implementation Method 3
a planar lightwave circuit structured to couple the optical fiber to the surface emitting laser and the photodetector
Data Source
AI summary
An optical transceiver supports bidirectional communication with another optical transceiver that is a communications partner via a single-mode optical fiber. A surface emitting laser has a T-band oscillation wavelength that is shorter than the cutoff wavelength of the optical fiber. A photodetector has detection sensitivity with respect to the T band. A planar lightwave circuit couples the optical fiber, the surface emitting laser, and the photodetector.