Performance of Er3+-doped chalcogenide glass MOF amplifier applied for 1.53 μm band

A model of Er3＋-doped chalcogenide glass （GasGe20Sb10S65） microstructured optical fiber （MOF） amplifier under the excitation of 980 nm is presented to demonstrate the feasibility of it applied for 1.53 μm band optical communications. By solving the Er3＋ population rate equations and light power propagation equations, the amplifying performance of 1.53 μm band signals for Er3＋-doped chalcogenide glass MOF amplifier is investigated theoretically. The results show that the Er6＋-doped chalcogenide glass MOF exhibits a high signal gain and broad gain spectrum, and its maximum gain for small-signal input （-40 dBm） exceeds 22 dB on the 300 cm MOF under the excitation of 200 mW pump power Moreover, the relations of 1.53 μm signal gain with fiber length, input signal power and pump power are analyzed. The results indicate that the Er3＋-doped Ga5Ge20Sb10S65 MOF is a promising gain medium which can be applied to broadband amplifiers operating in the third communication window.     

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.     

Preparation and laser properties of Yb3+-doped microstructure fiber based on hydrolysis-melting technique

The Yb3+-doped silica glass was prepared by the SiCl4 hydrolysis doping and powder melting technology based on high frequency plasma. The absorption and emission characteristics of the Yb3+-doped silica glass are studied at room temperature. The integrated absorption cross section, stimulated emission cross section and fluorescence lifetime are calculated to be 8.56×104 pm3, 1.39 pm2 and 0.56 ms, respectively. The Yb3+-doped microstructure fiber (MSF) was also fabricated by using the Yb3+-doped silica glass as fiber core. What’s more, the laser properties of the Yb3+-doped MSF are studied.     

Structure and spectroscopic properties of Er3+/Ce3+ co-doped TeO2-Bi2O3-TiO2 glasses modified with various WO3 contents for 1.53 μm emission

The Er^3＋/Ce^3＋ co-doped tellurite-based glasses （TeO2-Bi2O3-TiO2） modified with various WO3 contents are prepared using conventional melt-quenching technique. The X-ray diffraction （XRD） patterns and Raman spectra of glass sam- ples are measured to investigate the structures. The absorption spectra, the up-conversion emission spectra, the 1.53 /am band fluorescence spectra and the lifetime of Er3＋：4113/2 level are measured, and the amplification quality factors of Er3＋ are calculated to evaluate the effect of WO3 contents on the 1.53 μm band spectroscopic properties. With the in- troduction of WO3, it is found that the prepared tellurite-based glasses maintain the amorphous structure, while the 1.53 μm band fluorescence intensity of Er3＋ is improved evidently, and the fluorescence full width at half maximum （FWHM） is broadened accordingly. In addition, the prepared tellurite-based glass samples have larger bandwidth qual- ity factor than silicate and germanate glasses. The results indicate that the prepared Er3＋/Ce3＋ co-doped tellurite-based glass with a certain amount of WO3 is an excellent gain medium applied for the 1.53 μm band Er3＋-doped fiber ampli- fier （EDFA）.     

Absolute Measurement Fiber—optic Sensors in Large Structural Monitoring

The security of civil engineering is an important task due to the economic,social and evironmental significance.Compared with conventional sensors.the optical fiber sensors have their unique characteristics.Beijing durable,stable and insensitive to external perturbations,they are particular interesting for the long-term monitoring of civil structures.Focus is on absolute measurement optical fiber sensors,which are emerging from the monitoring large structural,including SOFO system,F-P optical fiber sensors,and fiber Bragg grating sensors.The principle,characteristic and application of these three kinds of optical fiber sensors are described together with their future prospects.     

Tunable microwave photonic filter based on a fiber ring and erbium-doped fiber amplifier

The tunable microwave photonic filter based on a fiber ring and erbium-doped fiber amplifier （EDFA） was proposed. By introducing a section of erbium-doped fiber （EDF） into the fiber ring, the loss of the signal can be compensated by the EDFA gain through adjusting the pump power. This can largely increase the number of the effective sampling taps, and then improve the performance of the microwave photonic filter notably. When the pump power was set to be 42.7 roW, a microwave bandpass filter with the 3-dB bandwidth of 0.15 MHz, the Q factor up to 100 and extinction ratio up to 20 dB was achieved. By employing a tunable optical delay line in the above fiber ring, a tunable microwave photonic filter has been realized through tuning the length of the optical delay line. The proposed tunable microwave photonic filter can fred great applications in microwave signal processing and ROF system.     

Optical Pulse Compression Based on High-doped Erbium Fiber Amplifier and Standard Single-mode Fiber

Proposed is a novel optical pulse compression technique based on high-doped erbium fiber amplifier and standard single-mode fiber（SMF）. We used the amplifier with the erbium ion concentration of 6.3）〈 10^-3 to amplify a hyperbolic secant pulse from a regeneratively mode-locked fiber laser. The central wavelength, pulsewidth and peak power of the pulse are 1 550 nm, 12. 5 ps and 3 mW, respectively. Then the amplified pulse with peak power level corresponding to a higher-order soliton is compressed when it propagates through a 3-km-long single-mode fiber. Studied are the compressed pulses under different pump powers and fiber lengths. The results show that it can get a narrower pulse, and solve the difficulty that pulses at low power can not be compressed directly in the fiber. And the construct is compact.     

Experimental study of the optical fiber characteristics by digital hologram

The characteristics of optical fiber are quite important for improving the performance of optical fiber communication and sensor systems.Based on the Mach-Zehnder interferometer,a new measuring method is proposed and the digital holograms between the single mode fibers(SMFs) and specialty double-cladding(DC) fibers are analyzed.The experimental results show that the fringe density can be changed under the conditions of coaxial and off-axial interferences.Therefore it can be used to analyze the optical fiber characteristics including refractive index distribution,fiber modes,phase difference,etc.     

Research on pulse edge extraction by using nonlinear optical fiber-loop mirror

The output characteristics of nonlinear optical fiber-loop mirror are analyzed in detail when the pump pulses with the same wavelength are input in the both directions for recovering the clock component of the signal spectrum.It is found that the double output pulses are produced in the transmission port of the nonlinear optical fiber-loop mirror.The output pulse peaks are located in time domain at the rising and falling edges of the pump pulses.It is demonstrated that the rising and falling edges of the pump pulse can be directly extracted by this method.Through numerical simulation,the effects of therelative delay of pump pulses and the dispersion of fiber on the characteristics of output pulses are studied.By spectrum analysis,it is found that the spectrum of output pulse sequence includes the clock components of the pump pulse sequence,and a new idea is provided for all-optical clock extraction.     

Polarization-insensitive fiber optical parametric amplifier based on polarization diversity technique with dual parallel pumps

By analyzing the principle of dual-pump parametric amplification and the polarization dependent gain of fiber optical parametric amplifier(FOPA),a polarization-insensitive FOPA based on polarization-diversity technique with dual parallel pumps is presented.The performances of polarization-insensitivity,gain and BER are theoretically analyzed and numerically simulated by comparing the proposed scheme with parallel pump solution and orthogonal pump solution.The presented solution can reduce the complexity of state of polarization(SoP) of pumps.     

新型掺铒离子氧氟碲酸盐玻璃的光谱性质

探求新的具有优良的热学和光学性能的基质玻璃系统，是获得具有宽带宽和增益平坦的掺Er^3＋光纤放大器（EDFA）的一种有效途径。制备了一种新型氧氟碲酸盐玻璃TeO2-BaF2-LaF3，并对其热学性能和光学性质进行了测试。应用乍得-奥菲尔特（Judd-Ofelt）理论计算了Er^3＋离子的J-O理论参量和荧光寿命r。探讨了氟化物的引入对碲酸盐玻璃结构的改变的影响，并分析了其对玻璃的热学性质和光学性质的影响。实验发现，获得的氧氟碲酸盐玻璃具有优良的热学稳定性（△T=156.6C），宽的荧光半峰全宽（72nm），长的荧光寿命（r=4．9ms）以及良好的平坦增益特性。该玻璃系统有望成为新的宽带光纤放大器用基质玻璃材料。     

Performance of a high concentration Er/sup 3+/-doped alumino silicate fiber amplifier

We report the gain, noise figure, output saturation power, and conversion efficiency of a highly concentrated Er/sup 3+/-doped alumino silicate fiber amplifier. We obtain a gain per unit length of 1.0 dB/cm, which corresponds to the highest gain per unit length obtained in an Er/sup 3+/-doped fiber amplifier. The pump power threshold ranges from 2 to 5 mW, depending on the fiber length.     

利用1．313μm激光泵浦掺铒石英光纤产生上转换放大自发辐射

报道了利用１．３１３μｍ波长调Ｑ锁模Ｎｄ３＋：ＹＬＦ激光泵浦国产掺铒石英光纤同时产生可见光４６３ｎｍ（４６３ｎｍ，４７５ｎｍ，４８５ｎｍ，４９４ｎｍ，５０１ｎｍ，５１０ｎｍ），５２５ｎｍ，５４０ｎｍ（５２５～５６４ｎｍ），二次谐波信号６５６ｎｍ（６５６～６７５ｎｍ）和近红外８０４ｎｍ（７８４～８２０ｎｍ）等波段放大自发辐射的实验结果．在可见光４６３ｎｍ波段，在高泵浦功率下观察到随泵浦光功率增大，邻近几个中心波长与４６３ｎｍ波长信号产生类似级联共振放大增强的现象。同时发现几个中心波长辐射光谱宽度随泵浦光功率增加有加宽的关系，这与现有实验结果报道不一致。实验中还发现３ｍ长光纤与４．５ｍ长光纤在输出可见光自发辐射光谱方面有很大的不同．３ｍ光纤在相等泵浦光功率下．出现邻近波长共振放大加强的几率比４．５ｍ光纤小得多。根据能级跃迁关系提出了共振四光子吸收将基态４Ｉ１５／２离子抽运到高能态２Ｇ７／２，然后跃迁辐射回到４Ｉ１３／２态的机制，给出了实验结果的初步机理解释。     

窄线宽光纤激光器

为满足传感系统的需求,研制了1 550nm单频窄线宽光纤激光器,采用环形腔结构,利用976nm激光器作为泵浦源,高掺杂掺铒光纤作为增益介质,以低掺杂掺铒光纤作为饱和吸收体,得到稳定的窄线宽激光输出。泵浦功率为200mW时,得到输出功率为21mW,线宽为7.2kHz,波长稳定度为1.26pm,相对强度噪声≤-102dB/Hz1/2。     

Er3+掺杂硫系光子晶体光纤的中红外增益特性研究

实验制备了质量比为1%的Er3+掺杂75GeS2-15Ga2S3-10CsI(GGSI)硫系玻璃,测试并计算了相关光谱参数,使用多级法计算了设计的光子晶体光纤(PCF)在2.8μm的中红外信号的模场分布。在此基础上,建立了Er3+的四能级粒子数速率-光功率传输方程模型,模型综合考虑了Er3+的交叉弛豫和能量上转换,模拟得到了Er3+掺杂GGSI硫系玻璃PCF在2.8μm的中红外增益与掺杂光纤长度、泵浦功率和信号功率的变化关系。研究结果显示,Er3+掺杂GGSI硫系PCF放大器在2 750～2 950nm波段平均信号增益值超过了40dB,明显优于传统结构光纤的平均信号增益值20dB。     

8-mV threshold Er/sup 3+/-doped planar waveguide amplifier

We report on the gain characteristics of a low threshold (8 mW) Er/sup 3+/-doped planar optical waveguide amplifier. Net fiber to fiber gain of 4.5 dB is achieved at a signal wavelength of 1536 nm with 80 mW of 980-nm pump power. This device represents significant progress toward a planar amplifier module pumped by a single laser diode.     

S+C bands amplification in a distributed Er-doped Raman fiber

A novel hybrid optical amplifier covering entire S- and C-bands has been proposed. A silica fiber configured with an erbium (Er)-doped cladding and a germanium-doped core was used. Amplification was achieved by stimulated Raman scattering along with the Er ions' radiative transition in a fiber. A numerical simulation has been performed to analyze the amplification characteristics. Fiber parameters such as optical loss, Er concentration, fiber length, and pump power were taken into consideration to calculate the optimum pump power and fiber length for a flat gain characteristic over the entire S- and C-bands.     

Polarization-dependent enhancement of population inversion and of green upconversion in Er:LiNbO/sub 3/ by Yb codoping

We have investigated the polarization dependence of both the population inversion of the /sup 4/I/sub 13/2/ state and the green upconversion to the /sup 4/S/sub 3/2/ state in Er:LiNbO/sub 3/ optical fiber amplifier when codoped with Yb and pumped around 980 nm. The presence of Yb/sup 3+/ enhances the population of the /sup 4/I/sub 13/2/ state of the Er/sup 3+/ ions when pumped at /spl sigma/-polarization (>2.5 times) and at /spl pi/-polarization (>5.5 times), and introduces a broad useful pump band around 940-960 nm at /spl sigma/-polarization, relaxing fabrication tolerances on semiconductor pump sources. An enhancement of green upconversion is also observed by the Yb codoping. Lifetime measurements indicate that, as in glass substrates, nonradiative energy transfer is responsible for these enhancements.     

掺Er~（3＋）和掺Er~（3＋）／Yb~（3＋）光纤中1313nm到780nm的频率上转换过程

研究了在连续锁模和调Ｑ锁模两种脉冲泵浦条件下，掺Ｅｒ（３＋）和掺Ｅ３＋／Ｙｂ３＋单模ＧｅＯ２／ＳｉＯ２石英光纤中，１３１３ｎｍＮｄ：ＹＬＦ激光到７８０ｎｍ波长的频率上转换过程。Ｅｒ３＋离子在共振吸收两个光子后到４Ｆ９／２态，再经快速的无辐射转移到４Ｉ９／２态．形成７８０ｎｍ辐射。在连续锁模泵浦条件下．１３１３ｎｍ至７８０ｎｍ的转换效率比调Ｑ锁模条件下更高．而后者的峰值功率是前者的几百倍。     

掺Er~(3+)碲硼酸盐玻璃1.53μm波段荧光强度提高研究

用高温熔融法制备了系列70TeO2-(25-x)B2O3-xGeO2-5Na2O(x=5,10,15和20 mol%)掺Er3+碲硼酸盐玻璃。为提高1.53μm波段的荧光发射强度,测试了玻璃样品的吸收光谱、红外透射谱、1.53μm波段荧光谱及4I13/2能级Er3+荧光寿命,结合Judd-Ofelt(J-O)理论分析了Er3+光谱特性随玻璃组分含量的变化,进而研究了玻璃中OH基对1.53μm波段荧光强度的影响。结果表明,碲硼酸盐玻璃具有较好的宽带荧光谱特性,其有效带宽大于72 nm;随着玻璃中GeO2逐步替代B2O3,1.53μm波段荧光强度相应提高。同时,通过O2鼓泡除水处理,能减少玻璃中OH基含量并减弱4I13/2能级上Er3+到OH基的无辐射能量传递,从而进一步提高了Er3+荧光寿命和1.53μm波段荧光强度。