169 MHz repetition frequency all-fiber passively mode-locked erbium doped fiber laser

Passively mode-locked stretched-pulse erbium fiber laser is presented. With all-fiber configuration 111 fs pulses were achieved with the fundamental repetition rate of 169 MHz and an average output power of more than 30 mW. Proposed setup shows excellent stability, reliability and ‘turn-key’ operation. The impact of the pump power on laser parameters is described.     

低温GaAs被动调Q锁模Nd:Gd0.42 Y0.58VO4 混晶激光器特性研究

采用低温生长GaAs晶体作为被动饱和吸收体兼输出镜,实现了Nd:Gd0.42Y0.58VO4混晶激光器的调Q锁模运转.研究了Nd:Gd0.42Y0.588VO4激光器的基频运转特性.在输出镜透射率T=10%、腔长L=40 mm的情况下,当抽运功率为8.6 W时,获得激光输出功率3.78 W,光-光转换效率为43.9%.并测量了Nd:Gd0.42Y0.58VO4混晶被动调Q激光器的输出特性.实验结果表明激光器调Q运转阈值为2 W,当抽运功率为3.7 W时,激光器出现调Q锁模行为;当抽运功率为8.6 W时,激光器调Q锁模深度达70%以上,对应的脉冲包络重复频率为670 kHz,半峰全宽为180 ns,平均输出功率为1.35 W,光-光转换效率为15.7%.     

基于单壁碳纳米管调Q锁模低阈值Tm,Ho:LiLuF_4激光器

采用垂直生长法制作的单壁碳纳米管作为可饱和吸收体,结合特殊的低阈值谐振腔设计,首次在Tm,Ho:LiLuF_4全固态激光器中实现了低阈值自启动被动调Q锁模运转.以波长可调的掺钛蓝宝石固体激光器作为抽运源,选用1.5%,3%和5%的输出耦合镜,获得了出光阈值低至52,59和62mW的连续光输出.采用3%输出耦合镜,获得了阈值低至250mW的稳定调Q锁模脉冲输出,调Q包络的脉宽为2μs,调Q包络下锁模脉冲重复频率178.6MHz,最大输出功率154mW,最大的单脉冲能量为0.86nJ,调制深度接近100%.     

Multiwavelength actively mode-locked fiber ring laser with a dispersion compensated cavity

A multiwavelength actively mode-locked fiber ring laser that utilises a single semiconductor optical amplifier as both a gain and mode-locking element is presented. It is verified experimentally that the number of mode-locked wavelengths may be maximised by compensating for the anomalous intra-cavity dispersion. This is achieved through the inclusion of an appropriate length of normal dispersion fiber in the laser cavity. Using this technique, the number of wavelengths simultaneously mode-locked at 10 GHz was increased from 2 to 5.     

Different operation states of soliton pulses in an erbium-doped fibre ring laser

We report on the experimental observation of soliton pulses in an erbium doped fibre ring laser. The passive mode-locking is achieved using the nonlinear polarization rotation technique. By adjusting the pump power and the intracavity polarization controllers, a normal soliton, a stable 8th harmonic mode-locked pulse and a noise-like pulse have been observed in our laser. The experimental results revealed that the noise-like pulse is not suitable for the optical telecommunication, and in order to obtain the stable harmonic mode-locked soliton, a strong unstable CW laser field is necessary to mediate global soliton interaction. The formation mechanism of the harmonic mode-locked pulse has also been analysed.     

全光纤激光器自启动锁模特性的理论研究

分析了带非线性放大光纤环的全光纤激光器的自启动锁模特性，得到了计算该激光器中光脉冲的有效能量增益的理论模型．结果表明，激光器的自启动锁模同掺Ｅｒ３＋光纤的增益及纤芯的有效截面积有关，并计算了自启动锁模的阈值峰值功率大小．应用本文的理论模型能成功地解释观察到的实验现象．     

Timing Jitter in Amplitude Modulated Harmonically Mode-Locked Er-Doped Fiber Ring Lasers

The phase noise and the amplitude noise of optical pulses from the amplitude modulated harmonically mode-locked (AM-HML) Er-doped fiber (EDF) ring laser was investigated by measuring the power spectra of the optical pulses. The root mean square (RMS) timing jitter and the RMS amplitude noise are 1.26 ps and 2.5% (500 Hz-50 kHz), respectively, when the pulse repetition frequency is 1.58 GHz. They are smaller than those in conventional harmonically mode-locked EDF ring lasers.     

Active–passive mode-locking using Cr:YAG crystal as saturable absorber

Cr⁴⁺ : YAG crystal was used as a saturable absorber in an active–passive mode-locked Nd : YAG laser. The stable and complete mode-locked pulse train was achieved at 1064 nm. The duration of a single pulse was obtained from 0.8 to 2.4 ns by changing the Cr⁴⁺ : YAG crystal with different initial transmission, when there was the shortest pulse width. The mode-locking dynamic process of Cr⁴⁺ : YAG crystal was analyzed by the rate equations to explain the experimental result, and the effect of excited-state absorption was considered.     

All-fiber erbium-doped dissipative soliton laser with multimode interference based on saturable-reserve saturable hybrid optical switch

Reverse saturable absorption is essential for the realization of dissipative solitons. In this paper, we introduce reverse saturable absorption by using nonlinear multimode interference (NL-MMI), for the first time, to the best of our knowledge, and obtain a stable dissipative soliton operation. By adjusting the coupling efficiency from multimode fiber to single mode fiber, the absorption properties of NL-MMI can be switched between saturation and reverse saturation. The dissipative soliton can be obtained with pulse width of 975 fs in the experiment, the 3-dB bandwidth at 1555 nm is 16 nm, and the maximum output power is 11.48 mW. The nonlinear absorption optical modulation and high damage threshold characteristics of the NL-MMI based ultrafast optical switch provide a new idea for realizing dissipative solitons.     

All-normal dispersion fiber lasers mode-locked with a nonlinear amplifying loop mirror

We review our recent progress on the design, modeling and construction of all-normal dispersion Yb-doped fiber lasers mode-locked using a nonlinear amplifying loop mirror. The all-fiber nature of the devices we consider permits accurate numerical simulations with minimal approximations or free-running parameters, and we describe in detail a refined numerical modeling scheme that combines generalized nonlinear envelope equations with analytically simulated gain dynamics. Guided by insights obtained from numerical modeling, we have experimentally realized robust, environmentally stable laser designs that offer flexible operation performance for a wide variety of applications. In particular, the unique all-PM-fiber design makes our devices ideally suitable for industrial laser micromachining applications.