  Breathers are localized structures that undergo a periodic oscillation in
their duration and amplitude. Optical microresonators, benefiting from their
high quality factor, provide an ideal test bench for studying the breathing
phenomena. In the monochromatically pumped microresonator system, intrinsic
breathing instabilities are widely observed in the form of temporal dissipative
Kerr solitons which only exist in the effectively red detuned regime. Here, we
proposed a novel bichromatic pumping scheme to create compulsive breathing
microcombs via respectively distributing two pump lasers at the effectively
blue and red detuned side of a single resonance. We experimentally discover the
artificial cnoidal wave breathers and molecular crystal-like breathers in a
chip-based silicon nitride microresonator, and theoretically describe their
intriguing temporal dynamics based on the bichromatic pumping Lugiato-Lefever
equation. In particular, the corresponding breathing microcombs exhibit diverse
comb line spacing ranging from 2 to 17 times of the free spectral range of the
resonator. Our discovery not only provides a simple and robust method to
produce microcombs with reconfigurable comb line spacing, but also reveals a
new type of breathing waves in driven dissipative nonlinear systems.
