initial work to add cos-profile

lasy/profiles/longitudinal/__init__.py

@@ -1,4 +1,5 @@
+from .cos_profile import CosLongitudinalProfile
 from .gaussian_profile import GaussianLongitudinalProfile
 from .longitudinal_profile_from_data import LongitudinalProfileFromData
 
-__all__ = ["GaussianLongitudinalProfile", "LongitudinalProfileFromData"]
+__all__ = ["CosLongitudinalProfile","GaussianLongitudinalProfile", "LongitudinalProfileFromData"]

lasy/profiles/longitudinal/cos_profile.py

@@ -0,0 +1,62 @@
+import numpy as np
+
+from .longitudinal_profile import LongitudinalProfile
+
+
+class CosLongitudinalProfile(LongitudinalProfile):
+    r"""
+    Derived class for the analytic longitudinal truncated cosinus profile  profile of a laser pulse.
+
+    More precisely, the longitudinal envelope
+    (to be used in the :class:CombinedLongitudinalTransverseProfile class)
+    corresponds to:
+
+    .. math::
+
+        \mathcal{L}(t) = \cos\left({ \frac{\pi}{2} \frac{t-t_peak}{tau_fwhm} }\right)
+            \theta( \frac{t-t_peak}{tau_fwhm} + 1 ) \theta( 1 - \frac{t-t_peak}{tau_fwhm} )
+            \exp\left({ + i\omega_0t_{peak} }\right)
+
+    Parameters
+    ----------
+    tau_fwhm : float (in second)
+        The Full-Width-Half-Maximum duration of the intensity distribution of the pulse.
+
+    t_peak : float (in second)
+        The time at which the laser envelope reaches its maximum amplitude,
+        i.e. :math:`t_{peak}` in the above formula.
+
+    cep_phase : float (in radian), optional
+        The Carrier Enveloppe Phase (CEP) :math:`\phi_{cep}`
+        (i.e. the phase of the laser oscillation, at the time where the
+        laser envelope is maximum)
+    """
+
+    def __init__(self, wavelength, tau, t_peak, cep_phase=0):
+        super().__init__(wavelength)
+        self.tau = tau
+        self.t_peak = t_peak
+        self.cep_phase = cep_phase
+
+    def evaluate(self, t):
+        """
+        Return the longitudinal envelope.
+
+        Parameters
+        ----------
+        t: ndarrays of floats
+            Define points on which to evaluate the envelope
+
+        Returns
+        -------
+        envelope: ndarray of complex numbers
+            Contains the value of the longitudinal envelope at the
+            specified points. This array has the same shape as the array t.
+        """
+
+        tn = (t - t_peak)/self.tau
+
+        envelope = np.cos(0.5*np.pi*tn)*np.theta(tn + 1)*np.theta(1 - tn)*
+            np.exp(+ 1.0j * (self.cep_phase + self.omega0 * self.t_peak))
+
+        return envelope