Showing papers on "Wavelength-division multiplexing published in 1980"

Local area network optical fiber data communication

Abstract: A method and apparatus are disclosed for high speed multiaccess data communication using guided wave components and angular division multiplexing for parallel optical signal transmission over a multimode optical fiber. A receiver at each station in the network comprises an optical coupler/demultiplexer, a pulse regenerator, an optical processor and detectors. The transmitter at each station comprises an array of lasers, a switching matrix for controlling emissions into the optical fiber and a multiplexer/coupler for coupling the laser emissions to the multimode optical fiber. The optical processor is directly coupled to the switching matrix. Preferably, the multiplexer/coupler comprises a graded-index planar lens, one major surface of which abuts the optical fiber and the other major surface of which is contacted by a plurality of single mode waveguides from the different lasers of the transmitter. As a result, the single mode signals introduced into the lens at different radial distances are coupled to different modal groups propagating in the optical fiber. The coupler/demultiplexer preferably comprises a graded-index lens and an array of concentric half-ring lasers. Annular cones of radiation propagating in the optical fiber are focused to an array of concentric rings near the half-ring lasers where they are converted into linear beams propagating in single mode guided wave structures.

Microoptic grating multiplexers and optical isolators for fiber-optic communications

Abstract: As new optical devices for increasing further the utility of and to expand the application of fiber-optic communications, grating multiplexers and isolators have been developed for 0.8 μm band employing microoptic approach. The development of these devices is the subject of this paper. The devices have desirable features of small size, compactness, high optical performances, and high reliability. The grating multiplexer consists of a graded-index rod, a blazed reflection grating replicated onto the graded-index rod slanting facet or a wedge facet, and an input-output fiber array. Simple calculations have been done to determine necessary element parameters for a given channel spacing. Experimental results are presented for five-channel multiplexers devised using a SELFOC®lens. Around 3 dB insertion loss and less than -30 dB crosstalk have been obtained for about 35 nm channel spacing in overall device size of 18 \times 13 \times 50 mm. Faraday rotation optical isolators for 0.8 μm band have been miniaturized by employing an efficient paramagnetic glass Faraday rotator, a magnet with a through hole and a folded optics in the Faraday rotator. The path number in the folded optics has been optimized in terms of trading-off between the magnet size and the insertion loss. A 0.9 dB insertion loss including fiber coupling loss and 36 dB isolation have been obtained in overall device size of 24 \times 24.5 \times 42 mm. Results on the temperature and wavelength dependence of the isolation are also presented. In addition, fundamental properties of optical circulators for 0.8 μm band and optical isolators and circulators both for 1.3 μm band, developed as extended modifications of the optical isolators for 0.8 μm band, are briefly described.

The Use of Fiber Optics for Communications, Measurement and Control Within High Voltage Substations

Abstract: Based on experience to date, fiber optic communications, in conjunction with novel optic translucers, may play an important role in the design of future measurement and control devices used in high voltage substations. This paper presents a summary of fiber optics systems installed and tested at Bonneville Power Administration (BPA) and includes a look at possible future development.

Optical grating multiplexer in the 1.1-1.5 μm wavelength region

Abstract: Experimental results of a multiplexer using a diffraction grating for a wavelength-division-multiplexing transmission system are described. The multiplexer has 10 channels and a wavelength spacing of 36.2 nm in the 1.1-1.5 μm wavelength region. Minimum insertion loss for each channel was less than 2.2 dB.

Compact wavelength multiplexer using optical-fiber pieces

Abstract: The optical-wavelength-division multiplexer reported here is composed of three multimode fiber pieces with dielectric multilayers evaporated on the ends of the fibers, which have been polished obliquely or squarely. The working faces of these fibers are bonded together in a crossed V groove to duplex two wavelengths (λ = 0.82 and 1.2 μm). The far ends of the joined fiber pieces are left intact for splicing with fiber cables or are terminated with connector ferrules for connection. The multiplexer is small (1 cm square) and lightweight (1.5–3 g). It also shows low insertion loss (1 dB) and cross-talk level (below −40 dB). We have estimated that the cost of this type of component can be reduced to 1 order of magnitude lower than that of conventional lens and mirror types.

Single‐mode fiber wavelength multiplexer

Abstract: Wavelength multiplexer for single‐mode optical communication is reported. The multiplexer is made of all single‐mode fibers and exhibits excellent stability. The separation between the multiplexed wavelengths was about 3.5 nm.

Simple structure high isolation multi/demultiplexer

Abstract: Wavelength division multiplexing (w.d.m.) techniques, which transmit light signals with different wavelengths through a single optical fibre, are required to increase transmission capacity. The letter describes a new type of multi/demultiplexer using an interference filter and a single graded-refractive-index (g.r.i.n.) rod lens. It has a simple structure and a low near-end crosstalk (less than −50 dB).

Progress in Fiber Optics Transmission Systems for Cable Television

Abstract: Developments in transmitter/receiver design and signal conditioning are described. Also, included is a discussion of the operating experience and retrofit update of a 12 channel, eight kilometer fiber optic super trunk. A unique feature of the system described is that only one repeater location is employed in contrast with a conventional cable TV system which would require 12 repeaters to cover the same distance.

Overview of telecommunications via optical fibers

Abstract: Light-wave transmission on a glass-fiber transmission medium has reached a fully commercial stage, with carrier wavelengths in the 0.82-0.85-µm region. Second generation systems will operate with carrier wavelengths in the 1.2-1.6-µm region where high-silica fibers have more attractive loss and dispersion characteristics. Research continues at a high level, and will lead to continued rapid evolution of light-wave systems.

Holographic Optical Element (HOE) For Demultiplexing In Fiber Optic Systems

Abstract: A simple, single-element, holographic ally formed device for use as a multiplexer/demultiplexer in wave-length division multiplexing in optical fiber systems is described. The single holographic element performs all the required functions of collection, separation, and focusing. Experimental results for a thick dichromated gelatin HOE are described. Efficiencies of 70% over a bandwidth of 30% have been measured in the visible. Methods of extending the operation to the near IR are discussed.© (1980) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Wavelength division multiplexer/demultiplexer in optical fiber communication systems

Abstract: An optical multiplexer/demultiplexer using wavelength division multiplexing comprises a fibre optic port for connection to an optical transmission fibre, a dispersive diffraction element, and an array of alternate light sources and light detectors. One or more focussing and collimating elements direct predetermined spectral components diffracted by the diffraction element from the light sources to the fibre optic port and from the fibre optic port to the light detectors, thereby allowing simultaneous reception and transmission of optical signals in a single unit.