Waveguide Polariser with Thin Blade for High Extinction
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Solution Overview
Problem
Integrated optical circuits with waveguide polarizers have limited polarization extinction rates due to parasitic reflections and unguided light propagation, which affects the quality of signals and applications relying on these devices.
Innovation Solution
A polarizing optical device comprising a first waveguide polarizer and a second thin blade polarizer, with specific refractive index and thickness, positioned between the waveguide polarizer and another optical waveguide to enhance polarization rejection rates without significant insertion losses or increased size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a waveguide polarizer on an integrated optical circuit is used, then the device allows integration of several functions on the same substrate improving compactness, but the polarization extinction rate is limited to approximately -45 to -65 dB due to parasitic reflections and unguided light propagation
Solution Approach 1:
The patent divides the optical path into multiple segments by introducing intermediate optical elements (such as additional waveguides, couplers, or polarizing components) between the input and output of the integrated optical circuit. This segmentation allows each segment to be optimized for specific functions, improving overall polarization extinction while maintaining compact integration.
Solution Approach 2:
The patent introduces intermediary optical components (such as isolation waveguides, couplers, or polarizing beamsplitters) that act as mediators to manage parasitic light paths. These intermediaries selectively guide or block unguided light, preventing it from reaching the output and thereby improving polarization extinction rate without significantly increasing device volume.
2Manufacturing precision
If the thickness of the thin blade polarizer is increased to improve polarization rejection, then the polarization rejection rate increases, but the insertion losses increase and the device size increases
Solution Approach 1:
The patent optimizes the thickness parameter of the thin blade polarizer to achieve the desired polarization rejection rate while minimizing insertion losses. By precisely controlling the thickness within a specific range, the device achieves high polarization selectivity without excessive absorption or reflection losses, and maintains a compact form factor.
3Manufacturing precision
If the thickness of the thin blade polarizer is increased to improve polarization rejection, then the polarization rejection rate increases, but the device size increases
Solution Approach 1:
The patent optimizes the thickness parameter of the thin blade polarizer to achieve the desired polarization rejection rate while minimizing insertion losses. By precisely controlling the thickness within a specific range, the device achieves high polarization selectivity without excessive absorption or reflection losses, and maintains a compact form factor.
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 combination of waveguide and thin blade polarizers significantly increases polarization rejection rates, achieving up to -70 dB to -100 dB, while maintaining low insertion losses and compactness.
Implementation Method 1
A polarizing optical device comprises a first polarizer, the first polarizer being a waveguide polarizer on an integrated optical circuit, a section of a second optical waveguide, and a second polarizer, the second polarizer being a thin blade polarizer
Implementation Method 2
An unguided beam 14 then propagates in the substrate as far as the lower face 4 of the substrate. A part of the unguided beam 14 can be reflected by total internal reflection on the lower face 4.
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention relates to a polarising optical device with waveguide, comprising a first waveguide polariser (6), a section of a second optical waveguide (31) and a second thin-section polariser (52) having a physical thickness T and a refractive index n, said second thin-section polariser (52) being disposed on the optical path between a waveguide end (8) of the first polariser (6) and one end (32) of the second optical waveguide (31), the physical distance d between the waveguide end (8) of the first polariser (6) and the end (32) of the second optical waveguide (31) being less than or equal to twice the Rayleigh length and the physical thickness T of the second polariser (52) being less than or equal to the physical distance d.