Metasurface-enhanced spatial mode decomposition

Acquiring precise information about the mode content of a laser is critical for multiplexed optical communications, imaging with active wave-front control, and quantum-limited interferometric measurements. Hologram-based decomposition devices, such as spatial light modulators, allow fast, direct measurement content, but they have limited precision due to cross-coupling between modes. Here we report first proof-of-principle demonstration metasurface, resulting in significantly enhanced precision. A mode-weight fluctuation $6\times 10^{-7}$ was be measured 1 second averaging at Fourier frequency 80 Hz, an improvement more than three orders magnitude compared state-of-the-art modulator decomposition. The attributable reduction enabled by exceptional small pixel size metasurface. We show systematic study limiting sources noise, that there promising path towards complete similar