Optical Diode Using Spin-Orbit Coupling for Miniaturization
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Solution Overview
Problem
Existing optical diodes, particularly those using Faraday isolators, face challenges such as the need for strong magnetic fields, poor integratability, wavelength dependency, narrow bandwidth, and high costs, making them unsuitable for miniaturization and integration with optical glass fibers or integrated waveguides.
Innovation Solution
An optical diode utilizing the spin-orbit coupling of light (SOCL) effect, which creates a miniaturized solution by leveraging the refractive index contrast between a waveguide core and surrounding medium to achieve directional light propagation, with absorber elements positioned in the near field to differentially absorb light based on polarization, allowing for adjustable absorption and broader bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Faraday isolators are used to implement optical diodes, then light propagation direction can be controlled, but the device size becomes large and integration is difficult
Solution Approach 1:
The invention changes the operating parameters by utilizing the spin-orbit coupling of light instead of the Faraday effect. This allows the optical diode to achieve directional light propagation control with a much smaller device footprint, enabling miniaturization while maintaining the core functionality of controlling light propagation direction.
Solution Approach 2:
The invention replaces the mechanical/magnetic system (Faraday isolators requiring strong magnetic fields) with an optical system based on spin-orbit coupling. This substitution eliminates the need for bulky magnetic field generation components and enables direct integration with optical waveguides and fibers, significantly reducing device volume.
2Reliability
If Faraday isolators are used, then optical diode function is achieved, but bandwidth is narrow and wavelength dependency is high
Solution Approach 1:
The invention changes the physical mechanism from the Faraday effect to spin-orbit coupling of light. This parameter change fundamentally alters the wavelength dependency characteristics, resulting in a broadband optical diode that functions across a wide range of wavelengths without requiring precise wavelength matching, thus significantly improving adaptability and versatility.
3Reliability
If Faraday isolators are used, then light direction control is achieved, but strong magnetic fields are required leading to interference with nearby components
Solution Approach 1:
The invention replaces the magnetic field-based Faraday effect with an optical effect based on spin-orbit coupling. This substitution eliminates the generation of strong magnetic fields that cause interference with nearby components, while maintaining the ability to control light propagation direction through the intrinsic properties of light-matter interaction in the optical waveguide.
4Reliability
If Faraday isolators are used, then optical diode functionality is achieved, but integration with optical circuits and fibers is poor
Solution Approach 1:
The invention replaces the bulky mechanical Faraday isolator structure with a compact optical waveguide-based structure that directly integrates with optical circuits and fibers. This substitution enables seamless integration by eliminating the need for separate magnetic field generation components and alignment mechanisms, making the optical diode suitable for compact photonic integrated circuits.
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 optical diode effectively filters out back-reflected light, ensuring unidirectional propagation while being suitable for integration with optical circuits and glass fibers, offering adjustable absorption and a wider bandwidth, thus overcoming the limitations of traditional Faraday isolator-based solutions.
Implementation Method 1
the optical waveguide has a waveguide core with a first refractive index n1 and the waveguide core is surrounded by at least one second optical medium, which has at least one second refractive index n2, where n1>n2
Implementation Method 2
utilizing the effect of so-called spin-orbit coupling of light
Implementation Method 3
at least one absorber element, which is disposed in a near field... exhibits absorption of different strength in the case of left-circular polarization on the one hand and in the case of right-circular polarization on the other
Data Source
AI summary
An optical diode (1) comprising an optical wave guide for guiding light, preferably of a light mode, with a vacuum wavelength λ0, wherein the optical wave guide has a wave guide core (2, 3, 14) with a first index of refraction (n1), and the wave guide core (2, 3, 14) is surrounded by at least one second optical medium which has at least one second index of refraction (n2), wherein n1>n2 applies, wherein the wave guide core (2, 3, 14) has at least in sections a smallest lateral dimension (7) which is a smallest dimension of a cross section (6) perpendicular to a propagation direction (5) of the light in the wave guide core (2, 3, 14), wherein the smallest lateral dimension (7) is greater than or equal to λ0/(5*n1) and less than or equal to 20*λ0/n1, wherein the optical diode (1) additionally comprises at least one absorber element (10, 11, 15, 16) which is arranged in a near field, wherein the near field consists of the electromagnetic field of the light of the vacuum wavelength λ0 in the wave guide core (2, 3, 14) and outside of the wave guide core (2, 3, 14) up to a standard interval (12) of 5*λ0, wherein the standard interval (12) is measured starting from one surface (8) of the wave guide core (2, 3, 14) forming an optical interface and in a direction perpendicular to the surface (8). The invention provides that the at least one absorber element (10, 11, 15, 16) for the light of the vacuum wavelength λ0 has a strongly different absorption for left circular polarization (σ−) and for right circular polarization (σ+).