Wavelength Conversion Element With Guided Light Attenuators
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Solution Overview
Problem
The challenge in fabricating wavelength conversion devices using nonlinear optical crystals like lithium niobate is the formation of unwanted slab waveguides during the etching process, which leads to inefficient waveguide selection and increased costs due to erroneous measurements and low yield.
Innovation Solution
Incorporating guided light attenuators in the slab waveguides with a different refractive index, formed as internal regions or grooves, to selectively attenuate light and prevent misalignment during optical characterization, allowing for precise selection of waveguides with desired optical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching process is used to form waveguides in nonlinear optical crystals, then waveguide structures can be created, but unwanted slab waveguides are formed causing measurement errors and reduced yield
Solution Approach 1:
The patent removes the harmful slab waveguides by selectively etching them away after the waveguide formation process, extracting the unwanted optical paths from the system to prevent measurement errors
Solution Approach 2:
The patent applies a preliminary coating layer before etching that selectively protects the desired waveguide regions while allowing the slab waveguide regions to be removed, preparing the structure in advance to prevent harmful effects
2Adaptability or versatility
If multiple waveguides are formed on substrate for selection, then desired waveguide can be selected, but fabrication time and costs increase due to erroneous measurements
Solution Approach 1:
The patent uses optical contrast differences (analogous to color changes) where removed slab waveguides create dark regions in optical micrographs, allowing rapid visual identification and selection of valid waveguides without time-consuming measurements
Solution Approach 2:
The patent introduces an intermediary optical characterization step using micrographs as a mediator between fabrication and final selection, providing quick feedback on waveguide validity without requiring full optical measurements
3Productivity
If etching mask covers maximum area to avoid low-volatility substance generation, then etching efficiency improves, but unwanted slab waveguides are formed outside desired structure
Solution Approach 1:
The patent segments the mask coverage into two distinct regions: a first area covering the desired waveguide structure for protection during etching, and a second area leaving slab waveguide regions exposed for selective removal, dividing the masking function into protective and selective components
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 efficient and accurate selection of waveguides with desired optical characteristics, reducing fabrication time and costs by minimizing the impact of unwanted slab waveguides and improving the overall yield of wavelength conversion devices.
Implementation Method 1
guided light attenuators 603-1 to 603-n+1 formed of a material having an index of refraction different from an index of refraction of a material forming the slab waveguides 602-1 to 602-n in the plurality of slab waveguides
Implementation Method 2
The ridge optical waveguide is formed by bonding two substrates to each other, thinning one of the substrates into a thin film and forming ridges in the thinned substrate
Implementation Method 3
The second-order nonlinear optical effect generates light of a new wavelength λ3 from input light of wavelengths λ1 and λ2. The wavelength conversion satisfying the following formula is referred to as sum frequency generation (SFG). 1/λ3=1/λ1+1/λ2
Implementation Method 4
With the periodically poled waveguide, the poles of the nonlinear optical material can be periodically inverted to achieve a quasi-phase matching
Data Source
AI summary
With a wavelength conversion device based on a nonlinear optical effect, when arrayed waveguides including an intended nonlinear waveguide are fabricated, unwanted slab waveguides are inevitably formed. The slab waveguides can cause an erroneous measurement in the selection of a waveguide having desired characteristics from the arrayed waveguides. The erroneous measurement can lead to redoing steps for fabricating the wavelength conversion device and a decrease in the yield and inhibit the evaluation of the characteristics in selection of the waveguide and the subsequent fabrication of the wavelength conversion device from being efficiently performed. A wavelength conversion device according to the present invention includes a plurality of waveguides formed on a substrate, and a plurality of slab waveguides that are arranged substantially in parallel with and spaced apart from the plurality of waveguides, and a guided light attenuator is formed in each of the slab waveguides. The guided light attenuators allow efficient selection of a waveguide having desired optical characteristics from the plurality of waveguides. The light attenuation by the guided light attenuators can be changed in steps for fabricating the wavelength conversion device.