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Showing papers on "Photonic-crystal fiber published in 1978"


Journal ArticleDOI
Roger H. Stolen1, Chinlon Lin1
TL;DR: In this paper, the authors report measurements of frequency broadening due to self-phase modulation (SPM) in optical fibers, using single-mode silica-core fibers and mode-locked argon-laser pulses.
Abstract: We report measurements of frequency broadening due to self-phase-modulation (SPM) in optical fibers. The use of single-mode silica-core fibers and mode-locked argon-laser pulses leads to the simplest and cleanest measurements yet made of SPM. The qualitative features of the frequency spectrum are in good agreement with theoretical expectations. The experiment provides an independent measurement of ${n}_{2}$, the self-focusing coefficient. The results also point to some simple and useful techniques based on fibers for the measurement and analysis of mode-locked laser pulses.

824 citations


Journal ArticleDOI
TL;DR: The formation and characterization of narrow-band-waveguide reflection filters in Ge-doped silica optical fibers is described, which can have complex response profiles and are tunable in frequency by mechanical strain.
Abstract: The formation and characterization of narrow-band-waveguide reflection filters in Ge-doped silica optical fibers is described. The filters can have complex response profiles and are tunable in frequency by mechanical strain.

247 citations


Journal ArticleDOI
TL;DR: In this paper, a new type of fiber optical waveguide utilizing TlBr and KRS•5 has been prepared; its infrared transparency extends to wavelengths well beyond those transmitted by known glassy materials.
Abstract: A new type of fiber optical waveguide utilizing TlBr and KRS‐5 has been prepared; its infrared transparency extends to wavelengths well beyond those transmitted by known glassy materials.

164 citations


Journal ArticleDOI
TL;DR: This paper investigates experimentally the change of the refractive index, due to forces such as pulling and pure bending, in an optical fiber fabricated by the CVD technique, and finds that this phenomenon can be interpreted in terms of a simple model of the fiber, that is, a mechanically homogeneous circular rod.
Abstract: This paper investigates experimentally the change of the refractive index, due to forces such as pulling and pure bending, in an optical fiber fabricated by the CVD technique. It is found that this phenomenon can be interpreted in terms of a simple model of the fiber, that is, a mechanically homogeneous circular rod. We compare the effect of the refractive-index change and that of a geometrical deformation of the fiber on transmission characteristics. A new method based on photoelasticity is also proposed to measure the curvature distribution of a fiber whose axis is deformed by external forces.

141 citations


Journal ArticleDOI
TL;DR: Zinc chloride glass is a potentially useful medium for ultralow-loss (∼1 dB/103 km) optical fibers for wavelengths in the 3.5-4μm region as discussed by the authors.
Abstract: Zinc chloride glass is a potentially useful medium for ultralow‐loss (∼1 dB/103 km) optical fibers for wavelengths in the 3.5–4‐μm region. In this region, intrinsic absorption, scatter, and material dispersion are all expected to be small, and the common fully oxidized transition metal impurities and H2O should exhibit extremely weak absorption as well.

110 citations


Journal ArticleDOI
TL;DR: In this article, a simple method for fabricating fibers with large strain birefringence starting with standard MCVD preforms is described, illustrated using borosilicate fibers.
Abstract: A simple method is described for fabricating fibers with large strain birefringence starting with standard MCVD preforms. The method is illustrated using borosilicate fibers. The birefringence and polarization properties are measured in a long fiber and the birefringence is also measured using a fiber slice and polarizing microscope.

80 citations


Journal ArticleDOI
TL;DR: Using this launching technique, it is possible to determine the index profile and index difference of graded core fibers and other important fiber parameters, such as the differential attenuation and the differential propagation delay time as a function of the mode parameter, giving insight into the fundamental propagation characteristics of the fiber.
Abstract: A method is described permitting excitation of a small number of modes in graded index fibers, the order of the launched mode being easily varied and determined. Using this launching technique, it is possible to determine the index profile and index difference of graded core fibers; results are compared with those obtained by other techniques. Other important fiber parameters, such as the differential attenuation and the differential propagation delay time as a function of the mode parameter, are also obtained, giving an insight into the fundamental propagation characteristics of the fiber.

75 citations


Journal ArticleDOI
I. Ikushima1, M. Maeda
TL;DR: In this paper, the authors measured the output intensity noise spectra of semiconductor laser coupled to optical fibers with end-butt joints and found periodic peaks with a fundamental frequency decided only by the fiber length, which coincides with the reciprocal of the roundtrip time of the light beam in the optical fibers.
Abstract: Output intensity noise spectra of semiconductor lasers coupled to optical fibers with end-butt joints are measured to show periodic peaks with a fundamental frequency decided only by the fiber length. The frequency is found to coincide with the reciprocal of the roundtrip time of the light beam in the optical fibers.

66 citations


Journal ArticleDOI
TL;DR: A new type of electric discharge fusion splicing apparatus for optical fibers offering several advantages is developed and evaluated, and Mechanical strength of the splice is also excellent.
Abstract: A new type of electric discharge fusion splicing apparatus for optical fibers offering several advantages is developed and evaluated. An average splicing loss of 0.10 dB is obtained for step-index multimode silica fibers with a 60-μm core diameter. Tolerances in discharge energy, fiber misalignment, compression force and stroke length during fusion, and end face conditions are discussed experimentally. No accurate fiber axis adjustment is necessary in this apparatus. Mechanical strength of the splice is also excellent.

48 citations


Journal ArticleDOI
TL;DR: Experiments on single-mode optical fibers that were prepared under carefully controlled conditions and studied for their polarization behavior resulted in a circular cross section in preform and fiber.
Abstract: A number of applications require single-mode optical fi­ bers in which the state of polarization of the guided light is sustained. The solid-core optical fibers described in the literature generally exhibit strong birefringence and also usually have a depolarizing effect. In this Letter we describe experiments on single-mode fi­ bers that were prepared under carefully controlled conditions and studied for their polarization behavior. The most fa­ vorable results were noted for fibers prepared by chemical vapor deposition (CVD). First, a Si02-B2O3 glass was de­ posited from the gas phase as cladding on the inside wall of a fused-silica tube, followed by pure quartz glass as the core material. The tube was then collapsed into a rod by raising the temperature and thereafter drawn into a fiber. Directly after leaving the furnace, the fiber was coated with silicon resin. Through precise control of the various step of the process, especially during the collapsing of the tube, a circular cross section in preform and fiber were realized. Figure 1 shows a transmission micrograph of a cross section of the preform. A comparison of round and oval fibers made of glass of the same composition showed a circularly symmetrical cross

46 citations


Journal ArticleDOI
01 Nov 1978

Journal ArticleDOI
TL;DR: In this article, the authors investigated the output coupling of light from a conically tapered optical fiber and showed that light which is coupled out of a taper is widely dispersed when the taper angle is large.
Abstract: Output coupling of light from a conically tapered optical fiber is investigated. Such a technique may be used to provide “wide-angle” illumination from a single fiber of low numerical aperture. Experimental results for a series of fibers of varying taper angles are presented. It is found experimentally that light which is coupled out of a taper is widely dispersed when the taper angle is large. Based upon modified geometrical optics we present a theory which qualitatively predicts the experimentally measured radiation intensity patterns.

Journal ArticleDOI
TL;DR: A single-mode fiber coupler to the Ti diffused LiNbO(3) strip waveguide has been devised that has a special feature wherein coupling degradation caused by fiber displacement after connection can be recovered to the initial state.
Abstract: A single-mode fiber coupler to the Ti diffused LiNbO3 strip waveguide has been devised. The influences of three axial displacements and two angular misalignments on the coupling efficiency have been investigated at 6328-A wavelength. The coupler has a special feature wherein coupling degradation caused by fiber displacement after connection can be recovered to the initial state. The total optical insertion loss is 3 dB after fixing the fiber to the LiNbO3 strip waveguide, which is 4 μm wide and 8 mm long.

Journal ArticleDOI
TL;DR: The data show that the intrinsic transmission of a CVD fiber is independent of temperature over the -110 to +150 C range.
Abstract: Results are presented concerning the effects of temperature on the transmission properties of various optical fibers including a silicone plastic clad, an acrylic plastic clad, and CVD step-index fibers both with and without polyurethane jackets Results are presented for the normalized transmitted power vs temperature, the index of refraction vs temperature, and induced attenuation coefficients vs temperature The data show that the intrinsic transmission of a CVD fiber is independent of temperature over the -110 to +150 C range Plastic clad fused silica fibers are subject to transmission losses at lower temperatures due to changes in the optical index of the cladding polymer Acrylic-clad and plastic-clad silica fibers also show transmission losses at lower temperatures, but to lesser extents

Patent
Stewart Edward Miller1
10 Mar 1978
TL;DR: In this paper, a method of fabricating an optical fiber having an asymmetric refractive index profile that varies periodically along the length of the fiber is described by means of a fabrication process that includes periodically varying the source of at least one of the optical fiber materials in a direction transverse to the fiber drawing direction.
Abstract: A method of fabricating an optical fiber having an asymmetric refractive index profile that varies periodically along the length of the fiber is described. The prescribed variations are obtained by means of a fabrication process that includes periodically varying the source of at least one of the fiber materials in a direction transverse to the fiber-drawing direction. This transverse periodicity is translated into the desired longitudinal periodicity along the fiber by the fiber-drawing process.

Patent
Dietrich Marcuse1
14 Apr 1978
TL;DR: In this article, the density distribution of the light focused by the fiber/preform core is measured along a direction normal to the fiber and preform axis at a distance L from the axis that is less than the focal length of the fiber.
Abstract: This application describes a nondestructive method for determining the refractive index profile of optical fibers and fiber preforms by measuring the density distribution of the light that is focused by the fiber/preform core acting as the lens. The fiber/preform is immersed in an index matching medium and illuminated by means of a collimated light beam directed at right angles to the fiber/preform axis. The density distribution of the light focused by the fiber/preform core is then measured along a direction normal to the fiber/preform axis at a distance L from the axis that is less than the focal length of the fiber/preform. The index profile is determined from these measurements by two numerical integrations.

Journal ArticleDOI
TL;DR: It is shown that control of the layer width is an effective means for achieving the desired loss and bandwidth and the wavelength dependence of microbending loss of a W-type fiber is described.
Abstract: The transmission mechanism of a multimode W-type optical fiber is clarified by the experimental study of the effect of the intermediate layer on the transmission characteristics. It is shown that control of the layer width is an effective means for achieving the desired loss and bandwidth. A W-type fiber with a thick intermediate layer has a transmission loss on the order of 2 dB/km. To determine the transmission characteristics of a W-type fiber applicable to system design, the length dependence of several fiber characteristics is investigated. Concepts such as splices used as mode scramblers and the effect of the intermediate layer as a barrier against OH absorption loss are introduced. The wavelength dependence of microbending loss of a W-type fiber is also described.

Journal ArticleDOI
G. W. Tasker1, W. G. French1, Jay R. Simpson1, P. Kaiser1, Herman M. Presby1 
TL;DR: In this article, design considerations, fabrication, and transmission characteristics of singlemode optical fibers made with different borosilicate compositions are discussed, and the minimum losses achieved with fibers up to 1-km lengths were 1.3 dB/km in the 1.02-1.1-microm range.
Abstract: Design considerations, fabrication, and transmission characteristics of single-mode optical fibers made with different borosilicate compositions are discussed. Fibers with core sizes as large as 15 microm and refractive-index differences below 0.1% were made with the modified chemical vapor deposition (MCVD) process. Minimum losses achieved with fibers up to 1-km lengths were 1.3-1.4 dB/km in the 1.02-1.1-microm range. Microbending losses were avoided by jacketing the fibers with silicone resin. Single-mode operation is maintained in moderately overmoded fibers (V ~ 3.0) because of leakage loss through a finite cladding thickness and because of bends in the fiber axis.

Journal ArticleDOI
TL;DR: This Letter presents an optical fiber switch driven by PZT bimorph as one attempt at switching speed improvement, which reduces chattering by applying a multistep voltage.
Abstract: Optical fiber communications need optical switches. For a multimode fiber system, an optical fiber switch is suitable for a low switching loss. At present, an optical fiber switch has low switching speed. Short switching time in a system results in increased traffic handling capacity. In this Letter, an optical fiber switch driven by PZT bimorph is presented as one attempt at switching speed improvement. Chattering, which is one cause of low switching speed, is reduced by applying a multistep voltage. The 1 × 2 optical switch consisted of one movable optical fiber and two fixed optical fibers, as shown in Fig. 1. The movable optical fiber was driven by a PZT ceramics bimorph. The optical fiber used in this experiment was a multimode fiber of the step-index type with a 60-μm core diam and 150-μm outer diam. The bimorph was constructed with two Fig. 1. Optical fiber switch description.

Journal ArticleDOI
TL;DR: A new method of measuring the complete optical field distribution (optical field mapping) is proposed and is applied to the measurement of Gaussian beam distribution at its beam waist and stability of the interference fringe against the distortion of the fiber is examined experimentally.
Abstract: A new method of measuring the complete optical field distribution (optical field mapping) is proposed and is applied to the measurement of Gaussian beam distribution at its beam waist. This method utilizes an interference technique and uses two single-mode optical fibers as flexible paths. The interference pattern caused by the output beams from the reference fiber and pickup fiber directly gives the relative phase distribution at the input end. For the intensity and phase distribution measurements the experimental ambiguity is as small as 0.1 microm and 1/10 of the wavelength, respectively. Stability of the interference fringe against the distortion of the fiber is also examined experimentally.

Patent
22 Nov 1978
TL;DR: An optical waveguide coupler having intersecting deep and shallow grooves in a planar solid substrate, in which the deep groove accommodates an alignment fiber for fine vertical alignment of an optical fiber with another optical fiber or with an optical component such as a switch, modulator, multiplexer or source of light as discussed by the authors.
Abstract: An optical waveguide coupler having intersecting deep and shallow grooves in a planar solid substrate, in which the deep groove accommodates an alignment fiber for fine vertical alignment of an optical fiber with another optical fiber or with an optical component such as a switch, modulator, multiplexer or source of light. The shallow groove accommodates the optical fiber. The alignment fiber may be tapered or have any configuration such that its manipulation causes the alignment fiber to contact the underside of the optical fiber for raising or lowering the optical fiber. There may be a plurality of shallow and deep grooves for coupling more than one optical fiber.

Patent
04 Oct 1978
TL;DR: In this paper, a single mode optical fiber having a central core region of uniform composition and thickness and core end regions each having a core with a graded composition and increasing thickness towards the ends of the fiber is presented.
Abstract: A single mode optical fiber having a central core region of uniform composition and thickness and core end regions each having a core with a graded composition and increasing thickness towards the ends of the fiber. The fiber maintains a constant normalized frequency with a minimum bending loss. Methods are also provided for forming the fibers from a fiber optic preform.

Journal ArticleDOI
TL;DR: A device which samples the optical signal in an optical fiber for use in source stabilization via feedback control incorporates a beam splitter formed on the fiber ends to deflect a portion of the light traveling down the fiber into a P-I-N photodetector.
Abstract: This paper describes a device which samples the optical signal in an optical fiber for use in source stabilization via feedback control. This device incorporates a beam splitter formed on the fiber ends to deflect a portion of the light traveling down the fiber into a P-I-N photodetector. Advantages of this device include low insertion loss, an output that is relatively independent of the modal distribution within the fiber, and is a rugged small package.

Patent
30 Jun 1978
TL;DR: In this paper, a plurality of optical fibers are heated, twisted, and boundled into a thin strand to form a light bonding part to increase the degree of light bonding between optical fibers.
Abstract: PURPOSE: To distribute the light in a single optical fiber into each optical fiber and to increase the degree of light bonding, by increasing the light bonding between optical fibers bundled without inserting optical parts such as mixer rods between input and output optical fibers CONSTITUTION: A plurality of optical fibers 12 are heated, twisted, and boundled into a thin strand to form a light bonding part 13 Photo input 14 propagated through one optical fiber is bonded with each optical fiber at the light bonding part 13 and distributed to be propagated as photo outputs 15 to 18 Thus, by bundling into a small diameter while heating and twisting an optical fiber bundle, the bundling of optical fibers becomes excellent and each core may be adjacent to each other Also, by applying twists, the light intensity distribution becomes wider In addition, since the flexibility is increased by bundling into a small diameter, even if a long light bonding part 13 is formed, it can be wound around a cylinder 27 so that the size can be reduced Thus, a long light bonding degree may be obtained, and the light bonding degree between optical fibers may be enhanced COPYRIGHT: (C)1980,JPO&Japio

Patent
07 Jun 1978
TL;DR: In this paper, the end of the fiber is monotonically flattened at a temperature at which the fiber's core has a viscosity of between 107 to 108.5 poises.
Abstract: Method of producing a coupling element for coupling a laser radiation source to a monomode optical transmission fiber. The end of the fiber is monotonically flattened at a temperature at which the fiber's core has a viscosity of between 107 to 108.5 poises. The fiber has a cladding glass chosen to have a viscosity of between 1010 -1011 poises at the flattening temperature. This causes the core glass to emerge in the form of a semi-ellipsoidal lens, when the fiber is flattened.

Journal ArticleDOI
TL;DR: This Letter gives an extension to fibers with an arbitrary rotationally symmetric index profile, while maintaining the essential features—simplicity and nondestructiveness.
Abstract: Recently, we presented a method for determining the re­ fractive-index profile in an optical fiber, consisting of a com­ bination of spatial filtering and electronic processing. It was limited, however, to rather thin fibers. In this Letter, therefore, we give an extension to fibers with an arbitrary rotationally symmetric index profile, while maintaining the essential features—simplicity and nondestructiveness. As in Ref. 1, the fiber is assumed to be immersed into index-matching oil and illuminated by a normally incident laser beam. Thus, in terms of a scalar diffraction theory, the distribution of the light amplitudes, which can be considered to be constant and real in front of the fiber, is changed to Uo (x) = exp[jφ(x)] in a plane directly behind it. φ(x) denotes the phase shift and is given by φ(x) = ∫k∆n(x,z)dz. For thin fibers [φ(x) « 1], Uo (x) can be replaced by 1 + jφ(x), so the diffraction pattern is essentially given by the Fourier trans­ form of the phase shift function. In the case of commonly used multimode fibers, however, this approximation is no longer valid, i.e., the diffraction pattern is represented by the complex function G(fx) = F{exp[jφ(x)]} rather than by F(fx) = F [φ(x)]. This means that F(fx) has lost its physical reality. Nevertheless, it is still related to the refractive-index profile by [see Ref. 1, Eq. (1)]

Journal ArticleDOI
TL;DR: A practical approach to the fine altitudinal alignment between single-mode optical fibers and channel waveguides, or between optical fibers with slightly different radii, wherein the preferentially etched silicon-fiber-alignment approach has been modified to have two-dimensional silicon grooves of different depths.
Abstract: We report a practical approach to the fine altitudinal alignment between single-mode optical fibers and channel waveguides, or between optical fibers with slightly different radii, wherein the preferentially etched silicon-fiber-alignment approach has been modified to have two-dimensional silicon grooves of different depths. The altitudinal alignment is achieved by pulling a tapered alignment fiber through the deep groove. This tapered alignment fiber is in contact with the signal fiber and raises or lowers it, depending on the diameter of the tapered fiber at the point of contact.

Patent
12 Oct 1978
TL;DR: In this article, the authors proposed to improve the optical coupling efficiency by making an optical fiber having a smaller core diameter so taper as to have a larger numerical aperture and giving a special condition to the taper angle when the optical fiber is coupled to an optical fibre having a larger core diameter.
Abstract: PURPOSE:To improve the optical coupling efficiency by making an optical fiber having a smaller core diameter so taper as to have a larger numerical aperture and by giving a special condition to the taper angle when the optical fiber is coupled to an optical fiber having a larger core diameter.

Patent
12 Apr 1978
TL;DR: In this paper, an optical fiber is drawn from an appropriate preform using a laser whose output power is varied periodically at a rate greater than ten times a second, which enhances the mode conversion properties of the fiber and reduces the pulse dispersion.
Abstract: An optical fiber is drawn from an appropriate preform using a laser whose output power is varied periodically at a rate greater than ten times a second. A fiber drawn in this manner has periodic variations in diameter which enhance the mode conversion properties of the fiber and thereby reduce the pulse dispersion of a signal transmitted through the waveguide.

Patent
06 Sep 1978
TL;DR: In this paper, an exit light emitted from a semiconductor laser is transformed into parallel lights by a focusing type fiber lens through a very small diameter glass rod, and then it is inserted into a single mode optical fiber lens to reduce the diameter of the parallel lights sufficiently large as compared with the radius of the propagation mode of the singlemode optical fiber.
Abstract: PURPOSE:To couple the semiconductor laser and single mode optical fiber at high efficiency, by transforming the laser exit light into parallel lights of large diameter by means of the lens system, and leading the parallel lights into a single mode optical fiber by way of a fiber lens. CONSTITUTION:An exit light emitted from a semiconductor laser 1 is transformed into parallel lights by a focusing type fiber lens 6 through a very small diameter glass rod 2, and enters a focusing type optical fiber lens 7 affixed to the entry end plane of a single mode optical fiber 3 to be reduced into a core 4 of the single mode optical fiber 3. By setting the diameter of the parallel lights sufficiently large as compared with the radius of the propagation mode of the single mode optical fiber, the aligning precision of the single some optical fiber and semiconductor laser may be alleviated.