  An external-cavity diode laser is reported with ultralow noise, high power
coupled to a fiber, and fast tunability. These characteristics enable the
generation of an optical frequency comb in a silica micro-resonator with a
single-soliton state. Neither an optical modulator nor an amplifier was used in
the experiment. This demonstration greatly simplifies the soliton generation
setup and represents a significant step forward to a fully integrated soliton
comb system.
