Optical Waveguide Core End Surface Shaping for Slit Width Tolerance
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Solution Overview
Problem
In optical waveguide circuits using the DP-QPSK modulation method with polarization multiplexing, variations in slit width cause loss variations due to changes in the distance between optical waveguide cores, which affect the efficiency of the optical waveguide.
Innovation Solution
The optical waveguide structure incorporates a slit with specific end surface configurations and cladding material parts to minimize the impact of slit width variations, using a silica glass material and optimizing the shape of the core ends to reduce coupling losses, such as employing MMI, structurally optimized, or tapered shapes to stabilize light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a slit is formed to cut the optical waveguide for inserting a waveplate, then the waveplate can be integrated into the optical waveguide circuit, but a variation in the slit width causes a variation in the loss of the optical waveguide
Solution Approach 1:
The end surfaces of the cores are configured in advance (before the slit is formed) to have specific shapes (tapered, MMI, or structurally optimized) that pre-compensate for the potential misalignment and width variations of the slit. This preliminary configuration ensures that even when the slit width varies, the light coupling between cores remains stable and loss variations are suppressed.
Solution Approach 2:
The invention changes the geometric parameters of the core end surfaces (taper angle, MMI region length, curvature radius) to optimize light coupling. By adjusting these parameters, the system adapts to slit width variations and maintains consistent optical performance, transforming the fixed geometry into an optimized parameter set that compensates for manufacturing tolerances.
2Manufacturing precision
If the slit width varies, then the distance between cores changes, but this causes loss variation in the optical waveguide
Solution Approach 1:
The end surfaces of the cores are given special local quality through specific shaping (tapered, MMI, or structurally optimized configurations) that differs from the rest of the core structure. This localized modification at the critical coupling region enhances light coupling efficiency and makes the system less sensitive to slit width variations, thereby reducing loss variation without affecting the overall manufacturing process.
3Ease of manufacture
If conventional core end surfaces are used, then the manufacturing process is simple, but coupling losses increase and stability decreases
Solution Approach 1:
The core end surfaces are configured in advance with optimized shapes (tapered, MMI, or structurally optimized) before the slit formation step. This preliminary configuration ensures that the light coupling is optimized and stable, and it can be integrated into the existing manufacturing process flow without requiring complex post-processing or additional fabrication steps.
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 effectively suppresses the variation in optical waveguide loss due to slit width variations, maintaining low coupling losses and enhancing the stability of the optical waveguide circuit.
Implementation Method 1
a first core in the cladding having a first end surface; a second core in the cladding having a second end surface
Data Source
AI summary
An optical waveguide structure includes: a cladding; a first core in the cladding having a first end surface; a second core in the cladding having a second end surface; slit formed horizontally with respect to a waveguide direction of the light to be waveguided by the first and second cores; and a first part and a second part composed of a material identical to a material of the cladding, wherein a pair of the first and second end surfaces disposed opposing each other with the slit interposed between the pair of the first and second end surfaces, the first part is interposed between the first end surface and the slit, and the second part is interposed between the second end surface and the slit.