Kerr Lens Mode-Locked Laser Tuning Device
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Solution Overview
Problem
Conventional Kerr lens mode-locked (KLM) oscillators face challenges in avoiding damage to optical elements during pulse build-up and shut-down due to chaotic high power spikes, and struggle to optimize output parameters like power, bandwidth, and pulse-duration while maintaining high peak-power.
Innovation Solution
A pulse laser apparatus with a tuning device that sets two distinct mode-locking conditions: a first condition for starting or shutting-down with minimized intra-cavity threshold-power to avoid spikes, and a second condition for continuous operation with increased peak-power, using a combination of Kerr-medium and gain-medium in the oscillator cavity, along with optional hard aperture and phase-mismatched second harmonic generation crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Kerr lens mode-locked oscillators operate with high peak-power to achieve high output power, then productivity is improved, but chaotic high power spikes occur during pulse build-up and shut-down causing damage to optical elements
Solution Approach 1:
The patent implements dynamic switching between two distinct mode-locking conditions (first condition with lower intra-cavity threshold-power for safe start-up/shut-down, and second condition with higher peak-power for high output power operation). The tuning device enables the system to adapt its operating parameters in real-time, selecting the appropriate mode-locking condition based on the operational phase, thereby avoiding damage during transient states while maintaining high productivity during continuous operation.
Solution Approach 2:
The patent changes the operating parameters of the mode-locking device by implementing two distinct mode-locking conditions with different intra-cavity threshold-power levels. The first condition uses lower threshold-power to suppress chaotic oscillations during start-up and shut-down, while the second condition uses higher peak-power for high output power operation. This parameter switching resolves the contradiction between achieving high output power and avoiding damage from power spikes.
2Reliability
If the mode-locking device saturates easily to suppress q-switching instabilities, then reliability is improved, but the maximum achievable peak-power is limited
Solution Approach 1:
The patent dynamically adjusts the saturation characteristics of the mode-locking device by switching between two mode-locking conditions. During start-up and shut-down phases, the first mode-locking condition uses parameters that promote easier saturation to suppress instabilities. During continuous operation, the second mode-locking condition adjusts parameters to allow higher peak-power while maintaining stability suppression, thus resolving the contradiction between reliability and maximum power.
3Device complexity
If a single mode-locking condition is used for both start-up and continuous operation, then device complexity is reduced, but the ability to optimize output parameters while avoiding damage is compromised
Solution Approach 1:
The patent implements a universal tuning device that can set the mode-locking device to either the first or second mode-locking condition based on operational requirements. This multi-functional approach allows a single device to handle both safe start-up/shut-down operations and high-power continuous operation, optimizing output parameters for each phase without requiring separate dedicated systems, thus balancing complexity with adaptability.
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 suppresses chaotic oscillations during pulse-buildup, allows for increased output power without damaging optical components, and achieves peak-powers up to 500 MW in anomalous dispersion-regime or 5 MW in normal dispersion-regime, ensuring safe and efficient operation.
Implementation Method 1
At least one Kerr-medium is arranged in the beam path of the oscillator cavity. Generally, the at least one Kerr-medium is adapted for introducing self-phase modulation and self-focusing to the circulating light field in the oscillator cavity
Implementation Method 2
at least one gain-medium is arranged in the beam path of the oscillator cavity. The gain medium is adapted for amplifying the circulating light field in the oscillator cavity
Implementation Method 3
At least one of the resonator mirrors is an out-coupling mirror for coupling out part of the circulating light field out of the oscillator cavity
Data Source
AI summary
A pulse laser apparatus (100) for creating laser pulses (1), in particular soliton laser pulses (1), based on Kerr lens mode locking of a circulating light field in an oscillator cavity (10), comprises at least two resonator mirrors (11, 12, . . . ) spanning a resonator beam path (2) of the oscillator cavity (10), at least one Kerr-medium (21, 22, 23) for introducing self-phase modulation and self-focusing to the circulating light field in the oscillator cavity (10), at least one gain-medium (31) for amplifying the circulating light field in the oscillator cavity (10), and a tuning device (40) for setting a first mode-locking condition and a second mode-locking condition of the oscillator cavity (10) such that an intra-cavity threshold-power for mode-locking at the first mode-locking condition is lower than that at the second mode-locking condition, wherein the first mode-locking condition is adapted for starting or shutting-down of the Kerr lens mode locking and the second mode-locking condition is adapted for continuous Kerr lens mode locking and a resonator-internal peak-power of the circulating light field is higher at the second mode-locking condition than at the first mode-locking condition. Furthermore, a method of operating a pulse laser apparatus is described.