Single-Shot Pulse Contrast Measuring Device Using Non-Harmonic Long-Wavelength Sampling
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Solution Overview
Problem
Current single-shot pulse contrast measuring devices face challenges in achieving high dynamic range and large temporal window simultaneously, with existing technologies limited by detector performance and nonlinear phase matching constraints.
Innovation Solution
The implementation of non-harmonic long-wavelength sampling pulse technology and large-angle non-collinear phase matching using periodically poled crystals, combined with a high sensitivity signal receiving unit, enhances the dynamic range and temporal window of the single-shot pulse contrast measuring device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-shot pulse contrast measuring devices use standard detectors and nonlinear phase matching, then the device structure is relatively simple, but the dynamic range is limited to 10^6-10^7 and temporal window is constrained
Solution Approach 1:
The patent changes the wavelength parameter of the sampling pulse from conventional short wavelength to long wavelength (e.g., 2 μm), which fundamentally alters the phase matching conditions and enables larger non-collinear angles. This parameter change directly increases the dynamic range to 10^9 while maintaining device structure simplicity through the use of standard detectors
Solution Approach 2:
The patent introduces a new dimension in phase matching by using large-angle non-collinear geometry instead of traditional collinear or small-angle phase matching. This dimensional change in the phase matching space enables both high dynamic range and large temporal window simultaneously
2Duration of action of moving object
If conventional single-shot pulse contrast measuring devices use standard phase matching angles, then the device is easier to operate, but the temporal window is limited and cannot reach ~50 ps
Solution Approach 1:
The patent changes the phase matching angle parameter from small angles to large non-collinear angles (e.g., 30°-45°), which directly expands the temporal window to ~50 ps. The use of periodically poled crystals with engineered poling periods simplifies the operation by providing precise phase matching conditions at these large angles
3Measurement precision
If conventional devices use short-wavelength sampling pulses, then light scattering noise is significant, but the dynamic range is limited to 10^6-10^7
Solution Approach 1:
The patent changes the sampling pulse wavelength from short wavelength to long wavelength (e.g., 2 μm), which fundamentally reduces light scattering noise due to the wavelength dependence of scattering. This parameter change enables the dynamic range to reach 10^9 by eliminating the noise that limited conventional devices to 10^6-10^7
4Measurement precision
If conventional devices use collinear or small-angle phase matching, then the setup is simpler, but both temporal window and dynamic range are constrained
Solution Approach 1:
The patent transitions from collinear or small-angle phase matching to large-angle non-collinear phase matching, introducing a new geometric dimension. This dimensional change in the interaction geometry enables both high dynamic range (10^9) and large temporal window (~50 ps) simultaneously, outweighing the increased operational 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
This approach achieves a dynamic range of ~10^9 and a temporal window of ~50 ps, comparable to scanning measurement schemes, with a resolution of ~1 ps, effectively addressing the limitations of previous technologies.
Implementation Method 1
one portion is used to pump the OPG crystal for generating the needed long-wavelength pulse
Implementation Method 2
the other portion is used to pump the OPA crystal to amplify the long-wavelength pulse
Implementation Method 3
both the lasers of under test and sampling, after proper beam expander and time adjustment, are separately focused in one dimension by a cylindrical plano-concave mirror and then make SFG cross-correlation in a periodically polarized lithium niobate crystal (PPLN)
Implementation Method 4
innovatively applies the large-angle non-collinear phase matching technology based on the periodically poled crystal, both technologies greatly improves the temporal window of the single-shot pulse contrast measuring device
Data Source
AI summary
A single-shot pulse contrast measuring device based on non-harmonic long-wavelength sampling pulse includes a long-wavelength sampling light generation unit, a large-angle non-collinear sum-frequency cross-correlation unit and a high sensitivity signal receiving unit. The long-wavelength sampling light sum-frequency cross-correlator can allow that the beams are interacted with each other at the large non-collinear angle in the quasi-phase matching crystal, match the measuring window of the high sensitivity signal receiving system, and is in favor of eliminating the scattered light noise, thereby achieving the single measurement of the pulse contrast with large temporal window and high dynamic range. The single-shot pulse contrast measuring device of the present invention has good extensibility at the temporal window and dynamic range, and is adapted for measuring the contrast of the high-power laser with various wavelengths.