Brewster-Window Polarization Splitters for Wideband Photonic Chips

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing technologies struggle to efficiently separate and control the polarization of light beams in photonic integrated circuits, particularly in systems requiring compact, on-chip polarization splitters that can handle a wide range of wavelengths.

Innovation Solution

The use of Brewster windows positioned at specific angles relative to the input light to generate polarized output beams, utilizing a set of output waveguides and intermediate waveguides to connect input waveguides, and a set of Brewster windows to split input light into polarized output beams.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional polarization splitting methods are used, then polarization separation can be achieved, but the device size becomes large and integration is difficult

Engineering Contradiction:

Improvepolarization splitter sizeVSAvoidpolarization separation performance

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The polarization splitter is divided into multiple functional segments: input waveguide, intermediate waveguide with Brewster windows, and output waveguides. This segmentation allows each component to be optimized independently while maintaining compact overall dimensions suitable for photonic integrated circuits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from bulk optical components to planar waveguide structures, utilizing the two-dimensional integration space of photonic chips. The Brewster windows are positioned at specific angles within the waveguide plane, enabling polarization splitting without requiring large three-dimensional space.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If Brewster windows are used for polarization splitting, then polarization purity is improved, but the device becomes more complex

Engineering Contradiction:

Improvepolarization purityVSAvoidpolarization splitter structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Brewster windows are positioned at specific locations and orientations within the intermediate waveguide where they are most effective. The windows are angled at the Brewster angle relative to the waveguide axis, creating localized polarization splitting zones that maintain high polarization purity without requiring complex overall device architecture.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If compact polarization splitters are integrated on-chip, then integration density is improved, but handling wide wavelength ranges becomes difficult

Engineering Contradiction:

Improvewavelength range coverageVSAvoidon-chip integration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The polarization splitter design using Brewster windows in waveguides creates a universal structure that can handle multiple wavelengths simultaneously. The Brewster angle condition is wavelength-dependent, allowing the same device structure to effectively split polarizations across a broad spectral range without requiring wavelength-specific components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach enhances the separation and control of the polarization of light across a wide range of wavelengths, maintaining high polarization purity and reducing orthogonal polarization components.

Implementation Method 1

each Brewster window of the set of Brewster windows is angled relative to the corresponding portion of the input light at a corresponding angle that is a Brewster angle for a corresponding target wavelength within the operating wavelength range

Methodology Applied

Scientific EffectBrewster's angle: Brewster's Angle

Implementation Method 2

The polarization splitter is configured such that when the input light is received at the input waveguide... each output waveguide of the set of output waveguides outputs a corresponding polarized light output having a corresponding polarization

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 3

an intermediate waveguide optically connecting the input waveguide to the set of output waveguides

Methodology Applied

Scientific EffectWaveguide: Waveguide (optics)

Data Source

PatentUS20250383504A1Polarization beamsplitters for photonic integrated circuits

Publication Date: 2025.12.18 APPLE INC

AI summary

A photonic integrated circuit as discussed herein may include a polarization splitter that includes a set of Brewster windows. The polarization splitter includes an input waveguide, a set of output waveguides, and an intermediate waveguide optically connecting the input waveguide to the set of output waveguides. Each Brewster window is positioned to intersect a corresponding portion of the intermediate waveguide. The polarization splitter is configured to receive input light that includes one or more wavelengths within an operating wavelength range, and to use the input light to generate polarized output light at each of the set of output waveguides. Collectively, the set of Brewster windows generates a passed beam that passes through each of the Brewster windows, as well as one or more reflected beams, each of which is reflected from a corresponding Brewster window. These beams may form the polarized output light generated by the polarization splitter.