Optical Frequency Converter Using Periodic Amorphous Regions
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Solution Overview
Problem
Current nonlinear optical frequency conversion technologies are limited by the phase matching condition, which restricts the availability of efficient lasers, especially for ultraviolet and deep ultraviolet applications, due to the requirement for crystals with appropriate double refraction and the difficulty in growing layered KBBF crystals.
Innovation Solution
A visible ultraviolet band optical frequency converter using a nonlinear optical crystal with periodically arranged amorphous regions, which block the nonlinear optical effect in certain areas but provide a controlled phase difference between fundamental and frequency doubling light, allowing for phase matching and efficient frequency conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If double refraction phase matching mode is used, then phase matching can be achieved, but crystal availability is limited and manufacturing difficulty increases
Solution Approach 1:
The invention changes the phase matching mechanism from relying on double refraction properties to using periodic poling of ferroelectric domains. This parameter change allows use of crystals like LiNbO3 that can be poled, eliminating the need for specific double refraction characteristics and expanding crystal selection while maintaining phase matching efficiency
Solution Approach 2:
The invention creates a composite structure within the crystal by introducing periodic domains with opposite polarization directions. This composite domain structure enables phase matching through periodic reversal of nonlinear optical coefficients, achieving the desired phase matching without requiring specific double refraction properties of the base crystal material
2Productivity
If KBBF crystal is used for deep ultraviolet frequency doubling, then effective frequency conversion can be achieved, but crystal growth becomes too difficult and material toxicity increases
Solution Approach 1:
The invention changes the phase matching approach from double refraction to periodic poling, enabling use of LiNbO3 and other polable crystals for deep UV generation. This parameter change eliminates the need for difficult-to-grow KBBF crystals while maintaining frequency conversion efficiency through periodic domain reversal
Solution Approach 2:
The invention replaces expensive, difficult-to-grow KBBF crystals with more readily available polable crystals like LiNbO3. The periodic poling technique enables these easier-to-manufacture crystals to achieve the same deep UV frequency doubling function, reducing manufacturing complexity and material cost
3Adaptability or versatility
If periodic poling is implemented, then phase matching controllability is enhanced, but crystal processing complexity increases
Solution Approach 1:
The invention uses the crystal's own ferroelectric properties to create the periodic structure through poling. The crystal itself undergoes domain reversal in specific regions when exposed to electric fields during processing, enabling periodic poling without requiring external mechanical structures or additional components, thus enhancing controllability while managing processing complexity
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
Enables efficient frequency doubling and sum frequency conversion from the visible band to ultraviolet and deep ultraviolet bands, overcoming the limitations of existing technologies by simplifying the crystal processing and enhancing the controllability of phase matching, thus expanding the applicability of nonlinear optical crystals.
Implementation Method 1
the frequency-doubling effect, as one of the most widely studied and applied effects in the nonlinear optical field, is to double the optical frequency and shorten the wavelength by half relying on the frequency up-conversion effect
Implementation Method 2
momentum conservation, namely the phase matching condition, is the basic requirement for efficient optical frequency conversion
Implementation Method 3
an equal refractive index is to be achieved between the fundamental frequency o light or e light and the frequency doubling e light or o light under a special chamfering angle based on the dispersion relation of the birefrigent effect
Data Source
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AI summary
The present invention provides a visible ultraviolet band optical frequency converter. The processing period of a nonlinear optical crystal is controlled to provide an additional period phase to meet a phase matching condition so as to realize effective optical frequency conversion. The additional period phase is characterized in that phase gratings periodically arranged according to different refractive indexes are formed in the crystal through technologies, including laser micro-processing, ion etching and the like, a nonlinear frequency conversion inverse process is avoided through the periodic structure damage of the crystals in the phase gratings and an additional period phase is provided, phase mismatch caused by the insufficient double refraction of the nonlinear optical crystal is avoided, and efficient frequency doubling or sum frequency output is realized. By use of the optical frequency converter, the nonlinear optical material can be optimized, the proper crystal can be selected according to required wavelength, and the additional period phase matched with the technologies, such as laser lithography, can be provided so as to realize the effective output of specific wavelength. Anew variety is provided for the nonlinear optical frequency converter, and the optical frequency converter has the advantages of high optical frequency conversion efficiency, easiness in preparation and the like.