锁模光纤激光的倍频及波长调谐实验研究

利用周期性极化铌酸锂（Periodically Poled Lithium Niobate, PPLN）晶体实现了对掺镱锁模光纤激光器输出单横模激光的倍频,产生了532nm波长附近的倍频脉冲光。基于准相位匹配（Quasi Phase Matching, QPM）技术,通过改变基频光到PPLN晶体的入射角,使不同中心波长的基频光达到准相位匹配条件,实现倍频光波长的调谐。对带宽60 nm的锁模激光倍频得到带宽1.5 nm、中心波长532nm的脉冲激光输出。以掺Yb锁模光纤激光作为基频光,调节PPLN晶体角度,获得了中心波长连续变化的倍频激光,入射角度调节范围0°~25°,对应的倍频光波长调谐范围531.8nm~535.6nm。波长变化趋势与理论分析一致。     

基于石墨烯的掺铒光纤锁模激光波长切换技术

报道了一种基于石墨烯锁模的全保偏掺铒光纤环形短腔实现锁模激光波长切换技术。利用多层石墨烯可饱和吸收镜不仅可实现被动锁模脉冲序列的稳定输出,并可通过三维精密调节,调制腔内信号损耗,有效控制不同波长激光的增益与损耗。实验表明,通过精密调制10层石墨烯膜可饱和吸收镜,在全保偏光纤激光短腔可实现波长1532 nm和1558 nm 处的锁模激光切换输出,并可实现这两波长附近的双波长锁模激光输出,线偏振度可达18 dB。     

Alternate and simultaneous generation of 1-GHz dual-wavelengthpulses from an electrically tunable harmonically mode-locked fiber laser

A new scheme of producing dual-wavelength mode-locked pulses from a fiber laser is proposed and experimentally demonstrated. In addition to the simultaneous generation of two selected wavelength components, the scheme also allows the alternate generation of mode-locked pulses at different wavelengths. The alternate switching of wavelengths is demonstrated at 1 GHz, and has been achieved over an electrical tuning range of 13.1 nm using the dispersion-tuning approach. A constant mode spacing of 7.1 nm is maintained during the tuning process     

Mode-Hop-Free, Optical Frequency Tunable 40-GHz Mode-Locked Fiber Laser

We have successfully achieved a mode-hop-free, optical frequency tunable 3-ps 40-GHz mode-locked fiber laser by installing an optical etalon in a 6.8-m laser cavity. The laser frequency was continuously tuned over 1 GHz without mode hopping by tuning the etalon peak frequency. The oscillation wavelength was also tuned over 1535-1560 nm by tuning an optical bandpass filter installed in the laser cavity.     

An electronically wavelength-tunable mode-locked fiber laser using an all-fiber acoustooptic tunable filter

We have demonstrated a novel scheme of a continuously wavelength-tunable and passively mode-locked fiber laser by using the sliding frequency effect of an all-fiber acoustooptic tunable filter. Stable and nearly transform-limited pulses of 800-fs pulsewidth were produced with this laser scheme for a wavelength tuning range of 17 nm at around 1550 nm.     

Generation of wavelength-switched optical pulse from a fiber ringlaser with an F-P semiconductor modulator and a HiBi fiber loop mirror

A simple configuration to perform wavelength switching in an actively mode-locked fiber ring laser is demonstrated. A Fabry-Perot laser diode was used as a modulator and a HiBi fiber loop mirror was used as a periodic multichannel wavelength filter in the cavity. By setting the channel spacing of nm can be achieved by tuning the fiber loop mirror filter. In the wavelength-switched process, the modulation frequency was not required to be changed     

Low threshold tunable soliton source

An actively mode-locked erbium-fiber laser with continuous wavelength tuning over the range 1528-1565 nm has been demonstrated. A gain-saturated InGaAsP NTW semiconductor optical amplifier (SOA) is used as the active mode locking element, functioning as an amplitude modulator which provides gain and has <1 dB polarization dependence. The fiber laser is diode pumped at 1480 nm with a threshold of 6 mW, and provides pulses of 25 ps (FWHM) with a transform product of 0.4 and >12 dBm peak power     

主动锁模光纤环形激光器的悬臂梁调谐法

利用悬臂梁来对光纤光栅的Bragg波长进行调谐,并将可调谐光纤光栅用于主动锁模光纤环形激光器中,获得了5.24nm的波长调谐范围。同时,在1547.883nm处,获得了脉宽为55ps,谱宽为0.017nm锁模脉冲输出。     

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。     

8字形腔锁模掺Yb3+光纤激光器

报道了利用非线性光纤环形镜（NOLM）锁模运行的掺Yb^3＋光纤激光器的实验研究。获得了脉冲宽度234ps。中心波长1053nm的锁模脉冲激光输出。光谱带宽6nm。输出功率2.05mW，重复频率3.842MHz。该锁模光纤激光器的工作中心波长可在1030～1081nm范围内调谐，锁模过程可以完全自启动，几乎不受外界环境变化的影响。可长时间稳定锁模工作，完全可以作为微焦耳级单脉冲能量光纤激光放大系统前端种子源使用，而且有望成为其他科学研究工作的中心波长可调谐的宽带锁模光纤激光光源。     

Pulse compression of an actively modelocked diode laser usinglinear dispersion in fiber

Pulses from a tunable actively mode-locked InGaAsP laser compressed using linear dispersion in single-mode optical fiber are discussed. High-repetition-rate pulses as short as 4.1 ps have been achieved. Compression is optimized by wavelength tuning of the mode-locked laser. Time-resolved spectral measurements show the compensation of pulse chirp by fiber dispersion     

Harmonically mode-locked fiber laser with optically selectablewavelength

In this letter, we demonstrate optical selection of wavelength in a harmonically mode-locked fiber laser that incorporates a semiconductor optical amplifier nonlinear fiber loop. Wavelength tuning is achieved by controlling the delay time between the modulation and the control signals in the compensated dispersion-tuning scheme. A tuning range over 19 nm is obtained. The power suppression of nonlasing modes reaches a maximum of 34 dB. The output wavelength and the delay time are governed by a linear relationship     

基于饱和吸收镜的被动锁模掺铒光纤激光器

为了研究基于半导体可饱和吸收镜的被动锁模光纤激光器的输出特性,采用1480nm的半导体激光器作为抽运源,利用掺铒光纤作为增益介质,以及光纤环行器、偏振控制器、波分复用器和耦合器等构成了环形腔结构的被动锁模光纤激光器。实验中获得了峰值波长1586nm、光谱宽度4.8nm、重复频率11.2MHz、最大平均输出功率8.4mW的稳定锁模激光脉冲输出。结果表明,调整光纤偏振控制器会使光纤激光器输出脉冲的时域波形略微发生变化,在实际应用中需要注意偏振态变化对锁模光纤激光器输出脉冲时域特性的影响。这一结果对于半导体可饱和吸收镜在被动锁模光纤激光器中的应用及其特性具有一定帮助。     

Investigation of a tuneable mode-locked fiber laser for application to multipoint gas spectroscopy

This paper reports on an initial investigation into the operation of a mode-locked fiber laser system for application in gas spectroscopy as a multipoint multigas sensor. Wavelength selection is performed by use of multiple chirped gratings and fine tuning by using the dispersion properties of the chirped gratings. A tuning rate of /spl sim/0.014 nm per kHz change in mode-lock frequency (at the third harmonic) has been demonstrated, which is suitable for scanning across gas absorption lines. Key issues that have an important bearing on the tuning are discussed, including gain flattening and polarization drift. This paper investigates a method of multiplexing the sensor cells with the mode-locked system. Preliminary results for a two cavity system are presented to verify the principles of the technique.     

基于半导体可饱和吸收镜的可调谐光纤激光器

为了实现锁模光纤激光器的波长可调谐, 采用半导体可饱和吸收镜(SESAM), 搭建了环形腔被动锁模掺镱光纤激光器。在腔内无偏振控制器及可调谐滤波器等器件的前提下, 通过改变光纤跳线端面至SESAM的距离, 实现光谱在1029.5nm~1042.7nm之间的稳定可调谐, 基频重复频率为18.0MHz, 脉冲宽度为130ps, 锁模脉冲信噪比达44dB。结果表明, 该锁模光纤激光器具有较高的信噪比及较宽的可调谐范围。该研究为可调谐被动锁模光纤激光器的研制提供了重要的参考价值。     

Multiwavelength pulse generation using an actively mode-locked erbium-doped fiber ring laser based on distributed dispersion cavity

A simple design of a stable multiwavelength pulse generator was demonstrated using a dispersion-tuned actively mode-locked erbium-doped fiber (EDF) ring laser with distributed dispersion cavity. The distributed dispersion cavity in the fiber laser successfully reduced the cross-gain saturation in EDF, and thus, enabled multiwavelength operation. Simultaneous generation of wavelength-tunable 10-GHz pulses up to four different wavelengths was achieved with the same wavelength space of 2.94 nm. The extinction ratio of all wavelengths was above 30 dB. In addition, smooth wavelength tuning was achieved over more than 41 nm when the laser was working at dual-wavelength mode. The super mode noise was /spl sim/60 dB below the signal level at both wavelengths. The laser state was found to be very stable.     

78 fs被动锁模掺Er3+光纤激光器

用性能稳定的976 nm激光二极管(LD)作为抽运光源,利用非线性偏振旋转(NPR)作为可饱和吸收体,实现了环形腔结构的被动锁模掺Er3 光纤激光器.在抽运功率为57 mW时,通过调节与波长无关的全光纤在线偏振控制器,获得了谱线宽度为40.8 nm,中心波长1544.0 nm,脉冲宽度为78 fs的稳定飞秒脉冲激光,其重复频率为11.18 MHz,平均输出光功率为5.4 mW,单个脉冲能量为0.5 nJ,峰值功率为6200 W.     

被动调Q锁模掺镱光纤激光器

报道了基于偏振旋转技术等效快可饱和吸收体的被动调Q锁模光纤激光器,采用976 nm半导体激光器作为抽运源,高掺杂浓度的Yb3 光纤作为增益介质构成环形腔,通过调节抽运光功率和偏振控制器的角度得到了调Q,调Q锁模与锁模三种稳定的输出脉冲。获得的锁模脉冲中心波长为1.05μm,重复频率为20 MHz,脉冲光谱宽度为13.8 nm,抽运功率为270 mW时,锁模平均输出功率为15.82 mW;调Q频率为17.54 kHz,调Q脉冲宽度为8μs,光谱宽度为4.7 nm;调Q锁模中调Q重复频率为300 kHz。     

掺Yb3 光纤环形腔锁模激光器的实验研究

报道了以掺Yb^3＋光纤作为增益介质的环形腔光纤激光器产生超短脉冲的实验研究。在掺Yb^3＋光纤环形腔激光器中，通过调节偏振控制器（PC）的状态和减少腔内损耗，利用非线性偏振旋转效应实现被动锁模，通过改变泵浦功率分别获得了调Q锁模和锁模2种稳定运转状态。其中，调Q锁模的中心波长为1051nm，激光光谱宽度为11．5nm；锁模输出的中心波长为1051nm，激光光谱宽度为13．8nm，重复频率为19MHz。给出了实验结果并作了简要的分析。     

6 MHz重频调谐范围的稳定锁模掺镱光纤激光器

针对精密测量的实际应用需求,开发了具有6 MHz重复频率调谐范围的掺镱锁模光纤激光器。该光纤激光器利用啁啾光纤光栅实现色散补偿,可以实现不同色散域的锁模。实验中,系统研究了不同腔内净色散对锁模激光器输出特性和稳定性的影响,发现当具有一定负腔内净色散时,在不同的重复频率下都可以输出相同的光谱,同时输出光谱具有较好的高斯型。根据以上研究,特殊设计了稳定的简化腔结构和空间延迟线,同时优化了腔参数,保证了大范围的重复频率调谐和稳定的锁模运转。当中心重复频率为26 MHz 时,调谐比率达到23%。激光器稳定输出平均功率为3.23 mW的飞秒激光脉冲,去啁啾后脉冲宽度为347 fs。基于此,将光纤锁模激光器重复频率锁定于铷原子钟,在1 s的平均时间内获得了2×10?10的艾伦方差。