Description
Thermal and Mechanical analysis output power and beam qualtiy analysis Rate equation systems Laser Stability, Beam Radius And Parameter Analysis amplifier Pump Light Analysis Active And Passive Q-Switch
Thermal And Structural Analysis

Thermal and structural analysis of laser crystals are needed to calculate thermal lens effects.

thermallens

An user friendly graphical user interface (GUI) allows a flexible design of cooling and geometry of the laser crystal. The Finite Element solver takes into account the frequency-dependent absorption of the laser crystal and allows to set spectrum of pump light.
ASLD contains a fast and highly accurate 3-dimensional Finite- Element Method (FEM). It can be applied for very long or thin lasers crystals and small pump lights with small pump radius as well.
It also includes a complete 3-dimensional time dynamic analysis (by FE) which is required for the simulation of thermal lens effects of lasers with pulsed pump light.

Output Power And Beam Quality Analysis

The Dynamic Multi-Mode Analysis DMA calculates output power and the beam quality (M2) depending on the beam radius, pump/resonator configuration, and special optical elements, such as, apertures and Gaussian output couplers.

output beam

These factors allow the calculation of the population inversion, in the laser crystal, based on a finite volume discretization grid. The time dynamic behavior of the laser is simulated by rate equations for different high and low order Gaussian modes.

Rate Equation Systems

ASLD can simulate dynamic behaviour of resonator modes based on a set of arbitrary rate equations. This includes simulation of co-doped materials and various interionic mechanisms like upconversion, energy transfer, or cross-relaxation. Rate equations are stored in a material database, which can be extended by the user. A user friendly GUI let the user setup individual rate equations by adding interionic mechanisms and energy levels.

rate equation

Simulation of an arbitrary set of rate equations allows an accurate simulation of the dynamic behaviour of resonator modes. Moreover, it enables user to accurately simulate the thermal lens effect in a laser crystal. The heat source can be calculated using the iterionic transitions and the populations. Lasers with gain medium like Nd:YAG, Ho:YAG, Er:YAG, Er:glass, or Tm,Ho:YAG can be simulated by ASLD. Also, ASLD rate equations take into account systems with multiple levels, temperature dependent stimulated emission cross section and reabsorption.

Laser Stability, Beam Radius And Parameter Analysis

ASLD analyzes the stability of a solid-state laser and calculates its beam radius depending on the resonator configuration and thermal lensing effects.

laser stability

ASLD provides a tool for parameter analysis in order to optimize the design of a laser resonator. The output power, beam quality and stability diagram of a laser resonator can be plotted for a range of input parameters:

• Power of pump light
• Pump frequency shift
• Reflectivity of the output mirror

ASLD is capable of calculating the impact of each input parameter variations on the above mentioned output quantities. The parameter analysis uses advanced algorithms for minimal computation time and saves resonator optimization costs.

Amplifier

The ASLD package simulates the ouput power and gain of solid-state amplifiers. This is done by modelling a seed laser by the composition of Gaussian functions, in order to achieve fast simulation rates. Population inversion is also accurately modelled on a three dimensional finite volume grid. This allows an accurate calculation of the influence of pump configuration on output power. The above effectively and accurately simulates single-pass, double-passand regenerative amplifiers. Furthermore, ultra-short and chirped-pulse amplifiers can also be simulated.

laser amplifier

Gain guiding can reduce the effectiveness of Laser amplifiers. ASLD simulates this effect providing accuracy in calculating output power. Pump light separation occurs in some lasers. ASLD accounts for this effect in its simulation tool. Ray tracing is included in order to define pump light in a user friendly manner. Moreover, ASLD rate equations take into account three and four level systems.

Pump Light Analysis
pump light

ASLD built-in ray tracing program can accurately simulate pump configuration. The following effects are taken into account:

• Absorption of light
• Scattering effects
• Reflection of light

An efficient algorithm is used for the computation of light scattering.

Active And Passive Q-Switch

ASLD enables the analysis of pulse energy, pulse-width, beam quality and pulse frequency of the output of both active and passive Q-switches.

active passive qswitch

 ASLD also includes an accurate algorithm accounting for the physical effects of passive Q-switching with a saturable absorber. The physical properties of the saturable absorber, like ground-state and excited-state absorption cross-sections, are accounted for this purpose

Mode competition in the resonator can also be simulated by a dynamic mode analysis of both low and high Gauss modes.

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