Light Modulation Device Complex-Valued Phase Encoding
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Solution Overview
Problem
Existing light modulation devices for complex-valued modulation of linearly polarized light require amplitude and phase modulators with similar switching times and matching characteristics, which complicates the design and increases radiation losses.
Innovation Solution
A light modulation device comprising two phase modulators with modulation axes aligned at an angle, where the polarization direction of the incident light and the polarizer are aligned at non-90° angles, allowing independent phase adjustment of light components and simplifying the driving mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If amplitude modulator and phase modulator are used successively, then complex-valued modulation is achieved, but device complexity and matching requirements increase
Solution Approach 1:
The patent combines amplitude modulation and phase modulation functions into a single phase modulator by using two-phase encoding. Adjacent pixels in the phase modulator are driven with complementary phase signals, and their interference patterns produce both amplitude and phase modulation effects, eliminating the need for separate amplitude and phase modulators.
Solution Approach 2:
The patent divides a single pixel into multiple subpixels (e.g., four subpixels arranged in 2x2 grid) that are driven with different phase signals. By controlling the phase of each subpixel independently and utilizing optical interference, the system achieves complex-valued modulation without requiring separate modulator components.
2Adaptability or versatility
If two phase modulators with beam splitter are used for two-phase encoding, then amplitude and phase can be adjusted, but radiation losses increase
Solution Approach 1:
The patent removes the beam splitter component from the optical path by using a single phase modulator with spatially distributed subpixels. The interference necessary for amplitude modulation is achieved through the spatial arrangement and phase control of subpixels within the same modulator, eliminating the need for beam splitting and recombination optics that cause radiation losses.
3Device complexity
If adjacent cells are used for two-phase encoding, then pixel structure is simplified, but alignment precision requirements increase
Solution Approach 1:
The patent incorporates alignment marks and reference structures directly into the substrate or cover glass during the manufacturing process. These pre-formed alignment features guide the positioning of electrode patterns and subpixel regions, ensuring precise alignment without requiring complex post-manufacturing adjustment procedures.
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 enables simple and efficient complex-valued light modulation with reduced radiation losses and improved alignment of light modulators, allowing for high contrast and efficient holographic image representation.
Implementation Method 1
The liquid crystals used to produce the light modulators are birefringent materials in which the orientation of the optical axis of the molecules can be adjusted in a desired direction, for example by an electric field.
Implementation Method 2
Under the effect of the electric field, the molecules of a nematic liquid crystal with a positive dielectric anisotropy rotate in the direction of the field.
Implementation Method 3
a polarization direction of the light incident on the first light modulator and a polarization direction of the polarizer are respectively aligned at predetermined non-90° angles with respect to a modulation axis of the first light modulator and a modulation axis of the second light modulator
Data Source
AI summary
The invention relates to a light modulation device for a complex-valued modulation of linearly polarized incident light, comprising a first light modulator, a subsequently arranged second light modulator and at least one polarizer, where the first light modulator and the second light modulator are configured as phase modulators, where a modulation axis of the first light modulator is aligned at an angle to the modulation axis of the second light modulator, and where the polarization direction of the light incident on the first light modulator and the polarization direction of the polarizer are respectively aligned at predetermined non-90° angles with respect to the modulation axis of the first light modulator and the modulation axis of the second light modulator.