Electro-Optical Q-Switch for Laser Pulse Timing Control
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Solution Overview
Problem
Existing laser arrangements face challenges in accurately predicting the timing of laser pulse emission due to dependence on external parameters like pumping energy and ambient conditions, and the energy of the pulse is also influenced by the gray glass used, making it difficult to achieve a laser pulse of variable and adjustable energy with high beam quality.
Innovation Solution
Incorporating a controllable modulator between the phase conjugate mirror and the end mirror allows for precise control over the start resonator's operation, enabling the generation of a laser pulse with defined strength and timing, using a switchable modulator that can block the start resonator after the phase-conjugating mirror switches to mirror mode, and employing an electro-optical Q-switch for nanosecond-range operation to protect the modulator from high energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gray glass is used between the phase-conjugating mirror and the end mirror to control pulse timing, then the delay time can be adjusted, but the timing precision deteriorates because the delay time depends on many external parameters such as pumping energy, pump power over time, gray value of the gray glass, and ambient conditions
Solution Approach 1:
The patent replaces the gray glass method with an electro-optical Q-switch that changes its optical properties (from transparent to reflective) by changing the electrical parameter (applying voltage to change refractive index via the Pockels effect). This allows precise control of the resonator Q-factor and thus the pulse emission timing, eliminating dependence on external parameters like pumping energy and ambient conditions.
Solution Approach 2:
The patent substitutes the passive optical method (gray glass absorption) with an active electro-optical control mechanism. The electro-optical Q-switch uses electrical field control to dynamically adjust the resonator properties, replacing the need for mechanical adjustment of gray glass properties and eliminating sensitivity to mechanical vibrations and shocks.
2Power
If gray glass with specific gray value is used to match pumping energy, then a single high-energy laser pulse can be generated, but the energy of the pulse cannot be easily varied or adjusted
Solution Approach 1:
The patent introduces a dynamic control mechanism (electro-optical Q-switch) that can be rapidly switched between different states (transparent/reflective) to control when the laser pulse is generated. This allows the system to adaptively control pulse energy by adjusting the pumping duration and timing of the Q-switch activation, enabling variable pulse energies without changing physical components like gray glass.
Solution Approach 2:
The system performs preliminary pumping of the laser medium to store energy, then uses the electro-optical Q-switch to trigger pulse generation at the optimal moment. This allows control over the amount of stored energy converted to pulse energy, enabling adjustable pulse outputs by varying the pumping time and power before Q-switch activation.
3Manufacturing precision
If the phase-conjugating mirror is used to achieve good beam quality by reversing optical errors, then beam quality is improved, but the timing of pulse emission becomes unpredictable due to dependence on external parameters
Solution Approach 1:
The electro-optical Q-switch acts as an intermediary control element between the phase-conjugating mirror and the pulse emission process. It provides a deterministic trigger mechanism that decouples the timing of pulse emission from the unpredictable parameters affecting the phase-conjugating mirror operation, allowing precise timing control while maintaining the beam quality benefits of phase conjugation.
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 solution allows for the precise specification of the laser pulse emission time and energy, achieving high beam quality and enabling the generation of a laser pulse with adjustable energy, exceeding 50 mJ for military applications, while protecting the modulator from high energy radiation.
Implementation Method 1
a phase conjugate mirror (PCS) based on stimulated Brillouin scattering (SBS)
Implementation Method 2
The modulator is designed as an electro-optical Q-switch, in particular as a Pockels cell
Data Source
Figure 1
Figure 2a~2b
Figure 3~4b
AI summary
The laser device has out-coupling mirror (10), laser medium (20), phase-conjugate mirror (30) based on stimulated Brillouin scattering, and end mirror (50) that are arranged alone an optical axis. A controllable modulator (40) e.g. electro-optical Q-switch is positioned between phase-conjugate mirror and end mirror, such that a start and main cavities (A,B) are formed between respective out-coupling mirror and end mirror, and phase-conjugate mirror. An independent claim is included for method for operating laser device.