Photonic Waveguide Thinning for Low Insertion Loss
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Solution Overview
Problem
Existing methods for manufacturing photonic guides with thin dielectric substrates less than 5 μm thick result in significant insertion losses and require cumbersome safety protocols, excite non-fundamental optical modes, and are not robust to high temperatures due to the ion implantation technique used.
Innovation Solution
A method involving the formation of optical waveguides with a vertical optical mode transition zone by progressively thinning the dielectric substrate, allowing for low insertion losses and high temperature robustness without the need for restrictive safety conditions, using a circular saw or laser for cutting, and maintaining only the fundamental optical mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation technique is used to thin the dielectric substrate, then the substrate can be thinned to less than 5 μm, but significant insertion losses occur and cumbersome safety protocols are required
Solution Approach 1:
The substrate thinning process is divided into multiple sequential etching steps rather than a single aggressive ion implantation step. Each step removes a portion of the substrate thickness, allowing progressive control over the final thickness while maintaining lower insertion losses through controlled material removal
Solution Approach 2:
The patent replaces the ion implantation technique (which requires restrictive safety conditions and causes high insertion losses) with conventional mechanical or chemical etching methods. This substitution eliminates the need for cumbersome safety protocols while achieving the same substrate thinning objective with reduced insertion losses
2Manufacturing precision
If ion implantation is used to thin the substrate, then thin substrates can be produced, but the process is not robust to high temperatures
Solution Approach 1:
The patent replaces ion implantation with conventional etching techniques that create a more thermally stable substrate structure. The etched substrate maintains its structural integrity and optical properties at high temperatures, enabling subsequent high-temperature processing steps without degradation
3Manufacturing precision
If ion implantation is used for substrate thinning, then thin substrates are achieved, but non-fundamental optical modes are excited
Solution Approach 1:
The gradual, stepped thinning process allows the optical mode to adapt progressively to the changing substrate thickness, preventing sudden mode transitions that would excite non-fundamental modes. This segmented approach maintains optical mode purity throughout the thinning process
Data Source
Figure 1a~1e
Figure 1f~2
Figure 3a~3c
AI summary
The invention relates to a method for manufacturing a photonic waveguide including the following steps: forming (100) an optical waveguide on a first surface (S1) of a dielectric substrate (10); thinning (200) the dielectric substrate (10) in order to form a photonic waveguide; characterised in that the thinning is carried out by cutting a second surface (S2) of the dielectric substrate (10) opposite the first surface (S1), the thinned section comprising a recess (15) with a profile which is parallel to the optical waveguide, the depth of the recess (15) varying continuously and gradually between a first point P1 with depth zero at the second surface (S2) and a maximum depth (e) at a predetermined distance (Iq) from the first end of the photonic waveguide intended for receiving the optical fibre, the variation of the depth of the recess (15) forming a vertical optical mode transition area (16) with length (Iq) between the photonic waveguide and the optical fibre.