Harmonics Generating Device With Inclined Domain Inversion Plane
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Solution Overview
Problem
Harmonics generating devices with periodic domain inversion structures experience unstable oscillation of higher harmonics due to diffraction phenomena, leading to reduced wavelength conversion efficiency and loss of fundamental-wave laser beam.
Innovation Solution
The angle between the domain inversion plane and the laser beam propagation direction is adjusted from 80 degrees to 89 degrees to prevent return light and resonance, thereby stabilizing the oscillation and reducing light loss within the periodic domain inversion structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a periodic domain inversion structure is used for wavelength conversion, then wavelength conversion capability is improved, but unstable oscillation of higher harmonics occurs due to diffraction phenomena
Solution Approach 1:
The patent changes the angular parameter of the domain inversion plane from the conventional perpendicular orientation (90 degrees) to an inclined orientation (80-89 degrees) relative to the light propagation direction. This parameter change modifies the diffraction characteristics of the periodic domain inversion structure, preventing return light from entering the laser source and thereby stabilizing oscillation while maintaining wavelength conversion capability.
2Power
If the domain inversion plane is perpendicular to light propagation, then wavelength conversion efficiency is maximized, but return light causes unstable oscillation
Solution Approach 1:
The patent converts the harmful diffraction effect into a beneficial one by inclining the domain inversion plane. The diffraction that previously caused return light and unstable oscillation is redirected away from the laser source. The inclined structure causes diffracted light to propagate at angles that do not return to the source, thereby eliminating the harmful effect while preserving the wavelength conversion function.
3Reliability
If a bulk device with resonator is used, then unstable oscillation is prevented, but fundamental-wave laser beam is reflected and scattered, lowering conversion efficiency
Solution Approach 1:
Instead of using a bulk device with resonator, the patent changes the geometric parameter of the periodic domain inversion structure by inclining the domain inversion plane. This modifies the light propagation and diffraction characteristics, preventing return light without requiring additional resonator structures or bulk device configurations, thereby avoiding extra reflection and scattering losses.
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 adjustment effectively prevents unstable oscillation of the fundamental-wave laser beam and enhances the wavelength conversion efficiency by minimizing diffraction-induced return light, resulting in stable operation and improved output power.
Implementation Method 1
a second-harmonic-generation (SHG) device of a quasi-phase-matched (QPM) system can be realized
Implementation Method 2
a second-harmonic-generation (SHG) device of a quasi-phase-matched (QPM) system can be realized
Implementation Method 3
higher harmonics may oscillate unsteadily in some cases... A description will be made with reference to FIGS. 1 and 2. The periodic domain inversion structure 8 is obtained by alternatively forming a number of domain inversion parts 6 and polarization non-inversion parts 7
Data Source
AI summary
A harmonics generating device has a periodic domain inversion structure 18 for converting a wavelength of laser beam to generate higher harmonics. An angle θ formed by a domain inversion plane P of the periodic domain inversion structure 8 and a propagation direction L of the laser beam is from 80 degrees to 89 degrees.