Optically synchronized fibre links using spectrally pure chip-scale lasers

Precision optical-frequency and phase synchronization over fibre is critical for a variety of applications, from timekeeping to quantum optics. Such applications utilize ultra-coherent sources based on stabilized table-top laser systems. Chip-scale versions of these systems may dramatically broaden the application landscape by reducing the cost, size and power of such exquisite sources. Links based on the required narrow-linewidth integrated lasers, compact reference cavities and control methodologies have not yet been presented. Here, we demonstrate an optically synchronized link that achieves an ultralow residual phase error variance of 3 x 10(-4) rad(2) at the receiver, using chip-scale stabilized lasers with laser linewidth of -30 Hz and instability below 2 x 10(-13) at 50 ms. This performance is made possible with integrated Brillouin lasers, compact reference cavities and a novel low-bandwidth optical-frequency-stabilized phase-locked loop. These results demonstrate a path towards low-power, precision applications including distributed atomic clocks, quantum links, database synchronization and digital-signal-processor-free coherent fibre interconnects.

Automated summary

Precision optical-frequency and phase synchronization over fibre is crucial for various applications, and chip-scale stabilized lasers have demonstrated ultralow residual phase error variance. This performance is achieved through integrated Brillouin lasers, compact reference cavities, and a novel low-bandwidth optical-frequency-stabilized phase-locked loop. The results pave the way for low-power, precision applications in distributed atomic clocks, quantum links, database synchronization, and digital-signal-processor-free coherent fibre interconnects.