Groove guide and H-guide: Supplementary information

Interest in groove guide and H-guide for application at millimeter waves is considerable at present. Hitherto unpublished material dealing with these waveguides is presented. The early history, patent applications, drawings and prototypes are described.     

Magnetopasma surface wave analysis for an H-guide structure containing semiconductor

The propagation characteristics of higher order magnetoplasmon surface waves have been studied for an H-guide structure. Hybrid TE-TM modes are found at frequencies above the cutoff value. We explore their non-reciprocal propagation characteristics as a basis for the design of non-reciprocal devices.     

Solid-state devices in H-guide, groove guide and fence guide

A novel concept of integrating solid-state devices with H-groove and fence guides at millimetre wavelengths is described. Microstrip circuits containing beam-lead diodes are inserted parallel to the sidewalls in the centre of the guides. As an example an integrated detector circuit is shown and results of experiements presented.     

Distributed single-mode fiber to single-mode planar waveguidecoupler

Light transfer between a curved single-mode fiber and a single-mode planar waveguide is investigated experimentally in dependence on the refractive index and thickness of the planar waveguide and for different polishing depths. Marcuse's model is applied to treat theoretically the coupler, leading to a very good agreement with the experimental results     

Submillimeter Components Using Oversize Quasi-Optical Waveguide

Components such as directional couplers, attenuators, introduction and phase shifters have been developed using optical techniques in oversize rectangular waveguide. These components were designed for operation in the 300- to 350-Gc range. They were scaled from a design that was successful at 27 Gc. Preliminary data taken at 330 Gc indicates the feasibility of this technique. The advantages of oversize waveguide as compared with conventional waveguide and freespace optical components are 1) lower attenuation and 2) simpler construction.     

Oversize Waveguide Directional Coupler (Correspondence)

Oversize rectangular waveguide using TE/sub 10/ mode propagation has been suggested as a means of reducing the attenuation and fabrication difficulties of transmission lines and components for frequencies above 40 Gc. Experiments on straight sections of such transmission lines show that it is superior to pure optical transmission for short distances.     

Polarization-controlled single-mode VCSEL

Relative intensity noise (RIN) in a vertical-cavity surface-emitting laser (VCSEL) was greatly reduced through the use of polarization control to eliminate competition between two orthogonal polarization states by ensuring there was only one polarization state. Polarization was stable with optical feedback of up to 10%. Polarization control was achieved by inducing a small loss anisotropy in fundamental transversal mode VCSEL's. Anisotropic post structures, such as a rectangular post, an oblique post, or a zigzag-sidewall post, were found to be effective in creating loss anisotropy without serious degradation of other VCSEL characteristics such as light-output power or beam profile     

Frequency-modulated single-mode laser

Three frequency-modulated single-mode lasers employing long multicavity resonators are presented. The f.m. is achieved by simultaneous changes of the length of the additional cavities in such a way that resonance conditions are preserved, and the resonator Q factor remains constant. The linear electro-optic Pockels effect in KDP crystals is used to change the optical length of the additional cavities.     

Two Oversize Waveguide-Polarization Diplexers (Short Papers)

Two new types of quasi-optical waveguide-polarization diplexers are described. They are based on the use of a metal grating, or a dielectric plate at Brewster's angle, placed in an oversize circular 3-port junction. Their performances are measured at a wavelength of 4.28 mm in a standard microwave circuit and at 337/spl mu/m with the HCN laser beam.     

基于单模-无芯-单模结构的光纤折射率传感器

提出了一种基于光纤单模-无芯-单模结构的光纤 折射率传感器。当外界折射率(SRI,surrounding refractive index)小于无芯光纤(NCF,no-core fiber)折射率,并且二者十分接 近的情况下,NCF 可以看作是具有阶跃折射率分布的弱导多模光纤(MMF),这样便构成了传统的单模-多模- 单模(SMS,single-mode multimode single-mode)光纤结构。利用线偏振模近似的方法理论分析了基于这种光 纤结构的折射 率传感器的模式激发特性以及输出特性,进而进行了相应的数值仿真及实验验证,结果表明 ,数值仿真与实验 结果均与理论分析结果相一致。在1.3～1.4的折射率范围内,实验测得传感器灵敏度达到 205.42nm/RIU。     

单模光纤的PMD

讨论了单模光纤的偏振模色散PMD，包括PMD与单模光纤的几何尺寸及应力的非圆对称的关系模间耦合的影响。PMD具有瞬时统计特性以及采用Monte Carlo模拟软件对光缆产品的PMDQ进行估算。     

Backscattering in single-mode fibres

The scattering process in single-mode optical fibres is considered in terms of wave optics rather than geometrical optics, which is inadequate in this case. Surprisingly, however, the result for the backscattering signal at the input end of the fibre is nearly the same as for multimode fibres.     

Single-polarization single-mode optical fibers

Strictly speaking, an ordinary axially symmetrical single-mode fiber is a "two-mode" fiber because two orthogonally polarized HE11modes can be propagated in it. This fact results in the instability of the polarization state of the propagated mode when geometrical perturbation exists in the fiber, and also the so-called polarization mode dispersion. These are harmful in some applications of single-mode fibers to communication and measurement. To prevent these adverse effects, single-polarization single-mode (SPSM) optical fibers have been developed. Three basic types of the SPSM fiber are elliptical-core fiber, stress-induced birefringent fiber, and side-pit fiber. This paper describes the principles of these three types, performance obtained experimentally, theoretical approaches, and measurement techniques related to the SPSM fibers. Finally, relevant technical tasks in the future are mentioned.     

Bend-optimized dispersion-shifted single-mode designs

A bend-optimized design for a dispersion-shifted single-mode fiber with segmented-core profile is described. With this design, dispersion-shifted fibers having the highest cutoff wavelengths reported to date have been achieved. Results on dispersion, attenuation, mode radius, bending, and microbending loss for such fibers are presented and compared to alternate designs.     

A single-mode waveguide laser

A laser has been constructed in which a neodymium-doped glass slab forms the core region of a single-mode optical dielectric waveguide. The observed laser output is in a single, spatially coherent, transverse mode, which is characteristic of the waveguide structure, and has a diffraction-limited beamwidth.     

Stable low-loss single-mode couplers

Single-mode optical-fibre couplers have been fabricated from standard production fibre using a fused biconical taper technique. The packaged devices have very low insertion loss (?0.1 dB), good thermal and mechanical stability, and exhibit negligible polarisation selectivity.     

Low-loss single-mode fibre connectors

A low-loss detachable connector with simple plug structure has been fabricated for single-mode fibres. The centre hole of the plug, in which the fibre to be joined is fixed, is machined precisely at the plug centre. The average connecting loss is reduced to as low as 0.5 dB, including fibre end reflection.     

Dispersion-shifted convex-index single-mode fibres

The structural design of the single-mode fibre with a convex-index profile is described to achieve zero dispersion at 1.55 ?m. As a result of the fibre design, it is clarified that the bending loss of the convex-index fibre is the smallest among the losses of various index profile fibres such as step, triangular and Gaussian ones.     

耐弯曲单模光纤

本文讨论了光纤弯曲损耗及其主要影响因素,比较了目前采用的改善光纤弯曲损耗各种方法,对照G．652D光纤的特性,分析了两种新型耐弯曲光纤G．657A和B光纤的特性,指出了它们的应用场合。