Laser Bonding Optical Elements With Low-Stress Interface Heating
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Solution Overview
Problem
Existing methods for bonding optical elements to substrates, such as laser welding, often result in residual stress, flaws, and misalignment, increasing the cost and complexity of optical devices like connectors and assemblies.
Innovation Solution
A low-temperature laser bonding process that uses a curved optical element, like a GRIN lens or optical fiber, to focus the laser beam and directly bond the optical element to a substrate, reducing residual stress and eliminating the need for expensive alignment substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional laser welding is used to bond optical elements to substrates, then strong bonds are formed, but residual stress and flaws increase
Solution Approach 1:
The patent changes the bonding parameters by using lower temperature laser bonding instead of traditional high-temperature laser welding. This parameter change allows bond formation without excessive melting, reducing residual stress and flaws while maintaining bond strength
Solution Approach 2:
The patent applies partial melting rather than complete melting of the substrate and optical element materials. By heating only to the point of sufficient bonding without excessive melting, the process achieves strong bonds while minimizing harmful residual stress and flaws
2Manufacturing precision
If expensive V-groove substrates with sub-micron tolerances are used to precisely locate optical elements, then alignment precision is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent enables the substrate to self-align optical elements through the laser bonding process itself. The low-temperature bonding allows optical elements to be precisely positioned and bonded without requiring pre-manufactured V-groove substrates, making the substrate serve its own alignment function
Solution Approach 2:
The patent extracts the alignment function from the substrate structure (V-grooves) and achieves it through the bonding process itself. This eliminates the need for complex pre-manufactured alignment features while maintaining precise optical element positioning
3Device complexity
If curved optical elements are used to focus the laser beam, then complex optical delivery systems are eliminated, but the laser beam must be precisely controlled
Solution Approach 1:
The patent uses the curved optical element itself as an intermediary to focus the laser beam. Instead of requiring separate focusing optics, the curved surface of the optical element acts as the focusing element, simplifying the overall system while achieving precise beam concentration
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 process achieves robust, low-stress bonds with minimal residual flaws, allowing for precise alignment and reducing the assembly time and cost by eliminating the need for adhesives and complex alignment systems.
Implementation Method 1
the optical element is a curved element, such as a GRIN lens, a micro-lens or an optical fiber, that acts as a cylindrical lens to focus the laser beam into the substrate
Implementation Method 2
The laser beam heats an interface between at least one optical element and the substrate to a temperature that is higher than a lowest temperature of the optical element change temperature and the substrate change temperature, thereby forming a bond
Implementation Method 3
The focused laser beam directly bonds the optical element to the substrate by melting the surface of the substrate material and/or the optical element material
Implementation Method 4
affixing the at least one optical element to the surface of the substrate using electrostatic charging
Data Source
AI summary
Methods for laser bonding optical elements to substrates and optical assemblies are disclosed. According to one embodiment, a method of bonding an optical element to a substrate includes disposing at least one optical element onto a surface of the substrate, electrostatically affixing the at least one optical element to the surface of the substrate, and directing a laser beam into the at least one optical element. The laser beam heats an interface between at least one optical element and the substrate to a temperature that is higher than a lowest temperature of the optical element change temperature and the substrate change temperature, thereby forming a bond between at least one optical element and the substrate at a bond area. The laser beam has a fluence that does not modify the substrate at areas of the substrate that are outside of the at least one optical element.