Ring Combiner Waveguide for Light Loss Prevention
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Solution Overview
Problem
Tapered optical waveguides experience increased numerical aperture (NA) as their cross-sectional area decreases, leading to light loss due to the beam escaping as it travels from a larger to a smaller cross-sectional area, necessitating a small input NA to maintain total internal reflection.
Innovation Solution
A ring combiner waveguide structure with an annular cross-section at the input end and a circular cross-section at the output end, where the effective cross-sectional area remains constant by varying the wall thickness, reducing the numerical aperture progressively from input to output, thereby preventing light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the waveguide cross-sectional area is reduced to concentrate power, then power concentration is improved, but numerical aperture increases causing light loss
Solution Approach 1:
The waveguide is divided into multiple sections with progressively varying cross-sectional areas. Each section has a controlled reduction in area that maintains numerical aperture within acceptable limits, preventing light loss while achieving overall power concentration
Solution Approach 2:
The waveguide structure transitions from static uniform cross-section to dynamic progressive tapering. The cross-sectional area changes continuously along the propagation direction, allowing the numerical aperture to be dynamically controlled to match the decreasing beam diameter at each position
2Volume of moving object
If the waveguide is tapered to reduce diameter, then power concentration is improved, but numerical aperture increases exceeding critical angle
Solution Approach 1:
Different sections of the waveguide have different tapering rates optimized for their local requirements. The tapering angle is locally adjusted to ensure that at each position, the numerical aperture remains below the critical angle for total internal reflection, while still achieving overall diameter reduction
3Loss of energy
If input NA is reduced to prevent light loss in tapered waveguide, then light loss is prevented, but light acceptance characteristics deteriorate
Solution Approach 1:
The waveguide design adds the propagation direction as a functional dimension for controlling numerical aperture. By varying the cross-sectional area along the propagation direction, the system achieves both good light acceptance at the input (larger area, higher NA) and light loss prevention at the output (smaller area, lower NA)
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 ring combiner waveguide structure effectively reduces the numerical aperture as the beam propagates, minimizing light loss and allowing for efficient concentration and propagation of light without escape, suitable for high-power applications and various optics-related uses.
Implementation Method 1
the NA at an input must be sufficiently small that any eventual increase in NA does not exceed a critical angle and the waveguide maintains total internal reflection
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A waveguide comprises an annular cross-section and a first numerical aperture (NA) at one end. The waveguide further comprises either an annular or circular cross-section at the other end, which has a second NA. The waveguide has a progressively-varying NA, which varies from the first NA (at one end) to the second NA (at the other end).