  Photonic chip-based soliton microcombs have shown rapid progress and have
already been used in many system-level applications, including coherent
communications, astrophysical spectrometer calibration and ultrafast ranging.
While there has been substantial progress in realizing soliton microcombs that
rely on compact laser diodes, culminating in devices that only utilize a
semiconductor amplifier or a self-injection-locked laser as a pump source,
accessing and generating single soliton states with electronically detectable
line rates from a compact laser module has remained challenging. Here we
demonstrate a current-initiated, $\mathrm{Si_3N_4}$ chip-based, 99-GHz soliton
microcomb driven directly by an ultra-compact, low-noise laser. This approach
does not require any fast laser tuning mechanism, and single soliton states can
be accessed by changing the current of the laser diode. A simple, yet reliable,
packaging technique has been developed to demonstrate the viability of such a
microcomb system in field-deployable applications.
