Real-Time Evolution of Passive Free-Space Cavity Solitons

The study of dissipative cavity solitons is an extremely active area of research that is primarily focussed on mode-locked (active) and passive waveguide resonators - such as fiber- and microresonators [1]. Recently, a free-space enhancement cavity (EC) has been demonstrated to support temporal solitons of 37-fs duration and hundreds of Watts intracavity power [2]. In this work we employ the dispersive Fourier transform technique (DFT) [3] to track the shot-to-shot evolution of the soliton inside an EC at MHz repetition rates in real-time. We stretch the soliton pulses from a free-space cavity in 2.5 km of single mode fiber and record the resulting spectra with a fast photoreceiver and oscilloscope. Equipped with this tool and extensive numerical simulations, we examine the build-up and destruction of (multiple) EC solitons as well as the attraction and repulsion between these pulses and with the driving field. Additionally, we explore the equilibria leading to bound states and a strong suppression of pump perturbations (in the form of timing jitter and relative intensity noise).