Optical Multiplexing Circuit With Light-Blocking Grooves
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Solution Overview
Problem
Existing optical beam combiner circuits face challenges in downsizing and monitoring precision, particularly when integrating bulk optical components for white balance adjustment in RGB light sources using laser diodes.
Innovation Solution
The implementation of a planar lightwave circuit (PLC) with light-blocking grooves positioned at specific angles to reflect stray light away from monitoring and output waveguides, preventing interference and enhancing monitoring precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bulk optical components (lenses, dichroic mirrors, half mirrors) are integrated together as a free-space optical system, then optical beam combining and monitoring functions can be achieved, but the optical system increases in size, hindering downsizing
Solution Approach 1:
The patent replaces the free-space optical system with a planar lightwave circuit (PLC) that integrates optical waveguides and optical circuits on a planar substrate. This substitution of mechanical optical components with integrated photonic circuits achieves the same beam combining and monitoring functions while dramatically reducing the system size.
Solution Approach 2:
The patent merges multiple optical functions (beam combining, wavelength separation, and intensity monitoring) into a single integrated PLC structure. The waveguides and optical circuits are combined on one planar substrate, eliminating the need for separate bulk components and reducing overall system volume.
2Measurement precision
If light is monitored on the front side in the forward direction (front monitoring), then monitoring precision is improved, but the optical system requires additional bulk components for white balance adjustment, increasing size
Solution Approach 1:
The patent integrates the monitoring function directly into the PLC structure by splitting optical beams within the waveguide system. The intensity monitoring is achieved through the waveguide geometry itself, eliminating the need for separate bulk photodetector components and reducing system complexity.
Solution Approach 2:
The PLC structure serves multiple functions simultaneously: it combines optical beams of different wavelengths, separates them through waveguide splitting, and monitors their intensities all within the same integrated device. This multi-functionality reduces the need for additional specialized components.
3Volume of moving object
If an RGB coupler using silica-based PLC is used instead of free-space optical system, then downsizing is enabled, but stray light couples to waveguides and interferes with monitoring precision
Solution Approach 1:
The patent converts the harmful stray light into a beneficial design feature by using light-blocking grooves that are intentionally positioned to reflect stray light away from monitoring waveguides. The grooves are designed at specific angles and positions to redirect stray light toward designated areas, transforming a problem into a solution for maintaining monitoring precision.
Solution Approach 2:
The light-blocking grooves act as intermediary elements between the waveguides and stray light. These grooves intercept stray light and redirect it through specific paths, preventing direct coupling to monitoring waveguides while maintaining the compact PLC structure.
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 allows for precise monitoring of optical beams and adjustment of white balance, while minimizing the size of the light source by reducing stray light interference and improving monitoring accuracy.
Implementation Method 1
light-blocking grooves provided on both sides with respect to each input waveguide, each of the plurality of light-blocking grooves being spaced apart by a predetermined interval from a corresponding one of the plurality of input waveguides, the plurality of light-blocking grooves being positioned to enable stray light not coupled to the plurality of input waveguides to be reflected toward an end surface different from an exit end surface of each monitoring waveguide and also different from an exit end surface of the output waveguide
Data Source
AI summary
An optical beam combiner circuit includes a plurality of branch portions configured to divide optical beams output from a plurality of input waveguides, a combiner unit configured to combine optical beams, each of the optical beams being one of the divided optical beams obtained by one of the plurality of branch portions, an output waveguide configured to output an optical beam obtained by the combiner unit combining the optical beams, a plurality of monitoring waveguides configured to output optical beams, each of the optical beams being another of the divided optical beams obtained by one of the plurality of branch portions, and a plurality of light-blocking grooves provided on both sides with respect to each input waveguide, the plurality of light-blocking grooves being positioned to enable stray light not coupled to the plurality of input waveguides to be reflected toward an end surface different from an exit end surface of each monitoring waveguide and also different from an exit end surface of the output waveguide.