Polarization-Insensitive Optical Receiver With Intertwined Spiraling Delay Lines
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Solution Overview
Problem
Current optical receivers for high-speed telecommunication systems face challenges in achieving polarization-insensitive operation due to fabrication inaccuracies and material non-uniformities, particularly when using submicron silicon-on-insulator waveguides that support only one polarization mode, leading to polarization-dependent frequency shifts and reduced compactness.
Innovation Solution
A polarization-insensitive optical receiver design that splits the input signal into orthogonal polarization components, which are then differentially demodulated and recombined using interferometric modules with intertwined spiraling delay lines to mitigate fabrication and material-related discrepancies, ensuring identical optical paths for both polarizations and allowing detection by a single set of detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If submicron silicon-on-insulator waveguides are used to maximize compactness, then device size is reduced, but polarization-dependent frequency shifts occur due to single polarization mode support
Solution Approach 1:
The optical receiver is segmented into two separate polarization-sensitive receivers, each handling one polarization component. The polarization splitter divides the input signal into orthogonal polarization components that are processed independently through separate interferometric modules and detector sets, eliminating polarization-dependent frequency shifts by dedicating separate processing paths to each polarization mode.
Solution Approach 2:
The optical receiver achieves polarization-insensitivity through multi-functionality by incorporating both TE and TM polarization processing capabilities within a single integrated device. The polarization splitter and subsequent interferometric modules are designed to handle both polarization modes, allowing the device to function correctly regardless of the input polarization state.
2Reliability
If separate processing paths are used for orthogonal polarizations, then polarization-insensitivity is achieved, but device complexity increases
Solution Approach 1:
The two polarization-sensitive receivers are merged into a single integrated optical receiver device. The polarization splitter, interferometric modules, and detector arrays are combined on one chip, allowing simultaneous processing of both polarization components through a unified structure rather than requiring separate discrete devices.
Solution Approach 2:
The patent utilizes the spatial dimension by arranging the two sets of interferometric modules and detectors in different physical regions or orientations within the integrated device. This dimensional separation allows independent polarization processing paths to coexist without excessive interference, managing complexity through spatial organization.
3Reliability
If intertwined spiraling delay lines are used to mitigate fabrication discrepancies, then polarization-insensitivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The delay lines are designed with asymmetric intertwined spiraling structures where the two polarization paths are deliberately configured with different geometric characteristics. This asymmetric design compensates for fabrication-induced symmetric errors by creating opposing dispersion effects that cancel each other out, improving polarization-insensitivity while maintaining manufacturability.
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 solution achieves compact, polarization-independent demodulation of phase-modulated signals, reducing sensitivity to fabrication errors and material non-uniformities, thereby enhancing the performance and reliability of optical receivers for advanced modulation formats like DPSK and DQPSK.
Implementation Method 1
a polarization splitter for splitting the input optical signal into a first and a second polarization component having substantially orthogonal polarization states
Implementation Method 2
each interferometric module includes a delay line receiving a portion of the respective polarization component and producing therefrom a time-shifted version of the respective polarization component
Implementation Method 3
each interferometric module being configured to mix the respective polarization component with the time-shifted version thereof so as to provide a plurality of output signals
Data Source
AI summary
A polarization-insensitive optical receiver for demodulating a phase-modulated input optical signal is provided. The optical receiver includes successively a polarization splitter, a first and second interferometric modules including respective delay lines, and a plurality of detectors. The input optical signal is split into two substantially orthogonally-polarized components, which are launched along respective optical paths into the corresponding interferometric modules where they demodulated and subsequently recombined prior to being detected by the plurality of detectors. Advantageously, the optical receiver allows mitigating undesired discrepancies between the optical paths traveled by the two polarization components by arranging the respective delay lines of the interferometric modules into intertwined spiraling structures. A waveguide assembly including a substrate and a pair of waveguides on the substrate and defining intertwined spiraling structures is also provided, as well as a waveguide coupling assembly for coupling, onto a same detector, two optical signals travelling along two parallel coplanar waveguides.