Photonic Integrated Device UV-Cure Adhesive Butt-Joint
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Solution Overview
Problem
Existing photonic integrated optical devices face challenges in achieving high accuracy butt-joining of optical waveguides and sufficient bonding strength due to processing and mounting errors, leading to incomplete curing of UV-cure adhesives and reduced optical coupling efficiency.
Innovation Solution
The proposed photonic integrated optical device incorporates a butt-joint holding substrate that transmits UV light, allowing for accurate centering and curing of UV-cure adhesive between the optical waveguides of the PLC and optical functional elements, thereby enhancing bonding strength and reducing optical losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If UV-cure adhesive is used to butt-join optical waveguides, then bonding strength is improved, but incomplete curing occurs due to substrate absorption of UV light
Solution Approach 1:
The substrate is segmented into two functional parts: a lower substrate that provides mechanical support and an upper substrate that transmits UV light for adhesive curing. This segmentation allows each part to fulfill its specific function without interference, solving the contradiction between bonding strength and curing completeness.
Solution Approach 2:
The upper substrate acts as an intermediary between the UV light source and the adhesive. It transmits UV light through itself to reach and cure the adhesive in the gap, while the lower substrate remains opaque to UV light. This intermediary structure enables complete curing without compromising bonding strength.
2Manufacturing precision
If optical waveguides are butted-joined with spacing due to processing errors, then alignment flexibility is improved, but optical coupling efficiency deteriorates due to beam spreading and diffraction
Solution Approach 1:
The UV-cure adhesive acts as an intermediary medium filling the gap between optical waveguides. It provides both mechanical bonding to accommodate alignment flexibility and optical transparency to maintain coupling efficiency by reducing beam spreading and diffraction effects.
Solution Approach 2:
The refractive index of the adhesive is optimized to match that of the optical waveguides, minimizing reflection and refraction losses at the interfaces. This parameter optimization ensures high optical coupling efficiency even when gaps exist due to processing tolerances.
3Device complexity
If end faces of substrates are butted-joined directly, then device complexity is reduced, but bonding strength is insufficient due to inadequate adhesive coverage
Solution Approach 1:
The substrate structure is segmented into upper and lower parts with different optical properties. The lower substrate provides a large bonding area for strong adhesion, while the upper substrate ensures complete UV curing of the adhesive. This segmentation achieves both strong bonding and simple structure.
Solution Approach 2:
Different regions of the substrate structure are assigned different qualities: the lower substrate is made opaque to UV light for mechanical support, while the upper substrate is made transparent to UV light for curing. This local differentiation solves the contradiction between bonding strength and structural simplicity.
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 simple and easy hybrid integration of optical functional elements using a PLC optical circuit as a platform, achieving high accuracy butt-joining of optical waveguides and improving the bonding strength and optical coupling efficiency of the photonic integrated optical device.
Implementation Method 1
a ultraviolet-cure adhesive which is transparent to light in a wavelength region ranging from an ultraviolet band to a visible light band
Implementation Method 2
optical waveguides of the optical circuits are centered with respect to each other
Data Source
AI summary
A photonic integrated optical device can implement hybrid integration of an optical functional element simply and easily using an optical circuit of a PLC as a platform and allows high accuracy butt-joining of optical waveguides. For that, on the side of an optical circuit on top of a substrate of the PLC, the device uses a butt-joint holding substrate that transmits light in the wavelength region ranging from the UV light band to the visible light band. A UV-cure adhesive is filled into a gap between an optical circuit of the PD and an optical circuit of the PLC and a gap between an end face of a substrate of the PD and an end face of the substrate. This allows a joint to be formed by the UV-cure adhesive filled into the gap between the butt-joining end faces and cured by UV light passing through the substrate.