Spectrally Adjustable Filter Using Non-Imaging Configuration
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Solution Overview
Problem
Current wavelength filtering devices in optical communication systems face challenges due to long optical path lengths and high costs associated with imaging configurations, which limit their applicability in size and performance-critical WDM systems.
Innovation Solution
A spectrally adjustable filtering apparatus using a spectrally dispersive element, optical elements to change the angles of dispersed spectral components, and a reflective surface to tilt and direct selected spectral components to a specific output path, employing non-imaging configurations to reduce optical path length while maintaining spectral performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If imaging configurations are used in spectral filters, then spectral performance and reliability are maintained, but optical path length becomes excessively long and cost increases
Solution Approach 1:
The patent inverts the traditional imaging configuration by placing the dispersive element after the input beam source but before the focal point, and positioning the reflective surface to intercept beams at a distance less than the focal length. This non-imaging arrangement reverses the conventional sequence and spatial relationships, achieving spectral filtering without requiring the full focal length optical path, thus reducing overall device length while maintaining spectral performance
2Reliability
If imaging configurations are used in spectral filters, then spectral performance is maintained, but device cost increases due to aspheric lenses
Solution Approach 1:
The patent replaces expensive aspheric lenses with simpler, less costly optical elements such as spherical lenses or diffraction gratings in a non-imaging configuration. By abandoning the requirement for high-precision aspheric optics needed in traditional imaging systems, the invention achieves acceptable spectral performance using more economical components that are easier to manufacture and integrate
Solution Approach 2:
The patent changes the key parameter from using aspheric lenses (high cost, high precision) to using spherical lenses or diffraction gratings (lower cost, easier manufacture). This parameter change in the optical element type, combined with the non-imaging configuration, maintains spectral functionality while dramatically reducing manufacturing complexity and cost
3Length of stationary object
If focal length is reduced in imaging configurations, then optical path length decreases, but spectral performance and cost are compromised
Solution Approach 1:
The patent inverts the conventional imaging approach by positioning the reflective surface at a distance from the dispersive element that is less than the focal length, rather than at or beyond it. This inverted spatial arrangement allows the optical path to be truncated without sacrificing spectral performance, as the non-imaging configuration does not require the full focal length development that traditional imaging systems depend upon
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 enables compact, cost-effective spectral filters and monitors that maintain spectral performance and reliability, addressing the limitations of traditional imaging configurations by reducing optical path length and utilizing less expensive optical components.
Implementation Method 1
a spectrally dispersive element configured to disperse spectral components of at least one input beam at different respective angles in a spectral plane
Implementation Method 2
one or more optical elements configured to change at least some of the angles of the propagation axes of the dispersed spectral components
Implementation Method 3
a reflective surface configured to receive a plurality of the dispersed spectral components at a location at which the central rays of each of the spectral components are incident at different points on the reflective surface, and to tilt to select at least one and fewer than all of the received spectral components to be directed to a selected output path
Data Source
AI summary
Spectrally filtering at least one input beam includes dispersing spectral components of at least one input beam at different respective angles in a spectral plane; changing at least some of the angles of the propagation axes of the dispersed spectral components so that the maximum angular separation among the propagation axes of the spectral components changes; receiving a plurality of the dispersed spectral components incident on a reflective surface at a location at which the central rays of each of the spectral components are incident at different points on the reflective surface; and tilting the reflective surface to select at least one and fewer than all of the received spectral components to be directed to a selected output path.