Rotating Image Optical Parametric Oscillator
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Solution Overview
Problem
Conventional optical parametric oscillators, particularly those using Fabry-Perot and ring geometries with plane mirrors, are sensitive to small mirror misalignments, leading to boresight, divergence, and pulse energy changes, and face manufacturing issues with mirror coatings prone to delamination and low laser damage thresholds.
Innovation Solution
A six-mirror rotating image optical parametric oscillator design incorporating a three-mirror image rotation assembly and a penta prism, which provides a predetermined beam rotation, enhancing beam homogeneity, reducing boresight sensitivity, and simplifying alignment, while using coatings that avoid delamination and improve laser damage resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Fabry-Perot or linear resonator is used, then the optical parametric oscillator can be configured simply, but small changes in mirror angle cause significant boresight, divergence and pulse energy changes
Solution Approach 1:
The patent transitions from a linear resonator configuration to a ring resonator configuration, adding a dimensional change in the optical path geometry. This ring structure with multiple mirrors (M1-M4) creates a closed-loop path that inherently stabilizes the beam against angular perturbations, resolving the contradiction between simple configuration and boresight stability.
Solution Approach 2:
The resonator is segmented into multiple discrete mirror components (M1, M2, M3, M4) arranged in a ring configuration, with the non-linear crystal positioned at a specific location. This segmentation allows each mirror to be independently positioned and aligned, reducing the cumulative effect of angular changes on overall beam stability.
2Object-generated harmful factors
If ring optical parametric oscillator configuration is used, then retro reflections into the pump laser are avoided, but the design remains sensitive to small mirror misalignments resulting in boresight, divergence and pulse energy changes
Solution Approach 1:
The patent introduces asymmetric elements into the ring resonator configuration, including the strategic positioning of the non-linear crystal and the use of a half-wave plate at a specific location in the optical path. This asymmetry breaks the symmetry of perturbation propagation, making the system less sensitive to mirror misalignments while maintaining the benefit of avoiding retro reflections.
Solution Approach 2:
The transition to a ring geometry adds a topological dimension to the optical path, creating a closed-loop structure that naturally directs reflected beams away from the pump laser source. This geometric transformation eliminates retro reflections while the multi-mirror configuration provides stability against misalignment through distributed beam path management.
3Adaptability or versatility
If thick coating is applied on fold mirror to achieve high reflectivity at both pump and signal wavelengths, then the mirror can reflect both wavelengths, but the coating is prone to de-laminate and has low laser damage threshold
Solution Approach 1:
The patent segments the wavelength-specific optical functions into separate components: fold mirror M3 is dedicated to pump wavelength reflection, while fold mirror M4 handles signal wavelength reflection. This functional segmentation allows each mirror to have optimized, thin coatings for its specific wavelength range, eliminating the need for thick multi-wavelength coatings and their associated reliability problems.
Solution Approach 2:
The ring resonator configuration provides multi-functionality where different mirrors perform different wavelength-specific roles. The system as a whole handles both pump and signal wavelengths through distributed specialized components rather than requiring each component to handle all wavelengths, improving overall system versatility without compromising component 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
The design achieves improved signal beam uniformity, reduced boresight sensitivity, simplified alignment, and minimized device dimensions, with enhanced mirror coating performance and increased flexibility in packaging, allowing for efficient operation in extreme environments.
Implementation Method 1
A non-linear crystal 140, such as Potassium Titanyl Phosphate (KTP), converts the pump light 120 into two longer wavelengths and provides parametric gain
Implementation Method 2
The input mirror 130 is highly transmissive at the pump wavelength and highly reflective at the circulating wavelength
Implementation Method 3
wherein three of the mirror surfaces are provided by a three mirrors image rotation assembly and two of the mirrored surfaces are provided by a penta prism and the sequence of mirrors is operable to provide a predetermined rotation of a beam passing therethrough
Data Source
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AI summary
The present invention relates to an optical parametric oscillator. In particular, the present invention relates to a more optimal rotating image optical parametric oscillator. More specifically, there is described an optical parametric oscillator comprising six mirrored surfaces; wherein two of the mirrored surfaces are provided by a penta prism and the sequence of mirrors is operable to provide a predetermined rotation of a beam passing therethrough.