High bandwidth laser frequency locking for wideband noise suppression

Ultra-low frequency noise lasers have been widely used in laser-based experiments. Most narrow-linewidth are implemented by actively suppressing their through a servo loop (FNSL). The bandwidths (LBW) of FNSLs currently below megahertz, which is gradually tricky to meet application requirements, especially for wideband quantum sensing This article has experimentally an FNSL with loop-delay-limited 3.5 MHz LBW, order higher than the usual FNSLs. Using this FNSL, we achieved 70 dB laser suppression over 100 kHz Fourier range. technology broad applications vast fields where inevitable.