Deterministic, Reconfigurable Micro‐Resonator Soliton Crystals for Intensity‐Modulated Direct Detection Data Transmission

ABSTRACT The perennial demand for highly efficient short‐haul communications is evidenced by a sustained explosion of growth in data center infrastructure. In these compact networks, cost‐sensitivity is of particular importance, limiting options to direct detection schemes that are more cost‐efficient than their coherent counterparts. Since their initial demonstration, multi‐soliton states in optical microresonators have been observed to manifest in self‐organised ensembles where soliton pulses are equally spaced around the resonators. In the spectral domain, these states, dubbed soliton crystals (SCs), result in significant enhancements to individual comb lines depending on the crystal state, making them well‐suited toward intensity‐modulated direct detection schemes. In this work, we experimentally demonstrate adiabatic, deterministic access to lower‐order soliton crystal states using an auxiliary‐assisted cavity pumping method, enabling robust, reconfigurable control of the soliton crystal order that is generated. We achieve up to 22.8 dB enhancement of the comb lines in the 7‐SC configuration compared to the single‐soliton state. Seven comb lines, each encoded with 46 Gbauds −1 pulse amplitude modulation 4 (PAM4) are transmitted over 4 km of fiber across the C‐band with bit‐error‐rates (BER) of 5E‐5. Our work showcases a promising approach to harnessing soliton crystals as future integrated sources for highly capacity data center communications.