Curved Nonlinear Crystal for Tuning Without Beam Deviation
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Solution Overview
Problem
Existing nonlinear crystal designs in frequency mixing cavities face challenges with beam deviation during frequency tuning, requiring complex and costly servo control electronics to maintain phase-matching conditions, which increases optical losses and system complexity.
Innovation Solution
A nonlinear crystal with curved faces providing rotational symmetry about an axis, allowing for frequency tuning by adjusting the wavelength and rotation of the crystal without significant beam deviation, eliminating the need for optical compensation optics or servo control electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Brewster-angle cut crystal is used, then beam deviation during frequency tuning is minimized, but system complexity increases due to required servo control electronics
Solution Approach 1:
The patent applies curvature to the crystal faces by introducing a small radius of curvature to the entrance and exit surfaces of the nonlinear crystal. This curved surface design allows the crystal to maintain phase-matching conditions during frequency tuning without requiring complex servo control electronics, as the curvature compensates for beam deviation in a passive manner.
2Ease of manufacture
If right-angle cut crystal is used, then manufacturing is easier, but transmission losses increase due to higher reflectance
Solution Approach 1:
The patent applies curvature to the crystal faces by introducing a small radius of curvature to the entrance and exit surfaces of the nonlinear crystal. This curved surface design reduces transmission losses by minimizing reflectance at the interfaces, while maintaining ease of manufacture compared to Brewster-angle cuts.
3Ease of manufacture
If right-angle cut crystal is used, then manufacturing is simpler, but damage threshold is reduced due to coating limitations
Solution Approach 1:
The patent applies curvature to the crystal faces by introducing a small radius of curvature to the entrance and exit surfaces of the nonlinear crystal. This curved surface design increases the damage threshold by eliminating the need for protective coatings that have lower damage thresholds, while maintaining manufacturing simplicity.
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 tuning of the output field with minimal deviation, simplifying the system design, reducing costs, and minimizing optical losses, thus improving the stability and affordability of nonlinear crystal-based devices.
Implementation Method 1
This technique is based on the annihilation of two input photons at angular frequencies ω1 and ω2 to generate one photon at frequency ω3
Implementation Method 2
This is a nonlinear process that involves combining two photons of different energies to produce a third photon whose energy equals the difference between those of the incident photons
Implementation Method 3
As an alternative process to SFM known in the art is difference frequency mixing (DFM). This is a nonlinear process that involves combining two photons of different energies to produce a third photon whose energy equals the difference between those of the incident photons
Implementation Method 4
a radius of curvature of the first and second curved faces are equal and centred on the axis of rotation to provide the nonlinear crystal with rotational symmetry about at least one axis of the nonlinear crystal
Implementation Method 5
For sum-frequency mixing to occur efficiently, the condition, as defined by equation (2), referred to as phase-matching, must be satisfied
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(b)
AI summary
A nonlinear crystal comprising a first curved face and an opposing second curved face is described. The first and second curved faces are arranged to provide the nonlinear crystal with rotational symmetry about at least one axis of the nonlinear crystal. The nonlinear crystal allows for frequency tuning of a generated optical field that is generated by propagating a fundamental optical field through the nonlinear crystal by rotation of the nonlinear crystal about an axis of rotation without any significant, or minimal, deviation being introduced to the generated optical field. These nonlinear crystals can therefore be incorporated into an external cavity frequency doubler or mixer without any need for the employment of optical compensation optics or servo control electronics to automatically realign the cavity mirrors