基于饱和吸收镜的被动锁模光纤激光器

在普通单模光纤环中插入半导体可饱和吸收镜(SESAM)作为非线性器件,实现了自启动的被动锁模光纤激光器,并产生了亚皮秒量级的稳定锁模激光脉冲。输出锁模脉冲的基频为几兆赫兹。利用基于倍频晶体的二次谐波自相关仪测得锁模脉冲的脉宽为422 fs,最窄时可达377 fs,利用光谱仪测得脉冲谱宽为6.35 nm,脉宽谱宽乘积为0.329,接近于双曲正割脉冲的变换极限。实验中激光器输出脉冲稳定,没有观察到子脉冲和直流分量。在一般的实验室条件下,未采取任何附加措施,激光器可连续稳定工作10 h以上,没有出现失锁现象。该装置结构简单,紧凑,易于调整,工作稳定,可以很方便地实现自启动锁模。     

Compact fully fibre integrated source of 100 fs pulses at 1.1 /spl mu/m based on compression in holey fibre

A simple, compact, fully fibre integrated source of /spl sim/100 fs pulses at a wavelength of 1.1 /spl mu/m is reported. 4 ps pulses at 1063 nm from a modelocked fibre laser were amplified to 23 mW in a ytterbium-doped fibre amplifier and subsequently propagated through 62 m of holey fibre with a zero dispersion wavelength at 1040 nm. Soliton formation, breakup and self frequency shift resulted in the formation of /spl sim/100 fs pulses at 1.1 /spl mu/m. Wavelength tunability from 1113 to 1220 nm is demonstrated.     

Femtosecond Cr/sup 4+/:YAG laser with 4 GHz pulse repetition rate

The construction of a compact, high-repetition-rate femtosecond Cr/sup 4+/:YAG laser is reported. Transform-limited pulses as short as 80 fs were generated at pulse repetition frequencies up to 4 GHz. The femtosecond pulses were tunable from centre wavelengths of 1505 to 1550 nm.     

Wavelength tunable source of subpicosecond pulses from CW passivelymode-locked two-section multiple-quantum-well laser

A wavelength-tunable passively-mode-locked semiconductor laser source of subpicosecond pulses is demonstrated. The system includes a two-section multiple-quantum-well laser which is coupled to an external grating for tuning and is followed by an external grating pair for pulse compression. A tuning range of 16 nm round 846 nm is obtained, resulting in compressed pulse widths as short as 260 fs and pulse widths shorter than 600 fs for all wavelength values within this tuning range. Time-bandwidth products are one to two times the transform limit     

飞秒激光脉冲倍频特性的数值模拟

模拟了随着传播长度的增加,基频和倍频激光脉冲的时域波形和光谱特性的演变过程。通过引入走离长度和非线性长度,给出了走离效应、群速度色散和三阶非线性效应对飞秒脉冲倍频的影响。研究了飞秒脉冲倍频的波长调谐特性,发现40ps基频脉冲波长调谐带宽仅有2.8nm,而40fs基频脉冲的倍频波长调谐带宽高达42nm。这在周期极化倍频晶体工艺中有重要应用价值。     

Passive mode locking of an energy transfer continuous-wave dye laser

The first passive mode locking of a continuous-wave energy transfer dye laser is reported. Using an argon ion laser-pumped mixture of rhodamine 6G and sulphur rhodamine 101 as the active medium, pulses of less than 500 fs duration have been generated over the spectral range 652-694 nm using two different saturable absorbers in a simple linear cavity without dispersion optimization. Pulses as short as 120 fs have been measured using standard second-harmonic generation autocorrelation techniques.     

用800nm表面态方法和低温方法结合吸收区的半导体可饱和吸收镜实现掺钛蓝宝石激光克尔镜锁模

研制了一种新型的800nm布拉格反射镜型半导体可饱和吸收镜,其吸收区是低温方法和表面态方法相结合.用该吸收体实现了氩离子激光器泵浦的掺钛蓝宝石激光器被动锁模,脉冲宽度达到40fs,光谱带宽为56nm,后者意味着它可以支持20fs的锁模.脉冲序列的重复率为97.5MHz,泵浦源为4.45W下平均输出功率为300mW.     

All-fiber source of 20-fs pulses at 1550 nm using two-stage linear-nonlinear compression of parabolic similaritons

Parabolic pulses from a similariton amplifier at 1550nm are compressed using a two-stage fiber compressor employing linear compression in photonic bandgap fiber and soliton effect compression in highly nonlinear fiber. Precise optimization of the compressor design using frequency resolved optical gating allows the generation of minimally chirped pulses as short as 20fs. This duration corresponds to only four optical cycles of the underlying electric field at this wavelength.     

高功率掺镱全固态飞秒激光器

开展了激光二极管泵浦的高功率掺镱全固态飞秒激光器的研究。利用Yb:LYSO晶体实现了高功率高效率的半导体可饱和吸收镜锁模飞秒振荡器,分别在1 035、1 042 nm实现了3 W的稳定锁模运转,相应的脉冲宽度分别为351、287 fs,斜效率分别为88.2%和89.7%;通过将增益介质与克尔介质分开,利用大功率多模LD直接泵浦Yb:CYA晶体实现了高功率的克尔透镜锁模飞秒振荡器,脉冲宽度70 fs,平均输出功率2.52 W,重复频率50 MHz,获得了50 nJ的单脉冲能量且峰值功率达到0.71 MW。表明上述掺镱晶体在高功率二极管泵浦全固态激光器领域中具有非常优异的性能。     

Nonlinear optical devices based on suspended-core microstructured optical fibers

Suspended-core microstructured optical fibers are employed in lasers that generate ultrashort pulses and supercontinuum generators. It is demonstrated that a femtosecond fiber laser based on the ytterbium-doped microstructured fiber generates pulses with a duration of 95 fs at a wavelength of 1045 nm and a mean power of 5 mW in the absence of additional compression. Supercontinuum is generated in tapered microstructured fibers with suspended core in the wavelength interval 400–1400 nm. Suspended-core micro-structured fibers may serve as promising elements for nonlinear optical devices due to specific waveguide characteristics, relative simplicity of manufacturing, and variable optical properties.     

主动锁模飞秒光纤激光器

报道了主动锁模飞秒脉冲掺Er3 光纤激光器的实验结果。在光纤环形腔中通过引入粗波分复用器(CWDM)作为宽带滤波器,实现了中心波长在1550 nm,重复频率为2.5 GHz,谱线3 dB带宽为10.2 nm(对应的脉冲宽度为247 fs)的激光脉冲输出。此时的抽运功率为186 mW,激光器输出平均功率为1.3 mW,从而获得了能够产生飞秒脉冲的高重复频率主动锁模掺Er3 光纤激光器。     

在Cr4+:YAG激光器中利用SBR锁模的分析研究

闸述了在Cr^4 ：YAG激光器里利用SBR锁模的基本原理,得出了SBR锁模的临界条件,获得了中心波长在1530nm处脉宽为120fs的锁模脉冲。     

High‐capacity soliton transmission for indoor and outdoor communications using integrated ring resonators

A system consisting of a series of microring resonators, incorporating an add/drop system, is presented in order to create ultra‐short spatial and temporal single and multisoliton pulses, which can be used for indoor and outdoor optical communications. Chaotic noise can be generated by a bright soliton pulse propagating inside a nonlinear microring resonator system. The results obtained show that a single temporal and spatial soliton pulse, with full width at half maximums of 75 fs, 80 fs, 700 fs, 4.4 ps, and 0.30 nm, can be generated. The add/drop system can be used to generate a high number of ultra‐short soliton pulses in the ranges of nanometer/second and picometer/second. The simulated multisolitons have full width at half maximums of 16 ps, 20 pm, 130 ps, and 35 pm and free spectrum ranges of 500 ps, 0.57 nm, 3.5 ns, and 1.4 nm, respectively. The multisolitons generated at the drop port can be used in indoor optical communications, where the ultra‐short pulses with a variety of central wavelengths (from λ = 1550 to λ = 1560) from the through port can be multiplexed‐demultiplexed along an optical fiber with a length of 50 km. The filtered signals can be obtained at the end of the transmission link used for optical outdoor communications. Copyright © 2013 John Wiley & Sons, Ltd.     

单脉冲飞秒激光作用下晶态GeSb2Te4相变薄膜的非晶化过程

利用飞秒激光的抽运探测技术，研究了单脉冲飞秒激光作用下GeSb2Te4相变薄膜的非晶化过程，测量了相变薄膜的时间分辨光学显微图。所研究的系统为多层薄膜结构100 nm ZnS-SiO2/ 35 nm GeSb2Te4 /120 nm ZnS-SiO2/0.6 mm ，飞秒激光的脉冲宽度为108 fs，波长为800 nm。实验发现相变薄膜从晶态至非晶态的相转变过程可以在 2.6 ns内完成。讨论了相变薄膜的厚度对系统的热传递、快速凝固过程的影响，分析了相关热过程和热效应，解释了抽运探测实验数据，并探讨了单脉冲飞秒激光诱导相变薄膜非晶化的机制。     

自启动、低功率泵浦的自锁模Ti：蓝宝石激光器和它的高效连续运转

报道了一台自启动、长时间稳定、低功率泵浦的自锁模Ｔｉ：蓝宝石激光器和它的高效连续运转的实验结果．实验中观测到５３ｎｍ的光谱带宽（ＦＷＨＭ）．此谱宽可支持１３ｆｓ的激光脉冲．受自相光仪测量仪器的限制．测得的脉宽为２４．６ｆｓ．实际脉冲脉宽可能小于２０ｆｓ．此激光器在自启动锁模、低功率泵浦时．脉宽小于５０ｆｓ．激光器在连续运行时获得０．２Ｗ的泵浦阈值．３５％的斜率效率和１．１Ｗ的激光输出（４Ｗ泵浦）．     

26fs自锁模掺钛蓝宝石激光器

采用４ｍｍ长的Ｔｉ：Ａｌ２Ｏ３晶体及一对熔石英色散棱镜，在腔内未加硬边光阑等元件的情况下，获得了平均功率５６０Ｗ、中心波长７７４ｎｍ、宽度２６ｆｓ、谱宽２８ｎｍ的锁模激光脉冲，分析了锁模的条件和工作特性。     

Femtosecond soliton generation over a 32-nm wavelength range usinga dispersion-flattened dispersion-decreasing fiber

The compression characteristics at femtosecond durations are compared for dispersion-decreasing fibers (DDF's) constructed out of standard step index fibers and fibers designed to have low third-order dispersion (dispersion-flattened fibers). It is shown that the dispersion slope of a standard fiber causes the compressed pulse spectrum to vary substantially with wavelength. Furthermore, the peak of the compressed pulse spectrum can appear in a different wavelength band than the input pulse. Both of these problems are substantially reduced by using a dispersion-flattened DDF. The compression of 3-3.6-ps pulses to durations less than 180 fs was achieved between 1533-1565 nm at a repetition rate of 10 GHz. The shortest pulses obtained were 98 fs with peak-to-pedestal ratios in excess of 20 dB     

全固态近红外、蓝光飞秒激光系统的实验研究

利用棱镜对引进频谱空间啁啾来补偿飞秒激光二次谐波产生中的相位失配,提高了倍频效率.建立了一套全固态、多波长(1064 nm,532 nm,823 nm,402 nm)飞秒脉冲激光系统.NdYVO4激光器输出的1064 nm激光功率可达10 W;532 nm绿光激光最高功率可达5.6 W.当用2.5 W绿光激光泵浦时,从钛宝石激光器及经BBO倍频可分别输出中心波长为823.1 nm和402 nm、平均功率300mW和73 mW、谱宽32.3 nm和5.1 nm、脉宽22fs和33.3fs、重复率108 MHz的近红外和蓝光飞秒激光.整个系统具有结构紧凑、倍频效率高、运行稳定的特点.     

Tunable near-infrared femtosecond soliton generation in photoniccrystal fibres

Femosecond Raman soliton generation, tunable from 850-1050 nm, has been demonstrated by pumping untapered photonic crystal fibre with 110 fs pulses from a modelocked Ti:sapphire laser. Experimental results are in excellent agreement with the results of numerical simulations using an extended nonlinear Schrodinger equation