  BICEP3 is a 520 mm aperture, compact two-lens refractor designed to observe
the polarization of the cosmic microwave background (CMB) at 95 GHz. Its focal
plane consists of modularized tiles of antenna-coupled transition edge sensors
(TESs), similar to those used in BICEP2 and the Keck Array. The increased
per-receiver optical throughput compared to BICEP2/Keck Array, due to both its
faster f/1.7 optics and the larger aperture, more than doubles the combined
mapping speed of the BICEP/Keck program. The BICEP3 receiver was recently
upgraded to a full complement of 20 tiles of detectors (2560 TESs) and is now
beginning its second year of observation (and first science season) at the
South Pole. We report on its current performance and observing plans. Given its
high per-receiver throughput while maintaining the advantages of a compact
design, BICEP3-class receivers are ideally suited as building blocks for a
3rd-generation CMB experiment, consisting of multiple receivers spanning 35 GHz
to 270 GHz with total detector count in the tens of thousands. We present plans
for such an array, the new "BICEP Array" that will replace the Keck Array at
the South Pole, including design optimization, frequency coverage, and
deployment/observing strategies.
