178 fs, 1.2 nJ pulses from an all-polarization maintaining fiber figure 8 laser based on 3 × 3 coupler at 1 μm

Abstract

We report on an Yb-doped all-polarization maintaining fiber mode-locked laser based on nonlinear-amplifying-loop mirror and 3 × 3 coupler. Thanks to this coupler inducing a non-reciprocal phase-bias, the mode-locked regime can be easily achieved at the high repetition rate of 52 MHz. The cavity delivers an average power of 62 mW corresponding to a pulse energy of 1.2 nJ. We have finally demonstrated an extra-cavity nonlinear spectral stage induced by the propagation along a standard nonlinear fiber. The pulse can be then compressed down to 178 fs via a grating compressor and the corresponding peak power is then around 6 kW.

Self-starting mode-locking in an all-PM Yb-doped fiber laser oscillator enabled by a 3x3 nonlinear optical lossy loop mirror

“…On the other hand, having many output ports impedes extracting significant pulse energy from a single port. Nevertheless, the largest average output power from port P1 corresponded to the pulse energy of 1.15 nJ, which can compete with pulse energies extracted from 3x3 NALMs (1.2 nJ in two 3x3 Yb-doped systems [34,36]). However, the output pulse energy is lower when compared to 2x2 NOLM systems [11,[48][49][50][51].…”

“…Kim et al [33] presented an all-PM Er-doped system mode-locked with a 3x3 NALM. Yb-doped 3x3 NALM all-PM-fiber systems were presented by Boivinet et al [34] and Nishiura et al [35] in an all-normal-dispersion configuration and by Graf et al [36] in a dispersion-managed cavity. Furthermore, all-PM Tm-doped oscillator has also been discussed in Ref.…”

Self-starting mode-locking in an all-PM Yb-doped fiber laser oscillator enabled by a 3x3 nonlinear optical lossy loop mirror

“…Inside the NOLLM, the power is significantly reduced, while in NALM, the power in the loop is increased through amplification. Thus, NALM configurations allow extracting higher pulse energies from a reflected port of a 3x3 coupler (corresponding to P2 in our setup) when compared to NOLLM [34]. Consequently, the spectral breathing characteristics are different for NALM and NOLLM.…”

All-polarization-maintaining Nd-doped ultrafast fiber laser oscillator at 929 nm mode-locked via a 3x3 nonlinear amplifying loop mirror

“…The initiation of the pulsed operation can also be utilized in an all-fiber-fused architecture via a 3x3 fiber coupler, which introduces 2𝜋/3 phase shift [33][34][35]. This approach has been demonstrated in all-PM Er-doped [36], Yb-doped [37][38][39][40] and Tm-doped oscillators [38]. Up to now, a 3x3 fiber coupler has not been applied in a Nd-doped system.…”