Vacuum-Sealed KDP Frequency-Doubling Crystal With Brewster Tubes
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Solution Overview
Problem
Current KDP frequency-doubling crystals face issues with coating damage from high-intensity fundamental frequency light, leading to short service life and increased coating complexity, as well as deliquescence in air, which complicates the coating process.
Innovation Solution
A KDP frequency-doubling crystal structure is designed with π and σ polarization tubes sealed at Brewster angles to vacuumize and protect the crystal's incident and emitting planes, eliminating the need for traditional coatings and preventing deliquescence, thereby enhancing the crystal's durability and ease of coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional coating is applied to KDP crystal to protect against high-intensity light, then the crystal can be used for frequency-doubling, but the coating layer is susceptible to damage from high-intensity fundamental frequency light, resulting in short service life
Solution Approach 1:
The patent removes the vulnerable coating layer from the KDP crystal surface and replaces it with a protective vacuum chamber. The crystal is sealed inside the chamber with its optical surfaces exposed to vacuum, eliminating the need for protective coatings that would otherwise be damaged by high-intensity laser light.
Solution Approach 2:
The vacuum chamber serves as an intermediary protective structure between the external environment and the KDP crystal. Instead of coating the crystal directly, the vacuum environment acts as a mediator that protects the crystal from deliquescence while allowing high-intensity laser light to pass through without damaging any coating layers.
2Reliability
If traditional coating is applied to KDP crystal, then protection is provided, but the coating process becomes more complex and requires vacuum sealing and sol-based coating
Solution Approach 1:
The patent extracts the protective function from the coating layer itself and relocates it to the vacuum chamber environment. This eliminates the complex multi-step coating process involving vacuum sealing and sol-based applications, replacing it with a simpler vacuum enclosure that provides protection without requiring intricate coating procedures.
Solution Approach 2:
The vacuum chamber provides self-contained protection for the KDP crystal. The sealed vacuum environment automatically prevents deliquescence and protects the crystal surfaces without requiring additional coating layers or complex protective mechanisms, simplifying both the structure and maintenance.
3Ease of manufacture
If KDP crystal is exposed to air, then coating can be applied, but the thin KDP crystal is easily deliquescent and must be placed in vacuum closed box
Solution Approach 1:
The patent removes the KDP crystal from the atmospheric environment and places it in a vacuum chamber. This extraction from air exposure prevents deliquescence entirely, making the crystal stable without requiring protective coatings. The vacuum environment replaces the need for coating while maintaining ease of manufacture.
Solution Approach 2:
The patent creates an inert vacuum environment around the KDP crystal to prevent deliquescence. By replacing air with vacuum, the crystal is protected from moisture absorption and chemical degradation, maintaining its compositional stability without requiring additional protective coatings or complex sealing mechanisms.
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 design extends the service life of the KDP crystal, simplifies the coating process, and maintains high conversion efficiency for ultra-intense pulses, providing a robust and practical solution for high-power frequency-doubling applications.
Implementation Method 1
the KDP crystal is configured to convert a π-polarized laser with a central wavelength of 800 nm into a σ-polarized laser with a central wavelength of 400 nm by frequency doubling
Implementation Method 2
since there is theoretically no loss when a linearly-polarized light is incident in a P plane at the Brewster angle
Data Source
AI summary
The present disclosure provides a potassium dihydrogen phosphate (KDP) frequency-doubling crystal structure, including a crystal fixing structure, a KDP crystal, a π polarization tube, and a σ polarization tube; where a π-polarized laser with a central wavelength of 800 nm enters the KDP crystal through the π polarization tube, and the KDP crystal converts the π-polarized laser with a central wavelength of 800 nm into a σ-polarized laser with a central wavelength of 400 nm by frequency doubling and then outputs the σ-polarized laser from the σ polarization tube. Close end bevels of the π polarization tube and the σ polarization tube are designed into a Brewster angle. The KDP crystal is placed in a vacuum-sealed cavity formed by the π polarization tube, the σ polarization tube, and the crystal fixing structure, which eliminates a complicated process of crystal coating and prevents the KDP crystal from deliquescing in air.