Generation of 100 nJ pulse, 1 W average power at from an intermode beating mode-locked all-fiber laser

Rongping Wang,Ruwei Zhao,Shixun Dai,Jiaji Zhang,Duanduan Wu

doi:10.1017/hpl.2019.50

Abstract

We report on the investigation of intermode beating mode-locked (IBML) pulse generation in a simple all-fiber Tm $^{3+}$ -doped double clad fiber laser (TDFL). This IBML TDFL is implemented by matching longitudinal-mode frequency between 793 nm laser and TDFL without extra mode locker. The central wavelength of ${\sim}1983~\text{nm}$ , the fundamental pulse frequency of ${\sim}9.6~\text{MHz}$ and the signal-to-noise ratio (SNR) of ${>}50~\text{dB}$ are achieved in this IBML TDFL. With laser cavity optimization, the IBML TDFL can finally generate an average output power of 1.03 W with corresponding pulse energy of ${\sim}107~\text{nJ}$ . These results can provide an easily accessible way to develop compact large-energy, high-power TDFLs.

Highlights

Eye-safe 2 μm pulsed fiber lasers have boomed in recent years due to their extensive use in medicine, material processing and national defense
Qswitched pulse trains are capable of large pulse energy and high average output power, but unstable pulse repetition rate caused by variable pump power
330 fs, 248 MHz ultra-short pulse train has been generated in an nonlinear polarization rotation (NPR) mode-locked 1950 nm Tm3+-doped double clad fiber laser (TDFL)[12]. 1.446 GHz NPR mode-locked pulse is achieved in a 1.85 μm TDFL[13]

Summary

Introduction

Eye-safe 2 μm pulsed fiber lasers have boomed in recent years due to their extensive use in medicine, material processing and national defense. Modelocked pulse trains are more expected to meet all the above conditions Besides these real saturable absorbers (SAs), some other artificial SAs-based passive mode lockers have gradually come into researchers’ sight and attracted great attention, e.g., nonlinear polarization rotation (NPR)[11,12,13,14,15,16,17], nonlinear amplifying loop mirror (NALM)[18,19,20,21], and self-phase modulation (SPM)[22]. Luo et al have successfully demonstrated a 352 pJ pulse energy, 12.2 mW average output power mode-locked TDFL through cavity length matching method[23], which is known as intermode beating modelocking[23,24,25,26,27]. The IBML TDFL can generate stable short pulses with large pulse energy and high average output power

Principle of intermode beating mode locking

Results and discussion

Conclusion