  Spintronic Terahertz Emitters (STE) represent a significant advancement in
source technology, exploiting the ultrafast demagnetization process of
spin-electrons to unveil a 30THz wide, gapless spectrum, accessible through
femtosecond lasers across the full VIS-IR range. This innovation not only
positions STEs as a pivotal advancement in THz source technology but also
underscores their role as a cost-effective, high-performance solution, thereby
redefining standards within the field. However, the inherent spintronic nature
of these devices introduces a challenge: a lower optical-to-terahertz
conversion efficiency, which positions them at a notable disadvantage relative
to other sources. In response, this work aims to substantially improve the
electromagnetic efficiency of these emitters. This is accomplished by
maximizing the energy conversion from the pumping laser for spin-electron
generation. Our design integrates STEs with an optimized 1D trapping cavity,
specifically engineered to fulfill critical aspects of ultrafast excitation and
THz extraction. As a result, we have realized a 245% enhancement in emission
and an increase of 8dB in overall intensity, positions our results among the
most substantial improvements documented in this field. Furthermore, we
delineate the optimal geometry for the deployment of STEs and explore the
strategic selection of substrates in depth. Such enhanced emitters advance
spintronic emitters towards broader applications in time-domain spectroscopy,
ellipsometry, and nonlinear THz-pump spectroscopy. Enhancing spintronic emitter
efficiency, combined with rapid magnetic field modulation, indicates the
potential for dynamic ranges that rival traditional sources. Our predictions of
STE's efficiencies, made through an electromagnetic approach, highlight its
capability to uncover overlooked aspects from an optical standpoint, leading to
subsequent improvements.
