laser docu: Add intro text

Author: steindev

docs/source/models/lasers.rst

@@ -6,6 +6,17 @@ Analytic Expressions for the 3D Laser Profiles
 .. sectionauthor:: Klaus Steiniger
 
 
+Among others, PIConGPU offers the ``GaussianPulse`` and ``DispersivePulse`` profiles to model complex, Gaussian-like laser pulse profiles in simulations.
+
+The ``GaussianPulse`` profile allows modelling standard Gaussian pulses defined by a Gaussian distribution of laser energy along the longitudinal and transverse directions.
+Furthermore, it allows including higher-order transverse modes via Laguerre-Gaussian modes [Pausch2022]_.
+
+The ``DispersivePulse`` profile allows modelling standard Gaussian pulses which feature dispersions, i.e. frequency specific modifications of the laser's spectral phase, up to third order.
+That is, time delay (TD), angular dispersion (AD), group-delay dispersion (GDD), and third-order dispersion (TOD) are self-consistently taken into account in the propagation of these pulses.
+The profile assumes a gaussian shape for the laser's spectrum.
+However, the electric field values in time domain are computed from the field's values in frequency domain by a discrete Fourier transform.
+Therefore, it is possible to use any other shape of the laser's spectrum by modifying the profile's source code.
+
 A very concise description of the equations used in the ``GaussianPulse`` and ``DispersivePulse`` profiles are provided in the following.
 Please also refer to the in-code documentation of these and the other profiles in order to obtain more profile-specific information.
 
@@ -206,13 +217,19 @@ In that case
 
 References
 ----------
-.. [Steiniger2024]
-        K. Steiniger et al.
-        *Distortions in focusing laser pulses due to spatio-temporal couplings: an analytic description*,
-        High Power Laser Science and Engineering 12 (2024).
-        https://doi.org/10.1017/hpl.2023.96
+.. [Pausch2022]
+        R. Pausch et al.
+        *Modeling Beyond Gaussian Laser Pulses in Particle-in-Cell Simulations - The Impact of Higher Order Laser Modes*
+        2022 IEEE Advanced Accelerator Concepts Workshop (AAC), Long Island, NY, USA (2022).
+        https://doi.org/10.1109/AAC55212.2022.10822876
 
 .. [Siegman1986]
         Siegman, Anthony E.
         *Lasers*,
         University science books (1986).
+
+.. [Steiniger2024]
+        K. Steiniger et al.
+        *Distortions in focusing laser pulses due to spatio-temporal couplings: an analytic description*,
+        High Power Laser Science and Engineering 12 (2024).
+        https://doi.org/10.1017/hpl.2023.96