LAUSR

We report on the realization of high-performance silica integrated 2-D lens assisted beam steering (LABS) arrays along with the first-of-their-kind point-to-multiplepoint optical frequency transfer. The LABS equips with $N$ antennas and has the capability to produce arbitrary number of output beams with different output angles with simple control complexity. We demonstrate that the LABS has 16 scanning angles, which can support the access capability for the maximum of simultaneous 16 user nodes. The coaxial configuration for transmitting and receiving the light as a monolithic transceiver allows us to reduce the out-of-loop phase noise significantly. Finally, the LABS-based nonblocking point-to-multiplepoint indoor free-space optical frequency transfer links with 24- and 50-m free-space links are shown. After being compensated for the free-space link up to 50 m, the fractional frequency instability of $4.5\,\,\times 10^{-17}$ and $7.7\,\,\times 10^{-20}$ at the averaging time of 1 and 20000 s, respectively, can be achieved. The present work proves the potential application of 2-D LABS in free-space optical time–frequency transfer and provides a guidance for developing a chip-scale optical time–frequency transfer system.