Optical pulse compression using a nonlinear optical loop mirror constructed from step-decreasing-dispersion fiber

Ultrashortopticalpulseisanimportantpartofsoli ton basedcommunicationsystem.Oneofthemainmeth odsofgenerationoftheultrashortopticalpulseisapulse compressiontechnique.Presently,twowidelya doptedwaysofpulse compressiontechniquesarethead iabaticcompressionindi…     

Switchable dual-wavelength erbium-doped fiber laser based on the photonic crystal fiber loop mirror and chirped fiber Bragg grating

The switchable dual-wavelength erbium-doped fiber laser(EDFL) with a two-mode photonic crystal fiber(PCF) loop mirror and a chirped fiber Bragg grating(CFBG) at room temperature is proposed and experimentally demonstrated.The two-mode PCF loop mirror is formed by inserting a piece of two-mode PCF into a Sagnac loop mirror,with the air-holes of the PCF intentionally collapsing at the splices.By adjusting the state of the polarization controller(PC) appropriately,the laser can be switched between ...     

一种新型的可调谐非线性啁啾光纤光栅制造技术

利用Matlab模拟了一种新型的非线性啁啾光纤光栅,当对光栅施加纵向应力时,通过改变光栅的调制周期来实现光栅啁啾的非线性,应力的改变是通过磁场的磁致伸缩效应来实现的．     

A fiber Bragg grating sensor demodulation technique using apolarization maintaining fiber loop mirror

We propose and experimentally demonstrate a simple, passive, and self-referencing wavelength shift detection scheme for use in fiber Bragg grating sensing systems. The demodulation system is based on the interference between two modes in a polarization maintaining fiber loop mirror. Although it involves the use of an interference technique, it is stable compared with other conventional interference demodulators     

Soliton-like pulse train generation using a nonlinear optical loop mirror constructed from dispersion decreasing fiber

A nonlinear optical loop mirror constructed from dispersion decreasing fiber is used to generate a high-quality pulse train from a dual frequency beat signal. Numerical simulations show that, unlike previous techniques based on adiabatic compression in dispersion decreasing fibers which limited the repetition rates to >50 GHz, the proposed method does not use adiabatic compression and can be extended to repetition rates <20 GHz using reasonable fiber lengths.     

Tunable passive all-optical pulse repetition rate multiplier using fiber Bragg gratings

We demonstrate a tunable passive all-optical pulse repetition rate multiplier based on the fractional temporal Talbot effect. The multiplier comprises a series of identical linearly chirped fiber Bragg gratings (LCFBGs) interconnected via two multiport (N/spl times/N) switches. Discrete multiplication factors are obtained by simply using the switch to set the optical path of the input pulse train to be reflected by the required number of gratings, and hence, corresponding dispersion, to satisfy the Talbot condition. In our demonstration, we reflect an 8.62-GHz input pulse train from a cascade of one to four LCFBGs, resulting in discrete repetition rate multiplication factors of 12, 6, 4, and 3, respectively. We obtain output repetition rates exceeding 100 GHz; the multiplied train exhibits excellent signal stability with low amplitude ripple and timing jitter, and the output pulses are of similar duration to those at the input.     

啁啾光栅解调的准分布式光纤Bragg光栅传感器

为了提高光纤Bragg光栅(FBG)的应用范围.提出一种线性啁啾光栅(CFBG)解调的准分布式FBG传感系统.利用波导理论分析了CFBG特性;利用传输矩阵法推导了CFBG反射谱模型及波长与相位延迟的关系,并给出了相位延迟曲线.实验表明:所设计的系统应变测量范围为0～2000 με,温度测最范围为0～80℃;相位变化与被...     

Wavelength switching of semiconductor laser pulses by self-seeding from a chirped fiber Bragg grating

Wavelength switching of four wavelengths spanning 5.1 nm was realized by gain switching and self-seeding of a commercial Fabry-Perot (F-P) laser diode with a single in-fiber linearly chirped Bragg grating as the external cavity. A driving frequency up to 2 GHz was used and single mode operation with a side mode suppression ratio of 10 dB overall and 25 dB at best was achieved.     

Improved transmission of chirped signals from semiconductor opticaldevices by pulse reshaping using a fiber Bragg grating filter

Spectral filtering of chirped signals with an edge of a fiber grating filter improves propagation in nondispersion-shifted fiber. The improvement is due to a temporal shift of the frequency modulation with respect to the amplitude modulation. By filtering the chirped output of a semiconductor optical amplifier (SOA) wavelength converter with a fiber grating edge we obtain error-free transmission of converted data through 100 km of nondispersion-shifted fiber at 5 Gb/s     

Generation of customized ultrahigh repetition rate pulse sequences using superimposed fiber Bragg gratings

We propose and experimentally demonstrate the use of superimposed fiber Bragg gratings (FBGs) as amplitude or phase filtering stages for generating ultrahigh-repetition-rate optical pulse bursts from a single ultrashort pulse. This approach offers the advantages of a compact all-fiber solution and provides high flexibility in tailoring the temporal features of the generated pulse sequence, namely, the repetition rate, as well as the shape and duration of both the individual pulses and the temporal envelope of the burst. To demonstrate the capabilities of the proposed approach, we generate near-flat-topped optical pulse bursts with repetition rates as high as /spl ap/170 GHz at a wavelength of 1.55 /spl mu/m using uniform and linearly chirped superimposed FBGs. We show that superimposed linearly chirped FBGs are more energetically efficient and provide increased design flexibility than superimposed uniform FBGs. Our experimental results also show the robustness of the technique to imperfections in the grating structures and to variations in the input pulse quality.     

基于啁啾FBG的三角形光脉冲发生器的优化设计

提出了利用啁啾光纤布拉格光栅(FBG)和马赫增德尔调制器产生三角形光脉冲的优化方案.方案采用FBG模拟单模光纤的色散特性,结合光载波抑制调制产生了三角形光脉冲, 并通过仿真分析,选择FBG的长度、调制深度、适当的折射率切趾函数对三角形光脉冲的线性特征进行了优化.仿真结果表明,在同一啁啾系数下,产生的三角形光脉冲的失真程度随啁啾光纤光栅的调制深度增大而增大,光栅长度、折射率切趾函数对三角形光脉冲的影响也比较明显.与现有系统相比,由于将FBG引入系统,省去长距离的光纤,优化方案系统结构更为简单,三角形光脉冲线性特征更好.     

基于分布增益非线性光纤环镜的弱脉冲放大与压缩

已有研究发现,用分布增益非线性光纤环镜放大和压缩超短光孤子不仅能避免常规掺铒光纤放大器中由于非线性效应引起的孤子崎变,而且可克服绝热放大技术放大器长度随输入脉宽增大而指数规律增大的困难。我们进一步计算了弱脉冲在分布增益非线性光纤环镜中的放大和压缩过程。结果表明,对于峰值功率比基阶孤子低得多的弱脉冲输入,用分布增益非线性光纤环镜同样可实现无崎变的脉冲能量放大和脉宽压缩;而且,经环镜放大输出的脉冲也接近基阶孤子。然而,输入脉冲峰值功率越低,实现最佳放大所需的环镜总增益越大,高阶效应对放大结果的影响越显著。     

利用光纤环形镜开关特性与孤子压缩效应获得无基座超短光脉冲

利用色散渐减光纤中高阶孤子非绝热压缩及非线性环形腔镜的消基座作用获得高质量无基座超短光脉冲.可以把波长为1.55 μm,脉宽为20 ps的光脉冲压缩为1.42 ps无基座超短脉冲.并与直接用色散渐减光纤的非绝热孤子压缩得到的同宽度光脉冲分别在光纤正负色散区传输进行了比较,发现用色散渐减光纤构成的非线性光纤环形腔镜获得的压缩光脉冲具有相对理想的波形和频谱结构,有利于在光纤中长距离稳定传输.     

High-quality pulse compression in a novel architecture based on a single-mode fiber cascading a nonlinear optical loop mirror

A novel all-fiber low-pedestal pulse compression scheme is proposed and investigated. The scheme is based on an anomalously dispersive single-mode fiber(SMF) cascading a nonlinear optical loop mirror(NOLM) with another anomalously dispersive SMF in the loop. Numerical results show that excellent pulse compression and pedestal reduction can be achieved by using the proposed scheme.     

L-band tunable erbium doped fiber ring laser using fiber loop mirror filters

We present a novel and efficient L-band wavelength-tunable Er^3＋ doped fiber laser of ring structure. In the cavity two segments of Er^3＋ doped fiber and a fiber Bragg grating are used to improve pump efficiency. Tunable filters based on fiber loop mirrors are also applied inside the cavity to act as both a wavelength selector and a line-width compressor. Using these techniques, a tunable laser with tuning range up to 42 nm, output power larger than 1 mW, power uniformity controlled within 1.75 dB and side mode suppression ratio about 40 dB is achieved.     

Picosecond square pulse generation using nonlinear fibre loop mirror

Square pulses with controllable picosecond durations have been generated from a CW input signal in the region of 1.5 mu m by using switching in a nonlinear loop mirror. The square pulses are generated in synchronism with a pulsed driver which can be a noise burst. Shaped pulses have also been derived using this technique.<>     

Simultaneous interrogation of fiber Bragg grating sensors using anacoustooptic tunable filter

We describe a novel technique to provide demultiplexing of fiber Bragg grating sensors, interrogated using interferometric wavelength shift detection. Amplitude modulation of multiple radio frequency driving signals allows an acoustooptic tunable filter to provide wavelength demultiplexing. We demonstrated a noise limited strain resolution of 150 nanostrain/√(Hz) and a crosstalk better than -50 dB     

Electrical wavelength-tunable actively mode-locked fiber ring laserwith a linearly chirped fiber Bragg grating

Electrical wavelength-tunable picosecond laser pulses were demonstrated in an actively mode-locked fiber ring laser with a linearly chirped fiber Bragg grating (FBG). Continuous wavelength tuning with a range of 7.2 or 5.8 mm was achieved by changing the modulation frequency respectively around 2.48 or 6.3 GHz. A pulsewidth of about 20 ps was obtained in the entire tuning range, which was limited mainly by the reflection bandwidth of the FBG     

Rectangular pulse generation based on pulse reshaping using asuperstructured fiber Bragg grating

We present a technique for the shaping of short pulses based on the use of superstructured fiber Bragg gratings (SSFBGs). We apply this technique to demonstrate the generation of 20-ps rectangular pulses by phase and amplitude profiling of 2.5-ps soliton pulses. Numerical calculations validate our experimental findings     

Apodized chirped fiber Bragg grating for postdispersion compensation in wavelength division multiplexing optical networks

In this paper, a postdispersion compensation unit is proposed leading to a better performance for the optical communication systems. This unit utilizes a chirped fiber Bragg grating (CFBG). For enhanced performance of the CFBG, a proper apodization function is chosen to improve the quality factor (Q‐factor) and the bit error rate (BER) of the system. A 110‐km wavelength division multiplexing (WDM) optical link is investigated. The system performance is evaluated through its Q‐factor, eye diagram, and BER showing best performance when using the Hamming apodization function.