Polarization angle modulator and polarizing device
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Solution Overview
Problem
Polarized image sensors face issues with critical dimension variation and low quantum efficiency due to fabrication challenges of wire grid polarizers (WGPs) oriented in different directions, leading to sparsity and reduced performance.
Innovation Solution
A polarization angle modulator is introduced, comprising a stacked configuration of quarter wave plates and liquid-crystal phase modulators with integrated electrodes, allowing for electrically controllable and adjustable grating effects, eliminating the need for WGP sub-pixels and enabling maximum quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wire grid polarizers (WGPs) oriented in four different directions are fabricated above each pixel, then polarization information can be captured, but critical dimension variation occurs leading to large sparsity and low quantum efficiency
Solution Approach 1:
The device divides the pixel array into four distinct pixel groups, with each group containing pixels equipped with WGPs oriented at specific angles (0°, 45°, 90°, 135°). This segmentation allows each group to capture polarization information at its specific orientation while maintaining manufacturing precision by fabricating all WGPs in a single layer rather than attempting to fabricate multiple orientations with precise dimensional control
Solution Approach 2:
The invention transitions from a planar 2D arrangement of multiple WGP orientations above each pixel to a vertical stacking approach where four pixel groups are arranged spatially with each group handling a specific polarization angle. This dimensional reorganization eliminates the need for precise critical dimension control of multiple WGP layers while preserving the ability to capture full polarization information
2Measurement precision
If wire grid polarizers (WGPs) are positioned above each pixel for polarization detection, then polarization angles can be differentiated, but quantum efficiency decreases due to fabrication limitations
Solution Approach 1:
The pixel array is segmented into four groups, with each group dedicated to a specific polarization angle (0°, 45°, 90°, 135°). Each group contains pixels with WGPs oriented at that specific angle, allowing precise polarization angle differentiation while maintaining high quantum efficiency by using a single WGP layer per pixel group rather than multiple layers that would reduce light transmission
Solution Approach 2:
Each pixel group is assigned a specific polarization sensitivity corresponding to its WGP orientation. This local specialization allows the system to differentiate all four polarization angles across the array while each individual pixel group maintains optimal quantum efficiency for its designated angle without being compromised by the presence of other orientations
3Adaptability or versatility
If multiple WGP sub-pixels are used per polarization pixel, then polarization information can be captured, but device complexity increases and packaging becomes difficult
Solution Approach 1:
The invention merges the electrode control functions for all four pixel groups into a single integrated electrode structure located at the bottom of the device. This unified electrode system simultaneously controls the liquid crystal layers across all pixel groups, eliminating the need for separate electrode control circuits for each pixel group and significantly reducing device complexity and packaging difficulty
Solution Approach 2:
The bottom electrode structure serves multiple functions: it provides electrical connection to all four pixel groups, controls the liquid crystal layers across the entire device, and acts as a common reference potential. This universal electrode design simplifies the electrical distribution network while maintaining the ability to independently address and control each pixel group's polarization state
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
The solution provides enhanced quantum efficiency, large aperture ratio, and adjustable polarizations, facilitating easier packaging and mass production, while reducing pixel defects and eliminating reflections.
Implementation Method 1
a liquid crystal layer (14, 24) between the lower base plate (11, 21) and the upper base plate (17, 27), the optical axis of which forms an angle of 45 degrees with the axis of polarization of the linearly polarizing wave plate (30)
Implementation Method 2
a first quarter wave plate (41), a first liquid-crystal phase modulator (10), a linearly polarizing wave plate (30), a second liquid-crystal phase modulator (20) and a second quarter wave plate (42), which are sequentially stacked from the bottom upwards
Data Source
AI summary
A polarization angle modulator and a polarizing device are disclosed. The polarization angle modulator includes a first quarter wave plate, a first liquid-crystal phase modulator, a linearly polarizing wave plate, a second liquid-crystal phase modulator and a second quarter wave plate, which are sequentially stacked from the bottom upwards. The first quarter wave plate is provided on its lower surface with a plurality of electrodes for external connection of upper and lower electrode layers of the first liquid-crystal phase modulator and of upper and lower electrode layers of the second liquid-crystal phase modulator. This polarization angle modulator is an integrally-formed single-piece modulator. All electrode control and electrical distribution tasks can be accomplished at a lower surface of first quarter wave plate, allowing for easier packaging. Mass production can be easily achieved using a wafer stacking process. The polarizing device of the present invention can be provided as a simple package.