AlGaN Wavelength Conversion Element Dislocation Density
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Solution Overview
Problem
Ferroelectric oxide crystals used in wavelength conversion elements, such as LiNbO3 and LiTaO3, suffer from property degradation due to voltage application, and AlGaN layers in these elements exhibit low crystallinity when formed on GaN substrates, leading to short property-maintaining life, while high dislocation density in wavelength conversion elements absorbs energy from incoming light, reducing their effectiveness.
Innovation Solution
A wavelength conversion element with a domain-inverted structure using AlxGa(1-x)N crystals, where the dislocation density is maintained between 1 × 10^3 cm^-2 and 1 × 10^5 cm^-2, suppresses energy absorption and heat increase, thereby improving the property-maintaining life by forming a periodically reversed polarization structure that satisfies quasi phase matching conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ferroelectric oxide crystals (LiNbO3, LiTaO3) are used to form polarized structures through voltage application, then wavelength conversion efficiency is improved, but crystal strength deteriorates due to voltage-induced weakening
Solution Approach 1:
The invention changes the fundamental parameter of polarization formation from voltage-induced domain inversion in ferroelectric crystals to spontaneous polarization in AlGaN crystals. This parameter change eliminates the need for voltage application while maintaining the domain-inverted structure necessary for efficient wavelength conversion, thereby resolving the contradiction between conversion efficiency and crystal strength.
2Ease of manufacture
If AlGaN layers are formed on GaN substrates, then device integration is achieved, but crystallinity deteriorates due to low crystalline quality
Solution Approach 1:
The invention changes the composition parameter of the AlGaN crystal to have an aluminum content x of 0.3 or more, which fundamentally alters the crystalline quality. This composition parameter change enables the formation of high-quality AlGaN crystals with sufficient crystallinity for wavelength conversion applications, resolving the contradiction between device integration and crystalline quality.
3Ease of manufacture
If high dislocation density is present in wavelength conversion elements, then manufacturing is easier, but energy absorption increases leading to reduced effectiveness
Solution Approach 1:
The invention changes the dislocation density parameter to be 1×10^6 cm^-2 or less, which is a significant reduction from conventional values. This parameter change directly reduces energy absorption from incoming light while maintaining the domain-inverted structure for wavelength conversion, thereby resolving the contradiction between manufacturing ease and energy loss.
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 approach results in a wavelength conversion element with enhanced property-maintaining life by reducing heat-induced attenuation and maintaining high transmittance, effectively converting incoming light wavelengths with improved efficiency and stability.
Implementation Method 1
a wavelength conversion element 10 which has an optical waveguide 13 and which converts a wavelength of incoming light 101 input from one end 13a side of the optical waveguide 13 and emits outgoing light 102 from the other end 13b side of the optical waveguide 13
Implementation Method 2
The domain-inverted structure satisfies quasi phase matching conditions with respect to the incoming light 101
Implementation Method 3
a first crystal 11 composed of AlxGa(1-x)N (0.5 ≤ x ≤ 1) and a second crystal 12 having the same composition as the first crystal 11. The first and second crystals 11 and 12 form a domain-inverted structure in which a polarization direction is periodically reversed along the optical waveguide 13
Data Source
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AI summary
A wavelength conversion element having an improved property-maintaining life and a method for manufacturing the wavelength conversion element are provided. A wavelength conversion element 10a has an optical waveguide 13. The wavelength of incoming light 101 input from one end 13a of the optical waveguide 13 is converted and outgoing light 102 is output from the other end 13b of the optical waveguide 13. The wavelength conversion element includes a first crystal 11 composed of AlxGa(1-x)N (0.5 ≤ x ≤ 1); and a second crystal 12 having the same composition as that of the first crystal. The first and second crystals 11 and 12 form a domain-inverted structure in which a polarization direction is periodically reversed along the optical waveguide 13, and the domain-inverted structure satisfies quasi phase matching conditions with respect to the incoming light 101. At least one of the first and second crystals has a dislocation density of 1 × 103 cm-2 or more and less than 1 × 107 cm-2.