高非线性光纤正常色散区产生超连续谱的数值研究

基于广义非线性薛定谔方程,通过数值计算对高非线性光纤正常色散区产生超连续谱进行了研究.结果表明,抽运脉冲的峰值功率、脉冲宽度以及脉冲初始啁啾对该光纤正常色散区超连续谱的形成有极其重要的影响;在高非线性光纤正常色散区产生超连续谱的过程中,三、四阶群速度色散甚至更高阶群速度色散对超连续谱的影响完全可以忽略,但与其他高非线性效应相比,自陡峭效应对超连续谱产生的影响更为明显.高功率超短光脉冲在高非线性光纤正常色散区,得到了没有泵浦成份残余、－20 dB谱宽达400 nm以上而频谱强度起伏小于10 dB的超宽而平坦超连续谱.     

高功率、低量子亏损同带抽运掺镱光纤放大器

开展了基于同带抽运的高功率、低量子亏损的掺镱光纤放大器实验研究. 搭建了一台输出功率为21 W的1018 nm短波 长掺镱光纤激光器, 并利用其对双包层掺镱光纤进行同带抽运, 获得18.6 W的1080 nm波段激光输出, 光-光转换效率高达90.86%. 关键词： 光纤放大器 同带抽运 双包层光纤 转换效率     

All-channel tunable optical dispersion compensator based on linear translation of a waveguide grating router

We propose and demonstrate a compact tunable optical dispersion compensation (TODC) device with a 100 GHz free spectral range capable of mitigating chromatic dispersion impairments. The TODC is based on longitudinal movement of a waveguide grating router, resulting in chromatic dispersion compensation of ±1000 ps/nm. We employed our TODC device for compensating 42.8 Gbit/sec differential phase-shifting keying signal, transmitted over 50 km fiber with a -2 dB power penalty at 10??.     

Raman-Assisted Passively Mode-Locked Fiber Laser

We propose and demonstrate a Raman-assisted passively mode-locked Yb-doped fiber laser in a normal dispersion regime. A section of highly nonlinear fiber is adopted to enhance the nonlinearity to extend the bandwidth of the gain spectrum by the stimulated Raman effect. The mode-locked fiber laser emits a broad spectral bandwidth of 64 nm at the-20 dB level and a highly stable pulse operation with a signal-to-noise ratio of 77 dB.     

(1+1)型长距离侧面泵浦光纤实现17.4 kW激光输出

长距离侧面泵浦激光光纤在泵浦光注入、热管理、非线性抑制等方面具有天然优势,是实现高功率激光输出的有效途径。研制了（1+1）型长距离侧面泵浦激光光纤,采用1018 nm同带泵浦反向注入方式实现了17.4 kW激光输出,斜率效率为82.1%,3 dB线宽为1.3 nm,拉曼抑制比为37.8 dB。研究结果展示了长距离侧面泵浦光纤作为数十千瓦光纤激光放大器增益介质的巨大应用潜力。     

色散位移光纤反常色散区平坦超宽超连续谱的产生

采用一种在色散位移光纤反常色散区产生平坦超宽超连续谱的方法。利用数值计算对色散位移光纤反常色散区高阶孤子压缩效应产生超连续谱展开了全面、深入的研究。结果表明,在色散位移光纤的反常色散区色散斜率(三阶色散)对超连续谱的形成起着决定性的作用;进一步研究表明,抽运脉冲的峰值功率及脉宽对超连续谱的谱宽和平坦度都有着重要影响,而高阶非线性效应对超连续谱产生没有显著影响。综合考虑以上因素,超续谱的谱宽和平坦度可以获得最大的优化。     

Tunable Supercontinuum Generated in a Yb~(3+)-Doped Microstructure Fiber Pumped by Ti:Sapphire Femtosecond Laser

We experimentally demonstrate that a tunable supercontinuum(SC) can be generated in a Yb3+-doped microstructure fiber by the concept of wavelength conversion with a Ti:sapphire femtosecond(fs) laser as the pump.Experimental results show that an emission light around 1040 nm in an anomalous dispersion region is first generated and amplified by fs pulses in the normal dispersion region. Then, SC spectra from 1100 to 1380 nm and 630 to 840 nm can be achieved by combined effects of higher-order soliton fission and Raman soliton self-frequency shift in the anomalous dispersion region and self-phase modulation, dispersive wave, and four-wave mixing in the normal dispersion region. It is also demonstrated that the 20 nm change of pump results in a 280 nm broadband shift of soliton and the further red-shift of soliton is limited by OH-absorption at 1380 nm.     

Narrowband phase sensitive fiber parametric amplifier

We describe a widely tunable phase sensitive fiber amplifier, based on narrowband parametric amplification in dispersion shifted fiber. Using a fiber with a zero dispersion wavelength of 1549?nm and a pump wavelength in the range of 1549?nm to 1532?nm, we obtained phase sensitive amplification between 1344?nm and 1781?nm, for an overall wavelength range of 437?nm. The amplifier threshold power is 7?W, and the maximum gain is 50?dB at a pump peak power of 25?W. The variance in gain due to phase sensitivity was measured to be up to 15?dB.     

Chirped pulse amplification with a nonlinearly chirped fiber Bragg grating matched to the Treacy compressor

We demonstrate a fiber chirped pulse amplification system that uses an engineered nonlinearly chirped fiber Bragg grating stretcher dispersion matched to the Treacy compressor. The seed pulses at 1558 nm are stretched to 720 ps, amplified by more than 50 dB to 6.5-microJ energy, and recompressed to 940 fs. After almost 1000 times compression the pulses are within 30% of the bandwidth limit and have a contrast ratio of better than 30 dB.     

Sub-60-fs ytterbium-doped fiber laser with a fiber-based dispersion compensation

We present a mode-locked ytterbium fiber laser with a higher-order mode fiber compensating the group-velocity dispersion and partially the third-order dispersion of the single-mode fiber at a wavelength of 1 microm. The generated pulses had an energy of 0.5 nJ and could be dechirped externally to a pulse duration of less than 60 fs. The power spectrum shows a spectral full width at half-maximum of 57 nm.     

All-fiber Yb:fiber frequency comb

We demonstrate an all-fiber Yb:fiber frequency comb with a nonlinear-amplifying-loop-mirror-based Yb:fiber laser oscillator. The fiber-spliced hollow-core photonic bandgap fiber was used as dispersion compensator, which was also directly spliced to a piece of tapered photonic crystal fiber for an octave-spanning spectrum. The spectrum of the compressed 107 fs laser pulses was broadened, covering 600 nm to 1300 nm in a high-nonlinearity tapered fiber for f to 2 f beating. The signal-to-noise ratio of offset frequency was measured to be 22 dB.     

一种与标准单模光纤高适配的低弯曲损耗光子晶体光纤

设计并研制出一种与普通单模光纤高适配的低弯曲损耗光子晶体光纤. 结构采用光纤预制棒制作工艺上易于实现的掺锗芯六孔结构. 应用间接测量方法, 对其模式、弯曲及色散特性进行了系统的评估. 在波长1550 nm处研制光纤的模场面积为79.26 μm², 色散为21.7 ps·km^-1·nm^-1, 模场面积和色散特性与标准单模光纤具有高的适配性. 在光纤弯曲半径为5 mm时, 在波长1550 nm处的弯曲损耗为0.0365 dB/圈, 小于G.657B的弯曲损耗0.5 dB/圈. 研究成果为光纤到户用低弯曲损耗光纤的实用化奠定了良好的基础. 关键词： 光子晶体光纤 低弯曲损耗 光纤到户 高适配性     

全固双层芯色散补偿光子晶体光纤的研究与设计

为了补偿光纤色散对高速信号传输的限制,提出一种全固双层芯色散补偿光子晶体光纤.首先对该光纤模式耦合特性进行理论分析,然后利用多极法进行模拟计算,得到该光纤包层结构参数与色散值以及相位匹配波长之间的关系,并对其规律进行研究.通过优化光纤结构参数,得到在1 550nm处,色散值达到-32 620ps/(nm·km)、损耗为0.29dB/km、与标准单模光纤的熔接损耗为4.77dB的色散补偿光纤.该光纤可补偿1 910多倍长度的SMF-28单模光纤的色散,补偿能力远大于常规色散补偿光纤.与空气孔-石英结构色散补偿光子晶体光纤相比,全固色散补偿光子晶体光纤具有易制备、易与传统通信光纤熔接等优点.     

Linear cavity fiber laser with 100 nm wavelength tuning range

We report a 100 nm widely tunable double-clad Ytterbium doped fiber laser. The fiber laser has a linear cavity configuration, where the feedback is provided by a Sagnac fiber mirror on one side, and an external bulk grating on the other side. On the bulk grating side, the fiber has a balled curved-core-termination that suppress backreflection by roughly 50 dB, and does not affect the pump coupling efficiency. The tuning range goes from 1055 nm through 1155 nm, with a maximum output power of 360 mW at 1080 nm, and 0.3 nm linewidth.     

Simultaneous Compensation of Dispersion and Losses using Er-Doped Double-Core Optical Fiber

The Er-doped double-core dispersion compensating fiber (EDDCF) has been fabricated using modified chemical vapor deposition (MCVD) technique. We have obtained 14 dB gain at 1550 nm (using a diode laser of 980 nm wavelength which provides 100 mW of pump power) with dispersion of about −165 ps/km nm. It is useful for the optical fiber network where amplification as well as negative dispersion is necessary. We are the first to report the experimental realization and characterization of the EDDCF.     

大容量长距离传输用低非线性效应非零色散位移光纤

利用非等温等离子体化学气相沉积 (PCVD)工艺制备了一种适合于大容量高速率长途干线网与城域网的中芯下陷型纤芯结构非零色散位移光纤。该光纤的有效面积大于 95 μm2 ,在 15 5 0nm波段的色散值约为9ps/(nm·km) ,有效的抑制了传输过程中光非线性效应的产生。通过对光纤剖面结构的优化设计 ,光纤的 15 5 0nm处的传输损耗降到约 0 .2 1dB/km ,与传统单模光纤的熔接损耗低于 0 .11dB ,且在直径为 6 0mm圆筒上绕 10 0圈后在 14 6 0nm到 16 2 5nm波长范围所引起的附加弯曲损耗均低于 0 .0 2dB/km。同时 ,该光纤色散斜率低于0 .0 6 5 ps/(nm2 ·km) ,偏振模色散 (PMD)小于 0 .0 5 ps·km-1/2 。此外 ,由于光纤的零色散点移到了 14 30nm以下 ,使波分复用 (WDM)传输在S波段 (14 6 0～ 15 30nm)、C波段 (15 30～ 15 6 5nm)、L(15 6 5～ 16 2 5nm)波段上都兼容。     

Investigation of all-solid photonic bandgap fiber with low losses in low-order bandgaps

We report synoptically an investigation of design, fabrication and characterization of a new all-solid photonic bandgap fiber. By introducing an index depressed layer around a high index core in every unit cell of photonic crystal cladding, a novel all-solid bandgap fiber is predicted to obtain low confinement and bend losses within low-order bandgaps. After optimizing the structure parameters, we fabricate a batch of rods used for cladding cells, select a pure-silica rod for core cell and an inner-hexagonal jacket tube. We demonstrate an all-solid bandgap fiber with the transmission loss as low as 2 dB/km at 1,310 nm and a bandwidth of over 700 nm within the first bandgap. The guiding properties are also measured, respectively, such as transmission spectrum, attenuation spectrum, bend loss, mode field intensity profile, and chromatic dispersion.     

Simultaneous measurement of anomalous group-velocity dispersion and nonlinear coefficient in optical fibers using soliton-effect compression

We present a novel and simple method to measure both the value of the second-order dispersion coefficient and the nonlinear coefficient in optical fibers. This method is based on the higher-order soliton-effect pulse compression phenomenon and is valid for dispersion values greater than 0.5 ps/km/nm. A non-zero dispersion-shifted fiber, a standard single-mode fiber and a highly-dispersive highly-nonlinear fiber have been measured using this method.     

Demonstration of soliton self-frequency shift below 1300 nm in higher-order mode, solid silica-based fiber

We demonstrate soliton self-frequency shift of more than 12% of the optical frequency in a higher-order mode solid, silica-based fiber below 1300nm. This new class of fiber shows great promise for supporting Raman-shifted solitons below 1300nm in intermediate energy regimes of 1 to 10nJ that cannot be reached by index-guided photonic crystal fibers or air-core photonic bandgap fibers. By changing the input pulse energy of 200fs pulses from 1.36 to 1.63nJ we observe Raman-shifted solitons between 1064 and 1200nm with up to 57% power conversion efficiency and compressed output pulse widths less than 50fs. Furthermore, due to the dispersion characteristics of the HOM fiber, we observe redshifted Cerenkov radiation in the normal dispersion regime for appropriately energetic input pulses.     

Experimental realization of a novel dispersion- compensating optical fiber amplifier for simultaneous compensation of positive dispersion and losses

Erbium-doped dispersion-compensating optical fiber (EDCF) has been theoretically simulated and experimentally fabricated using Modified Chemical Vapor Deposition (MCVD) for optimum operation at 5.0km. It is optimized for both gain as well as negative dispersion. The erbium has been doped into the cladding region while the core of the optical fiber is chosen to be narrow so as to have a high negative dispersion. Measured gain of 3.1 dB at 200 m using 100 mW pumping power (980 nm wavelength) at 1550 nm has been obtained and the gain of 32 dB at 5.0 km using same pumping scheme has been predicted. The chromatic dispersion of this EDCF has been also measured to be –43.5 ps/km-nm at 1550 nm and thus, providing the dispersion of –217.5 ps/nm at 5 km. The bend-induced losses are found to be negligible. We are the first to report the experimental realization of EDCF.