用于标定条纹相机的对撞脉冲锁模激光器

报道了一种被动皮秒对撞脉冲锁模Nd: YAG激光器的腔型及应用情况。用这样的对撞锁模脉冲激光器来标定皮秒条纹相机的非线性、触发晃动等得到了很好的结果。同时用条纹相机探测激光脉冲宽度也可以得到比示波器等设备准确的结果,最后得到输出脉冲宽度为10ps左右,比通常的反射式被动锁模脉冲宽度要窄3~5倍。     

Dual-wavelength 10-GHz actively mode-locked erbium fiber laser

We present the first 10 GHz dual-wavelength actively mode-locked erbium fiber laser (ML-EFL). Dual-wavelength operation is achieved by introducing two intracavity branches, each containing a tunable optical bandpass filter. A variable output coupler combining the filter branches also equalizes the effective cavity gain for the two wavelengths, By adjusting the filters and the coupler, dual-wavelength ML-EFL operation is achieved at different wavelengths. Nearly transform-limited, 4- and 6.2-ps-wide 10-GHz soliton pulses are e.g., simultaneously generated at 1542.3 and 1563.8 nm, respectively. The experimental results agree very well with analytical calculations     

Tunable monolithic colliding pulse mode-locked quantum-well lasers

The tunabilities of both the wavelength and the pulse-width of monolithic mode-locked semiconductor lasers are demonstrated. Pulses shorter than 1.6 ps, tunable over 8.8 mu m, have been generated by a temperature-tuned monolithic colliding pulse mode-locked (CPM) quantum-well laser. For a fixed wavelength, the pulse-width is independently controlled from 1.2 ps to longer than 3 ps by external bandpass filters. Near transform-limited time-bandwidth products of 0.34 were maintained throughout the tuning processes.<>     

Multicolor single-wavelength sources generated by a monolithic colliding pulse mode-locked quantum well laser

The authors report on the separation of single longitudinal modes from the mode-locked program spectrum of a 300-GHz monolithic colliding pulse mode-locked (CPM) semiconductor quantum-well laser. Experimentally, the selected longitudinal mode shows a 10-dB reduction of low-frequency relative intensity noise compared to that of the selected mode from the same laser in continuous-wave (CW) lasing conditions. The strong phase coherence among the passively mode-locked longitudinal modes reduces the partition noise of the unlocked CW laser.<>     

40-GHz transform-limited pulse generation from FM oscillation fiber laser with external cavity chirp compensation

A 40-GHz frequency modulation oscillation fiber laser is demonstrated and the continuous-wave (CW) output is used for generating a high repetition rate short pulse train by external cavity chirp compensation. A 1.37-ps transform-limited pulse is obtained from its chirped, 488.1-GHz width CW output.     

Electrical subharmonic hybrid mode locking of a colliding pulse mode-locked laser at 28 GHz

This letter discusses electrical subharmonic hybrid mode locking (SHML) of a colliding pulse mode-locked (CPM) laser in InP. The CPM laser fabrication adopts a simple wet etching process and bisbenzocyclobutene planarization process for realizing planarized low-capacitance devices. The experimental results show, for the first time to our knowledge, stable emission of nearly transform-limited pulses at 28 GHz of a CPM laser synchronized to a clock source by SHML. We further describe careful optimization steps of dc and radio-frequency biasing conditions which lead to minimal output pulsewidth of 1.4 ps, limited by the saturable absorber dimension.     

Colliding pulse mode-locked laser

The fabrication and performance of a colliding pulse-mode locked laser with an intracavity saturable absorber is described. The laser has a threshold current of 65 mA and differential efficiency of 0.04 mW/mA when coupled into a single-mode fiber. Mode-locked pulses with ~1 ps pulse width at ~10 GHz has been obtained     

Dual-wavelength 10-GHz actively mode-locked erbium fiber laser incorporating highly nonlinear fibers

We demonstrated a dual-wavelength actively mode-locked erbium-doped fiber ring laser with 0.8-nm wavelength spacing at a repetition rate of 10 GHz. A 1-km highly nonlinear fiber is introduced in the nonpolarization-maintaining cavity to suppress the gain competition of the homogeneously broadened gain medium in a self-driven manner. Output pulses at 1557.36 and 1558.17 nm are generated simultaneously. Amplitude fluctuations less than 0.45% and 1.7% of two wavelengths are measured. The corresponding timing jitters are less than 80 and 90 fs, respectively.     

80-160-GHz mode-locked fiber ring laser synchronized to external optical pulse stream

The authors present a novel scheme to generate ultrahigh repetition rate picosecond pulses synchronized to an optical pulse stream in an actively mode-locked fiber ring laser. A monolithic Mach-Zehnder interferometer with integrated semiconductor optical amplifiers serves as an 80-GHz optically controlled modulator. 80-GHz transform-limited 2.1-ps Gaussian pulse with low timing jitter, extinction ratios up to 25 dB, and 5 mW of average output power are demonstrated. The laser is wavelength tunable over more than 15 nm around 1555 nm. At 160 GHz, 2.5-ps pulse trains with 3-mW output power are generated by rational harmonic mode locking.     

Multiwavelength 10-GHz picosecond pulse generation from asingle-stripe semiconductor diode laser

A single-stripe GaAs-AlGaAs semiconductor optical amplifier (SOA) has been used to generate four tunable wavelength-division multiplexed (WDM) channels simultaneously, each transmitting 12-ps pulses at 2.5 GHz, for an aggregate pulse rate of 10 GHz. Wavelength tuning over 18 nm has been demonstrated with channel spacing ranging from 0.8 to 2.1 nm. A potential spectral correlation across the multiwavelength spectrum has been studied in both experiment and simulation methods. These results show the potential for utilizing single stripe laser diodes as multiwavelength sources in WDM-TDM network     

利用皮秒扫描相机研究对撞脉冲锁模Nd:YAG激光器的输出特性

本文报道了用BWS—5KⅡ型皮秒扫描相机对CPM Nd:YAG激光器进行研究的实验结果。得到了激光脉冲宽度为10.1PS的最佳结果,而且还得到了锁模单脉冲的真实波形。同时利用扫描相机研究了染料浓度、染料盒偏离中心位置对输出脉冲宽度及波形的影响,使激光器处于最佳工作状态。     

对撞脉冲锁模Nd:YAG激光器中可饱和吸收体的研究

在被动锁模激光器中,五甲川、十一甲川等染料在不同溶剂中的锁模现象已有报道,但在对撞脉冲锁模激光器中还未见报道。而研究对撞脉冲锁模中可饱和染料的特性对激光系统的性能来说是重要的。本文仅对CPM中使用的五甲川、十一甲川、BDN染料、溶剂、溶液小信号透过率等参数进行探讨和研究。所用的腔为抗共振环形CPM腔,其前反射镜的曲率半径为3m,对撞脉冲用的反射镜为22.5°,1.06μm全反射介质膜片,总腔长1705mm。染料盒放在环路的中心分界处,以布儒斯特角放置,保证损耗小,无子腔,染料溶液放在染料盒中不流动。     

Wavelength-tunable 40-GHz picosecond harmonically mode-locked fiber laser source

We demonstrate a novel 40-GHz mode-locked fiber laser that utilizes a single active device to provide both gain and mode-locking. The laser produces pulses as short as 2.2 ps, is tunable over a 27-nm band centered at 1553 nm, and exhibits long-term stability without cavity-length feedback control. The pulse train at 1556 nm was used in a 40-Gb/s transmission experiment over 45 km with a low 0.4-dB power penalty.     

Generation of wavelength-tunable transform-limited pulses from amonolithic passively mode-locked distributed Bragg reflectorsemiconductor laser

Generation of wavelength tunable transform-limited picosecond pulses from a monolithic passively mode-locked distributed Bragg reflector (DBR) laser is demonstrated for the first time. A wide tuning range of 12 nm is realized by changing the refractive index of the passive DBR region through a thin-film heater embedded on the DBR section without causing significant changes in pulse characteristics     

Tunable transform-limited pulse generation using self-injectionlocking of an FP laser

Wavelength-tunable, near transform-limited pulses have been generated using a Fabry-Perot laser diode coupled to a fiber loop containing a fiber Fabry-Perot resonator (FFPR) and a polarization controller. The ratio of transmitted to reflected light from the loop can be adjusted using the polarization controller. Single-mode operation of the gain-switched laser is achieved by self-injection locking, which is induced by light reflected from the fiber loop. The resulting output pulse has a time-bandwidth product of 0.4 and is tunable over about 15 nm by varying the tuning voltage of the FFPR     

16-wavelength 10-GHz actively mode-locked fiber laser with demultiplexed outputs anchored on the ITU-T grid

We propose and demonstrate a 16-wavelength polarization-maintaining fiber laser, actively mode-locked at 10 GHz. The fiber laser includes a 16-channel 100-GHz-spaced arrayed waveguide grating (AWG) in the laser cavity; therefore, the outputs are demultiplexed and the lasing wavelengths are anchored at the ITU-T grid. The multiwavelength lasing has been achieved by cooling the erbium-doped fiber in liquid nitrogen. Generation of simultaneous multiwavelength short pulses was demonstrated.     

20 GHz transform-limited optical pulse generation and bit-error-free operation using a tunable, actively modelocked Er-doped fibre ring laser

The authors report the generation of 20 GHz, 3.0-3.5 ps transform-limited optical pulses across the wavelength tunable range 1550-1557 nm using a wavelength tunable, polarisation-maintaining actively modelocked Er/sup 3+/-doped fibre ring laser. Stable bit-error-free modelocking operation is confirmed throughout the wavelength tuning range.<>     

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%。     

基于锁模脉冲泵浦的全光纤化超连续谱光源

采用基于半导体可饱和吸收镜(SESAM)的被动锁模方案,通过三级主振荡功率放大(MOPA)结构,构建了平均输出功率39.2 W的全光纤皮秒脉冲光纤激光器。输出激光脉冲宽度10.7 ps,重复频率68 MHz。利用该皮秒光纤激光器泵浦一段4.5 m长的国产光子晶体光纤(PCF),实现了平均功率20.1 W的全光纤化结构超连续谱(SC)光纤激光输出。光谱宽度超出所用光谱仪600~1700 nm 的观测范围,在观测范围内具有10 dB 的光谱平坦度。