Multi-Mode Interference Waveguide Polarizer with Slit
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Solution Overview
Problem
Existing light polarizing elements with Mach-Zehnder interferometer configurations suffer from significant radiation loss due to the width of the slit and relative refractive-index difference, leading to increased excess loss and potentially larger sizes, especially when a quarter wavelength plate is inserted.
Innovation Solution
A light polarizing element featuring a multi-mode interference waveguide with slits that provide different effective refractive indexes for orthogonal polarized light waves, allowing for efficient separation and combination of polarized light without the need for a quarter wavelength plate, and is formed using silica-based glass with optimized waveguide and slit shapes to minimize radiation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slit is formed in the arm waveguide to insert a quarter wavelength plate, then the polarizing function is achieved, but radiation loss increases due to the slit width and relative refractive-index difference
Solution Approach 1:
The invention extracts the quarter wavelength plate from the waveguide structure, replacing it with a slit formed directly in the waveguide. This eliminates the need for separate components while achieving the same polarizing function through the waveguide's own structure, thereby reducing radiation loss.
Solution Approach 2:
The invention changes the geometric parameters of the slit (width, length, position) and the waveguide structure to optimize the polarizing function while minimizing radiation loss. By carefully controlling these parameters, the design achieves effective polarization without excessive energy loss.
2Ease of manufacture
If the slit width is increased to reduce manufacturing difficulty, then ease of manufacture improves, but radiation loss increases
Solution Approach 1:
The invention optimizes the slit width parameter within a specific range that balances manufacturability and optical performance. The slit width is designed to be sufficient for easy fabrication while remaining narrow enough to minimize radiation loss, achieving a practical compromise through careful parameter selection.
Data Source
AI summary
A light polarizing element include: a first port waveguide; two second port waveguides; and a multi-mode interference waveguide optically connected to the first port waveguide and the two second port waveguides, the multi-mode interference waveguide having at least one slit formed therein, the at least one slit having a shape that enables the multi-mode interference wave guide to give different effective refractive indexes to respective mutually orthogonal polarized light waves input from the first port waveguide, thereby separating the mutually orthogonal polarized light waves, and that enables the separated mutually orthogonal polarized light waves to be output from the respective two second port waveguides.