Showing papers in "Fiber and Integrated Optics in 1982"
TL;DR: In this paper, the authors used a binary phase transmission gratings exhibiting a certain number N of central diffraction orders of equal intensity to construct star couplers of the 1-to-N and N-toN types.
Abstract: Binary phase transmission gratings exhibiting a certain number N of central diffraction orders of equal intensity can be used to construct star couplers of the 1-to-N and N-to-N type. The calculation of the grating's groove structure is described, and first experimental results are presented.
103 citations
TL;DR: In this article, the authors show that the pure bend loss of a curved dielectric optical waveguide can be reduced effectively with only a slight change in the transverse field distribution by replacing the cladding material outside the caustic by another material with a smaller refractive index.
Abstract: The pure bend loss of a curved dielectric optical waveguide can be reduced effectively with only a slight change in the transverse field distribution by replacing the cladding material outside the caustic by another material with a smaller refractive index. This is demonstrated by microwave model experiments.
18 citations
TL;DR: In this article, a mandrel wrap filter based on far-field patterns was used to select a mode filter for 50 μm core diameter, 125 μm outside diameter fibers with δ = 1.1%.
Abstract: A selection criterion for mode filters based on far-field patterns is developed. The criterion is used to select a mandrel wrap filter for 50 μm core diameter, 125 μm outside diameter fibers with δ=1.1%. When cut-back loss measurements were made using the mandrel wrap chosen in this way, loss scaled with length to within ± 0.05 dB/km in three 2-km fibers.
9 citations
TL;DR: In order to limit micro-bend losses in an optical fiber cable, it is possible to modify parameters relating to the fiber or the cable as discussed by the authors, such as the core diameter, the Young modulus of the coating and of the cable material, and the thickness of the cladding.
Abstract: Some practical and theoretical aspects of a V-grooved cylindrical cable (high performance optical fiber cable) are now being developed in several countries. Design of cables is important, because bendings may cause distortions. In order to limit micro-bending losses in an optical fiber cable, it is possible to modify parameters relating to the fiber or the cable. Some of the possibilities are: to decrease the core diameter in order to decrease the attenuation coefficient; to increase the diameter of the cladding so as to increase the tension above which micro-bendings occur; to increase the continuous bending radius due to cabling; to decrease the effects of roughness (μ); to integrate the effects of roughness as much as possible by decreasing the Young modulus of the coating and of the cable material and by increasing the cladding thickness; and to suppress the tension T of the fiber in the cable. The cabling element is made of a V-grooved cylindrical core, in which the fiber with an outside dia...
6 citations
TL;DR: In this article, a vapor phase axial deposition (VAD) method using a multiple burner with single source gas nozzle is presented, which is expected to provide a simple method of fabricating low loss and wide bandwidth fibers.
Abstract: A vapor phase axial deposition (VAD) method using a multiple burner with single source gas nozzle is presented. Fibers fabricated by this technique feature very low loss and wide bandwidth characteristics, although the refractive index profile slightly deviates from the ideal, on the outer side of the core part. This technique is expected to provide a simple method of fabricating low loss and wide bandwidth fibers.
6 citations
4 citations
TL;DR: In this paper, a detailed experiment is described that convincingly illustrates the mode of operation of the scattering sphere as used in daily practice, and the wavelength independent term in the total loss, different for fibers drawn from the same glass, is explained as being scattering partly due to 1-mode mixing of modes with the same β by imperfections that affect high-1-modes predominantly.
Abstract: The optical fiber scattering loss coefficient is measured directly in a scattering sphere or deduced indirectly from total loss measurements. The results show agreement for graded-index silica-based fibers, but they seem conflicting for graded-index compound-glass fibers. This is explained from the diffusion-controlled refractive index profile and the ensuing mode-dependent scattering and absorption loss due to the different optical properties of core and cladding glass. Using this model the two-lengths total loss measurement method is discussed. A detailed experiment is described that convincingly illustrates the mode of operation of the scattering sphere as used in daily practice. The wavelength-independent term in the total loss, different for fibers drawn from the same glass, is explained as being scattering partly due to 1-mode mixing of modes with the same β by imperfections that affect high-1-modes predominantly. The total loss of the glasses to be investigated can be measured using low NA...
3 citations
TL;DR: In this paper, a review of the development of integrated optical circuits using III-V compound semiconductors is presented, with reference to double heterostructure configurations for optical sources and detectors.
Abstract: Recent progress in the development of integrated optical circuits using the III-V compound semiconductors is reviewed. The application of double heterostructure configurations is emphasized, not only for optical sources, but also for detectors, with reference to both the A/GaAs/GaAs system and the InGaAsP quaternary. Devices utilizing periodic corrugations are described briefly, whereas alternate attempts to fabricate optical circuits by etching or sputtering techniques are discussed in more detail. Recent advances in processing techniques suitable for optical integration, such as reactive-ion etching, and the use of lasers or electron beams for device processing, are described.
3 citations
TL;DR: The role of long wavelength systems (1.0μm <λ < 10.0 μm) in fiber optics communications is evaluated in this paper, where the role of the GaInAs p-i-n detectors has emerged as the preferred choice because of their low noise, excellent sensitivity and high temperature stability.
Abstract: The role of long wavelength systems (1.0μm<λ< 10.0μm) in fiber optics communications is evaluated. For high-bit rate optical telecommunications at 1.3 μm or 1.5 μm, GaInAs p-i-n detectors have emerged as the preferred choice because of their low noise, excellent sensitivity, and high temperature stability. Ge and HgCdTe photodiodes offer nearly equivalent performance and a somewhat more advanced production technology. Beyond 2 μm, HgCdTe would seem to be the clear choice for photodetector applications. Avalanche photodiodes in long wavelength optical fiber links may find uses in situations involving high bit rate transmission using low cost components. Although avalanche gain will always improve the system sensitivity, the LED/APD combination is only half as sensitive as a laser/p-i-n system, as well as being bandwidth limited. Nontelecommunications applications involving data base and fiber guidance systems are discussed, and a prospective look is taken at the uses, such as power transmission, o...
2 citations
TL;DR: In this paper, an alternative criterion for estimating the baseband transfer function of multimode optical fibers is discussed, which is based on considering the launching condition that excites all fiber modes uniformly in amplitudes.
Abstract: This paper discusses an alternative criterion for estimating the baseband transfer function of multimode optical fibers. The optical fibers having little mode conversions show that the baseband frequency characteristics are affected strongly by the launching condition of an input optical pulse. In the criterion presented here, the baseband transfer function in such fibers is estimated by considering the launching condition that excites all fiber modes uniformly in amplitudes. In order to obtain such a transfer function, the actual responses affected by the launching conditions are measured together with the modal power distributions for different kinds of launching conditions. A numerical procedure is then presented that enables us to derive the baseband transfer function independently of modal power distributions. Experimental results at λ x= 633 nm and 856 nm are presented for step index fibers (0.1 and 0.2 km long) having a core radius of 30 pm (its refractive index is 1.452) and a refractive ...
1 citations
TL;DR: In this paper, the field distributions and propagation constants of weakly guiding circularly symmetric optical waveguides having arbitrary radial refractive index distribution are determinable from a variational analysis, which uses the solution of the scalar wave equation for the infinitely extended parabolic refractive profile as a reference.
Abstract: Field distributions and propagation constants of modes in weakly guiding circularly symmetric optical waveguides having arbitrary radial refractive index distribution are determinable from a variational analysis, which uses the solution of the scalar wave equation for the infinitely extended parabolic refractive index profile as a reference (Laguerre-Gaussian functions). The power coupling coefficients of the power, which is transferred from a focused Gaussian beam to an LPvp-mode, depend on frequency and on four normalized launching parameters. Once the field-describing matrix equation has been solved numerically, closed-form expressions are obtained. The condition for optimal matching of the fundamental mode is given, and it is found that the maximum power excitation coefficient may be close to 100% even for substantially disturbed profiles.
TL;DR: In this article, a loose tube buffer design and a list of reference cable plants are presented to provide the cable with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress.
Abstract: While conventional cable elements can tolerate strains on the order of 1%, optical fibers cannot. As aerial cables may suffer contraction and elongation from low temperatures and high ice or wind loads, or high temperatures, respectively, proper designs have to provide the cables with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress. The well-suited loose tube buffer design, the way of calculation, and a list of reference cable plants are presented.
TL;DR: In this paper, a 1 × 6 optical switch with built-in optical multiplexer was used for traffic monitoring system, and its transmission characteristics were measured, including insertion loss of the optical switch was 3.1 dB (including filter loss of 1.4 dB).
Abstract: Optical switches are useful for various optical systems. This paper describes a new form of optical transmission system, using 1 × 6 optical switch with built-in optical multiplexer. The insertion loss of the optical switch was 3.1 dB (including filter loss of 1.4 dB). This switch is useful for a traffic monitoring system, and its transmission characteristics were measured. The measured signal-to-noise ratio is 44 dB when the switch is applied to a 2-km video transmission line.
TL;DR: Several optical properties of a concentric core fiber are examined in this article, including attenuation, radiation patterns, pulse broadening, index profile, backscatter signatures, and capture fraction.
Abstract: Several optical properties of a concentric-core fiber are examined. These include attenuation, radiation patterns, pulse broadening, index profile, backscatter signatures, and capture fraction. Experimental techniques are briefly described, and the significance of the measured parameters is discussed.
TL;DR: The first junction line, at 0,85 μm, was installed in August 1980 in Paris as discussed by the authors, which consists of a 70-fiber cable pulled over a distance of 7,5 km between two exchange centers, Tuileries and Philippe-Auguste.
Abstract: For many years, the French PTT has devoted great effort for the development of optical fiber systems. Today, several types of applications are planned in the local, urban, or trunk networks. We report here the results of the first junction line, at 0,85 μm, which was installed in August 1980 in Paris. This line consists of a 70-fiber cable pulled over a distance of 7,5 km between two exchange centers, Tuileries and Philippe-Auguste. The bit rate is 34 Mb/s, leading to a potential capacity of 16 800-bidirectional channels.
TL;DR: In this article, the wavelength shift of a semiconductor laser during triangular pulse modulation has been investigated, using both a Michelson interferometer and direct spectral measurements, and a theoretical investigation shows under what conditions the method is equivalent to the standard dispersion measurement setup.
Abstract: The wavelength shift of a semiconductor laser during triangular pulse modulation has been investigated, using both a Michelson interferometer and direct spectral measurements. This property is used to establish a method for high-resolution dispersion measurements limited to 10 ps, and not affected by material dispersion or detector rise time. A theoretical investigation shows under what conditions the method is equivalent to the standard dispersion measurement setup. The technique is applied to measure polar mode dispersion in single-mode fibers. Examples of polarization noise caused by polarization anisotropy and the variation of source wavelength are presented.