Thin Ferroelectric Waveguide Curvature Loss
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Solution Overview
Problem
Optical waveguide devices face challenges in miniaturization due to increased radiation loss and insertion loss at curved parts, and high cross-talk at crossing parts, which are exacerbated by the need for thinner substrates to achieve velocity matching between microwave and light waves.
Innovation Solution
The optical waveguide device features a substrate thickness of 30 μm or smaller with a curved part radius of curvature of 30 mm or smaller, and a crossing part with a reduced whole crossing angle, utilizing a low dielectric substrate and recesses or grooves to confine light and reduce radiation loss and cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the substrate thickness is reduced to achieve velocity matching, then the modulation bandwidth is widened, but the mechanical strength is weakened and processing difficulty increases
Solution Approach 1:
The patent uses a composite structure consisting of a thin optical waveguide substrate (30 μm or less) bonded to a thick reinforcing substrate. This composite structure combines the optical properties of the thin substrate with the mechanical strength of the reinforcing substrate, resolving the contradiction between achieving velocity matching through thinning and maintaining mechanical strength.
2Volume of moving object
If the radius of curvature of the curved part is reduced for miniaturization, then the device size is reduced, but the optical radiation loss increases
Solution Approach 1:
The patent changes the physical parameters of the substrate by reducing its thickness to 30 μm or less. This parameter change allows the optical mode to be more tightly confined to the waveguide core, enabling smaller radius of curvature bends (30 mm or less) without excessive radiation loss, thus achieving miniaturization while controlling optical loss.
3Area of stationary object
If the whole crossing angle at the crossing part is reduced for miniaturization, then the device width is reduced, but the insertion loss and cross talk increase
Solution Approach 1:
The patent reduces the substrate thickness to 30 μm or less, which changes the optical confinement characteristics. This parameter change allows for smaller crossing angles with reduced insertion loss and cross talk by improving the vertical confinement of the optical mode, thereby enabling device miniaturization in the width direction.
4Speed
If the substrate thickness is reduced to 30 μm or less, then the velocity matching is achieved, but the processing difficulty and surface roughness damage increase
Solution Approach 1:
The patent segments the substrate structure into a thin optical waveguide substrate (30 μm or less) and a separate reinforcing substrate. The thin substrate is processed to achieve velocity matching, then bonded to the reinforcing substrate. This segmentation allows the thin substrate to be processed with controlled difficulty while the reinforcing substrate provides mechanical support.
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 configuration significantly reduces radiation loss and cross-talk while allowing for miniaturization of the optical waveguide device, maintaining mechanical strength and optimizing light confinement.
Implementation Method 1
the optical waveguide has a curved part whose radius of curvature is 30 mm or smaller
Implementation Method 2
an optical waveguide substrate having ferroelectricity
Data Source
AI summary
It is provided an optical waveguide device in which the radius of curvature of a curved part of an optical waveguide can be lowered and the radiation loss of light in the curved part can be reduced. An optical waveguide device 2 has a ferroelectric optical waveguide substrate and an optical waveguide 5 formed in or on the substrate and modulating electrodes 4A, 4B and 4C. The thickness of the optical waveguide substrate is 30 μm or smaller at least in a region where the optical waveguide is formed. The optical waveguide has curved part having a radius of curvature of 30 mm or smaller.