Stepped Reflecting Grating Overlap Design for Optical Loss Reduction
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Solution Overview
Problem
Optical gratings used in communications applications suffer from high levels of optical loss and polarization-dependent loss due to the design of stepped reflecting surfaces and manufacturing inaccuracies, which lead to unwanted reflections and absorption of light signals.
Innovation Solution
The optical device incorporates stepped reflecting surfaces with overlapping and un-overlapped regions, where the overlapping regions receive light signals before they can reach the overlapped regions, reducing optical loss by minimizing interaction with rounded intersections and using a buffer layer to reduce absorption by the metal reflecting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If stepped reflecting surfaces are used in optical gratings, then light signals can be reflected and separated by wavelength, but optical loss and polarization-dependent loss increase due to manufacturing inaccuracies and unwanted reflections
Solution Approach 1:
The overlapping regions are designed in advance to intercept light signals before they reach the rounded intersections of the stepped reflecting surfaces. This preliminary action prevents light from interacting with the manufacturing-defective rounded areas, thereby reducing optical loss and polarization-dependent loss caused by manufacturing inaccuracies
Solution Approach 2:
The overlapping regions act as intermediary elements that mediate between the light signals and the stepped reflecting surfaces. By positioning these overlapping regions to receive light first, they shield the light from directly interacting with the problematic rounded intersections, thus reducing unwanted reflections and absorption
2Loss of energy
If stepped reflecting surfaces are used in optical gratings, then light signals can be reflected and separated by wavelength, but polarization-dependent loss increases due to unwanted reflections
Solution Approach 1:
The overlapping regions are positioned to preliminarily intercept light signals before they reach the stepped reflecting surfaces. This preliminary interception prevents light from undergoing unwanted reflections at the rounded intersections, thereby reducing polarization-dependent loss
Solution Approach 2:
The design converts the potentially harmful rounded intersections (caused by manufacturing) into a beneficial configuration where overlapping regions deliberately intercept light first. This transforms the manufacturing limitation into an advantage by using the overlapping structure to shield light from harmful reflections
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 optical loss and polarization-dependent loss by directing light signals effectively and minimizing absorption, enhancing the separation of light signals by wavelength.
Implementation Method 1
The optical grating includes a reflecting surface that reflects the received light signals back into the free propagation region. The light signals are reflected such that the light signals of different wavelengths separate as they travel through the free propagation region.
Implementation Method 2
Optical gratings for separating light signals of different wavelengths are often formed in the light-transmitting medium.
Implementation Method 3
The un-overlapped regions are positioned such that the un-overlapped regions receive the light signals but the overlapping regions are positioned between the overlapped regions and the light signals so that the overlapping regions receive the light signals before the light signals can be received by the overlapped regions.
Data Source
AI summary
An optical device includes a light-transmitting medium positioned on a base. The light-transmitting medium at least partially defines a free propagation region through which light signals travel. A reflective grating includes stepped reflecting surfaces positioned such that light signals that travel through the free propagation region are received by the reflecting surfaces. The reflecting surfaces are configured to reflect the light signal back into the free propagation region such that the light signals associated with different wavelengths separate as the light signals travel through the free propagation region. At least a portion of the reflecting surfaces each includes an overlapping region. Additionally, at least a portion of the reflecting surfaces each includes an overlapped region and un un-overlapped region. The reflecting grating is configured such that the light signals travel toward the overlapped regions and the un-overlapped regions before being reflected. The un-overlapped regions are positioned such that the un-overlapped regions receive the light signals but the overlapping regions are positioned between the overlapped region and the light signals so that the overlapping regions receive the light signals before the light signals can be received by the overlapped regions.