Hydrogenated Germanium Optical Filters for 1550 nm to Reduce Angle Shift
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Solution Overview
Problem
Existing optical filters using hydrogenated silicon as a high index material for a spectral range with a center wavelength of approximately 1550 nm result in excessive angle shift, while using germanium as a high index material leads to less than threshold transmissivity.
Innovation Solution
Employing hydrogenated germanium as a high index material with alternating layers of silicon dioxide as a low index material to create an optical filter that achieves less than threshold angle shift and greater than threshold transmissivity for a passband centered at approximately 1550 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hydrogenated silicon is used as a high index material, then the refractive index is sufficient, but the angle shift becomes excessive
Solution Approach 1:
The patent changes the material parameter from hydrogenated silicon to hydrogenated germanium, which has a higher refractive index and lower angle shift characteristics. This material substitution resolves the contradiction by selecting a material that simultaneously provides sufficient refractive index and minimal angle shift.
2Object-affected harmful factors
If germanium is used as a high index material, then the angle shift is reduced, but the transmissivity falls below threshold
Solution Approach 1:
The patent modifies the germanium layer by hydrogenation, changing its physical-chemical parameters to achieve a balance between refractive index, angle shift, and transmissivity. The hydrogenated germanium provides sufficient transmissivity while maintaining low angle shift characteristics.
3Length of stationary object
If the physical thickness is reduced, then the device size is minimized, but the filtering performance may be compromised
Solution Approach 1:
The patent changes the refractive index parameter of the high index layer material to hydrogenated germanium, which has superior optical properties. This allows the filter to achieve effective filtering performance with reduced physical thickness, as the higher refractive index and optimized optical characteristics enable more efficient light modulation in thinner structures.
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 optical filter provides improved transmissivity and reduced angle shift, maintaining high refractive index while minimizing physical thickness and angle deviation.
Implementation Method 1
a set of alternating high refractive index layers and low refractive index layers disposed onto the substrate to filter incident light
Implementation Method 2
The optical filter includes a set of alternating high refractive index layers and low refractive index layers... The set of dielectric thin film layers may include a first subset of layers of hydrogenated germanium with a first refractive index
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A bandpass filter may include a set of layers. The set of layers may include a first subset of layers. The first subset of layers may include hydrogenated germanium (Ge:H) with a first refractive index. The set of layers may include a second subset of layers. The second subset of layers may include a material with a second refractive index. The second refractive index may be less than the first refractive index.