Polarization Insensitive Optical Modulator for Single-Fiber Systems
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Solution Overview
Problem
Existing external modulators, such as silicon Mach-Zehnder modulators, are polarization-dependent, which limits their effectiveness in optical networks and requires separate handling of carrier and uplink signals, increasing costs and complexity.
Innovation Solution
A polarization insensitive integrated optical modulator (PIIOM) that splits incoming continuous wave light into transverse electric and magnetic polarized beams, rotates the magnetic beam to match the electric beam, and uses a multiport modulator to generate and combine output signals independently of polarization, allowing for a separate input and output configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an external modulator such as silicon Mach-Zehnder modulators is used, then the modulator can be packaged in non-hermetic form and operated in high temperature environment without TEC, but the modulator becomes dependent on the polarization orientation of the incoming optical carrier
Solution Approach 1:
The incoming optical carrier is segmented into two orthogonal polarization components (TE and TM modes) using a polarization beam splitter. Each component is then processed independently through separate waveguide paths, allowing the system to handle any polarization state without performance degradation.
Solution Approach 2:
The modulator is designed to universally accept optical carriers with any polarization orientation. By integrating polarization beam splitting and dual-waveguide modulation, the device achieves polarization independence while maintaining high-temperature operation capabilities.
2Device complexity
If polarization-dependent modulators are used, then the device complexity is reduced, but separate handling of carrier and uplink signals is required, increasing costs
Solution Approach 1:
The carrier signal and uplink signal handling capabilities are merged into a single polarization-insensitive modulator device. The dual-waveguide structure allows simultaneous processing of different signal types through the same physical component, eliminating the need for separate signal handling paths.
Solution Approach 2:
A polarization beam splitter acts as an intermediary component that separates the incoming optical carrier into orthogonal polarization components. This intermediary enables the modulator to process signals of any polarization state while maintaining a relatively simple overall device structure.
3Ease of manufacture
If polarization-dependent modulators are used, then the modulator design is simplified, but the polarization orientation of the incoming optical carrier must be precisely controlled
Solution Approach 1:
The optical signal is segmented into two orthogonal polarization components that are processed through separate waveguide paths. This segmentation eliminates the need for precise polarization alignment during operation, as each path is optimized for its specific polarization mode.
Solution Approach 2:
The modulator achieves universal compatibility with any polarization state through its dual-waveguide design. While the fabrication process remains relatively simple, the device automatically adapts to any incoming polarization orientation without requiring operational alignment adjustments.
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
The PIIOM eliminates polarization dependence, enabling efficient external modulation without the need to separate carrier and uplink signals, reducing costs and complexity while supporting high-speed operations with a single fiber for both input and output.
Implementation Method 1
splitting, by a first polarization splitter-rotator (PSR), the CW light into a first light beam having a transverse electric (TE) polarization and a second light beam having a transverse magnetic (TM) polarization
Implementation Method 2
rotating, by the first PSR, the second light beam having the TM polarization to generate a third light beam having the TE polarization
Implementation Method 3
modulating, with one multiport modulator, the first light beam with data to generate a first output signal and the third light beam with data to generate a second output signal
Implementation Method 4
combining, by a second PSR, the first output signal and the second output signal to form a modulated output CW light
Data Source
Figure 1~3
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Figure 6~8
AI summary
A method of modulation implemented by a polarization insensitive integrated optical modulator (PIIOM, 200). The method includes receiving, at an input (202), a continuous wave (CW) light, splitting, by a first polarization splitter-rotator (PSR, 204), the CW light into a first light beam having a transverse electric (TE) polarization and a second light beam having a transverse magnetic (TM) polarization, rotating, by the first PSR (204), the second light beam having the TM polarization to generate a third light beam having the TE polarization, modulating, with a multiport modulator (206), the first light beam with data to generate a first output signal (S) and the third light beam with data to generate a second output signal (S'), combining, by a second PSR (208), the first output signal (S) and the second output signal (S') to form a modulated output CW light, and transmitting, at an output (210) separate from the input (202), the modulated output CW light to an optical receiving device.