Mid-Infrared Polarization Splitter-Rotator With Tapered Waveguide Bifurcation

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Solution Overview

Problem

Conventional silicon photonics waveguides for mid-infrared applications are bulky, inefficient, and require significant space, leading to high losses and incompatibility with existing systems, particularly when transitioning between transverse magnetic (TM) and transverse electric (TE) modes.

Innovation Solution

A compact mid-infrared polarization splitter and rotator using a bifurcated tapered-bent waveguide design that efficiently converts TM modes to TE modes with minimal loss and crosstalk, utilizing a silicon-on-insulator platform and precise waveguide structures to achieve both TE modes at outputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional waveguide designs are used for mid-infrared applications, then polarization mode conversion can be achieved, but the device occupies excessive spatial footprint and causes significant signal losses

Engineering Contradiction:

Improvesignal lossVSAvoidspatial footprint

Core Design Contradiction:

Loss of energyVSArea of stationary object

Solution Approach 1:

The waveguide is divided into distinct functional sections: an input section, a tapered section for mode conversion, and an output section. This segmentation allows each section to be optimized for its specific function, achieving efficient polarization conversion in a compact overall structure that minimizes both spatial footprint and signal loss.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a tapered waveguide that transitions the optical mode in the transverse dimension, converting TM modes to TE modes through gradual geometric modification. This dimensional transformation enables compact polarization conversion without requiring long propagation distances, thereby reducing both area and energy loss.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If conventional polarization converters are used, then mode conversion between TM and TE can be achieved, but the device size becomes excessively large for integration

Engineering Contradiction:

Improvemode conversion capabilityVSAvoiddevice length

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The tapered section is designed to pre-condition the optical mode before it reaches the output waveguide. By gradually transforming the TM mode into a TE mode within the taper, the conversion is accomplished proactively rather than requiring a separate conversion stage, thereby shortening the overall device length while maintaining full conversion capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The tapered waveguide section serves multiple functions simultaneously: it acts as a mode converter, a mode conditioner, and a transition element between different waveguide sections. This multi-functionality eliminates the need for separate dedicated components, reducing device length while preserving adaptability for various mid-infrared applications.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If standard waveguide structures are used, then system compatibility can be maintained, but integration into existing compact systems becomes difficult

Engineering Contradiction:

Improvesystem compatibilityVSAvoidretrofittability

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The waveguide structure maintains standard dimensions and material properties in sections that interface with existing systems, ensuring compatibility. The tapered conversion section is localized to a specific region, allowing the majority of the waveguide to conform to standard specifications, thereby facilitating easy integration and retrofitting while preserving system compatibility.

Inventive Principle:

Principle #3Local quality

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 design achieves low insertion and polarization conversion losses, enabling integration into existing systems with minimal size and retrofittability, suitable for applications in thermal imaging, medical diagnosis, and security, with improved modal overlap and reduced bending radii.

Implementation Method 1

conditioning, by a taper of the waveguide, the input signal which may convert the TM mode to an additional TE mode

Methodology Applied

Scientific EffectAdiabatic mode transformation:

Implementation Method 2

bifurcating, after the conditioning and by a bifurcation section of the waveguide positioned after the taper, the input signal into a first branch and a second branch of the waveguide

Methodology Applied

Scientific EffectWaveguide bifurcation:

Data Source

PatentUS20260043964A1Efficient and compact mid-infrared polarization splitter and rotator based on a bifurcated tapered-bent waveguide

Publication Date: 2026.02.12 KHALIFA UNIV OF SCI & TECH

AI summary

A method for a compact mid-infrared polarization splitter and rotator (PSR) that may include receiving an input signal at a waveguide, the input signal having a transverse electric (TE) mode and a transverse magnetic (TM) mode such that the TE mode may be a zero order or higher mode. The method may further include conditioning, by a taper of the waveguide, the input signal to convert the TM mode to an additional TE mode and bifurcating, after the conditioning and by a bifurcation section of the waveguide positioned after the taper, the input signal may be split into a first branch and a second branch of the waveguide. The method may further include outputting, out of the first branch, a first output signal having the TE mode and outputting, out of the second branch, a second output signal.