Fluoride glass Raman fiber laser at 2185 nm

We report on the first Raman laser based on a fluoride glass optical fiber. The Raman fiber laser was pumped by a 9.6?WTm3+:silica CW fiber laser operating at a wavelength of 1940?nm. A maximum output power of 580?mW was measured at 2185.1?nm, corresponding to a frequency shift of 579?cm(-1) (17.37?THz). We observed a threshold power of 3.8?W and a low power slope efficiency of 29% with respect to the launched pump power. Using those results and the known fiber parameters, we estimated a Raman gain peak value of 3.52*10(-14)?m/W, which is lower than the previously reported values.     

Direct laser writing of near-IR step-index buried channel waveguides in rare earth doped YAG

A new (to our knowledge) ultrashort laser pulse irradiation regime that allows us to directly modify and increase the refractive index of rare earth doped YAG polycrystalline ceramics has been identified. Single-mode buried channel waveguides in both Ho:YAG and Er:YAG ceramics at the near-IR wavelengths of 1.55?μm and 1.95?μm are demonstrated by fabricating positive square step-index cores. Minimum propagation losses of 1.5?dB?cm(-1) at a 1.51?μm wavelength have been preliminarily obtained. Confocal microluminescence mapping reveals that the increased refractive index regions retain the near-IR spectral properties of Er3+ ions in the YAG crystalline matrix.     

基于铋基和硅基掺铒光纤联合的超宽带ASE光源

提出了并实验演示了利用247 cm新型铋基掺铒光纤和10 m传统硅基掺铒光纤联合作为增益介质、采用双向泵浦结构的超宽带放大自发辐射光源.分析了其物理机理,并与其它不同形式的结构,包括已报道的类似结构,做了实验比较和理论分析.在低于240 mW的总泵浦功率和没有使用任何外部谱平坦滤波器的情况下,通过优化传统硅基掺铒光纤长度和两泵浦源的功率,获得了96 nm（1 522 nm～1 618 nm）的波长范围（大于－20dBm/2nm功率密度时）和超过11dBm的总输出功率,该ASE光源的－10dB带宽超过了87nm,其谱的峰值功率密度达到了－2.5 dBm/2 nm.     

一种新型的专用于光学相干层析系统的宽带光纤光源

报道了一种新型的专用于光学相干层析系统的输出光谱为准高斯型的宽带超荧光光纤光源.该光源采用掺饵光纤作为增益介质.其关键技术是在抽运源的输出端增加了光耦合器，并在光源输出端插入多级长周期光纤光栅对铒离子的自发光谱进行调制和整形；同时采用光控器和温控器来控制抽运源的输出以提高光源输出功率的稳定性.该光源的中心波长为1.57μm，输出光谱的3dB带宽大于75nm，输出功率为27mW.实验结果表明，该光源输出光谱的自相关函数的旁瓣峰被大大削弱，可以满足光学相干层析系统的应用. 关键词： 光学相干层析术 超荧光光纤光源 长周期光纤光栅 光耦合器     

High-power broadband laser source tunable from 3.0 μm to 4.4 μm based on a femtosecond Yb:fiber oscillator

We describe a tunable broadband mid-IR laser source based on difference-frequency mixing of a 100?MHz femtosecond Yb:fiber laser oscillator and a Raman-shifted soliton generated with the same laser. The resulting light is tunable over 3.0?μm to 4.4?μm, with a FWHM bandwidth of 170?nm and maximum average output power up to 125?mW. The noise and coherence properties of this source are also investigated and described.     

2-μm mode-locked nanosecond fiber laser based on MoS_2 saturable absorber

We demonstrated a 2-μm passively mode-locked nanosecond fiber laser based on a MoS_2 saturable absorber(SA).Owing to the effect of nonlinear absorption in the MoS_2 SA, the pulse width decreased from 64.7 to 13.8 ns with increasing pump power from 1.10 to 1.45 W. The use of a narrow-bandwidth fiber Bragg grating resulted in a central wavelength and 3-dB spectral bandwidth of 2010.16 and 0.15 nm, respectively. Experimental results show that MoS_2 is a promising material for a 2-μm mode-locked fiber laser.     

Tunable passively Q-switched ytterbium-doped fiber laser using MoWS2/rGO nanocomposite saturable absorber

We demonstrated a tunable Q-switched ytterbium-doped fiber laser (YDFL) using MoWS₂/rGO nanocomposite as passive saturable absorber. Further, the Mo_1?xW_xS₂/rGO nanosheets, with x proportion of 0.2, are synthesized using hydrothermal exfoliation technique. The proposed nanocomposite-PVA based thin film is fabricated by mixing the MoWS₂/rGO nanosheets with polyvinyl alcohol (PVA). The fabricated thin film is sandwiched between two fiber ferrules to realize the proposed saturable absorber (SA). Further, the proposed MoWS₂/rGO-PVA based thin film SA exhibits a fast relaxation time and a high damage threshold which are suitable to realize a Q-switched pulsed laser with a tunable wavelength range of 10?nm that extends from 1028?nm to 1038?nm. For the highest pump power of 267.4?mW, the generated Q-switched pulses exhibit a narrow pulse width of 1.22 μs, the pulse repetition rate of 90.4?kHz, the highest pulse energy of 2.13?nJ and its corresponding average power of 0.193?mW. To the best of author’s knowledge, this is the first realization of a tunable Q-switching fiber laser in a 1?μm wavelength using MoWS₂/rGO nanocomposite saturable absorber.     

非相干光纤激光组束系统耦合效率的优化分析

单光束耦合效率是决定非相干组束系统输出功率的关键,它受到透镜焦距、光栅周期和光斑半径等参数的影响。为了寻求较为优化的系统参数,通过理论分析和仿真研究,结果表明对于中心波长1060nm的光纤激光,应当选择透镜焦距20cm,光栅周期5μm,并且需要将光斑半径控制在50μm左右。通过反解光栅频率及组束波长带宽的第一个零点来选择组束阵列宽度一定条件下较优的光栅参数。通过理论分析和数值计算,结果表明较小的光栅频率和光栅厚度对提高衍射效率是有利的。     

掺Er3+光纤环腔激光器的初步研究

本文报道采用环形腔使用偏振灵敏性光纤隔离器(P-SensitiveISO)构成的掺Er³⁺光纤激光器的激光输出特性研究结果.用976nm激光作为泵浦激光获得了0.42mW最大功率、中心波长1.5287μm的激光输出,阈值泵浦功率17mW.在改变腔内光纤偏振控制器(PC)的状态时,输出激光光谱分裂为二个分立的峰值,波长分别为1.5317μm和1.5502μm.     

Single-mode and tunable VCSELs in the near- to mid-infraredInvited Paper

Single-mode, long-wavelength vertical-cavity surface-emitting lasers (VCSELs) in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3μm are presented. This wide spectral emission range opens applications in gas sensing and optical interconnects. All these lasers are monolithically grown in the InGaA1As-InP material system utilizing a buried tunnel junction (BTJ) as current aperture. Fabricated with a novel high-speed design with reduced parasitics, bandwidths in excess of 10 GHz at 1.3 and 1.55 μm have been achieved. Therefore, the coarse wavelength division multiplexing (CWDM) wavelength range of 1.3 to 1.6 μm at 10 Gb/s can be accomplished with one technology. Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated. One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning. Micro-electro-mechanical system (MEMS) tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity. All these devices feature continuous-wave (CW) operation with typical single-mode output powers exceeding 1 mW. The operation voltage is around 1 - 1.5 V and power consumption is as low as 10 - 20 mW. Furthermore, we have also developed VCSELs based on GaSb, targeting at the wavelength range from 2.3 to 3.0 μm. The functionality of tunable diode laser spectroscopy (TDLS) systems is shown by presenting a laser hygrometer applying a 1.84-μm VCSEL.     

Compact double-layer subwavelength binary blazed grating 1×4 splitter based on silicon-on-insulator

We describe a compact double-layer waveguide grating splitter that not only achieves efficient coupling between single mode fiber and a silicon-on-insulator optical waveguide but also realizes effective splitting. By appropriate choice of waveguide/grating parameters, including thicknesses, periods, height, and fill factor to optimize the mode matching, coupling efficiency is improved and the value of power difference of each output port is also significantly decreased. The maximum of power difference between four output ports is about 6.2%; however, the minimum value is only 0.6% or so. Moreover, the average power difference of four output ports is lower than 10% for TE polarization light over the 10?nm wavelength bandwidth centered at 1.54?μm. In addition, the splitter structure has the best tolerance for grating fabrication with deviations of grating depth 90?nm.     

高效毛细管电泳法测定全天麻胶囊中天麻素的含量

建立了利用毛细管电泳技术测定全天麻胶囊中天麻素含量的新方法.所用熔融石英毛细管规格为50μm×60cm(有效长度为45cm),检测波长为220nm,分离电压为12kV,缓冲液为pH7.6的200mmol/L硼酸缓冲溶液.结果表明,天麻素在10-800μg/mL范围内线性关系良好(r=0.9995),加样回收率为98.5...     

掺铒硫系玻璃的制备及其微结构光纤的中红外信号放大特性研究

为进一步揭示硫系玻璃基掺Er³⁺微结构光纤对于中红外波段信号的放大特性, 采用熔融淬火法研制了Er³⁺离子掺杂的Ga₅Ge₂₀Sb₁₀S₆₅硫系玻璃, 测试了玻璃样品的吸收光谱和2.7 μm波段荧光光谱, 利用Judd-Ofelt和Futchbauer-Ladenburg理论分别计算得到了Er³⁺离子的辐射跃迁概率、辐射寿命以及2.7 μm波段受激发射截面. 在此基础上, 建立了一个980 nm抽运下该玻璃基掺Er³⁺微结构光纤2.7 μm波段中红外信号的放大模型, 理论上研究了其作为2.7 μm波段中红外信号增益介质时的光放大特性. 结果显示, 硫系玻璃基掺Er³⁺微结构光纤具有优异的高增益和宽带放大品性. 在200 mW抽运功率激励下的100 cm光纤长度上, 最大小信号增益超过了40 dB, 高于30 dB信号增益的放大带宽达到了120 nm (2696—2816 nm). 研究表明, Ga₅Ge₂₀Sb₁₀S₆₅硫系玻璃基掺Er³⁺微结构光纤是一种理想的可应用于2.7 μm波段中红外宽带放大器的增益介质.     

飞秒激光在光子晶体光纤中产生超连续光谱机制的实验研究

报道了利用零色散在780nm处的光子晶体光纤与纳焦耳量级的飞秒激光脉冲相互作用的实验结果.实验使用35fs，中心波长810—840nm，单脉冲能量可达14nJ的飞秒激光光源获得了超过一个倍频程的平坦超连续光谱（500—1100nm）.在不同功率、不同中心波长、不同啁啾和有无直流成分的多种飞秒脉冲激光的条件下，研究了超连续光谱的产生情况.并对一系列现象进行了对比，分析了超连续光谱产生的机制. 关键词： 光子晶体光纤 飞秒脉冲激光 超连续光谱     

CWDM source based on AlGaInAs/InP monolithically integrated DFB laser array

The monolithic integration of four 1.5?μm range AlGaInAs/InP distributed feedback lasers with a 4×1 multimode-interference optical combiner, a curved semiconductor optical amplifier, and an electro-absorption modulator using relatively simple technologies--sidewall grating and quantum well intermixing--has been demonstrated. The four channels span the wavelength range of 1530 to 1566?nm with a channel spacing of 12?nm. The epitaxial structure was designed to produce a far-field pattern as small as 21.2°×25.1°, producing a coupling efficiency with an angled-end single-mode fiber at twice that of a conventional device design.     

近紫外到近红外光谱辐射计及定标方法研究

为实现目标光谱辐射亮度的高精度测量，研制了一种小视场近紫外到近红外光谱辐射计，光谱范围为300 nm~2 000 nm，光谱辐射亮度测量范围为50μW/cm2·nm·sr~1 000μW/cm2·nm·sr。阐述了近紫外到近红外光谱辐射计设计原理及关键部件，使用基于钨带灯的直接定标法实现了光谱辐射计光谱辐射亮度绝对定标，测量了标准积分球光源的光谱辐射亮度，测量值与积分球光源标准值偏差优于0.5%。     

飞秒泵浦不同锥长微结构光纤超连续谱的产生

对飞秒脉冲泵浦下,不同锥长及锥腰直径的微结构光纤的超连续谱产生进行了实验研究。采用“快速低温拉锥方法”,在保持d/Λ不变的情况下,对实验室自制的空气孔间距Λ=6.53 μm,归一化孔径d/Λ=0.79的微结构光纤进行了拉锥,分别得到6,8,10 mm等不同锥长微结构光纤。理论计算表明,随着锥长变长,锥腰直径变小,锥腰处零色散波长向短波移动：未拉锥及6,8和10 mm锥微结构光纤锥腰处零色散波长分别为1 129,885,806和637 nm。利用中心波长为810 nm,重复频率76 MHz,脉宽120 fs的钛蓝宝石飞秒激光器对拉锥后微结构光纤进行了实验研究：锥长为6 mm时,泵浦光中心波长位于整根光纤的正常色散区,锥腰的零色散点附近,内脉冲拉曼散射和级联四波混频是光谱初始展宽的主要因素。泵浦功率达到450 mW时,在可见波段390～461 nm及红外波段1 134～1 512 nm形成-5 dB的平坦宽带连续光谱。泵浦功率达到500 mW时,出现366～2 450 nm覆盖紫外、可见、近红外、中红外的超连续谱,其光谱红蓝移边缘已经接近实验用微结构光纤的传输带宽。锥长为8 mm、泵浦功率为450 mW时,在群速度匹配和群加速度失配的共同影响下,连续谱蓝移边缘达到366 nm,比6 mm锥时蓝移9 nm;锥长为10 mm时,由于锥腰处零色散点移动到可见光区域,可见区光谱仍能满足相位匹配条件。通过级联四波混频效应,在可见区域实现了频率上转换及光谱蓝移。泵浦光功率达到500 mW时,在382～412 nm得到谱宽仅为30 nm,转换效率达到27.7%的频率上转换。     

S/S+ Band Tunable Thulium Doped Fiber Laser Anchored on 50 GHz ITU-T Grid

We demonstrate a S/S+ band tunable thulium doped fiber laser (TTDFL) anchored on 50GHz ITU-T Grid. Over 57nm of tuning range (1454.9 ～1512.0 nm) covering most of the Thulium bandwidth and more than 8dBm output power has been obtained with the pigtailed solid etalon filter and dual wavelength (1.5μm and 1.4μm ) pumping.     

Watt-level, all-fiber supercontinuum source based on telecom-grade fiber components

Supercontinuum (SC) generation in a standard telecom fiber using 1 ns pulses of a 1,550-nm DFB laser amplified in a cascade of erbium and erbium/ytterbium fiber amplifiers is reported. The SC source operated at 200 kHz repetition rate and delivered up to 2 W of average output power in the band of 1,300–2,500 nm with a diffraction limited beam. For the wavelengths over 1,650 nm, the output power of 1.1 W was recorded. The spectrum was very flat with the flatness of <5 dB in the wavelength interval of 1.6–2.18 μm. To the best of our knowledge, it is the first report on W-level SC generation obtained only in a standard single-mode fiber (SMF-28) with almost the entire spectrum in the eye-safe spectral region (λ > 1.4 μm) permitted by silicate glass transparency.     

Experiments of all-optical switching due to cross-phase modulation in fiber grating coupler by lock-in amp. detection scheme

We report results of experiments examining cross-phase modulation effect on fiber grating coupler (FGC). All-optical switching are observed in both cases of high pump pulses emitted from high-power Nd:YAG laser and mode-locked EDF laser. Based on coherent detection using a lock-in amplifier, the red-shift of the Bragg wavelength for a FGC was estimated to be 0.04-0.06 nm/1.5-1.7 kW peak power of EDF pump light at 1.55 μm. To avoid mixture of pump pulse and signal light at 1.55 μm, we have also performed the experiment using high power Nd:YAG laser as a pump power. For a Nd:YAG laser, the red-shift of Bragg wavelength is estimated to be 0.06 nm at maximum pump power of 2.1 kW. A simple model for the proposed detection scheme is given and the resultant red-shift is analyzed numerically.