fix[adjoint]: remove pulse amplitude and phase when using the simulation forward source time as broadband adjoint pulse

Author: Gregory Roberts

CHANGELOG.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 - Fixed issue with `CustomMedium` gradients where other frequencies would wrongly contribute to the gradient.
 - Fixed bug when computing `PolySlab` bounds in plotting functions.
+- Fixed bug in broadband adjoint source creation when forward simulation had a pulse amplitude greater than 1 or a nonzero pulse phase.
 
 ## [2.8.3] - 2025-04-24
 

tidy3d/components/data/sim_data.py

@@ -1188,7 +1188,9 @@ def _make_broadband_source(self, adj_srcs: list[SourceType]) -> SourceType:
         """Make a broadband source for a set of adjoint sources."""
 
         source_index = self.simulation.normalize_index or 0
-        src_time_base = self.simulation.sources[source_index].source_time.copy()
+        src_time_base = self.simulation.sources[source_index].source_time.updated_copy(
+            amplitude=1.0, phase=0.0
+        )
         src_broadband = adj_srcs[0].updated_copy(source_time=src_time_base)
 
         return src_broadband