GRIN Lens Optical Coupler Wavelength Adaptability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical couplers with GRIN lenses face challenges in achieving optimal coupling efficiency across different wavelengths due to refractive index distribution changes in the GRIN lens material, leading to suboptimal performance when transmitting light with varying wavelengths.
Innovation Solution
Setting the center position of the inter-lens distance to match the beam waist position for the shortest wavelength and adjusting the GRIN lens length along the optical axis to minimize coupling loss for other wavelengths, ensuring consistent coupling efficiency across the spectrum without changing the inter-lens distance for each wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the GRIN lens length is increased to improve coupling efficiency for longer wavelengths, then coupling efficiency for longer wavelengths improves, but beam waist position shifts causing increased coupling loss for shorter wavelengths
Solution Approach 1:
The patent applies parameter changes by optimizing the GRIN lens length to a specific value (0.3mm to 0.6mm) that balances the beam waist positions for multiple wavelengths. This parameter optimization ensures that the beam waist of transmitted light coincides with the beam waist of incident light across different wavelengths, resolving the contradiction between coupling efficiency and wavelength adaptability
Solution Approach 2:
The patent addresses the dynamic nature of beam waist position shifts with wavelength changes by designing the GRIN lens system to maintain optimal coupling across varying wavelengths. The lens length is specifically chosen to accommodate the dynamic behavior of different wavelengths through the dispersive material, ensuring consistent performance
2Volume of moving object
If the inter-lens distance is reduced to minimize overall coupler size, then device compactness improves, but coupling efficiency deteriorates due to insufficient beam waist alignment
Solution Approach 1:
The patent optimizes the inter-lens distance parameter to achieve the best balance between compactness and coupling efficiency. By carefully selecting this distance parameter in conjunction with the GRIN lens length, the system achieves effective beam waist alignment while maintaining a compact overall structure
Solution Approach 2:
The patent addresses the size-efficiency tradeoff by operating in the optical domain rather than purely in the spatial domain. Through precise control of beam waist positions and utilizing the GRIN lens's refractive index distribution, the system achieves efficient coupling in a compact configuration
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 approach allows for appropriate coupling efficiency with each wavelength, maintaining low coupling loss differences across different wavelengths, even when light with varying wavelengths is transmitted, by optimizing the inter-lens distance and lens length settings.
Implementation Method 1
a refractive index distribution with a highest refractive index m at the central axis and with a refractive index n decreasing continually in a quadratic curve away from the central axis
Implementation Method 2
an optical fiber collimators pair is known... in which an optical fiber and a GRIN lens (gradient index lens) are joined coaxially... the tip end surfaces of a pair of the GRIN lenses are arranged to face each other with a predetermined inter-lens distance being provided
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
In an optical coupler in which optical fibers with GRIN lenses are disposed to face each other coaxially with a predetermined inter-lens distance being provided, even in the case where light with different wavelengths is transmitted, an appropriate coupling efficiency is obtained with each wavelength without changing the setting of the inter-lens distance for each wavelength,. In an optical coupler 1 in which optical fibers with GRIN lenses 10, each having an optical fiber 11 and a GRIN lens 12 joined coaxially, are disposed to face each other coaxially, with a preset inter-lens distance WD being provided, and to couple transmission light of one of the optical fibers with GRIN lenses 10 to the other one of the optical fibers with GRIN lens 10, an intermediate position of the inter-lens distance WD is set to match a beam waist position of light with a shortest wavelength λm out of the transmission light, and a lens length z along an optical axis direction of the GRIN lens 12 is set in accordance with a bottom of a coupling loss due to a distance-shift D of a beam waist position of light with a wavelength λi different from the λm out of the transmission light.