石榴石主动-被动锁模激光器

该锁模激光器的主要特点是输出锁模脉冲信噪比高(≥107),输出稳定,输出系列脉冲能量起伏≤±8%,脉冲宽度起伏±10%。输出最窄脉冲宽度～25微微秒,单脉冲能量～1毫焦耳。     

石榴石主动-被动锁模激光器

研究了主动-被动锁模技术中超短脉冲形成过程,分析了出现卫星脉冲原因,解决了驻波型声光调制器频率准确性和衍射效率问题。该振荡器的主要输出特性如下:1)输出锁模脉冲几率～100％;2)输出系列脉冲能量起伏<±8％;3)输出锁模脉冲脉宽起伏<±10％;4)信噪比10~7;5)输出锁模脉冲宽度20～100微微秒,分段可调。当脉宽为100微微秒时,光谱宽度～0.15埃,     

脉冲Nd:YAG主/被动锁模激光器特性

1.引言实验的复杂性增加和精度的提高,包括微微秒激光器,需要比至今能得到的微微秒源更可靠更稳定。1974年已报道通过加主动Q开关和主动Q调制改进被动锁模Nd:YAG激光器的稳定性。采用普克尔盒调制需要在10MHz范围内的高RF电压。后来,可得到的相应的声光调制器用作复杂性低的实验装置。资料〔2,3〕报道改进Nd玻璃激光器脉冲列振幅稳定性到±5％。资料〔3〕也提到Nd:YAG主动/被动工作。资料〔4〕叙述Nd:YAG激光器以1Hz重复率工作,但未给出激光器特性。采     

主-被动对撞脉冲锁模Nd:YAG激光器

报道主-被动和纯被动对撞脉冲锁模Nd~(3+)∶YAG激光器的实验研究结果.主-被动锁模激光脉宽为15ps,激光输出序列脉冲能量起伏小于±2%.被动锁模激光脉宽为12ps,序列脉冲能量起伏小于±1O%.利用腔内插入标准具,获得脉宽在15～26ps间可变的锁模激光.实验还研究了非共振环形腔的激光偏振特性.     

主被动锁模Nd:YLF激光器

在脉冲抽运主动锁模Nd:YLF激光器中,用倍频晶体CLBO和双色镜构成的非线性镜取代输出镜,实现了主被动锁模,与纯主动锁模相比,脉冲宽度压缩了8倍,获得了15 ps的锁模脉冲.     

主被动锁模Nd∶YLF激光器

在脉冲抽运主动锁模Nd∶YLF激光器中 ,用倍频晶体CLBO和双色镜构成的非线性镜取代输出镜 ,实现了主被动锁模 ,与纯主动锁模相比 ,脉冲宽度压缩了 8倍 ,获得了 15ps的锁模脉冲     

主动锁模激光器脉冲的瞬态形成

本文通过建立一合理的锁模模型,采用数值算法模拟了Nd:YAG主动锁模激光器脉冲的瞬态形成.发现初始的自发辐射,在腔内必须往返105～106次(对应时间为1ms左右),才进入稳定的锁模状态.实验中,我们采用一简单的方法测出了锁模脉冲的这一稳态建立时间,而且与理论计算结果基本相符.     

主被动锁模脉冲氙灯抽运Nd:YAG激光器的研究

为了克服主动锁模脉冲能量低、被动调Q锁模稳定性差、锁模不完全的缺点,采用Cr<'4+>:YAG和声光锁模器进行主被动联合锁模脉冲氙灯抽运的Nd:YAG激光器,实验验证和分析了Cr<4+>:YAG被动锁模,声光锁模器主动锁模及两者联合主被动锁模3种情况下输出脉冲的特性.结果表明,主被动联合锁模可得到200mJ输出能量、输...     

双SESAM被动锁模超短脉冲光纤激光器

针对基于半导体可饱和吸收体（Semiconductor Saturable Absorber Mirror,SESAM）被动锁模光纤激光器脉冲底座宽和脉冲能量小的问题展开研究,设计了一种线型腔结构的双SESAM锁模超短脉冲光纤激光器。首先,通过增加SESAM个数的方式使得光脉冲在谐振腔中的一个振荡周期内多次经过可饱和吸收体,有效增加了可饱和吸收体对光脉冲前后沿的吸收,抑制了因泵浦功率过大而产生的调Q锁模效应,有助于压缩脉冲宽度、提高单脉冲能量,摆脱了因SESAM调制深度较低而对压缩脉冲宽度和提高单脉冲能量造成的限制。其次,通过在系统中引入一段正色散光纤,降低了因峰值功率过高而引起的非线性效应,进一步提高了脉冲能量。最后,在相同调制深度及饱和通量条件下,与单SESAM锁模相比,双SESAM锁模光纤激光器输出脉冲宽度由693 fs降低到449 fs,缩短了35.2%,脉冲能量由2.92 nJ提高到5.31 nJ,上升45%。     

1300-nm pulsed fiber lasers mode-locked by purified carbon nanotubes

For the first time, we demonstrate a novel passively mode-locked fiber laser operating at 1300 nm using purified single-walled carbon nanotubes (CNTs) as a saturable absorber. The saturable absorber incorporates diameter-controlled CNTs with peak absorption /spl sim/1300 nm, guaranteeing mode-locking over the same wavelength region. The ring laser uses praseodymium-doped fiber as a gain medium. The pulse repetition rate is 3.18 MHz, and the spectral half-width is 0.15 nm. Dual-wavelength mode-locking is also demonstrated with a channel spacing of 1.1 nm.     

Noise of mode-locked lasers

A theory of noise in mode-locked lasers is developed that applies to additive pulse mode-locked and Kerr lens mode-locked systems. Equations of motion are derived for pulse energy, carrier linewidth, frequency pulling, and timing jitter. The effect of gain fluctuations, mirror vibrations, and index fluctuations are determined. Measurements that can determine all four fluctuation spectra are described. Experimental data in the literature are compared with theory     

Tm-doped mode-locked fiber lasers

Ultrashort pulse fiber lasers are increasingly used in various areas for scientific as well as industrial purposes. In contrast to ultrashort pulse lasers based on ytterbium- and erbium-doped fibers, the dispersion of silica fibers in the amplification band of thulium-doped fibers around 2 μm is typically anomalous, which has fundamental impact on the pulse propagation. In this paper, mode-locked thulium-doped fiber lasers operating in different pulse propagation schemes are presented. The transfer of various concepts into the 2 μm wavelength range, which have been successfully applied for pulse parameter scaling in the 1 and 1.5 μm spectral region, are discussed on the basis of experimental and numerical results.     

完全锁模半导体激光器

本文对含F-P标准具的外腔半导体激光器进行了主动锁模研究。适当选择F-P标准具参数可形成单一的纵模群振荡,并可因此得到完全锁模光脉冲。实验中得到了脉宽为13.5ps、重复频率为925MHz的光脉冲输出。     

Theory of mode-locked semiconductor lasers

We present a theoretical study of semiconductor mode-locked lasers at a phenomenological level. We use the slow absorber model of New and Haus, but extend the analysis by taking into account the shift in the gain maximum due to the changing number of carriers. In our analysis of the resulting equation, we show that due to stability requirements the shortest attainable pulse duration is limited. The use of self-phase modulation due to a slow medium can at most lead to a shortening of the pulse by a factor of 2. We show that the shifting of the gain maximum due to the changing number of carriers in the laser is a crucial aspect in the operation of mode-locked semiconductor lasers. We further find that the end mirrors must be reflecting more than about half of the light intensity to prevent a self-pulsation type instability similar to the relaxation oscillation     

Monolithic colliding-pulse mode-locked quantum-well lasers

Integration of the whole mode-locked laser onto a single piece of semiconductor offers a number of advantages, including total elimination of optical alignment processes, improved mechanical stability, and the generation of short optical pulses at much higher repetition frequencies. Semiconductor laser processing technologies were used to implement the colliding-pulse mode-locking (CPM) scheme, which is known to effectively shorten the pulses and increase stability, on a miniature monolithic semiconductor cavity. The principles of and recent progress in monolithic CPM quantum-well lasers are reviewed     

High-power passively mode-locked semiconductor lasers

We have developed optically pumped passively mode-locked vertical-external-cavity surface-emitting lasers. We achieved as much as 950 mW of mode-locked average power in chirped 15-ps pulses, or 530 mW in 3.9-ps pulses with moderate chirp. Both lasers operate at a repetition rate of 6 GHz and have a diffraction-limited output beam near 950 nm. In continuous-wave operation, we demonstrate an average output power as high as 2.2 W. Device designs with a low thermal impedance and a smooth gain spectrum are the key to such performance. We discuss design and fabrication of the gain structures and, particularly, their thermal properties     

波长可调谐被动锁模光纤激光器

为在光纤激光器中获得特定中心波长的锁模激光,进行了采用非线性光纤环形镜锁模的掺Yb3+光纤激光器的波长可调谐实验研究。获得了自启动锁模、中心波长在1030nm~1081nm范围内连续调谐的锁模脉冲输出;在中心波长1053nm时,测得光谱带宽6nm、脉冲宽度234.375ps、输出功率2.05mW、重复频率3.842MHz。这种被动锁模光纤激光器的锁模过程可以完全自启动,几乎不受外界环境变化的影响,可以长时间稳定工作,不仅可以提供特定中心波长的锁模激光,而且有望成为其它科学研究工作的中心波长可调谐的宽带锁模光纤激光种子源。     

Chirp and stability of mode-locked semiconductor lasers

A numerical study of mode-locked semiconductor lasers is presented with special attention to the chirp characteristics and to dispersion-related criteria for stable pulse-train emission. The dependence of the pulse chirp upon the refractive-index change, both with carrier density and carrier temperature changes, is discussed. The experimental observation of blue-chirped pulses for passive mode-locking in contrast to red-chirped pulses for active mode-locking is found to be due to the different contributions of gain and absorber media to the refractive-index change. In addition, it is revealed that the boundary of the stable operation regime is critically influenced by the spectral characteristics of laser and external cavity. Design considerations toward the achievement of high pulse energy, narrow spectral bandwidth, and linear chirp are given