Nonlinear Crystal UV Output Coupling via Dichroic Coating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing UV laser systems face issues with radiation loss and optically nonlinear crystal degradation when generating ultraviolet radiation, particularly due to the use of dichroic-coated elements and antireflection coatings in frequency-conversion processes, which lead to inefficiencies and material degradation.
Innovation Solution
The proposed solution involves an optical resonator with an optically nonlinear crystal where the dichroic coating is deposited on the exit face, allowing UV radiation to be reflected laterally out of the resonator, eliminating the need for separate beamsplitters and antireflection coatings within the resonator path, and enabling crystal translation to avoid degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dichroic-coated beamsplitter is used to separate UV radiation from converted radiation, then UV radiation can be reflected out of the resonator, but UV radiation loss increases due to coating losses
Solution Approach 1:
The patent combines the frequency conversion function and the UV output coupling function into a single optically nonlinear crystal. The crystal both converts the fundamental radiation to UV radiation and, through its exit face, couples the UV radiation out of the resonator. This eliminates the need for a separate dichroic-coated beamsplitter, thereby removing the associated UV loss while maintaining effective UV extraction.
Solution Approach 2:
The optically nonlinear crystal is given multiple functions: it serves as the frequency conversion medium to generate UV radiation and simultaneously acts as the output coupler for UV radiation through its exit face. This multi-functional design eliminates the need for separate components and reduces overall system loss.
2Loss of energy
If antireflection coatings are applied to crystal faces within the resonator path, then radiation loss is reduced, but UV degradation of the crystal occurs
Solution Approach 1:
The patent extracts the UV output coupling function from the internal resonator path and places it at the exit face of the crystal. By doing so, UV radiation is coupled out laterally before it can cause degradation to other crystal faces that would be exposed to circulating UV radiation. This allows the use of antireflection coatings on the exit face without suffering from UV degradation issues elsewhere in the resonator path.
3Device complexity
If the optically nonlinear crystal is stationary, then the system is simpler, but UV degradation accumulates on crystal surfaces reducing performance
Solution Approach 1:
The patent introduces a translation mechanism that allows the optically nonlinear crystal to be moved laterally. This dynamic adjustment capability enables the system to compensate for UV degradation by translating the crystal to expose fresh portions of the exit face, thereby maintaining performance over extended operation periods.
Solution Approach 2:
The translation mechanism allows degraded portions of the crystal exit face to be effectively 'discarded' by moving to a fresh, undegraded portion of the crystal. This extends the usable life of the crystal without requiring replacement, maintaining system reliability.
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 configuration reduces UV radiation loss and extends the lifespan of the nonlinear crystal by avoiding degradation from circulating radiation, while maintaining high efficiency in extracting UV power without requiring antireflection coatings within the resonator.
Implementation Method 1
Intra-resonator frequency multiplication of solid-state or optically pumped semiconductor (OPS) radiation laser radiation in optically nonlinear crystals is commonly used to generate ultraviolet UV laser radiation
Implementation Method 2
The optically nonlinear crystal is arranged to convert the circulating first-wavelength wavelength radiation the second wavelength radiation, and to reflectively couple the second-wavelength radiation out of the resonator at an angle to the resonator axis
Implementation Method 3
The optical coating is a dichroic coating that is transmissive for the first wavelength radiation and reflective for the second wavelength radiation
Data Source
AI summary
In traveling-wave ring-resonator an optically nonlinear crystal for converting visible radiation to ultraviolet (UV) radiation has an input face and two output faces. The visible light propagates through the crystal from the input face to one of the output faces. That output face is coated with a dichroic optical coating that transmits unconverted visible light and reflects the ultraviolet light. The reflected ultraviolet light exits the optically nonlinear crystal via the other output face and is coupled out of the resonator at an angle to the resonator axis.