Thin Film Optical Filter for Spectral Angular Polarization Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optical filters struggle to combine spectral filtering, angular filtering, and polarization in a single unit efficiently, leading to increased complexity and size, with existing tunable filters having limited bandwidth and transmission issues.
Innovation Solution
A compact optical filter design using a prism with multiple thin film layers forming waveguide structures, where only specific polarized photons within a narrow spectral and angular range are transmitted, with tunable parameters controlled by mechanical motion or electric fields, allowing for precise filtering and rejection of unwanted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If spectral filtering, angular filtering, and polarization are combined into a single unit, then device complexity is reduced, but achieving high performance in all three functions simultaneously becomes difficult
Solution Approach 1:
The patent combines spectral filtering, angular filtering, and polarization functions into a single integrated optical element using thin-film interference structures. This merging approach reduces the number of separate components needed while maintaining high performance in all three filtering functions through carefully designed multi-layer thin film coatings that simultaneously control wavelength, angle, and polarization state of transmitted light.
Solution Approach 2:
The optical element is designed to perform multiple functions simultaneously: it acts as a spectral filter, angular filter, and polarizer all in one component. The thin-film interference structure is engineered to provide broadband spectral filtering, angular filtering for photons incident within a specific angular range, and polarization control, making the device universal for applications requiring all three filtering functions.
2Measurement precision
If traditional filters are used for spectral filtering, then spectral selectivity is achieved, but angular filtering and polarization control are not provided
Solution Approach 1:
The patent merges spectral filtering, angular filtering, and polarization control into a single thin-film interference-based optical element. The multi-layer thin film structure is designed to simultaneously provide spectral selectivity through interference effects, angular filtering by controlling the incident angle range, and polarization control through the anisotropic properties of the film layers, thereby achieving all three functions in one component.
Solution Approach 2:
The optical element is engineered to be universal by incorporating multiple filtering functions: it provides spectral filtering for selecting specific wavelength ranges, angular filtering for accepting photons within a defined angular cone, and polarization control for selecting specific polarization states. This multi-functional design eliminates the need for separate filters for each function.
3Measurement precision
If apertures are used for angular filtering, then angular selectivity is improved, but device size and complexity increase
Solution Approach 1:
The patent extracts the angular filtering function from separate physical apertures and integrates it directly into the thin-film interference structure. The thin film layers are designed with specific optical properties that inherently provide angular filtering capability, eliminating the need for additional aperture components and reducing overall device complexity while maintaining angular selectivity.
Solution Approach 2:
The patent merges angular filtering with the spectral and polarization filtering functions in a single thin-film optical element. The multi-layer thin film structure is engineered to simultaneously control spectral transmission, polarization state, and incident angle acceptance, combining what would traditionally require separate components into one integrated device.
4Adaptability or versatility
If tunable filters are used to change transmission wavelength, then spectral range is expanded, but bandwidth is reduced
Solution Approach 1:
The patent employs tunable thin-film filters where the optical properties of the film layers can be dynamically adjusted to change the transmission wavelength. By incorporating materials or mechanisms that allow modification of the thin film structure (such as electro-optic or thermo-optic effects), the filter can be tuned across a broad spectral range while maintaining a relatively wide transmission bandwidth through optimized film design.
Solution Approach 2:
The patent utilizes parameter changes in the thin-film structure to achieve tunability. By changing physical or chemical parameters of the thin film layers (such as refractive index, thickness, or material composition) in response to external stimuli, the transmission wavelength can be adjusted across a wide spectral range while preserving adequate bandwidth through careful parameter optimization.
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 solution enables efficient spectral and angular filtering while reducing device complexity, offering tunable transmission wavelengths for applications like spectroscopy and telecommunications, with improved rejection of unwanted light across a wide range.
Implementation Method 1
Optical filters that exploit thin-film interference effects to spectrally filter the light are commonly used
Implementation Method 2
a number of optical thin film layers deposited upon it that forms a series of waveguide structures
Implementation Method 3
optical energy transfers from the first waveguide structure to the second waveguide structure
Data Source
AI summary
A filter and fabrication process for a thin film filter that is based on frustrated total internal reflection and multiple waveguide layers, in which the waveguide modes are resonantly coupled. The physics of the design is related to prism coupling of light into planar waveguides, and waveguide coupling between planar waveguides in close proximity. Embodiments include a filter that acts as a bandpass filter and polarizer, a filter that acts as a bandpass filter, polarizer and angle filter (spatial filter), a filter that is widely tunable, and a filter that is widely tunable in both peak transmission wavelength and width. Methods of fabrication are disclosed, and methods to correct for manufacturing errors in thin film deposition are described. The filter embodiments can also be used in reflection as notch filters in wavelength and angle, for a particular polarization component.