类明孤子脉冲在单模光纤中传输特性的变分研究

应用变分法,研究了三阶色散对类明孤子脉冲在单模光纤中的传输特性,导出了类明孤子脉冲参数的演化方程组。     

Wavelength-tunable multicolor Raman soliton generation using an ellipse polarized pump pulse and highly birefringent optical fibers

Wavelength-tunable multicolor optical pulse generation based on the self-frequency shift of a Raman soliton was demonstrated. An ellipse polarized pump source, a highly birefringent (HB) optical fiber, and a highly nonlinear dispersion-shifted fiber were used to generate Raman soliton pulses. The wavelength was tuned by controlling the polarization of the pump source. Raman soliton pulses with six different colors and low wavelength crosstalk under 20 dB have been successfully generated.     

Compact system of wavelength-tunable femtosecond soliton pulsegeneration using optical fibers

Using passively mode-locked femtosecond (fs) fiber laser and polarization maintaining fibers, the compact system of wavelength-tunable femtosecond (fs) fundamental soliton pulse generation is realized. The monocolored soliton pulse, not multicolored ones, with the ideal sech² shape is generated, and its wavelength can be linearly shifted by varying merely the fiber-input power in the wide wavelength region of 1.56-1.78 μm for a 75-m fiber. The soliton pulses of less than 200 fs are generated with the high conversion efficiency of 75%-85%. This system can be widely used as a portable and practical wavelength-tunable fs optical pulse sources     

Integrated optical, acoustically tunable wavelength filter

A TM/TE convertor is combined with a TE-pass polariser on a common LiNbO/sub 3/ chip to obtain an integrated optical, acoustically tunable wavelength filter. Its tuning range is 1.45-1.57 mu m wavelength with a filter half-width of 2.8 nm. Due to the combined acoustical/optical strip guide structure used in the mode convertor, a very low acoustic drive power of only 9 mW is required.<>     

Effective generation of tunable single- and multiwavelength optical pulses from a Fabry-Perot laser diode

A tunable pulse source capable of both single- and multiwavelength oscillations has been developed by self-injection seeding of a laser diode. A side-mode-suppression ratio (SMSR) of about 20 dB has been obtained in the outputs. The key element in our setup is a wavelength multiplying stage consisting simply of 50/50 beam splitters, a diffraction grating, and a mirror. The maximum number of available wavelengths increases rapidly with the beam splitters. Our scheme can be adopted for use in high-speed wavelength switching.     

Zero-dispersion wavelength mapping in short single-mode optical fibers using parametric amplification

We demonstrate a novel convenient nondestructive method based on optical parametric amplification that allows retrieval of the zero-dispersion wavelength map along a short optical fiber span with a high-spatial resolution. The improved resolution relies on the high sensitivity to the local longitudinal dispersion fluctuations of the parametric high-gain spectrum.     

Theory of quasi-linear pulses in optical fibers

The evolution of quasi-linear pulses in optical fibers, with strong dispersion management, is studied analytically. The nonlinear terms of the Gabitov–Turitsyn equations are analyzed asymptotically. In this paper, the polarization preserving fibers as well as the birefringent fibers are studied. Finally, the study is extended to the case of multiple channels, namely dispersion flattened fibers. The numerical simulations support the analysis.     

The compression of optical pulses using self-phase-modulation andlinearly chirped Bragg-gratings in fibers

We report the first demonstration of pulse compression in optical fiber using linearly chirped Bragg gratings as quadratic compressors for pulses spectrally broadened by self-phase modulation. With the system investigated an initial 2 ps, bandwidth limited pulse is compressed by a factor of >10. The experimental results are found to be in good agreement with analytical and numerical calculations. Such a system allows high quality compression of pulses in optical fiber for the first time     

可调谐双波长低抖动增益开关光脉冲的产生

提出了一种产生可调谐双波长低抖动超短光脉冲的新方法。采用外光注入法来降低增益开关F-P激光脉冲的时间抖动,实现了脉冲光谱的双波长可调谐输出。实验中利用两个多量子阱DFB激光器作为外部种子光源,通过温度控制和偏振态调节使外部种子光有效地耦合到增益开关F-P激光器中,输出的光脉冲时间抖动(均方根)从2.57ps降低至1.06ps,双波长的边模抑制比可达25dB。通过改变DFB激光器和F-P激光器的工作温度,可实现波长从1540nm到1560nm的可调谐输出。     

Widely (132 nm) wavelength tunable laser using a semiconductor optical amplifier and an acousto-optic tunable filter

A widely wavelength tunable laser combining a semiconductor optical amplifier, an acousto-optic tunable filter and a Fabry-Perot etalon has been developed. It exhibited good characteristics over a 132 nm (1480-1612 nm) tuning range.     

Second-harmonic generation by picosecond optical pulses

The generation of second-harmonic radiation in a non-linear dielectric by an arbitrary broad-band optical signal is analyzed and application of the theory is made to harmonic generation by a short pulse. The spectrum and time dependence of the harmonic radiation is calculated in terms of the corresponding quantities for the fundamental pulse. Several types of pulses, including a frequency-swept pulse, are treated. Experimental results on the second-harmonic spectrum are presented and compared with the theory, as are previously reported results on the time dependence.     

Multichannel FSK experiment using an optical amplifier repeater and wavelength tunable direct detection receiver

A four channel direct detection FDM operating at 565 Mbit/s with a channel spacing of 12 GHz which achieves a receiver sensitivity of -40 dBm is reported. A laser preamplifier is used to overcome the optical processing loss of the channel selective filter.<>     

Widely tunable wavelength converter using a double-ring fiber laser with a semiconductor optical amplifier

Widely tunable wavelength conversion has been demonstrated using broad-band orthogonal-pump four-wave mixing in a semiconductor optical amplifier placed at the intersection of two fiber ring lasers. The all-optical wavelength converter operates without using any external pump source. A 3-dB conversion-range over 40 nm is obtained. The measured power penalty is 1.5 dB for a 2.5-Gb/s converted signal at 10/sup -9/ bit error rate.     

三阶色散对光纤中基孤子脉冲传输的影响

通过数值求解非线性薛定谔方程,研究了三阶色散效应对基孤子脉冲在单模光纤中传输的影响.结果表明,在三阶色散作用下,基孤子脉冲在传输过程中被展宽,峰值能量逐渐减小,脉冲形状发生畸变,脉冲的中心偏向一侧,并形成非对称的拖尾振荡结构;当与二阶色散共同作用时,三阶色散引起的脉冲振荡会变缓.考虑非线性效应后,在一定程度上补偿了由于色散效应导致的峰值功率的减小,同时抑制了非对称拖尾结构的产生.     

Temporal reshaping of optical pulses using quadratic spatialsoliton generation and spatial filtering

We perform a temporal reshaping of laser pulses by means of quadratic spatial soliton excitation combined with a spatial filtering of the output beam. We demonstrate that the device presents a behavior similar to the one of a saturable absorber, and numerically investigate the parameters giving optimum temporal filtering     

Broad-band wavelength tunable picosecond pulses from CW passivelymode-locked two-section multiple quantum-well lasers

Wavelength tunable CW (continuous-wave) passive mode-locking of a two-section quantum-well laser coupled to an external cavity is demonstrated. A tuning range of 26 nm is achieved with typical autocorrelation full widths at half maximum of 4.5 ps. The pulses are not transform limited, having a typical time-bandwidth product of 2.5     

Fiber Bragg grating for optical dark soliton generation

We investigate theoretically and experimentally the generation of dark soliton pulse trains at several gigahertz repetition rate by means of a fiber Bragg grating used as a passive filtering element at the output of a mode-locked laser. We show that a proper choice of the grating parameters allows for the transformation of bright pulse train into odd dark pulse trains with continuous-wave (CW) background.     

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.     

利用可调谐激光器产生可调谐的连续波光载信号

针对采用传统的电子器件的调频/连续波(FM/CW) 产生方法由于带宽限制无法达到较高分辨率的问题,提出一种基于增益开关可调谐半导体激 光器(TLD)产生高频FM/CW信号的方案,具有中心 频率和波长双重可调谐性、结构简单和易于扩展的特点与优势。本文方案可用于基于光纤无 线电(ROF,radio-over-fiber)技术 的多雷达头分布系统,可方便实现多通道切换。实验中,通过2GHz的调制信号,实现了10倍频20GHz的信号产生以及中心频率为10GHz 、带宽为500MHz的调频连续波信号产生。     

1.5 μm two-section Fabry-Perot wavelength tunable optical filter

A 1.5 μm two-section Fabry-Perot wavelength tunable optical filter is studied. As opposed to DFB filters, this wavelength tunable optical filter has the advantage that the wavelength tuning range and the transmission bandwidth can be designed independently. This two-section Fabry-Perot filter also controls the transmissivity (gain) and the transmission wavelength independently by current injection and the constant-gain and constant-bandwidth wavelength tuning is achieved. The wavelength tuning range is as wide as 188 GHz (15 Å), the constant-gain is as high as 23 dB and the constant-bandwidth is as narrow as 5 GHz during wavelength tuning. A 25-channel wavelength selection with less than -10 dB crosstalk is expected with this filter