Compact Polarization Splitter Rotator Using Stacked Waveguides
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Solution Overview
Problem
Current polarization splitter rotators (PSRs) require additional space and are lossy due to transitioning the more lossy TM0→TE1 mode, leading to increased polarization-dependent loss (PDL), while also needing dedicated space for modemuxing operations.
Innovation Solution
A compact PSR design with three vertically stacked waveguides, where the Si layer is translated relative to a fixed SiN layer, allowing simultaneous polarization rotation and modemuxing without additional space, keeping the TM0→TE0 mode in SiN to minimize loss and PDL.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional two-component PSR design is used, then polarization rotation function is achieved, but device length increases to 200-220 um and additional space is required for modemuxing
Solution Approach 1:
The patent merges the polarization rotation function and modemuxing function into a single integrated waveguide structure. The vertically stacked three-layer waveguide configuration allows both functions to be performed simultaneously within the same physical space, eliminating the need for separate rotation and modemuxing sections that would otherwise require 200-220 um total length.
Solution Approach 2:
The patent transitions from a planar, sequential arrangement of rotation and modemuxing components to a vertically stacked three-dimensional configuration. By stacking waveguides in the vertical dimension (TM0, TE1, TE0 modes in separate layers), the device achieves both rotation and modemuxing functions within a compact footprint, reducing the overall device length significantly.
2Ease of operation
If TM0→TE1 mode transition is used for polarization rotation, then rotation is achieved, but polarization-dependent loss increases due to lossy TM0→TE1 transition
Solution Approach 1:
The patent changes the operational parameters by maintaining the TM0 mode throughout the rotation process rather than transitioning to TE1 mode. The vertically stacked waveguide structure enables polarization rotation while keeping the optical signal in the low-loss TM0 mode, thereby minimizing polarization-dependent loss while achieving the required rotation function.
3Adaptability or versatility
If separate rotation stage and modemux are used, then both functions are achieved, but total device length increases to 200-220 um
Solution Approach 1:
The patent combines the rotation stage and modemux into a single integrated structure where the vertically stacked three-layer waveguide performs both functions simultaneously. The TM0 waveguide handles rotation while the TE0 waveguide handles modemuxing, eliminating the need for separate components and reducing total length from 200-220 um to a compact integrated design.
Solution Approach 2:
The vertically stacked waveguide structure serves multiple functions within a single component. The same physical structure enables both polarization rotation and modemuxing operations, making the device universal and eliminating the need for separate dedicated components for each function.
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
Achieves high optical power handling and efficient polarization rotation with over 90% efficiency in a compact 50 um length, reducing PDL and eliminating the need for additional space for modemuxing, while maintaining high transmission efficiency across relevant wavelengths.
Implementation Method 1
a high index contrast material is typically used to strongly break the optical symmetry of the waveguide, enabling polarization rotation (TM0→TE1)
Implementation Method 2
A compact PSR design with three vertically stacked waveguides, where the Si layer is translated relative to a fixed SiN layer
Data Source
AI summary
A photonic polarization splitter rotator (PSR) includes a substrate, a first optical waveguide disposed in the substrate on a first layer, the first optical waveguide having a curved portion between a first end of the first optical waveguide and a second end of the first optical waveguide, and a second optical waveguide disposed in the substrate on a second layer, above the first layer, the second optical waveguide having a substantially rectangular shape and longitudinally arranged between the first end of the first optical waveguide and the second end of the first optical waveguide.