Design and characteristics of a branching component for bunched optical fiber using two graded-index rod lenses

An optical branching component is proposed for coupling bunched optical fiber to mono-core optical fibers and the component loss and crosstalk characteristics are investigated. The component is constructed with two graded-index (GRIN) rod lenses for matching different parameters between bunched and mono-core optical fibers. The method of analyzing mismatching and misalignment losses is based on geometrical optics. Measured losses are found to be in agreement with the calculated results and demonstrate that bunched optical fibers can be branched with low loss. Crosstalk measurements show that crosstalk attenuation greater than 30 dB can be easily maintained in the component.     

Analysis and evaluation of graded-index fiber lenses

Graded-index multimode fibers are investigated for use as fiber-lenses. The performance of the fiber-lenses is based on the coupling efficiency between two single-mode fibers with fiber-lenses fused to their end faces. Coupling losses ranged from 0.1 to 1.6 dB for the various fiber-lenses. Expanded beam waists up to 39.5 μm were measured and a fiber separation of > 3.0 mm was possible while retaining the excess loss within the above range. Low loss coupling was observed with multiple-pitch ( > 3.0 mm long) VAD lenses. A theoretical analysis considers a ray matrix transformation of the complex beam parameter and predicts the coupling efficiency as a function of the relative transverse and axial displacements of the two fibers. A comparison to the corresponding measurements is made.     

一种大有效模面积的折射率渐变型模分复用器研究

提出了一种大有效模面积的折射率渐变型分布模式 信道的新型6模式复用器,采用光束传播法和全矢 量有限元方法研究了模分复用器的性能指标。结果表明,本文复用器实现了折射率渐变型分 布、大有效模场 面积、低非线性系数、高耦合效率和宽工作波段6模式复用解复用操作;在1450650n m工作波段, 模分复用器耦合效率优于－0.449dB,模式LP₀₁ 、LP 11a、LP11b、LP_21a 和LP_21b耦合效率分别优于0、 －0.018、－0.018、－0.449和－0.036dB, 呈现出平坦特性;在C波段内,模分复用器耦合效率 呈现出更好的平坦特性,所有模式对应的平坦度均优于0.066dB;在 1550nm,所有模式的有效面积均大于标准单模光纤(SMF)的14.9倍,非线性系数均远小于标准SMF。     

Researchon mode division multiplexer with graded-index distribution, low loss and low crosstalk

A graded-index mode division multiplexer with low loss and low crosstalk is proposed. The transmission channel adopts a pure silica core with large effective area to achieve low attenuation, which effectively reduces the splicing loss with pure silica core few-mode transmission fiber. Low differential mode group delay is realized by using graded-index distribution. Also the effective index difference of the modes is greater than 0.5×10-3 to ensure low crosstalk between modes. The performance of the mode division multiplexer is investigated using the beam propagation method and full-vector finite element method. The result shows that the coupling efficiency of multiplexer is better than ?0.479 dB, and the extinction ratio is higher than 31.2 dB in the wavelength of 1 400—1 700 nm. In C band, the average coupling efficiency of all mode channels of multiplexer is better than that of ?0.140 dB, which shows flatness. The proposed scheme is an effective way to implement a multiplexer with low crosstalk, low loss, low fusion loss, high coupling efficiency, high extinction ratio and wide operating band.     

Angular multiplexing for multichannel communication in a single fiber

A concept of angular multiplexing of several communication channels in a relatively short step-index fiber is described. The angular dependence of the outgoing light flux and the temporal impulse response are calculated for slab waveguides and round fibers in terms of the fiber's length and the excitation conditions. Calculations of the inpulse response in the presence of mode coupling are based on a simple model which is found to be adequate for short fibers. Crosstalk levels are calculated by integrating the flux over the aperture of the detectors. Measurements of angular flux distribution, temporal impulse response, and crosstalk levels agree with theoretical prediction and validate the proposed concepts. To increase light levels, parallel excitation of each channel by several light sources is suggested and tested. Also, light collection efficiency is increased by employing lenses and annular mirrors to deflect and focus the light from each channel to small-area detectors. Given a 25 m long fiber with a coupling constant of 10^-5rad²/m, it is possible to multiplex four channels with cross-talk of about -25 dB and information rates ranging from 10⁹bits/s to 10¹⁰bits/s for each channel.     

NMOS multiplexer for fiber optics

The design, layout, and testing of a 5 Mb/s digital multiplexer using 2-/spl mu/m design rules for fiber-optic applications are described. Using a common 10-bit bus, the chip reads data from 16 sources in response to a DATA READY signal. Serial output includes a parity bit and is sent to an LED driver. Handshaking, sequential control, parity checking, and data formatting are covered.     

可调谐双芯光子晶体光纤波分复用器设计

数值分析了双芯光子晶体光纤的耦合特性,设计出0.85/1.55μm、0.98/1.55μm和1.3/1.55μm基于通信波段的波分复用器件,其光纤长度分别为542μm、996μm和932μm.在双芯光子晶体光纤的基础上,光纤长度固定不变时,通过调节中心空气孔材料折射率,材料折射率分别为1.281、1.343和1.348...     

一种基于光纤Bragg光栅的全光纤分/插复用器

研制了用于ＷＤＭ全光网的全光纤型分／插复用器,由两个相同的光纤环行器和串接其间的光纤Ｂｒａｇｇ光栅组成。其中光纤Ｂｒａｇｇ光栅是用紫外光直写方式在普通单模光纤上制成。文中给出了该复用器的上／下路端口隔离度和信道插入抽耗等主要测量结果。其特点是结构简单,可实现信道波长再利用,从而提高网络的灵活性。     

A wavelength division multiplexer based on plastic surfacerelief grating applied to local area communication network

A plastic surface-relief grating as a wavelength division multiplexer is designed and fabricated with the conventional mould pressing technique using the transmission-type fused quartz phase grating as mask pattern and polycarbonate as basal material.The experiment results show that in an optimizing process,the plastic surface-relief grating has the highest firstorder diffraction efficiency under adequate groove depth and incident angle,and can be used as the best optical path for wavelength division multiplexing(WDM).We also establish the experiment setup for testing the WDM performance of the plastic surface-relief grating based wavelength division multiplexer.The results show that the proposed wavelength division multiplexer has the high-stability temperature characteristics,the low insertion loss of less than 5 dB,the large isolation of greater than 20 dB,the low polarization-dependent loss(PDL) of less than 0.4 dB and the relatively steep pass-band characteristics.It is a WDM device with good performance,which can be applied in short distance communication.     

Mode-matched ion-exchanged glass-waveguide bridge for high-performance dense wavelength division multiplexer

Data bit rate, 1-dB passband, and device dimensions are the key properties of dense wavelength division multiplexing (WDM) devices. For blazed-grating-based dense WDM devices, analysis shows that all these three properties can be enhanced by reducing the output fiber-array channel spacing. In this paper, we propose an ion-exchanged glass waveguide to reduce the output channel spacing. To fabricate the low-loss fiber-compatible waveguide, a field-assisted ion-exchange process is developed. The waveguides fabricated by this process have a propagation loss of 0.16 dB/cm and a coupling loss to single-mode fiber (SMF) of 0.1 dB. A 47-channel 100-GHz-spacing dense WDM integrated with the glass waveguide is then packaged and demonstrated. The device performance has verified the effectiveness of the proposed solution and the successfulness of the ion-exchanged glass-waveguide technique in this application.     

Integrated laser and add-drop optical multiplexer for narrowband wavelength division multiplexing

The fabrication and characterisation of a monolithically integrated narrowband add-drop multiplexer and DBR laser are reported. Multiplexer bandwidth of 2-3.5 nm have been measured with a Bragg extinction ratio >23 dB.<>     

Laser coupling to single-mode fibre using graded-index lenses and compact disc 1.3 ?m laser package

A 1.3 ?m laser in a compact disc package is coupled to single-mode fibre using two graded-index lenses in a nearly confocal scheme. An increase in the alignment tolerance at the lens-lens interface by a factor of six suggests the design for a potentially very low-cost connectorised laser package. The coupling efficiency of approx. 6% (?12 dB) is shown to be adequate for local loop applications.     

1.0 dB low-loss coupling of laser diode to single-mode fibre using a planoconvex graded-index rod lens

Marked low-loss coupling between a laser diode and a single-mode fibre has been realised, utilising a planoconvex, high-numerical-aperture graded-index rod lens with greatly improved small wavefront aberration.     

20-Channel micro-optic grating demultiplexer for 1.1?1.6 ?m band using a small focusing parameter graded-index rod lens

A 20-channel micro-optic grating demultiplexer with a single-mode input fibre has been developed for 1.1?1.6 ?m band using a newly developed graded-index (Selfoc) rod lens with a small focusing parameter and an Si-etched reflection grating. Insertion losses were 1.9 to 3.5 dB. Isolation between adjacent channels was less than ?20 dB.     

光纤通信空分复用技术研究进展分析

带宽容量需求的快速增长驱动光纤通信技术不断演进,目前多芯光纤复用、少模光纤复用、少模多芯光纤复用和轨道角动量模式复用等空分复用技术成为业界的关注焦点.基于此,对空分复用技术涉及的新型光纤设计、模式转换与控制、信道复用/解复用、光放大等关键技术及其研究进展进行了分析,同时对其技术特征进行了对比总结,并对光纤通信空分复用技术目前存在的问题和未来发展的应用前景进行了探讨和展望.     

用于频分复用相干光纤通信的半导体激光器稳频系统

本文以Fabry-Perot干涉仪为鉴频器,并利用其众多梳状透过峰,实现了若干半导体激光器的稳频,相对频率稳定度可达10~(-11)量级(τ=10s)。还实现了数个激光器对一主激光器的频率跟踪。     

Highly stable optical add/drop multiplexer using polarization beam splitters and fiber Bragg gratings

We demonstrate a novel wavelength-division add/drop multiplexer employing fiber Bragg gratings and polarization beam splitters. The multiplexer is easy to fabricate without any special technique such as UV trimming, and yet shows very stable performance with less than 0.3-dB crosstalk power penalty in a 0.8-nm-spaced, 2.5-Gb/s-per-channel wavelength-division multiplexing (WDM) transmission system.     

Numerical analysis of intermodal delay in few-mode fibers for mode division multiplexing in optical fiber communication systems

In order to achieve higher spectral efficiency, mode division multiplexing (MDM) in few-mode fibers is a new research area. The idea faces lots of technical issues including intermodal delay and mode coupling which limit the achievable length of the system. This paper is designated to complete the analysis of intermodal delay in step-index few-mode fibers. We analyze numerically all the parameters of fiber, which could impact intermodal delay in few-mode fibers and identify the conditions which can increase the number of multiplex modes without significant increase in maximum intermodal delay.     

关于通信光纤传输中波分复用技术的运用研究

目前我们使用的光纤通信是网速最快的,而波分复用技术在光纤网络通讯中的应用使得带宽容量得到了很好的扩展.本文就波分复用技术在光纤网络通讯中的应用以及可能出现的问题进行论述.     

发散纤维透镜新的成象公式

本文利用高斯光束传播理论以及ABCD定律,导出了发散纤维透镜新的成象公式。