  A hybrid system that combines the advantages of a superconducting flux qubit
and an electron spin ensemble in diamond is one of the promising devices to
realize quantum information processing. Exploring the properties of the
superconductor diamond system is essential for the efficient use of this
device. When we perform spectroscopy of this system, significant power
broadening is observed. However, previous models to describe this system are
known to be applicable only when the power broadening is negligible. Here, we
construct a new approach to analyze this system with strong driving, and
succeed to reproduce the spectrum with the power broadening. Our results
provide an efficient way to analyze this hybrid system.
