Simple all-PM-fiber laser mode-locked with a nonlinear loop mirror

Abstract

In this Letter, we present a figure-eight all-PM-fiber laser oscillator design with a nonlinear optical loop mirror as an artificial saturable absorber. Unlike previous constructions using the same mode-locking technique, our cavity is constructed entirely of polarization-maintaining (PM) fibers, making the oscillator more resistant to thermal and mechanical perturbations. Two simple and robust laser configurations that differ by the output coupling ratio (70% or 30%) are presented. The first configuration delivers high energy pulses of 3.5 nJ, and the second configuration delivers pulses of 1.6 nJ at a common repetition rate of 15 MHz. In either configuration, the pulsed operation is stable, and the laser operates in a single pulse train regime, even for pump powers approaching twice the power required for mode-locking. We have also observed that, at higher intracavity powers, stimulated Raman scattering plays a significant role.

Towards ‘smart lasers’: self-optimisation of an ultrafast pulse source using a genetic algorithm

“…We consider a Figure-8 (F8) laser design: one of the earliest reported passively mode-locked laser schemes, employing a nonlinear amplifying loop mirror (NALM) as an artificial saturable absorber4, and currently receiving renewed interest as a flexible all-fibre ultrafast source26272829303132. F8 lasers consist of a unidirectional and bidirectional ring.…”

Megawatt peak power from a Mamyshev oscillator

“…To date, no work has been able to combine the high performance of NPE in standard SMFs with an all-PM design. Semiconductor saturable absorber mirrors (SESAMs) [8,9] and nonlinear loop mirrors using PM fibers [10][11][12] have been employed as alternative saturable absorbers. Material-based saturable absorbers, however, suffer from long-term reliability and poor power-handling capabilities.…”

Nonlinear polarization evolution of ultrashort pulses in polarization maintaining fibers

“…For many years it was believed that NPE method is assigned uniquely to non-Polarization Maintaining [7,11] or partially PM fiber cavities in which NPE occurs in isotropic fiber sections [12]. The most prospective techniques are, however, these that can be used in all-fiber cavities build solely from PM fibers as they provide the high environmental stability of the laser [13]. Alternatives: the Nonlinear Optical Loop Mirror (NOLM) [14] or its variation Nonlinear Amplifying Loop Mirror (NALM) [15] are, however, to this day the most prominent artificial SAs used in environmentally stable all-PM-fibers cavities.…”

“…Environmentally stable and reliable lasers are required in both scientific and industrial applications. All-PM-fiber configurations with increased stability mode-locked with NOLM [13] and NALM [16] have been presented. Fermann et.…”