Passive Q-switch Laser Pulse Width Optimization
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Solution Overview
Problem
The range of repetition frequency in passive Q-switch lasers is limited due to the need for expert adjustment of the output mirror, making it difficult for users to achieve stable oscillation across a single pulse to kHz frequencies, particularly in applications like spectrometry and LIBS.
Innovation Solution
A passive Q-switch laser system that includes an excitation source, a laser medium, a saturable absorber, and a control element using a matrix table to optimize the output of the excitation source and pulse width based on input repetition frequency, allowing for stable operation across a broader frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expert adjustment of the output mirror is performed to achieve stable oscillation, then the laser can operate at specific repetition frequencies, but the range of repetition frequency is limited and user operation becomes difficult
Solution Approach 1:
The patent applies parameter changes by systematically varying pump power and pulse width parameters across different repetition frequencies. A matrix table stores optimal parameter combinations for various frequencies, allowing the system to adapt to different operating conditions without requiring physical adjustments to the output mirror, thus expanding the frequency range while maintaining stable oscillation.
2Reliability
If expert adjustment of the output mirror is performed, then stable oscillation can be achieved, but ease of operation deteriorates due to requiring expert knowledge
Solution Approach 1:
The system implements self-service by automatically selecting and applying optimal pump power and pulse width parameters from the pre-calculated matrix table based on the input repetition frequency. This eliminates the need for expert manual adjustment of the output mirror, allowing users to operate the laser across a wide frequency range simply by inputting the desired frequency without requiring specialized knowledge.
3Power
If the pump power is set to maximum energy level and pulse width is set longer than threshold, then the desired output frequency can be obtained, but the range of applicable repetition frequencies remains limited
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal pump power and pulse width parameter combinations for multiple repetition frequencies in a matrix table before operation. When the user inputs a desired frequency, the system retrieves the pre-optimized parameters, avoiding the need to use fixed maximum settings and enabling adaptation to various frequencies while maintaining optimal power output.
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 system enables stable laser oscillation across a single pulse to kHz frequencies, expanding the range of repetition frequency and ensuring optimal operation conditions, as demonstrated by experimental results.
Implementation Method 1
a laser medium that is in-place between a pair of reflection mirrors consisting of an optic resonator emits a laser beam excited by the excitation light from the excitation source
Implementation Method 2
a saturable absorber that is in-place between the pair of the mirrors increases a transmittance in accordance with an absorption of the laser beam from the laser medium; The saturable absorber 4 becomes transparent when the electron density in the excited level is saturated and the Q-value of the light resonator rapidly increases
Implementation Method 3
When obtaining 355 nm UV-output, the original wave (pump wave) that is an output of the passive Q-switch laser is converted to the second harmonic by the second harmonic generation (SHG) 6
Implementation Method 4
The original wave and the second harmonic is converted to the third harmonic by the third harmonic generation (THG) 7
Data Source
AI summary
A passive Q-switch laser has an excitation source 1 for outputting excitation light; a laser medium 3 between a pair of reflective mirrors 5a, 5b that constitute part of an optical resonator, the laser medium emitting laser light upon being excited by the excitation light from the excitation source: a saturable absorber 4 disposed between the pair of reflective mirrors, the saturable absorber being configured such that the transmittance thereof increases as the laser light beam the laser medium is absorbed, a matrix table 22 in which the excitation-source output and the optimal value of the pulse width are stored in association with the repetition frequency; and a control unit 21 for referring to the matrix table, reading out the excitation-source output and the optimal value of the pulse width that correspond to an inputted repetition frequency, and controlling the excitation source such that the read-out excitation-source output and optimal value of the pulse width are attained.