Visualization 1: Label-free imaging of thick tissue at 1550 nm using a femtosecond optical parametric generator

Z stack of brain tissue. Originally published in Optics Letters on 01 August 2015 (ol-40-15-3484

Temporal cavity solitons in a laser-based microcomb: a path to a self-starting pulsed laser without saturable absorption

We theoretically present a design of self-starting operation of microcombs based on laser-cavity solitons in a system composed of a micro-resonator nested in and coupled to an amplifying laser cavity. We demonstrate that it is possible to engineer the modulational-instability gain of the system’s zero state to allow the start-up with a well-defined number of robust solitons. The approach can be implemented by using the system parameters, such as the cavity length mismatch and the gain shape, to control the number and repetition rate of the generated solitons. Because the setting does not require saturation of the gain, the results offer an alternative to standard techniques that provide laser mode-locking

Self-emergence of robust solitons in a microcavity

In many disciplines, states that emerge in open systems far from equilibrium are determined by a few global parameters. These states can often mimic thermodynamic equilibrium, a classic example being the oscillation threshold of a laser that resembles a phase transition in condensed matter. However, many classes of states cannot form spontaneously in dissipative systems, and this is the case for cavity solitons that generally need to be induced by external perturbations, as in the case of optical memories. In the past decade, these highly localized states have enabled important advancements in microresonator-based optical frequency combs. However, the very advantages that make cavity solitons attractive for memories—their inability to form spontaneously from noise—have created fundamental challenges. As sources, microcombs require spontaneous and reliable initiation into a desired state that is intrinsically robust. Here we show that the slow non-linearities of a free-running microresonator-filtered fibre laser can transform temporal cavity solitons into the system’s dominant attractor. This phenomenon leads to reliable self-starting oscillation of microcavity solitons that are naturally robust to perturbations, recovering spontaneously even after complete disruption. These emerge repeatably and controllably into a large region of the global system parameter space in which specific states, highly stable over long timeframes, can be achieved.</p