Introduction to Harmonic Mode Locking

The SPM effect stimulates the 24th harmonic mode-locking operation.

The concept of the self-starting harmonic mode-locking (SSHML) by electro-optical feedback in a solid-state laser is studied.

Significant variation of output pulse energy and various regimes (harmonic mode-locking, multipulses) are observed.

With an increased pump power, the laser operates in Q-switched mode-locking, fundamental mode-locking, and harmonic mode-locking (HML) states.

Furthermore, harmonic mode-locking was also achieved by increasing the pump power, yielding a peak repetition rate of 588 MHz.

Additionally, the mechanism of harmonic mode-locking is discussed in detail and is found to be caused by gain depletion and recovery effect.

We demonstrate an all fiber high-repetition-rate erbium-doped ultrashort laser based on the Ti3C2T x -Mxene saturable absorber (SA), and the 56th harmonic mode-locking with a repetition rate of 622.

To circumvent this, harmonic mode-locking can be utilized, as this increases the channel spacing while keeping the cavity size fixed.

5 GHz harmonic mode-locking from an Yb-doped fiber laser was realized with a short cavity length corresponding to a 167 MHz fundamental repetition rate.

We report the stabilizing frequency shift effect in harmonic mode-locking ring soliton fiber laser that is studied theoretically and numerically.

Besides, multi-pulse patterns such as PDW splitting, harmonic mode-locking, and periodic soliton collision are also observed under larger net negative dispersion (-3.

Time-domain, frequency-domain and spectral domain measurement results in dependence on feedback strength and feedback delay demonstrate pulse width and higher harmonic mode-locking control.

Furthermore, these lasers can also be a source of interesting pulsed dynamics, as the double gain pass within one round-trip in the external cavity favors the emergence of pulse clusters over harmonic mode-locking [1].

Soliton fiber lasers with passive harmonic mode-locking (HML) have been known for several decades as reliable sources of pulse trains with a high repetition rate.

Multiple dynamic patterns of pulses, including single pulses, bound-state pulses, and harmonic mode-locking pulses, are observed at different pump powers and filter spectral separations.

5 MHz conventional soliton mode-locking pulse, 140 MHz 9-order-harmonic mode-locking pulse, 27.

Using a cascaded long-period fiber grating as a spectral filter, several modes of passively harmonic mode-locking including passive high-order harmonic mode-locking, passive multiple-pulse harmonic mode locking and passive large-pulse-width harmonic mode locking (over 300 ns ) were obtained by adjusting the tunable CW semiconductor laser (pumping source in the experiment) and polarization controller, in which the intense nonlinear effects, large fiber dispersion and phase bias played an important role.

Here, we report for the first time, to the best of our knowledge, fully passive harmonic mode locking in an all-polarization-maintaining (PM) fiber laser.

Experimental observations of spatiotemporal mode-locked multiple-soliton, including harmonic mode locking and multiple pulses, in multimode fiber (MMF) lasers are reported.

A scheme to generate 50 GHz pulse train using rational harmonic mode locking technique is proposed and studied experimentally.

Strong enhancement of optoacoustic interactions in the micrometer-sized core of a photonic crystal fiber (PCF) enables stable, harmonic mode locking of a soliton fiber laser at GHz frequencies.

A controllable passive harmonic mode locking (HML) in an erbium-doped fiber laser with a soliton pulse shaping using a single-wall carbon nanotube has been experimentally demonstrated.

We systematically study the impact of average cavity dispersion and pulse spectral bandwidth on harmonic mode locking in the long-wavelength band from an Er-doped fiber laser using carbon nanotubes polyvinyl alcohol (CNTs-PVA) film mode locker.