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Coherent optical frequency combs have revolutionized precision measurement with light. However, the complex setups needed to generate and stabilize these systems limit their relevance in field-testing scenarios. Combs generated in a microcavity (“micro-combs”) are evolving rapidly, and provide a pathway to miniaturize frequency comb systems. While early micro-combs were subject to instabilities and lacked the critical ability to form femtosecond pulses, an important advancement has been the realization of temporal soliton in optical micro-cavities. First observed in optical fibers, this form of ultrashort pulse formation has been demonstrated across many micro-cavity material platforms. 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, optical-frequency synthesis and ultrafast ranging. One challenge to realize a fully integrated soliton microcomb is to combine a high-Q integrated microresonator (made of e.g. silica or silicon nitride) and a high-power laser, in order to avoid the use of an optical amplifier or an external modulator to meet the power requirements for soliton generation. 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. In this talk, the recent demonstration of a compact photonic package will be presented, where a high-Q microresonator is driven by an ultralow-noise diode laser and generates a single-soliton state with a repetition rate below 100 GHz.
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