Thick Doped Silica Waveguide Fabrication via Laser Sintering
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Solution Overview
Problem
Current techniques are unable to produce silica waveguides with the required high power properties for laser applications, as they fail to achieve the necessary thickness, high doping levels, and optical quality.
Innovation Solution
A novel process involving silica deposition, sintering, post-sintering laser treatment, and deep reactive ion etching to create a thick, doped silica waveguide with improved transparency and refractive index modification, using a CO2 laser to eliminate crystallites and voids, and additional layers for light guiding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional waveguide fabrication techniques (thermal oxidation, sputtering, ion exchange, sol-gel) are used, then waveguides can be produced, but they cannot achieve the required thickness (10-100 microns), high doping levels, and optical quality for high power laser applications
Solution Approach 1:
The invention changes the fundamental parameters of the fabrication process by using flame hydrolysis deposition to create thick porous layers (10-100 microns) that are then sintered at high temperatures (1500-1600°C). This allows achieving both the required thickness and optical quality simultaneously, overcoming the limitations of conventional techniques that could only produce thin films with good optical quality or thick films with poor optical quality.
Solution Approach 2:
The invention uses composite doping by incorporating rare-earth ions (lasing media) along with germanium dioxide (refractive index modifier) in the silica matrix. This composite approach enables simultaneous achievement of high optical quality, high doping levels for rare-earth ions, and proper refractive index contrast for waveguide operation, which conventional single-purpose techniques cannot achieve.
2Power
If the waveguide layer is made thicker to enable high power applications, then power handling capability improves, but maintaining high optical quality and uniform doping becomes more difficult
Solution Approach 1:
The invention performs preliminary doping during the flame hydrolysis deposition process itself, incorporating rare-earth ions and germanium dioxide into the porous silica layer as it is being formed. This preliminary action ensures uniform distribution of dopants throughout the thick layer before sintering, avoiding the difficulty of achieving uniform doping in thick structures that would result from post-deposition doping methods.
3Ease of manufacture
If standard microelectronics production techniques are used for waveguide fabrication, then manufacturing cost decreases, but the ability to produce thick, highly doped waveguides with high optical quality is lost
Solution Approach 1:
The flame hydrolysis deposition process serves multiple functions simultaneously: it deposits thick silica layers, incorporates dopants (germanium dioxide and rare-earth ions) during deposition, creates a porous structure that facilitates uniform doping, and the subsequent sintering process densifies the structure while maintaining uniform composition. This multi-functional approach replaces multiple separate conventional processes while achieving superior results.
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 results in high-quality silica waveguides with reduced optical loss, enabling effective light propagation and potential for high power laser applications.
Implementation Method 1
the core layer transparency is improved by heating with a laser beam on a surface of the layer
Implementation Method 2
the laser beam has a wavelength that is absorbed by the silica layer
Implementation Method 3
the layer is sintered at a temperature range of 1500-1600° C.
Data Source
AI summary
An optical device including an active core layer of silica glass doped with ions which serve as optical emitters, the active core layer being on a silica glass substrate and having a layer thickness of at least 5 μm, and wherein the layer is sintered at a temperature range of 1500-1600 C. and subsequently heat treated by a laser.