Reflective Crystal Light Modulator for Fast Short-Wavelength Modulation
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Solution Overview
Problem
Existing light modulators, such as those using liquid crystals, have limited response speeds and struggle to operate effectively in wide wavelength regions, particularly at wavelengths shorter than 1300 nm, while EO polymer-based modulators suffer from high light absorption in these regions.
Innovation Solution
A light modulator and array utilizing a nonlinear optical crystal layer sandwiched between a reflective metal layer and a conductive pattern layer, where the refractive index is altered by applied voltage to modulate light intensity, with a grating-shaped conductive pattern layer arranged periodically to suppress high-order diffraction and enable high-speed operation across a wide wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If liquid crystal layer is used for light modulation, then the device can modulate light phase, but the response speed is limited to less than 1 kHz
Solution Approach 1:
The patent changes the material parameter of the modulation layer from liquid crystal to electro-optic polymer, which fundamentally alters the response mechanism. The electro-optic polymer exhibits significantly faster response speed compared to liquid crystal, enabling high-speed light modulation while maintaining effective modulation performance.
Solution Approach 2:
The patent employs a composite structure consisting of electro-optic polymer layer, metal layers, and dielectric layers. This composite material approach combines the fast response of electro-optic polymer with the optical control capabilities of the layered structure, achieving both high speed and reliable modulation.
2Speed
If EO polymer is used in modulation layer, then high-speed intensity modulation can be achieved, but light absorption is large at wavelengths shorter than 1300 nm
Solution Approach 1:
The patent extracts the EO polymer layer from the direct light path by positioning it between metal layers that form a reflective cavity. The object light does not pass through the EO polymer; instead, the modulation is achieved through electric field control of the cavity resonance, eliminating absorption losses while preserving fast modulation speed.
Solution Approach 2:
The patent introduces metal layers and dielectric layers as intermediary elements between the light source and the EO polymer. These intermediaries create a reflective cavity that mediates the interaction between light and the electro-optic material, allowing indirect modulation without direct light transmission through the absorbing polymer.
3Adaptability or versatility
If conventional light modulator structure is used, then simple fabrication can be achieved, but it cannot operate effectively in wide wavelength region
Solution Approach 1:
The patent designs a multi-functional layered structure where metal layers serve multiple purposes: as reflective mirrors for the optical cavity, as electrodes for voltage application, and as part of the resonant structure. This universal design enables the device to operate across wide wavelength ranges while maintaining a relatively compact and integrated structure.
Solution Approach 2:
The patent transitions from planar light modulation to three-dimensional cavity resonance by stacking multiple layers in the vertical dimension. This dimensional change creates a resonant cavity that supports multiple modes across different wavelengths, expanding the operational wavelength range without proportionally increasing lateral complexity.
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 proposed modulator achieves high-speed intensity modulation suitable for wavelengths shorter than 1300 nm and can be integrated into one- or two-dimensional arrays, offering improved performance and integration compared to conventional technologies.
Implementation Method 1
the modulation layer is configured to change a reflectance for the object light by changing a refractive index when a voltage is applied between the reflective layer and the conductive pattern layer
Implementation Method 2
a grating-shaped conductive pattern layer arranged periodically to suppress high-order diffraction
Implementation Method 3
the object light being incident from the upper surface of the modulation layer through the conductive pattern layer, transmitted through the modulation layer, and reflected by the reflective layer
Data Source
AI summary
A light modulator includes a base layer, a metal reflective layer formed on the base layer, a modulation layer of a nonlinear optical crystal formed on the reflective layer, and a conductive pattern layer including a plurality of pattern portions arranged periodically in a first direction and each extending in a second direction, and formed on the modulation layer. The modulation layer changes a reflectance for object light by changing a refractive index when a voltage is applied between the reflective layer and the conductive pattern layer. The light modulator outputs the object light being incident from an upper surface side of the modulation layer, transmitted through the modulation layer, and reflected by the reflective layer to the outside as modulated light with an intensity modulated by the reflectance change.