Single-Fiber Bidirectional Transceiver Using Polarization Multiplexing
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Solution Overview
Problem
Existing single-fiber bidirectional optical transceiver modules with same wavelength suffer from excessive power loss, high cost, and size limitations, making them unsuitable for high-speed and cost-effective applications, particularly due to the need for multiple optical elements and complex structures that increase assembly difficulty and polarization mode dispersion.
Innovation Solution
The use of a polarization reflector based on a sub-wavelength grating structure, which simplifies the optical structure, reduces the number of optical elements, and combines with a Faraday rotator to enable efficient polarization separation and combination, allowing for a compact and low-cost single-fiber bidirectional optical transceiver module with minimal crosstalk and loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beam splitters are used to enable same-wavelength bidirectional transmission, then the transceiver modules can be identical and paired easily, but the link loss increases by 6 dB
Solution Approach 1:
The patent changes the operating parameters by using polarization-maintaining fibers and polarization-sensitive components instead of standard fibers and non-polarization-sensitive components. This allows the system to differentiate between forward and reverse signals using polarization states rather than wavelength, eliminating the need for beam splitters and reducing link loss while maintaining transceiver compatibility
2Reliability
If multiple optical elements are used to achieve polarization separation, then bidirectional transmission can be enabled, but the device complexity and assembly difficulty increase
Solution Approach 1:
The patent merges the functions of multiple separate optical elements (polarization beam splitters, wave plates, and isolators) into an integrated polarization-maintaining fiber optic structure. The fiber itself provides polarization maintenance, eliminating the need for separate polarization control components and simplifying the overall device architecture while maintaining effective polarization separation
3Reliability
If traditional polarization beam splitters and wave plates are used, then polarization control is achieved, but the module size increases and miniaturization is limited
Solution Approach 1:
The patent extracts the polarization control function from bulky discrete optical components and embeds it directly into the optical fiber structure itself through polarization-maintaining fiber design. This integration eliminates the need for separate wave plates and beam splitters, dramatically reducing module volume while maintaining polarization control reliability
4Reliability
If dual-wavelength scheme is used, then bidirectional transmission can be achieved, but the clock synchronization accuracy deteriorates due to dispersion-induced delay inequality
Solution Approach 1:
The patent changes the differentiation parameter from wavelength to polarization state. By using the same wavelength for both directions but differentiating them through orthogonal polarization states, the system eliminates dispersion-induced delay differences while maintaining bidirectional transmission capability, thereby improving clock synchronization accuracy
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 solution achieves a compact, low-cost, and efficient single-fiber bidirectional optical transceiver module with reduced power loss and crosstalk, suitable for high-speed applications by leveraging the sub-wavelength grating's polarization properties and non-reciprocal Faraday rotator, enabling miniaturization and cost-effectiveness.
Implementation Method 1
use the same wavelength and wavelength group with no need for the optical transceiver module to be paired on wavelength for single-fiber bidirectional transmission
Implementation Method 2
polarization reflector based on a sub-wavelength grating structure
Implementation Method 3
combines with a Faraday rotator to enable efficient polarization separation and combination
Data Source
AI summary
A single-fiber bidirectional optical transceiver module of the same wavelength. A sub-wavelength grating and a Faraday rotator are used, and the same element is reused to implement a polarization multiplex/de-multiplex function, so as to implement transmission and receiving of an optical signal in a small space. The single-fiber bidirectional optical transceiver module has less optical elements, a compact structure, and low cost, meeting the needs on a miniaturized, integrated, and high speed optical transceiver module for a modern optical communication system.