Hollow-core tapered coupler for large inner diameter hollow-core optical fibers

A novel hollow-core tapered coupler has been theoretically designed and fabricated by fiber drawingmachine. The coupler's inner wall is coated with a polycrystalline GeO_2 film. The coupling loss ofhollow-core tapered coupler is about 0.2 dB. Hollow-core tapered coupler reduces the transmission loss ofhollow-core optical fiber(HCOF) by 0.5 dB/m, therefore the coupler is suitable for coupling high powerCO_2 laser in industrial application.     

New plastic optical fiber using polycarbonate core and fluorescence-doped fiber for high temperature use

This article describes the development of a plastic optical fiber composed of a polycarbonate core with a glass transition temperature of 150°C, and a cladding of newly developed poly-4-methyl penten-1, which softens at 173°C. This cladding is suitable for use at temperatures up to 130°C. The minimum optical attenuation is 0.8 dB/m at 765 nm in the near-infrared region. The cause of the attenuation of the PC-core fiber was analyzed and the intrinsic loss limit was estimated to be 0.4 dB/m at 765 nm. The fiber has excellent characteristics, including thermal stability up to 125°C, high flexibility, high strength, and self-extinguishing properties.

The polycarbonate core fiber, doped organic fluorescing materials, has also been developed for automotive uses such as light guide and illuminator. Light can be transmitted through this fiber with incident optical beam perpendicular to the fiber as well as the beam parallel to the fiber.     

New plastic optical fiber using polycarbonate core and fluorescence-doped fiber for high temperature use

This article describes the development of a plastic optical fiber composed of a polycarbonate core with a glass transition temperature of 150°C, and a cladding of newly developed poly-4-methyl penten-1, which softens at 173°C. This cladding is suitable for use at temperatures up to 130°C. The minimum optical attenuation is 0.8 dB/m at 765 nm in the near-infrared region. The cause of the attenuation of the PC-core fiber was analyzed and the intrinsic loss limit was estimated to be 0.4 dB/m at 765 nm. The fiber has excellent characteristics, including thermal stability up to 125°C, high flexibility, high strength, and self-extinguishing properties.

The polycarbonate core fiber, doped organic fluorescing materials, has also been developed for automotive uses such as light guide and illuminator. Light can be transmitted through this fiber with incident optical beam perpendicular to the fiber as well as the beam parallel to the fiber.     

Experimental study of an elliptical-core photonic bandgap fiber with thin core wall and high aspect ratio and its birefringence characteristics

We fabricate an elliptical hollow-core photonic bandgap fiber (EC-PBGF) with a core-wall thickness of 65 nm and an aspect ratio of 1.4. The core is expanded by applying positive pressure in the hollow-core region during the fiber-drawing process. Both the reduction of core-wall thickness and the increase of aspect ratio result in the enhancement of optical properties in terms of a low attenuation loss and group birefringence. The minimum loss and group birefringence of the fabricated EC-PBGF2 are measured to be 0.1 dB/m and 0.012, respectively.     

内窥镜的红外激光传输用柔性空芯光纤的研制

通过理论计算确立了多功能介质-金属结构空芯光纤的结构参量,优化了液相镀膜法的有关条件,明确了具体制作参量。制作了以聚碳酸酯毛细管为基管的,高柔韧性的,可同时低损耗传输红外目标波长激光和可见导航光红外的空芯光纤。对光纤传输性能进行了测试。在2.94μm波长的Er∶YAG和0.63μm波长的红色半导体激光器的直线损耗分别为0.4 dB/m和3 dB/m。组装在医疗内窥镜中的柔性空芯光纤,在先端以0.9 cm半径135°角弯曲时,对Er∶YAG激光仍有近70%的传输效率;绿色导航光在内窥镜中的的损耗值为11 dB,绿色指示点在内窥镜的视窗中清晰可见。结果表明此种光纤在内窥镜的激光传输方面有重要的应用价值。     

Spatial optical filter sensor based on hollow-core silica tube

A spatial optical filter based on a hollow-core silica tube is proposed. Because of the hollow-core dimensions, it is possible to obtain a periodical spatial filter ranging from 1200 to 1700 nm with a channel spacing of 2.64 THz. The bandwidth is approximately 5.32 nm, and the isolation loss is ~30 dB. The optical losses are approximately ~0.67 dB/mm for a wavelength of 1500 nm. The 40 mm long spatial optical filter is tested as a sensing element and subjected to different physical parameters. The spatial optical filter is wavelength sensitive to strain and temperature, while for refractive-index variations there is an optical power dependency. This fiber structure can be used as a sensing element for extreme conditions, such as in very high temperature environments, where it presents a sensitivity of 27.5 pm °C(-1).     

GeO2-Sb22O3-K22O玻璃空芯光纤材料的光学特性研究

系统地研究了传输CO2激光用的新型光纤材料GeO2-Sb2O3-K2O玻璃空芯光纤的光学特性。通过理论计算,得到了该材料nr＜1的波长范围,消光系数Ｋ和损耗系数a,通过工艺和材料的选择,使a理论值达到0.05 dB/m。同时讨论了HE11,TM01,TE01模式损耗和频率的关系。     

GeO_2－Sb_2O_3－K_2O玻璃空芯光纤材料的光学特性研究

系统地研究了传输ＣＯ２激光用的新型光纤材料ＧｅＯ２－Ｓｂ２Ｏ３－Ｋ２Ｏ玻璃空芯光纤的光学特性。通过理论计算，得到了该材料ｎｒ＜１的波长范围，消光系数Ｋ和损耗系数ａ，通过工艺和材料的选择，使ａ理论值达到０．０５ｄＢ／ｍ。同时讨论了ＨＥ１１，ＴＭ０１，ＴＥ０１模式损耗和频率的关系。     

复合纺丝法制备聚合物瓣状光纤的研究

瓣状光纤(SCF)由高折射率均匀芯层和高低折射率区域交替的皮层组成, 可有效地实现大纤芯单模运行。提出了采用复合纺丝法一步制备瓣状光纤。采用聚碳酸酯(PC)和聚甲基丙烯酸甲酯(PMMA)成功地制备截面符合设计要求的聚合物瓣状光纤。所制光纤的纤芯直径为40 μm。并用白光作为光源, 考察了所制光纤在500～1000 nm波段范围的出射光谱。从出射光谱可以看出, 所制光纤在730～830 nm波段范围内透射率比较高。通过截断法对所得光纤在500～1000 nm波段范围的传输损耗进行测试, 结果表明所制光纤的传输损耗比较大, 最大为30 dB/m。采用532 nm绿色激光作为光源, 通过CCD采集60 cm所得光纤的光斑。     

Octave-spanning supercontinuum generation of vortices in an As2S3 ring photonic crystal fiber

We propose As(2)S(3) ring photonic crystal fiber (PCF) for supercontinuum generation of optical vortex modes. Due to the large material index contrast between As(2)S(3) and air holes in the designed ring PCF, there is a two-orders-of-magnitude improvement of the difference between the effective refractive indices of different vortex modes compared with regular ring fiber. The design freedom of PCFs enables a low dispersion (<60 ps/nm/km variation in total) over a 522 nm optical bandwidth. Moreover, the vortex mode has a large nonlinear coefficient of 11.7/W/m at 1550 nm with a small confinement loss of <0.03 dB/m up to 2000 nm. An octave-spanning supercontinuum spectrum of the vortex mode is generated from 1196 to 2418 nm at -20 dB by launching a 120 fs pulse with a 60 W peak power at 1710 nm into a 1 cm long As(2)S(3) ring PCF.     

中红外空心Bragg光纤的制备及在气体传感中的应用

空心Bragg光纤可广泛用于气体传感, 但要求它的传输通带处于中红外波段, 以便与待测气体的基频吸收峰匹配. 本文提出了空心Bragg光纤传输通带的一种设计方法与波长控制工艺, 可以实现传输通带在2.5-12 μ m内任意波长的空心Bragg光纤的制备. 实验制备出一阶传输通带分别在10.6 μ m和 3.3 μ m的光纤样品, 利用截断法测量出其一阶传输通带损耗分别为5.9 dB/m和8.8 dB/m. 利用在传输通带在3.3 μ m的样品中注入和排出甲烷/氮气混合气体, 观察到了光纤样品透射谱随注入气体浓度的变化, 并用指数稀释法初步测量了该系统的浓度探测极限约为26 ppm, 验证了该光纤应用于气体传感的可行性.     

新型杂萘联苯型聚芳醚砜硐聚合物光子材料成膜和光学特性

对新型聚合物光子材料杂萘联苯型聚芳醚砜硐(PPESK)波导薄膜的成膜工艺进行了系统的研究。分析了溶剂吸水性对成膜质量的影响,并通过氮气保护的方法获得了具有良好均一性的波导薄膜,其厚度一致性可优于1%,折射率一致性优于0.03%。采用棱镜耦合技术测量分析了PPESK波导薄膜的折射率、双折射、热光系数等光学特性,测量得到该材料在1310 nm波长处的损耗小于0.24 dB/cm,在1550 nm波长处的损耗小于0.52 dB/cm,表明该材料是一类性能良好的聚合物光子材料。     

Transmission of terahertz radiation using a microstructured polymer optical fiber

A hollow-core microstructured polymer optical fiber was analyzed in the terahertz (THz) region. Spectral analysis of time domain data shows propagation of THz waves in both the hollow-core and the microstructured cladding with a time delay of approximately 20 ps. The frequency range and shift of the transmission bands between different sized waveguides suggested photonic bandgap or resonant guidance. Finite-difference time domain calculations agree relatively well to the experimental transmission results. Propagation losses were estimated to be as low as 0.9 dB/cm.     

Optical properties of polymer poly(phthalazinone ether sulfone ketone) film waveguide

The optical properties of novel polymer poly(phthalazinone ether sulfone ketone, PPESK) film waveguide are studied by prism coupler. The optical properties of PPESK-8020, including refractive index, birefringence, thermo-optical coefficient and optical loss, are demonstrated. This kind of material has the advantages of low optical loss (less than 0.24 dB/cm at 1310 nm and 0.52 dB/cm at 1550 nm) and high thermal stability (1% weight loss temperature: 488 ℃). Due to these excellent properties, it may have great potential in optical waveguide applications.     

2.5THz环烯烃聚合物中空芯光子晶体光纤设计与实验

采用全矢量有限元法,仿真设计了一种工作在2.5THz频段的中空芯太赫兹光子晶体光纤,用环烯烃聚合物材料(COC)制备了光纤样品,利用CO2激光泵浦气体太赫兹源搭建了测试平台并对光纤的太赫兹波传输性能进行了测试。实测光纤最低损耗0.17dB/cm、平均损耗约0.5dB/cm,在弯曲90°情况下光纤传输损耗波动小于5%,具有良好的可弯曲性;光纤输出端口的模场分布测试结果表明,光纤是以主模进行传输,太赫兹能量很好地被束缚在光纤芯中。     

Broadband micro-Michelson interferometer with multi-optical-path beating using a sphered-end hollow fiber

We demonstrate a high-sensitivity broadband (1250-1650 nm) fiber micro-Michelson interferometer using a single-mode fiber end-spliced with a sphered-end hollow-core fiber. The hollow core is slightly smaller than the solid core of a single-mode fiber, so the fractional power of the core mode is converted into cladding modes. The excited cladding modes propagate at distinct optical paths along the hollow-core fiber and have individual foci outside the spherical lens. The reflected core mode, generated at the solid core-air interface, and the reflected cladding modes, generated at external material, interfere with each other to produce beating in the interference signals.     

Partially liquid-filled hollow-core photonic crystal fiber polarizer

A compact fiber polarizer is demonstrated by the filling of selected air holes of a hollow-core photonic crystal fiber (PCF) with a liquid. The liquid-filling results in an asymmetric waveguide structure, leading to a large polarization dependent loss. A 6 mm long ethanol-filled PCF exhibits a polarization extinction ratio of ～18 dB over a wavelength range from 1480 nm to 1600 nm.     

A new solution of reducing polymer optical fiber losses

Polymethyl methacrylate (PMMA) is one of the most commonly used optical materials. However, the application of it in the area of optical communication is strongly limited by the intrinsic absorption loss of carbon-hydrogen stretching vibration. In this paper, we present a method to solve the problem by adopting the hollow-core fibers with cobweb cladding structure. The fibers use a single dielectric material and may solve the problem of structural support. Thus the feasibility of the “OmniGuide” fibers is improved, while a series of advantages of the “OmniGuide” hollow-core fiber are retained. It is promising that a fiber with low transmission loss, high bandwidth, large-core, and low costs can be designed and fabricated using PMMA. At the same time, a very broad range of the wavelengths (from visible to near infrared region, for instance, wavelengths at 0.65-1.12 μm, and even 1.30 μm, 1.54 μm and their neighbors) may be adopted for signal wavelength.     

Anomalous dispersion in a solid, silica-based fiber

We demonstrate an all-solid (nonholey), silica-based fiber with anomalous dispersion at wavelengths where silica material dispersion is negative. This is achieved by exploiting the enhanced dispersion engineering capabilities of higher-order modes in a fiber, yielding + 60 ps/nm km dispersion at 1080 nm. By coupling to the desired higher-order mode with low-loss in-fiber gratings, we realize a 5 m long fiber module with a 300 fs/nm dispersion that yields a 1 dB bandwidth of 51 nm with an insertion loss of approximately 0.1 dB at the center wavelength of 1080 nm. We demonstrate its functionality as a critical enabler for an all-fiber, Yb-based, mode-locked femtosecond ring laser.     

Extremely low-loss hollow core waveguide for VUV light

A new type of an extremely low-loss optical waveguide is proposed. In the vacuum-ultra-violet (VUV) region (wavelength less than 300 nm) most solid-state materials have a refractive index less than unity due to plasma vibration of electrons. The energy of VUV light is confined within the hollow core due to the smaller n_r than unity of the cladding material of the hollow core waveguide. Typical expected loss for 50 nm-wavelength VUV light of a 0.1 mm hollow-core waveguide is on the order of 0.05 dB/km.