Electro-optical Element Waveguide Branching for XR Light Source Efficiency
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Solution Overview
Problem
In light source modules for XR glasses, the intensity ratio of output light to input light from the optical waveguide is low due to temperature fluctuations affecting the light source and electro-optical elements, leading to inefficient light usage.
Innovation Solution
An electro-optical element with an optical coupling and branch part that branches modulated light into multiple optical-output-side waveguides, using only a fraction of the modulated light as monitoring light, allowing for efficient feedback control and increasing the output light intensity ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monitoring light is extracted from modulated light using a multimode interferometer, then feedback control can be performed to detect light intensity fluctuation and DC drift, but the ratio of output light to input light becomes low
Solution Approach 1:
The optical path is segmented into multiple independent waveguides: monitoring waveguides for feedback control and output waveguides for light output. This segmentation allows the monitoring function to be separated from the main optical path, enabling feedback control while preserving most of the modulated light for output.
Solution Approach 2:
A small portion of modulated light is extracted from the main optical path to create monitoring light in separate monitoring waveguides. This extraction is minimal compared to traditional MMI-based monitoring, allowing the majority of light to continue to output waveguides, thus improving the output light ratio while maintaining feedback control capability.
2Ease of operation
If DC voltage is applied to change refractive index of lithium niobate optical waveguide, then optical modulation is achieved, but DC drift occurs with elapsed application time
Solution Approach 1:
Photodetectors monitor the light intensity in monitoring waveguides and provide feedback signals to control units. The control units adjust the DC voltage applied to the lithium niobate optical waveguide in real-time to compensate for DC drift, thereby maintaining waveform stability while preserving modulation capability.
Solution Approach 2:
The patent replaces direct monitoring of the modulated light path with an electrical feedback system using photodetectors and control units. This substitution allows for precise electronic adjustment of the DC voltage to counteract drift effects, improving waveform stability without compromising modulation performance.
3Temperature
If light source intensity fluctuates with temperature, then light output varies, but feedback control requires significant monitoring light intensity
Solution Approach 1:
The optical system is segmented into multiple dedicated monitoring waveguides that separately monitor different aspects of light intensity. This segmentation allows for more efficient use of monitoring light by distributing it across multiple detection channels, reducing the overall monitoring light requirement while maintaining temperature compensation capability.
Solution Approach 2:
The monitoring waveguides serve multiple functions: detecting light intensity fluctuations, measuring DC drift, and providing feedback for both light source and electro-optical element control. This multi-functionality maximizes the utility of the minimal monitoring light extracted, reducing energy loss while addressing temperature-induced variations.
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 enhances the light source module's efficiency by minimizing monitoring light usage and maximizing output light intensity, effectively addressing temperature-induced fluctuations and improving light utilization.
Implementation Method 1
an optical waveguide configured to guide light emitted from a light source
Implementation Method 2
an electro-optical element to which light beams emitted from a light source are input
Data Source
AI summary
An electro-optical element includes a substrate, and an optical functional layer formed on a main surface of the substrate, in which the optical functional layer includes an optical-input-side optical waveguide configured to guide light emitted from a light source, an optical branch part configured to branch the optical-input-side optical waveguide into two optical-modulation optical waveguides, a Mach-Zehnder optical modulation part configured to modulate light guided through the two optical-modulation optical waveguides, an optical coupling and branch part configured to branch the two optical-modulation optical waveguides configured to guide modulated light modulated by the Mach-Zehnder optical modulation part into one monitoring optical waveguide and a plurality of optical-output-side optical waveguides, and an optical coupling part configured to make the plurality of optical-output-side optical waveguides as one optical-output optical waveguide.