Shared Free-Propagation Echelle Gratings for Compact PIC Layouts
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Solution Overview
Problem
Echelle gratings occupy a significant amount of area on photonic integrated circuits, limiting their integration and efficiency in applications like optical filters and multiplexers.
Innovation Solution
Implementing a system with multiple echelle gratings sharing a common free propagation region, reducing the overall chip area required and minimizing crosstalk through optimized waveguide and grating positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple echelle gratings are implemented on a photonic integrated circuit, then the functionality and versatility of the device is improved, but the occupied area increases significantly
Solution Approach 1:
Multiple echelle gratings share a common free propagation region, combining their operational spaces. The first and second echelle gratings both use the same Rowland circle and free propagation region, allowing multiple gratings to coexist on a single photonic integrated circuit without requiring separate dedicated areas for each grating, thus significantly reducing the total occupied area while maintaining multiple functionalities
Solution Approach 2:
The patent utilizes the Rowland circle geometry and curved waveguide paths to arrange multiple gratings in a compact two-dimensional layout. By positioning waveguide ends on the Rowland circle and using curved paths, the system achieves efficient spatial packing of multiple gratings that would otherwise require large flat areas, effectively using dimensional geometry to reduce occupied space
2Area of stationary object
If echelle gratings are positioned close together to reduce area, then the occupied area is reduced, but crosstalk between adjacent gratings increases
Solution Approach 1:
The patent introduces wavelength-dependent spatial separation through the echelle grating geometry. Different wavelengths are diffracted to different spatial locations on the Rowland circle, creating local quality differentiation. This allows the system to accommodate multiple gratings close together in physical space while maintaining spectral separation, reducing crosstalk between adjacent gratings through wavelength-selective spatial positioning
Solution Approach 2:
The free propagation region acts as an intermediary space between the input waveguides and the gratings. By optimizing the positioning of waveguide ends on the Rowland circle and using the curved geometry of the free propagation region, the system creates beneficial optical paths that reduce direct coupling between adjacent gratings, thereby minimizing crosstalk while maintaining compact integration
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
Significantly reduces the occupied area on photonic integrated circuits while maintaining spectral resolution and reducing crosstalk, enabling more efficient and compact optical devices.
Implementation Method 1
echelle gratings with a shared free propagation region... first grating on the first Rowland circle; and a first output waveguide having an end on the first Rowland circle
Implementation Method 2
a first input waveguide having an end on a first Rowland circle... an optical path between the first input waveguide and the first grating
Data Source
AI summary
Echelle gratings with a shared free propagation region. In some embodiments, a system includes: a first echelle grating; and a second echelle grating. The first echelle grating may include: a first input waveguide having an end on a first Rowland circle; a first grating on the first Rowland circle; and a first output waveguide having an end on the first Rowland circle. The second echelle grating may include: a second input waveguide having an end on a second Rowland circle; a second grating on the second Rowland circle; and a second output waveguide having an end on the second Rowland circle. The second input waveguide may be separate from the first input waveguide, the second output waveguide may be separate from the first output waveguide, and the first Rowland circle may overlap the second Rowland circle.