Terahertz Pump-Probe Delay via Repetition Rate
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Solution Overview
Problem
Existing methods for generating time-delayed pulses are limited by mechanical arrangements that require frequent readjustment and are prone to inaccuracies due to vibrations, with the time delay being coupled with the length of the delay path, restricting variability and stability.
Innovation Solution
A method involving a pulsed beam split into two sub-beams, where the time delay is adjusted by varying the pulse repetition rate, allowing for flexible and wide-ranging time delay settings without the need for mechanical adjustments, using a beam splitter and fiber couplers to guide the pulses with fixed optical path lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical delay line with adjustable mirrors is used to set time delay, then the time delay can be adjusted, but the mechanical arrangement requires frequent readjustment and is prone to inaccuracies due to vibrations
Solution Approach 1:
The patent replaces the mechanical delay line with an optical fiber-based system. Instead of using movable mirrors and mechanical adjustments to change delay time, the invention uses optical fibers with different lengths to provide fixed delay times. This eliminates mechanical components that are prone to vibration and readjustment issues, while still providing adaptable time delay settings through selection among multiple fiber lengths.
Solution Approach 2:
The patent introduces a dynamic switching mechanism that allows the system to switch between different fixed delay time settings. By using a switching element to select among multiple optical fiber paths with different lengths, the system achieves adjustable time delay without requiring mechanical adjustment of the delay line itself, thereby maintaining stability while providing versatility.
2Loss of time
If the length of the delay line is increased to achieve larger time delays, then the time delay range is improved, but lateral deviations increase proportionally with longer optical path lengths
Solution Approach 1:
The patent replaces the traditional mechanical/optical delay line with optical fiber implementations. Optical fibers confine light through total internal reflection, eliminating lateral beam deviations that occur in free-space optical paths. This allows for longer delay times to be achieved without the lateral deviation problems that plague conventional delay lines with long optical paths.
Solution Approach 2:
The patent uses optical fiber technology where the light path is nested within the fiber structure. The optical path is contained within the fiber core, protected by cladding layers, which prevents lateral deviations even over long distances. This nested structure allows achieving large time delays (long optical paths) without the lateral deviation issues of conventional open-path delay lines.
3Adaptability or versatility
If a spirally curved mirror surface is used to change delay distance by rotation, then the delay can be varied, but the variability is severely limited by component geometries and mechanics
Solution Approach 1:
The patent replaces complex mechanical rotation mechanisms with simple optical switching. Instead of rotating spirally curved mirrors to change delay distance, the invention uses switching elements to select among multiple pre-configured optical fiber paths with different lengths. This eliminates the need for complex mechanical arrangements while providing equivalent or superior variability in delay settings.
Solution Approach 2:
The patent divides the delay line into multiple discrete segments (optical fibers of different lengths). Instead of using a continuous mechanical adjustment mechanism like a spirally curved mirror, the system segments the delay path into distinct fixed-length fiber segments and uses switching to select the appropriate segment or combination of segments, thereby achieving variability without mechanical complexity.
4Loss of time
If the delay line is made longer to achieve larger time intervals between pulses, then the time delay range is improved, but the structure becomes more susceptible to vibrations and readjustment issues
Solution Approach 1:
The patent replaces mechanical delay lines with optical fiber implementations. Optical fibers are inherently stable and immune to vibrations that affect mechanical structures. By confining light within the fiber core, the system achieves long time delays without the vibration susceptibility and readjustment issues that plague conventional mechanical delay lines with long paths.
Solution Approach 2:
The patent introduces a dynamic switching mechanism that allows rapid reconfiguration of delay settings without mechanical adjustment. The switching element can quickly change between different fiber paths in response to control signals, eliminating the need for manual readjustment of mechanical components even when time delay settings need to be changed.
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 enables precise and stable generation of time-delayed pulses with reduced need for mechanical adjustments, allowing for large time intervals between pulses and improved accuracy, particularly in terahertz technology, by decoupling time delay from the length of the delay line and using fiber optics for stable signal guidance.
Implementation Method 1
splitting the pulsed beam, the first sub-beam containing a first pulse and the second sub-beam containing a second pulse
Implementation Method 2
using a beam splitter and fiber couplers to guide the pulses with fixed optical path lengths
Implementation Method 3
a femtosecond laser in a method in order to excite a photoconductive dipole antenna with its optical pulses. The laser pulses generate free charge carriers in the dipole antenna
Implementation Method 4
The laser pulses generate free charge carriers in the dipole antenna, which are accelerated by an external electric field. In the form of a short current pulse, the accelerated charge carriers form the source
Data Source
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AI summary
The invention relates to a method for generating two delayed pulses, in particular in terahertz spectroscopy and/or in pump-probe experiments, with the following method steps: - generating a pulsed beam using a beam source (1), in particular a pulsed laser; - dividing the pulsed beam (2), wherein the first partial beam (4) comprises a first pulse and the second partial beam (5) comprises a second pulse; - directing the two pulses onto a respective target area (9, 10), wherein the first pulse directly reaches a first target area (9) and the second pulse reaches a second target area (10) after passing through a delay path, and wherein the two target areas can be coincident; - using the two pulses, particularly for a measurement method; wherein the time delay of the two pulses in the respective target area can be set by the pulse repetition rate of the pulsed beam (2).