Optical Dispersion Measurement Using Opposite-Sign Pulse Chirping
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Solution Overview
Problem
Existing dispersion measuring devices face inaccuracies in measuring wavelength dispersion due to non-linear optical phenomena and damage risks when peak intensities of optical pulses exceed certain thresholds, leading to distorted temporal waveforms and reduced detection accuracy.
Innovation Solution
The dispersion measuring device employs a pulse forming unit that applies positive or negative group delay dispersion to optical pulses to suppress peak intensities below non-linear optical phenomenon thresholds, followed by a dispersion medium with opposite group delay dispersion to enhance detection threshold compliance, ensuring accurate temporal waveform detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the peak intensity of the optical pulse is increased, then the detection accuracy of the temporal waveform is improved, but non-linear optical phenomena occur causing waveform distortion and measurement inaccuracy
Solution Approach 1:
The patent applies group delay dispersion in advance to the optical pulse before it enters the measurement object. This preliminary action suppresses the peak intensity to below the non-linear optical phenomenon threshold, preventing waveform distortion before it occurs. The dispersion is applied proactively rather than reactively, ensuring the pulse maintains its integrity throughout the measurement process.
Solution Approach 2:
The patent changes the temporal intensity distribution parameters of the optical pulse by applying group delay dispersion. This transforms the pulse from a high peak intensity shape that would cause non-linear effects into a shaped pulse with suppressed peak intensity that remains below the non-linear threshold while still allowing accurate detection of the measurement object's characteristics.
2Object-affected harmful factors
If the peak intensity of the optical pulse is decreased, then non-linear optical phenomena are avoided, but the peak intensity falls below the detection threshold value
Solution Approach 1:
The patent applies group delay dispersion to reshape the temporal intensity distribution of the optical pulse. This parameter change suppresses the peak intensity to remain below the non-linear optical phenomenon threshold while maintaining sufficient overall intensity for accurate detection. The dispersion modifies the pulse shape to achieve both protection from non-linear effects and adequate signal strength.
3Device complexity
If a single optical pulse is used for measurement, then the measurement process is simple, but the temporal waveform may be distorted due to non-linear optical phenomena
Solution Approach 1:
The patent applies group delay dispersion as a preliminary action to the optical pulse before it enters the measurement object. This single-step preprocessing action suppresses the peak intensity below the non-linear threshold, preventing waveform distortion during the measurement process. The approach maintains simplicity by using a single pulse with pre-applied dispersion rather than complex multi-pulse sequences.
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 allows for precise measurement of wavelength dispersion by maintaining peak intensities within detectable limits, thereby enhancing measurement accuracy and preventing distortion, while offering flexibility in selecting dispersion media types.
Implementation Method 1
a positive or negative group delay dispersion is given to a first optical pulse in a pulse forming unit
Implementation Method 2
a group delay dispersion having a sign opposite to the group delay dispersion given to the first optical pulse is given to the second pulse or the third pulse by the dispersion medium
Data Source
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AI summary
A dispersion measuring device includes a pulsed laser light source, a pulse forming unit, a correlator, and an arithmetic operation unit. The pulse forming unit forms an optical pulse train from an optical pulse output from the pulsed laser light source, the optical pulse train including a plurality of optical pulses having a time difference from each other and having center wavelengths different from each other. The correlator detects a temporal waveform of correlated light formed from the optical pulse train. The arithmetic operation unit estimates a wavelength dispersion amount of an optical component disposed on an optical path between the pulsed laser light source and the correlator, based on the temporal waveform of the correlated light. A dispersion medium gives a positive or negative group delay dispersion to the optical pulse train to increase the peak intensity of the correlated light to be equal to or greater than a detection threshold value of the correlator. The pulse forming unit gives a group delay dispersion having a sign opposite to the group delay dispersion given to the optical pulse train to the optical pulse.