Bridging Waveguide Optical Coupling for Fluoride Microresonators
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Solution Overview
Problem
The challenge of efficiently coupling light to and from crystalline optical microresonators, particularly due to the low index of refraction of fluoride materials, which complicates integration with optical coupling mechanisms.
Innovation Solution
A photonic chip-based optical coupling device featuring a bridging waveguide structure that emulates a tapered optical fiber, allowing for efficient evanescent field coupling to optical microresonators, including those made from fluoride materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If tapered optical fibers are used for coupling, then coupling efficiency and flexibility are improved, but packaging complexity increases
Solution Approach 1:
The patent creates an on-chip waveguide structure that copies the functional characteristics of a tapered optical fiber, achieving the same evanescent field coupling capability without requiring actual tapered fibers and their complex alignment mechanisms
Solution Approach 2:
The patent replaces the mechanical fiber coupling system with an integrated photonic waveguide system, eliminating the need for manual fiber alignment and packaging while maintaining efficient optical coupling
2Ease of operation
If prism coupling is used, then coupling to crystalline microresonators is achieved, but coupling efficiency is limited to maximum 75%
Solution Approach 1:
The patent modifies the waveguide geometry parameters (width, height, taper angle) to optimize the evanescent field distribution, enabling superior coupling efficiency compared to conventional prism coupling methods
3Reliability
If fluoride crystalline materials are used, then transparency windows and quality factors are improved, but coupling difficulty increases due to low refractive index
Solution Approach 1:
The patent introduces an intermediary waveguide structure with carefully engineered refractive index properties that bridges the optical mode mismatch between standard optical fibers and low-index fluoride crystalline microresonators
Solution Approach 2:
The patent creates a localized region in the waveguide with modified optical properties (different refractive index, geometry) specifically at the coupling interface to match the mode characteristics of the fluoride resonator
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 close to critical coupling with a quality factor of 10^8, enabling robust and compact optical packaging of microresonators and facilitating applications such as injection locking of laser diodes.
Implementation Method 1
allowing for efficient evanescent field coupling to optical microresonators
Data Source
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AI summary
The present invention concerns an optical coupling device including at least one supporting layer comprising a first support wall and a second support wall. The at least one supporting layer comprises at least one bridging waveguide for coupling electromagnetic radiation to and from an optical resonator or optical device, the at least one bridging waveguide extending between the first support wall and the second support wall.