Characterization of special fibers and fiber devices

Methods for characterizing birefringent fibers (both those with high circular or linear birefringence and those with negligible intrinsic birefringence) are presented, and their relative merits are discussed. Fibers with high nonlinear coefficients exhibit interesting optical phenomena, and methods are developed to determine second harmonic, Pockels and Kerr effects, parametric phenomena, and the Verdet constant of silica and higher-loss, nonsilica fibers. Fibers containing rare-earth ions are of interest both as active (laser and amplifiers) and passive systems. Techniques are developed to characterize these devices, and conventional methods are modified to quantify dopant parameters within the fiber. Techniques for the measurement of the diverse properties of all these different fibers are presented with results, and, where appropriate, the problems with their characterization are discussed     

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.     

Measurements in fiber optics

Recent advances in optical-fiber technology dictate that attention must be given to establishing accurate and precise measurement techniques. In this paper measurements currently employed to determine the characteristics of optical fiber waveguides are reviewed. Included in the review are techniques for measuring attenuation, delay distortion, refractive-index profile, fiber diameter, and mechanical strength. Since establishment of accurate measurement procedures cannot be accomplished without some knowledge of the physical mechanisms controlling the parameters to be measured, a brief review of the dominant causes of attenuation and modal delay in fibers is also included.     

基于超构表面的非线性光学与量子光学

近年来,超构表面在经典光场调控领域受到了广泛的关注,获得了优异的成果。同时,超构表面在非线性光学和量子光学方面的应用也引起了人们越来越多的兴趣。文中分别介绍了非线性超构表面和量子超构表面的基本原理和应用,总结了近几年的相关报道,包括谐波产生和增强,谐波产生和对称性的关系,非线性相位调控和全息成像,以及基于超构表面的纠缠光子对产生,测量和调控。最后,对超构表面在这两个领域的进一步应用和前景进行了展望。     

Cost-effective side-coupling polymer fiber optics for opticalinterconnections

Potentially low-cost optical side-couplers embedded along a polymer optical fiber are demonstrated using etched micromirrors. Both serial and parallel mirror fabrication possibilities are discussed. Light distributions to as many as 300 such side-coupling ports along a single straight fiber were experimentally obtained with uniformity of 74%. Various unidirectional and bidirectional all polymer array coupler concepts are presented. Some of them are experimentally demonstrated     

Millimeter-wave fiber optics systems for personal radiocommunication

System concepts for millimeter-wave personal communication systems and the advantages of millimeter-wave band usage are briefly described. Demonstration of broadband millimeter-wave subcarrier transmission concepts over fiber-optic links is performed. Several fiber-optic link architectures, including one using a combination of direct laser modulation and indirect (external) optical modulation, are outlined with respect to signal transmission at millimeter-wave frequencies. Several configurations are experimentally investigated using 70-MHz, 300-MHz, and 26-GHz subcarriers which transmit either FM or QPSK data signals. Additionally, the use of optical MMIC technology, which can result in the design of compact and cost-effective optical receivers, is described with respect to personal communication radio base station equipment. MMIC HEMTs operating as photodetectors are newly characterized in terms of digital and analog signal reception with excellent performance being observed     

Multidimensional processing: Nonlinear optics and computing

The purpose of this paper is to overview some of the trends and directions in computing, as performed by optical hardware, resulting from the demands made by multidimensional signal processing. Optical information processing or optical computing is a vast field and some of the more significant issues are discussed here. We discuss future developments and architectural consequences for such potentially highly parallel and interconnected processing systems. Particular emphasis is placed on energy and speed considerations, associated with the use of nonlinear optical materials in optical systems and devices.     

Nonlinear codes for dispersive nonlinear fibers

We consider a single wavelength channel in a nonlinear dispersive single-mode fiber. We simulate the propagation of binary sequences using on-off keying return-to-zero modulation at a bit rate of 10 Gb/s, under different dispersion and input power conditions. We determine the impact that dispersion and nonlinearity have on the pulse sequences by measuring the Euclidian distances (EDs) among all pairs of received sequences. We then model the set of EDs as a fully connected graph and by means of a clique-finding algorithm we search for subsets of sequences that form codes matched to this nonlinear channel, resulting in significant bit-error-rate improvement.     

On the scalar approximation in fiber optics

It is widely accepted that the scalar approximation is valid when the gradient of the permittivity distribution Δε/ε is small. Such a condition is demanding since it precludes a rapidly varying permittivity distribution, which is usually the case in a practical optical fiber due to some kind of fluctuation in a fabrication process. Here, the scalar approximation is derived from the electric field integral equation. From the result it is seen that the applicability of the scalar approximation does not depend on the roughness in the permittivity distribution as long as the permittivity in the core is close to that in the cladding     

Nonlinear microwave optics in liquid suspensions of shapedmicroparticles

The use of shaped microparticle suspension for such active processes as phase conjugate via degenerate four-wave mixing at microwave and millimeter wavelengths is addressed. The theoretical method used to describe the interaction of shaped microparticles with coherent radiation is outlined. The generation of up to 250 mW phase conjugate radiation in a medium composed of rod-shaped carbon fibers suspended in a passive fluid dielectric that is maintained in a waveguide is reported. The theory for the nonlinear optical behavior of shaped particle suspensions is shown to be in excellent agreement with the available experimental data     

Nonlinear optics, anharmonic oscillators, and pyroelectricity

An anharmonic vibronic oscillator model is set up and used to derive general expressions for nonlinear susceptibilities. The system is handled both classically and quantum-mechanically, and the results are shown to agree. It is shown that, when one of the interacting fields has a frequency close to that of an optical phonon, the nonlinear susceptibility is dominated by the same term in the anharmonic potential that is dominant in Raman scattering. This result agrees with the experiments and analysis of Faust and Henry. These arguments are extended to cover electrooptic coefficients, for which the model is consistent with the work of Kaminow and Johnston. On the basis of the anharmonic vibronic oscillator model, estimates are made of the magnitude of infrared electroreflectance effects and their counterpart, optical rectification. The conversion gain of such a rectifier is calculated. The model is also used to determine Raman or parametric gain, depending on whether the idler frequency is or is not close to the optical phonon frequency. Finally the model is used to compute the pyroelectric coefficient, which, it is shown, ought to be proportional to the specific heat, in agreement with recent measurements by Heiland and Ibach on zinc oxide.     

光纤微弱磁场传感技术研究进展

文章扼要评述了光纤微弱磁场传感器的工作原理及在换能器、信号处理、传感器等阵列等方面的研究进展。     

Birefringence measurements in fibers without polarizer

A method for measuring the delay between polarization eigenmodes in either high- or low-birefringence fibers is described. The main advantage of this interferometric method is its ability to perform the measurements without the use of any polarizing device. This results in particularly easy handling and makes this technique very suitable for systematic fiber controls. The obtained accuracy using an all-fiber setup is 0.02 ps/m for highly birefringent fibers and 0.003 ps/m when the birefringence is low     

A local view of radiation effects in fiber optics

The reasons for the difficulties that can arise in assessing the potential behaviour of fiber optics in real radiation environments in devising realistic test procedures are considered. Present knowledge of the radiation effects is reviewed by relating the author's own measurements to those of other workers. Some common features of behavior across fiber types are pointed out, and a possible empirical model for the response of undoped core fibers is presented