  Soliton microcombs offer the prospect of advanced optical metrology and
timing systems in compact form factors. In these applications, pumping of
microcombs directly from a semiconductor laser without amplification or
triggering components is desirable for reduced power operation and to simplify
system design. At the same time, low repetition rate microcombs are required in
many comb applications for interface to detectors and electronics, but their
increased mode volume makes them challenging to pump at low power. Here, 10 GHz
repetition rate soliton microcombs are directly pumped by low-power (< 20 mW)
diode lasers. High-Q silica microresonators are used for this low power
operation and are packaged into fiber-connectorized modules that feature
temperature control for improved long-term frequency stability.
