Micro Mirror Grating Coupler Optical Energy Alignment
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Solution Overview
Problem
Current methods for coupling light from semiconductor lasers or optical fibers to high-index contrast waveguides suffer from low efficiency due to the mismatch in mode sizes and significant light diffraction, leading to unsatisfactory coupling efficiency.
Innovation Solution
The development of an optical assembly apparatus that includes a high-index contrast waveguide with a grating coupler and a lithographically-defined micro-mirror formed in a UV cross-linkable polymer material, which redirects light into the grating coupler at a perpendicular angle, enhancing coupling efficiency between semiconductor lasers or optical fibers and high-index contrast waveguides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional coupling methods (GRIN lens, grating coupler, tapered waveguide) are used to couple light from optical fiber to high-index contrast waveguide, then coupling mechanism is established, but coupling efficiency remains poor due to mode size mismatch and diffraction
Solution Approach 1:
The coupling mechanism is divided into separate functional elements: a micro-mirror for angular redirection and a grating coupler for mode conversion. This segmentation allows each element to be optimized independently for its specific function, improving overall coupling efficiency while maintaining manageable complexity
Solution Approach 2:
The micro-mirror acts as an intermediary element that redirects light from the optical fiber at a specific angle to match the acceptance angle of the grating coupler. This intermediary mechanism bridges the gap between the different coupling methods, achieving efficient energy transfer without requiring complex integrated structures
2Manufacturing precision
If micro-mirror is formed in UV cross-linkable polymer material through lithographic alignment, then precise angular redirection is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The mechanical alignment process is replaced with a lithographic photolithography process to define the micro-mirror geometry. This substitution enables precise angular redirection through optical means rather than mechanical positioning, achieving high manufacturing precision while simplifying the overall fabrication process
Solution Approach 2:
The micro-mirror angle is precisely controlled by changing the lithographic exposure parameters and UV cross-linking conditions. By adjusting these parameters, the exact angular orientation is achieved without requiring complex mechanical alignment procedures, balancing precision with ease of manufacture
3Loss of energy
If light is redirected at perpendicular angle to grating coupler surface, then coupling efficiency is maximized, but device structure becomes more complex
Solution Approach 1:
The micro-mirror introduces a vertical angular dimension to the coupling mechanism by redirecting light from horizontal propagation to a specific angled path. This dimensional change enables efficient coupling to the grating coupler without requiring complex lateral structures, achieving high energy transfer efficiency through three-dimensional optical path control
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 solution significantly improves the coupling efficiency between semiconductor lasers or optical fibers and high-index contrast waveguides, allowing for more effective energy transfer and enabling the creation of wavelength-tunable laser modules.
Implementation Method 1
a lithographically-defined and aligned micro mirror (105) with an acute angle (115) formed in a UV cross-linkable polymer material on top of the grating coupler, wherein the acute angle is configured to redirect the light source into the grating coupler to form a perpendicular ray entry angle with the grating coupler
Implementation Method 2
for coupling light from an optical fiber to a high-index contrast waveguide, several methods have been disclosed in the past. In one example, US2010/0135615A1 and U.S. Pat. No. 7,643,719B1 publications disclose a coupling mechanism based on a graded-index (GRIN) lens... Other conventional methods for coupling light from an optical fiber to high-index contrast waveguides include using grating couplers
Data Source
AI summary
A novel optical assembly apparatus for coupling optical energy and a related method for creating the novel optical assembly apparatus are disclosed. In one embodiment, the novel optical assembly apparatus includes a high-index contrast waveguide constructed on a semiconductor die or another base substrate with an aligned optical coupling section, a grating coupler etched onto a surface, a micro mirror with an acute angle relative to the surface, and a waveguide taper that narrows an optical beam width. A light ray entered into the optical coupling section is redirected by the micro mirror to form a perpendicular ray entry angle with the grating coupler. The grating coupler then efficiently couples the light ray with the waveguide taper, which in turn narrows the optical beam width. The light ray may originate from a semiconductor die or from an optical fiber, which is purposefully aligned with the high-index contrast waveguide.