用腔内半导体可饱和吸收镜钛宝石激光器中自锁模状态的实验研究

用可饱和吸收体镜(SESAM)的掺钛蓝宝石激光器能够稳定运转在三种不同的锁模状态,即可饱和吸收体被动锁模、孤子锁模加被动锁模和KLM锁模.分析了三种自锁模的机理和SESAM的作用.对SESAM实现KLM锁模的自启动机制进行了实验观察和讨论.从该激光器的KLM锁模状态,获得了小于18飞秒的锁模脉冲序列. 关键词： 半导体可饱和吸收镜 自锁模 钛宝石激光器     

正色散激光器中的增益导引孤子

采用非线性薛定谔方程模拟了全正色散介质激光器中实现脉冲锁模输出的动态过程,理论表明,不同于工作于净色散为负的孤子锁模激光器以及腔内具有色散延迟线净色散为正的色散管理孤子和自相似脉冲锁模激光器,在纯正色散介质构成的锁模激光器中,增益饱和和增益窄化对形成稳定的锁模脉冲起重要的作用,在两者的作用下脉冲形成增益导引孤子.采用不同的锁模方式在纯正色散光纤锁模激光器中得到了稳定的增益导引孤子锁模,实验结果与理论模拟一致. 关键词： 锁模 正色散 增益导引孤子     

利用被动锁模技术实现超短脉冲激光输出实验

基于被动锁模技术,设计了结构紧凑的Z型谐振腔,采用半导体可饱和吸收镜作为被动锁模元件,利用激光二极管泵浦增益线宽较宽的Nd∶YVO4晶体,最终实现了连续锁模的脉冲输出.在输入功率为8.20W时,获得了输出功率为1.72W的1 064nm连续锁模脉冲激光输出,光-光转换效率达21%,锁模脉冲重复频率为110MHz.     

基于非线性偏振旋转锁模的高功率光子晶体光纤飞秒激光振荡器

为了探索大模场面积光子晶体光纤锁模激光器在全正色散锁模域内的耗散孤子锁模机理, 以获得更大的单脉冲能量和更高的峰值功率, 本文搭建了以掺镱大模场面积光子晶体光纤作为增益介质的耗散孤子锁模激光器. 激光器使用环形腔结构, 利用非线性偏振旋转以及滤光片提供的耗散作用实现了稳定的锁模运转. 实验中, 从激光器振荡级直接获得了平均功率10 W, 重复频率49.09 MHz(对应202 nJ的单脉冲能量), 脉冲宽度为1.03 ps的稳定锁模脉冲输出, 经过腔外色散补偿得到的脉冲宽度为95.5 fs.     

高重复频率全光纤被动锁模掺铒光纤激光器

报道了一种高重复频率全光纤非线性偏振旋转锁模掺铒光纤激光器, 获得了重复频率217 MHz的锁模脉冲输出. 该激光器使用一个偏振相关隔离器和一个偏振控制器即可获得稳定的锁模脉冲输出, 结构简单, 系统稳定. 激光器锁模脉冲的脉冲宽度为69 fs, 3 dB光谱宽度为56 nm, 射频频谱信噪比为76 dB.     

303MHz高重复频率掺Er光纤飞秒激光器

高重复频率掺Er光纤飞秒激光器在光学频率梳、超高速光学采样等领域具有很重要的作用. 本文采用非线性偏振旋转锁模机理, 在掺Er光纤飞秒激光器中实现了重复频率为303 MHz的锁模脉冲输出. 通过优化腔内色散, 激光器腔内色散在零色散附近偏负值, 锁模后工作在展宽脉冲锁模状态. 在817 mW抽运功率下, 激光器在连续光状态下可以输出125 mW的平均功率, 在锁模状态下可以输出69 mW的平均功率, 脉冲宽度为90 fs. 当抽运功率处于700-817 mW时, 激光器可以实现自启动锁模. 激光器重复频率在5 h内的漂移量为30 Hz.     

参考面的选取对利用自洽法建立染料激光器锁模方程的影响

本文讨论了利用自治法建立链模方程时,各种参考面位置的选取对锁模方程的影响,找到了合理的参考面位置,据此重新建立了适用于同步锁模,混台锁模和被动锁模的锁模方程.并给出了同步锁模的数值解,它与实验结果是一致的.     

高能量掺Yb偏振型大模场面积光子晶体光纤孤子锁模飞秒激光器

实验研究了基于掺Yb偏振型大模场面积光子晶体光纤的孤子锁模激光器,获得了高脉冲能量的飞秒激光输出. 激光器基于线形腔结构,利用光栅对补偿腔内色散,并通过半导体可饱和吸收镜实现锁模的自启动. 实验中从振荡级直接获得了平均功率为700mW, 重复频率为47.3MHz(对应于14.8 nJ的单脉冲能量),脉冲宽度为518 fs的稳定锁模脉冲输出. 与普通孤子锁模飞秒光纤激光器相比,输出的单脉冲能量提高了两个数量级. 关键词： 光子晶体光纤 飞秒 光纤激光器 孤子锁模     

低抽运三镜腔自锁模掺钛蓝宝石激光器的理论与实验研究

实现了低抽运三镜腔自锁模掺钛蓝宝石激光器的自锁模运转,对该激光器的自锁模区进行了实验研究,并对象散、稳定性、光束参量和克尔自聚焦强度与腔参量的关系进行了系统的理论计算.该计算为自锁模固体激光器的设计和调整提供了理论依据.     

光泵为正弦波的被动锁模钕玻璃激光器的锁模工作区

本文给出了光泵为正弦波时光泵脉宽等参数对被动锁模激光器的影响,提出了“锁模工作带”的概念.从理论上分折了锁模过程中多个工作参数的综合效应及各参数之间的相互联系,依据给出的工作参数选择原则,在实验上获得了良好的锁模脉冲序列.     

Characterization of laser-diode end-pumped intracavity frequency doubled, passively Q-switched and mode-locked Nd:YVO4 laser

Simultaneous Q-switching and mode-locking in a laser-diode end-pumped intracavity frequency doubled Nd:YVO₄/KTP green laser using Cr⁴⁺:YAG saturable absorber is experimentally demonstrated. The influence of the initial transmission (T₀) of the Cr⁴⁺:YAG crystal on the Q-switched mode-locked green pulses as well as on the average green power is characterized by using Cr⁴⁺:YAG crystal with various T₀. The effect of T₀ on the pulse build-up time in intracavity second harmonic configuration is theoretically investigated. It was found that the depth of modulation for the mode-locked pulses is greatly improved at the second harmonic wavelength as compared to that for the fundamental wavelength. The average pulse duration of the individual mode-locked pulse for the second harmonic beam measured to be less than 500 ps with a repetition rate of 400 MHz.     

飞秒脉冲正交位相压缩光的产生

利用锁模飞秒脉冲激光二次谐波为抽运源, 同步抽运单共振光学参量振荡器, 抽运光中心波长为425 nm, 重复率为76 MHz, 脉宽180 fs, 光学振荡器下转换晶体采用Ⅰ类共线PPKTP, 实验上实现了压缩度为2.58 dB的正交位相压缩光.考虑到实验系统的效率, 可以推知光学参量振荡器输出的下转换光压缩度为 4.48 dB. 关键词： 同步抽运光学参量振荡器 压缩光 锁模飞秒脉冲     

Analysis of mode-locked internally frequency doubled broad-band continuous wave lasers

Closed-form analysis of pulse evolution in the transient regime in an actively modelocked internally frequency doubled broad-band continuous wave laser is presented. The analysis enables investigation of the effect of nonlinear crystal inside the laser cavity on mode-locked pulse parameters at the fundamental frequency. It is shown that the presence of internal second harmonic crystal broadens the fundamental mode-locked pulse while accelerating the approach of the system to steady-state. The dependence of pulse parameters on the bandwidth of the tuning element, modulation depth of the active mode-locker and conversion efficiency of the frequency doubler is presented in detailed graphical form.     

Direct measurement of pulse broadening in the second harmonic of mode-locked Nd: glass laser

Direct measurement of pulse broadening in the second harmonic of a mode-locked Nd: glass laser has been made using a high-speed streak camera. Recorded pulsewidths varied from 3.8 psec to greater than 15 psec.     

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.     

A 40-GHz Colliding Pulse Mode-Locked Semiconductor Laser

A monolithically active-passive integrated colliding pulse mode-locked semiconductor laser is demonstrated in the InGaAsP/InP material system.The device is mode locked at the second harmonic passive mode-locking regime with a wide mode-locking range.Pulse trains with the repetition rate of 40 GHz,3-dB rf line width of 25 kHz,the pulse width of 2.5ps,and a nearly transform-limited time-bandwidth product of 0.53 are obtained.     

不同皮秒非稳腔中的KTP晶体的腔内倍频效应

以ＫＴＰ晶体作为Ｎｄ：ＹＡＰ锁激光器的内腔倍频元件,在带非共振环（ＡＲＲ）的对撞脉冲锁模（ＣＰＭ）非稳腔虚共焦非稳腔中实现高效倍频转换,其倍频能量转换效率 ５３．４％和６０．２％,测定了两种腔型的基波脉宽分别为８ｐｓ和１８ｐｓ,二次谐波输出的最大能量起伏分别为１０．６％和１２．５％。理论分析了两种没腔型及其实验结果的特点。     

基于类噪声方波脉冲的掺铒光纤激光器

搭建了长腔"8"字型掺铒光纤激光器,并对产生的谐波锁模方波脉冲进行了实验研究.结果表明,该脉冲具有光滑的宽带光谱,示波器上显示为方波脉冲,但自相关迹证实其为类噪声脉冲,即为类噪声方波脉冲;通过调节偏振控制器和泵浦功率等激光器腔内参量,获得了高达5阶的谐波锁模类噪声方波脉冲;该类噪声方波脉冲并非可以无限增大脉冲能量,而是在一定条件下产生脉冲分裂,出现谐波锁模方波脉冲现象.     

基于色散不对称光纤环形镜的锁模光纤激光器

在理论上数值计算了各种常量对色散不对称非线性光纤环形镜透射特性的影响。并分析了它作为被动锁模器件用于光纤激光器压窄脉冲的物理机制。利用8字形主被动混合锁模的结构在调制频率为9．998748700 GHz，波长为1566．65nm处获得了11ps的稳定锁模脉冲输出．对应谱宽0．297nm．同时在重复频率为9．995792825 GHz和9．996778256 GHz时分别得到了振幅均匀的二阶和三阶谐波锁模输出。证明色散不对称非线性光纤环形镜可以有效消减脉冲的尾翼和噪声．得到脉幅稳定的脉冲序列。     

Ti:sapphire laser pumped by a long train of pulses from mode-locked Nd:YAG laser with negative feedback

Investigation of the buildup dynamics of a Ti:sapphire laser pumped by a 500 ns long second harmonic pulse train from a mode-locked Nd:YAG laser with a passive negative feedback using GaAs is reported. The 400 ns long output pulse has a buildup time of 70 ns for a pump energy of 1.25 mJ. A slope efficiency of 15.1% was achieved with a 94% reflective output coupler.