Abstract

Photonics chip-based soliton microcombs have been used in many applications including LIDAR, spectroscopy, coherent communication and astronomical spectrometer calibration [1]. Current-initiated soliton microcombs have been demonstrated [2, 3] recently, signifying improvements in the fabrication of high-Q Si₃N₄ microresonators. However, both approaches suffer from limited input laser power, thus only demonstrated single-soliton at repetition rates above 149 GHz, which are challenging to detect with commercially available photodetectors. Here we demonstrate a single-soliton generation in 100-GHz-FSR Si₃N₄ microresonators fabricated using the photonic Damascene reflow process [4], yielding the intrinsic Q-factor exceeding 15 million [5]. Using a compact hybrid laser with narrow linewidth, low relative intensity noise (–160 dBc/Hz at f_offset=100 kHz) and high output power up to 100 mW [6], different comb states are observed by simply changing the current of the laser diode, without the need of complex tuning mechanism such as a single sideband modulator [7].

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