Ultrafast fiber lasers based on self-similar pulse evolution: a review of current progress

Abstract

Self-similar fiber oscillators are a relatively new class of mode-locked lasers. In these lasers, the self-similar evolution of a chirped parabolic pulse in normally-dispersive passive, active, or dispersion-decreasing fiber (DDF) is critical. In active (gain) fiber and DDF, the novel role of local nonlinear attraction makes the oscillators fundamentally different from any mode-locked lasers considered previously. In order to reconcile the spectral and temporal expansion of a pulse in the self-similar segment with the self-consistency required by a laser cavity's periodic boundary condition, several techniques have been applied. The result is a diverse range of fiber oscillators which demonstrate the exciting new design possibilities based on the self-similar model. Here, we review recent progress on self-similar oscillators both in passive and active fiber, and extensions of self-similar evolution for surpassing the limits of rare-earth gain media. We discuss some key remaining research questions and important future directions. Self-similar oscillators are capable of exceptional performance among ultrashort pulsed fiber lasers, and may be of key interest in the development of future ultrashort pulsed fiber lasers for medical imaging applications, as well as for low-noise fiber-based frequency combs. Their uniqueness among mode-locked lasers motivates study into their properties and behaviors and raises questions about how to understand mode-locked lasers more generally.

High-power ultrafast Yb:fiber laser frequency combs using commercially available components and basic fiber tools

“…28 The physics and many implementations of these oscillators have been discussed extensively in the literature (for a review see Ref. 33), but NPE mode locking has a reputation for being finicky, and this literature is not necessarily helpful when standing over the laser and trying to make it work. We instead focus on practical procedures for achieving and characterizing mode-locked single-pulse operation, low noise, and long-term stability.…”

High repetition rate multi-similariton laser

“…Propagation in the fibers has been modeled using the generalized nonlinear Schrödinger equation and the lumped amplification by a saturable gain term with spectral bandwidth typical of rare-earth amplifiers. The suggested scheme demonstrates clearly that lumped amplification can be used to achieve modelocking via DFI allowing for improvement in high power ultrafast laser design [3]. The features of the resonator can be easily modified resulting in a tunability of the repetition rate by 2 orders of magnitude flexibly depending on power, dispersion, nonlinearity and fiber length.…”

Nonlinear sculpturing of optical pulses with normally dispersive fiber-based devices

“…While sinusoidal, Gaussian and hyperbolic secant intensity profiles are now routinely produced by modulators or mode-locked lasers, other signal waveforms such as parabolic, triangular or flat-top pulse shapes remain rather hard to synthesize. Advances in fiber lasers have indicated promising ways to produce such waveforms [1][2][3], but the tunability of these lasers in terms of pulse repetition rate remains quite low and their experimental implementation and stability may require further work.…”