Fixed loss in ideal.waveguide

Author: parkeraa

Diff for: CHANGELOG.md

@@ -5,7 +5,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ---
 
-## [0.7.1](https://github.com/BYUCamachoLab/simphony/tree/v0.7.0) - <small>2024-01-09</small>
+## [0.7.2](https://github.com/BYUCamachoLab/simphony/tree/v0.7.2) - <small>2024-01-09</small>
+
+Minor bug fixes.
+
+### Fixed
+- Bug in loss of waveguide in ideal library was fixed.
+  
+---
+
+## [0.7.1](https://github.com/BYUCamachoLab/simphony/tree/v0.7.1) - <small>2024-01-09</small>
 
 Minor bug fixes.
 

Diff for: simphony/libraries/ideal.py

@@ -86,7 +86,10 @@ def waveguide(
     dneff_dwl = (ng - neff) / wl0
     _neff = neff - dwl * dneff_dwl
     phase = 2 * jnp.pi * _neff * length / wl
-    amplitude = jnp.asarray(10 ** (-loss * length / 20), dtype=complex)
+    # amplitude = jnp.asarray(10 ** (-loss * length / 20), dtype=complex)
+    loss_mag = loss / (10 * jnp.log10(jnp.exp(1)))
+    alpha = loss_mag * 1e-4
+    amplitude = jnp.asarray(jnp.exp(-alpha * length / 2), dtype=complex)
     transmission = amplitude * jnp.exp(1j * phase)
     sdict = sax.reciprocal(
         {