Add example for phase extraction from Rayleigh coefficients

examples/phase_extraction.py

@@ -0,0 +1,82 @@
+"""Example: Extracting reflection/transmission phase from meent results.
+
+conv_solve() returns a Result object containing complex Rayleigh
+coefficients (R_s, R_p, T_s, T_p) in addition to real-valued
+diffraction efficiencies (de_ri, de_ti).
+
+The complex coefficients carry phase information, which is essential
+for metasurface design and wavefront engineering applications.
+
+Access pattern:
+    result = mee.conv_solve()
+    R_s = result.R_s          # complex array (top-level property)
+    R_s = result.R_s      # equivalent, via sub-result
+    phase = np.angle(R_s)     # phase in radians
+
+For 1D gratings, R_s has shape (1, 2*fto+1) where the 0th order
+is at index [:, fto].
+"""
+
+import numpy as np
+import meent
+
+
+def run():
+    wavelength = 900  # nm
+    n_si = 3.48
+    n_air = 1.0
+    fto = 10
+
+    # 1D Si grating on Si substrate
+    nx = 100
+    ucell = np.ones((1, 1, nx)) * n_air
+    ucell[0, 0, 30:70] = n_si  # 40% fill factor
+
+    mee = meent.call_mee(
+        backend=0,
+        pol=0,  # TE
+        n_top=n_air,
+        n_bot=n_si,
+        theta=0,
+        fto=[fto],
+        wavelength=wavelength,
+        period=[500],
+        ucell=ucell,
+        thickness=[200],
+        type_complex=np.complex128,
+    )
+
+    result = mee.conv_solve()
+
+    # --- Diffraction efficiencies (real) ---
+    de_ri = result.res.de_ri  # shape: (1, 2*fto+1)
+
+    # --- Complex Rayleigh coefficients ---
+    R_s = result.R_s  # complex reflection amplitude (TE)
+    T_s = result.T_s  # complex transmission amplitude (TE)
+
+    # 0th order: index [0, fto] for 1D
+    r0 = R_s[0, fto]
+    t0 = T_s[0, fto]
+
+    print("=== 1D Si grating, TE, normal incidence ===")
+    print(f"Wavelength: {wavelength} nm, Period: 500 nm, Thickness: 200 nm")
+    print(f"\n0th order reflection:")
+    print(f"  |r0|^2 = {abs(r0)**2:.6f}  (de_ri = {de_ri[0, fto]:.6f})")
+    print(f"  phase  = {np.degrees(np.angle(r0)):+.2f} deg")
+    print(f"\n0th order transmission:")
+    print(f"  |t0|^2 = {abs(t0)**2:.6f}")
+    print(f"  phase  = {np.degrees(np.angle(t0)):+.2f} deg")
+
+    # --- Phase vs grating thickness ---
+    print("\n=== Reflection phase vs grating thickness ===")
+    print(f"{'Thickness (nm)':>15s} {'Phase (deg)':>12s} {'|r0|^2':>10s}")
+    for t in [50, 100, 150, 200, 250, 300]:
+        mee.thickness = [t]
+        res = mee.conv_solve()
+        r = res.R_s[0, fto]
+        print(f"{t:>15d} {np.degrees(np.angle(r)):>+12.2f} {abs(r)**2:>10.6f}")
+
+
+if __name__ == '__main__':
+    run()

meent/on_jax/emsolver/rcwa.py

@@ -31,6 +31,38 @@ def de_ti(self):
         else:
             return None
 
+    @property
+    def R_s(self):
+        """Complex reflection amplitude (TE component)."""
+        if self.res is not None:
+            return self.res.R_s
+        else:
+            return None
+
+    @property
+    def R_p(self):
+        """Complex reflection amplitude (TM component)."""
+        if self.res is not None:
+            return self.res.R_p
+        else:
+            return None
+
+    @property
+    def T_s(self):
+        """Complex transmission amplitude (TE component)."""
+        if self.res is not None:
+            return self.res.T_s
+        else:
+            return None
+
+    @property
+    def T_p(self):
+        """Complex transmission amplitude (TM component)."""
+        if self.res is not None:
+            return self.res.T_p
+        else:
+            return None
+
 
 class ResultSubJax:
     def __init__(self, R_s, R_p, T_s, T_p, de_ri, de_ri_s, de_ri_p, de_ti, de_ti_s, de_ti_p):

meent/on_numpy/emsolver/rcwa.py

@@ -25,6 +25,38 @@ def de_ti(self):
         else:
             return None
 
+    @property
+    def R_s(self):
+        """Complex reflection amplitude (TE component)."""
+        if self.res is not None:
+            return self.res.R_s
+        else:
+            return None
+
+    @property
+    def R_p(self):
+        """Complex reflection amplitude (TM component)."""
+        if self.res is not None:
+            return self.res.R_p
+        else:
+            return None
+
+    @property
+    def T_s(self):
+        """Complex transmission amplitude (TE component)."""
+        if self.res is not None:
+            return self.res.T_s
+        else:
+            return None
+
+    @property
+    def T_p(self):
+        """Complex transmission amplitude (TM component)."""
+        if self.res is not None:
+            return self.res.T_p
+        else:
+            return None
+
 
 class ResultSubNumpy:
     def __init__(self, R_s, R_p, T_s, T_p, de_ri, de_ri_s, de_ri_p, de_ti, de_ti_s, de_ti_p):

meent/on_torch/emsolver/rcwa.py

@@ -28,6 +28,38 @@ def de_ti(self):
         else:
             return None
 
+    @property
+    def R_s(self):
+        """Complex reflection amplitude (TE component)."""
+        if self.res is not None:
+            return self.res.R_s
+        else:
+            return None
+
+    @property
+    def R_p(self):
+        """Complex reflection amplitude (TM component)."""
+        if self.res is not None:
+            return self.res.R_p
+        else:
+            return None
+
+    @property
+    def T_s(self):
+        """Complex transmission amplitude (TE component)."""
+        if self.res is not None:
+            return self.res.T_s
+        else:
+            return None
+
+    @property
+    def T_p(self):
+        """Complex transmission amplitude (TM component)."""
+        if self.res is not None:
+            return self.res.T_p
+        else:
+            return None
+
 
 class ResultSubTorch:
     def __init__(self, R_s, R_p, T_s, T_p, de_ri, de_ri_s, de_ri_p, de_ti, de_ti_s, de_ti_p):