Development of MKIDs for measurement of the Cosmic Microwave Background
  with the South Pole Telescope
  We present details of the design, simulation, and initial test results of
prototype detectors for the fourth-generation receiver of the South Pole
Telescope (SPT). Optimized for the detection of key secondary anisotropies of
the cosmic microwave background (CMB), SPT-3G+ will measure the temperature and
polarization of the mm/sub-mm sky at 220, 285, and 345 GHz, beyond the peak of
the CMB blackbody spectrum. The SPT-3G+ focal plane will be populated with
microwave kinetic inductance detectors (MKIDs), allowing for significantly
increased detector density with reduced cryogenic complexity. We present
simulation-backed designs for single-color dual-polarization MKID pixels at
each SPT-3G+ observation frequency. We further describe design choices made to
promote resonator quality and uniformity, enabling us to maximize the available
readout bandwidth. We also discuss aspects of the fabrication process that
enable rapid production of these devices and present an initial dark
characterization of a series of prototype devices.
