国产化大模场掺镱光子晶体光纤的设计与制备

理论分析了空气孔尺寸与晶格常数对光子晶体光纤(PCF)单模特性的影响,设计了大模场双包层PCF的波导结构。采用自主知识产权的专利技术,制备出高数值孔径大模场掺Yb双包层PCF,其内包层数值孔径为0.65,纤芯数值孔径为0.06,有效模场面积为1 465.7μm2。     

The measurement of non-Gaussian mode fields by the far-field axial scanning technique

A new measurement technique is proposed for determining the second Petermann definition of mode field diameter (MFD) for single-mode fibers with both near-Gaussian and non-Gaussian radial field distributions. The method involves measuring the power passed through a circular aperture as it is scanned along the far-field optical axis of a fiber. Using this technique, it is possible to select those acceptance angles that are most critical to the accurate determination of MFD for a particular fiber design. Also, the aperture can be positioned close enough to the fiber endface so that collection of the total far-field power is assured. Measurements of MFD for conventional and disperson-modified single-mode fibers have been made at 1.3 μm and 1.55 μm with a precision of +/-0.05 μm and a comparison with the far-field angular scanning method gives agreement ot within 1 percent for both fiber types.     

Mode-field diameter measurements for single-mode fibers with non-Gaussian field profiles

The mode-field diameter (MFD) of a single-mode fiber can be measured using several different techniques. The extent to which these techniques are consistent depends upon the definition used to compute the MFD and upon the fiber design. In this paper, three measurement techniques (far-field scan, offset joint, and knife-edge scan) are applied to the measurement of both conventional step-index fibers and to non-step-index dispersion-shifted fibers. Using the far-field second moment definition, which is often called the "Petermann 2" definition, measurements made using these three techniques agree to within 1.6 percent.     

国产化大模场掺镱光子晶体光纤的设计与制备

文章作者设计了大模场双包层光子晶体光纤(PCF)的波导结构,并采用自主知识产权的专利技术,在国内首次制备出了高数值孔径大模场掺镱双包层光子晶体光纤.该光子晶体光纤的内包层数值孔径为0.65,纤芯数值孔径为0.06,有效模场面积为1465.7/μm2     

Determining the mode-field diameter of single-mode optical fiber: An interlaboratory comparison

The National Bureau of Standards, in cooperation with the Electronic Industries Association, conducted an interlaboratory measurement comparison among fiber manufacturers. Evaluated were transverse splice offset, near-field, far-field, and variable aperture far-field methods for determining mode-field diameter. Measurements were performed on five single-mode fibers at both 1300- and 1550-nm wavelengths. At 1300 nm, agreement was fairly good with the average one standard deviation being 0.15 μm for mode-field diameters in the8-11 mum range. Distinct systematic differences among various techniques were observed at 1550 nm where mode distributions are not as Gaussian.     

两种扩束透镜光纤的研制与模场分析

介绍了两种对光纤端面进行修饰以扩大模场直径（MFD）的方法（加热扩散法和熔接透镜光纤法）。利用刀片远场扫描法对单模光纤（SMF）、加热扩芯光纤（TECF）与熔接透镜光纤（GIF）这两种修饰后的高斯分布光纤进行了测量比较。验证了其模场直径分别为10．700μm,13．129μm和12．7l7μm。并针对实际问题作出修正，通过对单模光纤以及上述两种扩束透镜光纤的分析，得到了相当合理的结果。说明这两种端面修饰法确实能起到扩大模场直径同时又不破坏模式分布的作用。并且验证了修正后的刀片法用于测量修饰后的光纤的各参量是非常有利的。     

Fabrication of optical waveguides by the outside vapor deposition process

The outside vapor deposition process (OVD) represents one of the principle vapor deposition methods used to make glass fiber optical waveguides [1], [2]. In this brief review, each of the basic process steps (deposition, sintering, drawing) are described and the present performance capabilities are presented. Process improvements leading to hydroxyl removal, increased numerical aperture (NA), and long wavelength operation are discussed. Selected examples of fiber compositions and properties are tabulated which range from high-NA fibers suitable for short-distance applications through very-high-performance fibers for long-distance transmission.     

Mode-field diameter of single-mode fiber by knife-edge scanning in the far field

Knife-edge scanning has been applied to the far-field patterns of both matched-clad and depressed-clad single-mode fiber at 1300 nm. The method offers several advantages as compared with other techniques. The mode-field diameter (MFD) has been derived according to a Gaussian fitting procedure, and values agree closely with those obtained with the other standardized procedures.     

Ultrawide-band single-mode transmission performance in a low-loss photonic crystal fiber

We describe the ultrawide-band single-mode transmission performance of a photonic crystal fiber (PCF) in the 850 to 1550 nm wavelength range. We confirmed that the fabricated PCF achieves a single-mode operation over the 850 to 1550 nm wavelength range by measuring the mode-field diameter (MFD) and modal delay characteristics. The 10-Gb/s-based wavelength-division multiplexing (WDM) signals with a total capacity of 190 Gb/s were successfully transmitted over a 5.2-km low-loss PCF utilizing the 850, 1310, and 1550 nm regions simultaneously. Our experimental results show that an endlessly single-mode PCF provides an ultrawide-band of more than 160 THz for future optical communication systems.     

远场扫描和可变孔径定义模场直径与Petermann定义一致

ＩＵＴ－Ｔ在Ｇ．６５０建议中，模场直径定义是严格基于远场扫描测量给出的，然而实际上它与现今普遍采用的Ｐｅｔｅｒｍａｎｎ定义是完全一致的，本文从理论上推证远场扫描，可变孔径法定义的模块直径与Ｐｅｔｒｍａｎｎ定义的模场直径一致。     

Wide-beam propagating fiber for inline optical components

A new technique is proposed for integration of bulky optical components by means of a specific graded-index fiber in which the fundamental mode has a large mode-field diameter (MFD). A wide-beam propagating (WBP) fiber with the field diameter as large as 60 /spl mu/m was successfully fabricated, which will enable bulky optical components that have no wave-guiding structures to be embedded into a fiber circuit without any lenses. It was confirmed that a 5-mm-thick silicon plate, for example, can be integrated into the fiber with a loss of less than 1 dB. A hemispherically ended WPB fiber for much longer bulky components is also proposed.     

1.47μm LD泵浦掺铒光纤放大器的实验研究

本文报道了采用国产器件进行的1.47μm激光二极管(LD)泵浦的掺铒光纤放大器的实验结果。采用模场匹配技术使标准单模光纤(MFD=9.125μm)与掺铒光纤(MFD=3.88μm)之间的熔接损耗降至0.2dB。研究了放大器的增益特性,获得了24dB的小信号增益。     

激光二极管线列阵与多模光纤列阵的光纤耦合

利用一段数值孔径(NA)较小的多模光纤作为一个低成本的微透镜,对激光二极管线列阵的大数值孔径方向准直,将激光二极管线列阵的输出光束耦合到多模光纤列阵中.激光二极管线列阵每个发光单元的光分别耦合到光纤列阵的单根光纤中.总的耦合效率和输出光功率分别为75%和15W.     

激光二极管线列阵与多模光纤列阵的光纤耦合

利用一段数值孔径(NA)较小的多模光纤作为一个低成本的微透镜,对激光二极管线列阵的大数值孔径方向准直,将激光二极管线列阵的输出光束耦合到多模光纤列阵中.激光二极管线列阵每个发光单元的光分别耦合到光纤列阵的单根光纤中.总的耦合效率和输出光功率分别为75%和15W.     

Analysis of mode-field measurements using orthogonal polynomials

Mode-field measurements can be analyzed using a sum of orthogonal polynomials as the fitting function. This method is demonstrated theoretically and experimentally for the mode-field diameter (MFD) measurement of single-mode fibres using the transverse-offset (TO) technique. The fit error is reduced by an order of magnitude in comparison with an ordinary Gaussian fit, and is limited by instrumental noise. Using the Petermann 2 definition, expressions for the MFD and its estimated error are derived. The convergence of the method is demonstrated experimentally. It is shown that the MFD is independent of the chosen range of TO values. In the limit of a large range of equidistant X_i values, the orthogonal polynomials are Hermite-Gaussian polynomials. The transformation from TO field transmission coefficient to strip integrated far-field power can then be carried out easily, and the polynomial coefficients can be used for characterization of the field distribution     

System design methodology for power budgeting of 62.5 μmmultimode fiber systems

The authors present the data to support a recommendation of a new system loss budgeting rule applicable to high-component-count systems using 62.5 μm core diameter multimode fiber. The limited phase space or restricted launch characterization of fiber is demonstrated again to give the most accurate system loss prediction. However, for this fiber size, components such as connectors, switches, and couplers are shown to exhibit loss equivalent to the overfilled launch loss. Two mechanisms are found to explain why the overfilled launch component loss best characterizes their actual loss in common multimode fiber systems. Both are related to the large numerical aperture (NA) of the power distribution launched by the light-emitting diode (LED) system sources. It is important to note that these mechanisms only have been observed on components made with 62.5 μm multimode fiber. This behavior is likely to be different in other fiber sizes     

976nm单管激光器光纤耦合技术研究

对典型量子阱激光器的光束特性和光纤特性进行了简要分析,在此基础上,利用光线踪迹理论,对光纤激光器所用976 nm泵浦模块的耦合光路进行设计,并采用光学设计软件Tracepro对设计的光路进行模拟。通过对C-mount封装的单管进行耦合试验,测得90μm条宽激光器耦合到105μm芯径时,数值孔径NA=0.22楔形光纤(未镀增透膜)的耦合效率可高达92%;100μm条宽激光器耦合到105μm芯径时,NA=0.22楔形光纤(未镀增透膜)的耦合效率可达80%以上。将测量得到的结果和理论的模拟结果进行比较,分析了影响耦合效率的原因。     

New approach to resolution limit and advanced image formationtechniques in optical lithography

Practical resolution, the minimum feature size with a depth of focus (DOF) required for LSI fabrication process, is analyzed. Dependence of practical resolution on various factors, such as optical system parameters (exposure wavelength λ, and numerical aperture NA), resist processes, and required DOF, is investigated. It is shown that practical resolution in the sub-halfmicrometer region is not improved, and may even be degraded, with increasing NA. Furthermore, resolution improvement by increasing NA becomes less effective as λ becomes shorter. This means that the high-resolution capability of high-NA/short-wavelength optics cannot be utilized to create fine-pattern LSIs. In order to overcome this limitation, the effectiveness of advanced image formation techniques, the phase-shifting method and the FLEX method, in practical resolution enhancement is investigated. It is experimentally verified, using a phase-shifting mask and the excimer laser stepper, that a pattern feature size less than 0.2 μm can be clearly delineated with sufficient focus latitude. These advanced techniques make it possible to overcome the resolution limitation of conventional optical lithography     

Characteristics of thermally expanded core fiber

Thermally expanded core (TEC) fiber is expected to reduce fiber-to-fiber and fiber-to-laser diode connection loss. This paper describes the characteristics of TEC fiber theoretically and experimentally. We reveal theoretically that when fabricating TEC fiber the mode field diameter (MFD) is enlarged more effectively by increasing the heating temperature rather than the heating time. In the 1300-1600°C temperature range with heating times between 0 and 60 min, it is necessary to control the temperature accurately so that no deviation from the target temperature is more than ±30°C. This is in order to ensure that any connection loss caused by MFD mismatch is less than 0.1 dB. We show experimentally that the propagation loss of TEC fiber is dependent on the heating region and wavelength by using a micro burner with a propane/oxygen flame. Based on the relationship between the loss characteristics and the expanded MFD, we suggest a method for nondestructively measuring the MFD in TEC fibers     

High-Speed GaN-Based Green Light-Emitting Diodes With Partially n-Doped Active Layers and Current-Confined Apertures

We demonstrate a high-speed GaN-based green light-emitting diode for plastic optical fiber (POF) communication applications. By using a combination of n-type doping and undoped In_xGa_1-xN/GaN based multiple quantum wells (MQWs), and a 76-mum-diameter current-confined aperture structure, we can obtain an extremely high electrical-to-optical (E-O) 3 dB bandwidth (~330 MHz), which is limited by the spontaneous recombination lifetime of the MQWs. A reasonable coupled power (-264 muW) can be simultaneously achieved for a 2 mm in diameter POF with a 0.5 numerical aperture (NA).