A kind of multiwavelength erbium-doped fiber laser based on Lyot filter

A multiwavelength tunable ring-cavity erbium-doped fiber laser(EDFL)based on a Lyot filter was presented.For the proposed Lyot filter,a comb filter consisting of an EDF-polarization-maintaining fiber(EDF-PMF),a polarization controller(PC),and a circulator with four ports was used to suppress the mode competition.The light transmission direction was guaranteed by the circulator.For the proposed fiber laser,tunable single,dual,triple,quadruple,quintuple,sextuple,and septuple wavelengths were realized.A single-wavelength laser output with an optical signal-to-noise ratio(SNR)of up to30.56 dB was realized,and a tuning range of 1590.54 nm to 1599.54 nm was achieved by tuning the PC.The stability of the single,dual,triple,and quadruple-wavelength center power fluctuations was less than 0.05 dB,0.98 dB,5.07 dB,and7.71 dB respectively.When the laser was operated in the multiwavelength condition,the SNR was more than 20.97 dB.The proposed erbium-doped fiber laser is suitable for fiber-sensing system applications.

On-chip readout plasmonic mid-IR gas sensor

Gas identification and concentration measurements are important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change.Here a novel mid-IR plasmonic gas sensor with on-chip direct readout is proposed based on unity integration of narrowband spectral response,localized field enhancement and thermal detection.A systematic investigation consisting of both optical and thermal simulations for gas sensing is presented for the first time in three sensing modes including refractive index sensing,absorption sensing and spectroscopy,respectively.It is found that a detection limit less than 100 ppm for CO2 could be realized by a combination of surface plasmon resonance enhancement and metal-organic framework gas enrichment with an enhancement factor over 8000 in an ultracompact optical interaction length of only several microns.Moreover,on-chip spectroscopy is demonstrated with the compressive sensing algorithm via a narrowband plasmonic sensor array.An array of 80 such sensors with an average resonance linewidth of 10 nm reconstructs the CO2 molecular absorption spectrum with the estimated resolution of approximately 0.01 nm far beyond the state-of-the-art spectrometer.The novel device design and analytical method are expected to provide a promising technique for extensive applications of distributed or portable mid-IR gas sensor.

Spacing-adjustable and wavelength-tunable multiwavelength fibre laser with nonlinear Brillouin gain and birefringence fibre loop mirror

This paper demonstrates a room-temperature multiwavelength fibre laser with spacing-adjustability and wavelength-tunability. The nonlinear gain of self-excited stimulated Brillouin scattering can suppress mode competition induced by homogeneous broadening of Erbium-doped fibre. With the use of a birefringence fibre loop filter, the wavelength spacing can be adjusted by changing the length of the used birefringence fibre, and the lasing wavelengths can be finely tuned through modifying the filtering profile of the birefringence filter. Multiwavelength output with spectral spacing as small as 0.076 nm and a wavelength number of more than 80 has been successfully produced.

Determination of Light Rare Earths by a Spectrophoto-metry Based on the Linear Combination of Multiwavelength Data

The present paper proposes a new method of spectrophotometry based on linear combination of multiwavelength data by means of selecting a set of properly weighted coefficients and combination methods. It is clear that the weighted combination absorbance attained is only in direct proportion to the concentration of the analysed component and independent of coexisting interferents.The accuracy of the analytical results is improved greatly for the analysis of light rare earths with the coexistence of heavy rare earths.The analyti- cal error from the reagent blank and co-coloration of light and heavy rare earths have also been overcome. The greatly improved linearity and additivity of absorbance are obtained.

UV-Inscribed Optical Fiber Gratings in Mid-IR Range and Their Laser Applications

We have UV-inscribed fiber Bragg gratings （FBGs）, long-period gratings （LPGs） and tilted fiber gratings （TFGs） into mid-IR 2μm range using three common optical fiber grating fabrication techniques （two-beam holographic, phase mask and point-by-point）. The fabricated FBGs have been evaluated for thermal and strain response. It has been revealed that the FBG devices with responses in mid-IR range are much more sensitive to temperature than that in near-IR range. To explore the unique cladding mode coupling function, we have investigated the thermal and refractive index sensitivities of LPGs and identified that the coupled cladding modes in mid-IR range are also much more sensitive to temperature and surrounding medium refractive index change. The 45° tilted fiber gratings （45°-TFGs） as polarizing devices in mid-IR have been investigated for their polarization extinction characteristics. As efficient reflection filters and in-cavity polarizers, the mid-IR FBGs and 45°-TFGs have been employed in fiber laser cavity to realize multi-wavelength 2μm Tm-doped CW and mode locked fiber lasers, respectively.

A Mid-IR Optical Parametric Oscillator Pumped by an Actively Q-Switched Ho:YAG Ceramic Laser

We demonstrate a mid-IR ZnGeP2 （ZGP） optical parametric oscillator （OPO） pumped by a dual-end-pumped actively aeoasto-optie Q-switched Ho：YAG ceramic laser. The maximum average output power of 35 W is obtained at a pulse repetition frequency of 20 kHz from the Ho：YAG ceramic laser. Under the maximum incident pump power of Ho：YAG ceramic laser, the maximum output power of 14 W is obtained from the ZGP OPO, corresponding to the slope efficiency of 49.6% with respect to the incident pump power. The wavelength can be tuned from 3.5 μm to 4.2μm （signal）, corresponding to 5.24.1 μm （idler）. The beam quality M2 is less than 2.3 from the ZGP OPO.

Mid-IR dual-wavelength difference frequency generation in uniform grating PPLN using index dispersion control

A novel widely tunable dual-wavelength mid-IR difference frequency generation （DFG） scheme with uniform grating periodically poled lithium niobate （PPLN） is presented in this paper. By using the temperature-dependent dispersion property of PPLN, the quasi-phase matching （QPM） peak for the pump may evolve into two separate ones and the wavelength spacing between them increases with the decrease of the crystal temperature. Such two pump QPM peaks may allow simultaneous dual-wavelength mid-IR laser radiations while properly setting the two fundamental pump wavelengths. With this scheme, mid-IR dual-wavelength laser radiations at around 3.228 and 3.548, 3.114 and 3.661, and 3.019 and 3.76 μm, are experimentally achieved for the crystal temperatures of 90, 65, and 30 ℃, respectively, based on the fiber laser fundamental lights.

Multiwavelength Actively Mode-locked Fiber Laser with a Double-ring Configuration and Integrated Cascaded Sampled Fiber Bragg Gratings

A modified multiwavelength actively mode-locked fiber ring laser is proposed and experimentally demonstrated. In this kind of laser, stable multiwavelengths lasing is achieved by integrating cascaded sampled fiber Bragg gratings(SFBGs) into the laser cavity. To implement actively mode-locking technique, a double-ring cavity configuration is used to assure that the cavity lengths for all wavelengths lasing are identical. Thus, simultaneous mode locking of all wavelengths has been successfully achieved by using the same mode-locking signal.

基于双纳米孔的超表面全息成像

为提高超表面的信息存储能力,从波长复用的角度出发,基于几何相位理论设计了一种由两种不同结构参数的椭圆纳米孔构成的超表面。利用时域有限差分法分析超表面的各参数的影响规律,通过超表面各个参数的调节,获得了530 nm和710 nm双工作波长下电磁波独立调控能力。并利用Gerchberg-Saxton算法对超表面的排布进行规划,利用该结果获得了同一位置双图像的呈现。530 nm处的成像图与原图像之间的均方误差约为0.082,710 nm处成像图与原图像之间的均方误差约为0.058,实现了超表面对于波长方面的双通道复用。

炸药爆轰温度的瞬时多光谱测量

从多光谱测温的基本原理出发 ,对瞬时多光谱爆温测量装置的工作原理、系统结构、爆温计算以及测量过程中可能引入的误差和进一步提高测量精度的方法进行了阐述和分析 利用该装置对液体炸药硝基甲烷的爆温进行了实际测量 ,取得了满意的测量结果 ,其爆温为 36 72K ,扩展不确定度为 10 0K(k =2 ) ,该温度下的光谱发射率为 0 .6

实用双纵模激光精密测距仪

分析了无导轨大尺寸测量技术的现状 ,指出采用He -Ne激光器进行多波长干涉小数重合法测量大尺寸能较为有效地解决无导轨大尺寸测量问题 ,在分析了现有的两种He -Ne激光多波长干涉无导轨大尺寸测量技术的特点的基础上 ,介绍了一种稳频系统简单可靠 ,频率及频差稳定 (在工业现场环境 ) ,合成波长合适 ,测量过程简捷的双纵模激光精密测距仪 ,它完全满足对大尺寸工件进行测量的精度及环境的适用性的要求 ,其在 5 0m测量范围内精度可达± (5 0 + 1.5× 10 -6L ) μm 。

基于受激布里渊散射的波长间隔可变多波长光纤激光器

提出了一个基于自激发受激布里渊散射的波长间隔可变多波长光纤激光器.利用单模光纤中自激发产生的非线性布里渊增益和掺铒光纤的线性增益组成混合增益光纤激光器,从而使光纤激光器在室温下产生稳定的多波长输出.改变双折射光纤环镜滤波器中保偏光纤的长度,可以实现波长间隔可变多波长激光产生,提高了多波长光纤激光器操作的灵活性和实用性.实验实现了波长间隔从0.8nm至0.076nm可变的多波长激光产生,波长数随波长间隔减小而增加,间隔为0.08nm的激光波长数达86.

多波长K系数法测定混合干扰组分

本文提出测定混合干扰组分的多波长K系数法,给出了算式△A=A-sum from n=1 to n(K_iA_i)=kC。测定采用一个测量波长及与干扰组分个数相等的参数比波长。以本法对PAR-Co、Ni、Cu、Zn体系进行了测定,获较满意的结果。

多波长线性回归光度法同时测定食品中钙镁

在pH =8 .8的硼砂缓冲溶液中 ,三氯偶氮氯膦分别与Ca2 + 和Mg2 + 形成稳定的配合物。用多波长线性回归光度法同时测定钙、镁。合成样品中钙和镁的回收率分别为 94%～ 10 5 %和 95 %～ 10 4%。该方法应用于食品中钙、镁含量的测定 。

多波长线性回归紫外吸光光度法同时测定炼油厂污水中苯酚和苯胺

提出用多波长线性回归紫外吸光光度法同时测定炼油厂污水中的苯酚和苯胺.方法省去了萃取、蒸馏、显色等步骤,操作简单.对合成水样进行测定,相对标准偏差≤4.57%,相对误差≤±2.3%.对炼油厂水样进行测定并进行加标回收试验,苯酚和苯胶的回收率分别为99.4%～103.0%和97.2%～104.0%,结果良好.苯酚和苯胶的最低检出限分别为0.010和0.048μg·ml^(-1).

多波长分光光度法同时测定铁合金中锰和铜

通过对铁合金中锰、铜测定条件的研究,提出以pH 10.2 Na2B4O7-NaOH为缓冲介质,氯化十六烷基吡啶作为稳定剂,4-(2-吡啶偶氮)-间苯二酚(PAR)作显色剂,最小二乘法-分光光度法测定铁合金中锰和铜.锰和铜的测量波长分别为510 nm和505 nm,参比波长分别为550 nm和470 nm.在50 mL溶液中锰与铜总和在0～70μg符合比尔定律,方法用于铁合金标样中锰和铜的测定,所得结果与认定值十分吻合,相对标准偏差小于4%.

多波长K系数分光光度法测定脑清片中氨基比林和咖啡因的含量

本文报道了应用多波长Ｋ系数分光光度法测定脑清片中氨基比林和咖啡因的含量。样品可不经分离，在选定波长下直接测定两者的吸光度，根据Ｋ和ΔＡ值便可分别求出两者的含量。氨基比林和咖啡因的平均回收率及相对标准偏差分别为９９．８２％，０．８１％；９９．６８％，０．３８％。方法简便快速，结果准确可靠。

多波长数据线性双组合同步荧光法测定苯酚与间苯二酚

提出了多波长数据线性双组合法计算解析苯酚和间苯二酚混合物的同步荧光光谱，考察了△λ＝λ＿（ｅｍ）－λ＿（ｅｘ），ｐＨ，光路中光照时间对二种酚的荧光强度影响，建立了同时测定混合物中苯酚和间苯二酚的新方法。用于复方雷琐辛涂剂中苯酚与间苯二酚的同时测定，平均回收率分别为：苯酚９８．５％±１．４％；间苯二酚９８．８％±１．３％。

两种吸收光度法同时测定果味饮料中苯甲酸钠和山梨酸钾含量的比较研究

目的:选择果味饮料中苯甲酸钠和山梨酸钾含量的测定方法。方法:分别采用等吸收点法、多元线性回归法测定饮料中苯甲酸钠和山梨酸钾的含量,并对测量结果进行比较。结果:多元线性回归测得苯甲酸钠回收率99.75%～100.9%,山梨酸钾回收率99.16%～101.1%,等吸收点法测得苯甲酸钠回收率98.58%～99.38%,山梨酸钾回收率98.42%～99.56%。结论:多元线性回归方法更适用于果味碳酸饮料中苯甲酸钠和山梨酸钾的同时测定。

钨基复合材料烧蚀真温测量

设计制做了氧乙炔焰模拟烧蚀装置 ,运用快速响应的棱镜分光式多波长比色高温计测量了钨基复合材料烧蚀表面的温度 ,并测得材料在烧蚀过程中的快速升温曲线 。