Showing papers on "Single-mode optical fiber published in 1970"
TL;DR: In this paper, a new method of coupling a laser beam to thin-film optical guided waves was proposed, which utilizes an optical grating that is made from photoresist and fabricated directly on the film.
Abstract: We report a new method of coupling a laser beam to thin‐film optical guided waves which utilizes an optical grating that is made from photoresist and fabricated directly on the film. High efficiency coupling (∼40 %) into a single mode in a glass film is observed.
242 citations
TL;DR: The radiation losses of single mode dielectric slab waveguide for TE and TM modes with abrupt steps of a 2:1 ratio are surprisingly low and can be kept below 1 percent by dimensioning the guide properly.
Abstract: In this paper we calculate radiation losses of a single mode dielectric slab waveguide for TE and TM modes. The theory is based on the determination of the radiation losses of one abrupt step. We obtain the losses of arbitrarily deformed waveguides by regarding the arbitrary deformations as a succession of infinitely many infinitesimal steps. This method yields the same results as a very different method presented earlier. It allows us to calculate the losses of TM modes that were hard to obtain by the earlier method. The radiation losses of single mode slab waveguides with abrupt steps of a 2:1 ratio are surprisingly low and can be kept below 1 percent by dimensioning the guide properly. The loss advantage of linear tapers becomes noticeable only when the tapers are very long. An optimized taper changes more rapidly in its wider portion and becomes more gradual in its narrow part.
238 citations
NEC1
TL;DR: In this article, a lens-like glass fiber guide with a parabolic variation of refractive index has been developed, which has the following characteristics: simultaneous transmission of laser beams modulated by wide-band signals through narrow space; optical image transmission; realization of a lens with tiny aperture or with extremely short focal length.
Abstract: A lenslike glass fiber guide with a parabolic variation of refractive index has been developed. This optical guide named SELFOC® has the following characteristics: simultaneous transmission of laser beams modulated by wide-band signals through narrow space; optical image transmission; realization of a lens with tiny aperture or with extremely short focal length; and the possibility of being bent with a small radius of curvature without spoiling transmission characteristics. In the case of a typical fiber guide with length 1 meter and diameter 0.3 mm, transmission loss is about 0.2 dB and depolarization is about 20 dB at wavelength 0.63μ. The mode pattern of a laser beam after passing through the fiber guide is scarcely deformed. The fiber guide can be used as a transmission line or lens, in optical communication, optical data processing, and optical instruments.
167 citations
TL;DR: In this paper, the authors describe a prism coupler as a convenient means to feed light into a single mode of a guiding thin optical film, which is of great interest for integrated optical devices.
Abstract: Recently P. K. Tien and his co-workers have described a prism coupler as a convenient means to feed light into a single mode of a guiding thin optical film.1 Distributed couplers of this kind are of great interest for integrated optical devices. In this brief we describe thin
152 citations
TL;DR: In this paper, the authors presented the results of numerical calculations of the cutoff wavelength of nineteen successive modes in a hollow perfectly conducting pipe with an elliptical cross section and some inaccuracies in the usual mode classification were proven and corrected.
Abstract: The propagation of electromagnetic waves in a hollow perfectly conducting pipe with an elliptical cross section and the results of numerical calculations of the cutoff wavelength of nineteen successive modes are presented. Some inaccuracies in the usual mode classification are proven and corrected. As a large number of numerical calculations are required to determine the cutoff wavelength for a single set of dimensions and a single mode, approximate formulas for the eight lowest order modes are suggested. These formulas are of a simple algebraic form and give a relative error smaller than 0.25 percent. With the exact succession of the different modes it becomes possible to compare the bandwidth of an elliptical waveguide to the bandwidth of the rectangular and circular guide. The measured values of the cutoff wavelength of different modes agree very well with the theoretical calculated values.
140 citations
TL;DR: In this paper, inelastic spin-wave dispersion in antiferromagnetic FeF2 has been investigated using a chopper time-of-flight spectrometer.
Abstract: Spin-wave dispersion in antiferromagnetic FeF2 has been investigated by inelastic neutron scattering using a chopper time-of-flight spectrometer. The single mode observed has a relatively flat dispersion curve rising from 53 cm-1 at the zone centre to 79 cm-1 at the zone boundary. A spin Hamiltonian which includes a single-ion anisotropy constant D (Hsi=-DSiz2), three exchange parameters Jl(Hex12=JlS1.S2) and dipolar interactions has been fitted to the measured energies. The authors find D=6.46 (+0.29, -0.10) cm-1, J1 (coupling neighbouring ions along the c axis)=-0.048 (+or-0.060) cm-1, j2 (coupling neighbouring ions at the corner and body centre of the cell)=+3.64(+or-0.10) cm-1, and J3 (coupling neighbouring ions along the a axis)=+0.194 (+0.060) cm-1.
104 citations
TL;DR: In this article, a single mode TE or TM propagation is demonstrated in an optical waveguide consisting of a high resistivity semiconductor (GaAs) layer (≈ 10 μ) which is sandwiched between a metal film and a lower resistor semiconductor.
61 citations
TL;DR: In this article, the authors used a passively Q-switched ruby laser, operating in a single axial and transverse mode, to produce sparks produced in a number of gases at pressures ranging from 760 to 9000 mmHg.
Abstract: Using a passively Q -switched ruby laser, operating in a single axial and transverse mode, sparks produced in a number of gases at pressures ranging from 760 to 9000 mmHg have been studied. Breakdown threshold measurements for both single and multimode laser radiation have been made and in addition, the characteristics of the sparks produced with single-mode radiation have been investigated. Photography at 90° of the scattered laser light showed the existence of scattering regions with transverse dimensions not exceeding the 5-μ resolution of the optical system. Furthermore, a large amount of laser light is scattered in the forward direction. The intensity, angular distribution, and spectral characteristics of this scattered radiation have been determined. Various possible mechanisms that could account for these phenomena are discussed, and it is concluded that self-focusing of the laser beam after the initiation of the breakdown process may be occurring.
55 citations
TL;DR: The condition that limits the volume that will sustain fundamental mode operation in a YAG:Nd laser has been determined and the relationship between the pump lamp power and fundamental mode power has been derived which correctly predicts the single mode power.
Abstract: The condition that limits the volume that will sustain fundamental mode operation in a YAG:Nd laser has been determined. The relationship between the pump lamp power and fundamental mode power has been derived which correctly predicts the single mode power. The analysis incorporates the results of a computer analysis of the laser rod, which, among other things, computes the heat absorbed per unit volume and plots the isotherms for the interior of the rod. Recommendations for the design of high power, fundamental mode lasers are given.
8 citations
TL;DR: In this paper, a new diagnostic technique permitting the measurement of the relative power in several modes propagating simultaneously on optical waveguides and resonators is suggested. But it is only suitable for circular-cylinder dielectric waveguide (optical fibers), where it is seen to provide high discrimination between modes far from cutoff.
Abstract: A new diagnostic technique permitting the measurement of the relative power in several modes propagating simultaneously on optical waveguides and resonators is suggested. It is evaluated theoretically for circular-cylinder dielectric waveguides (optical fibers), where it is seen to provide high discrimination between modes far from cutoff. Experiments with HE1,1 and HE1,2 modes confirm the applicability of the method.
4 citations
01 May 1970
TL;DR: In this article, the influence of spatial hole-burning effects on the output of Q-switched giant pulse lasers is investigated and generalised fundamental equations are established and analytically treated to obtain the total output energy and the remaining inversion density.
Abstract: The influence of spatial hole-burning effects on the output of Q-switched giant pulse lasers is investigated. Generalised fundamental equations are established and analytically treated to obtain the total output energy and the remaining inversion density. The results are completed by numerical computations which made it possible to obtain the time-dependent output intensity and the width of the pulses. The solutions of the modified equations are compared with earlier calculations where spatial hole-burning has not been included. It is shown that the formation of standing waves inside the cavity leads to a reduction of the total output energy but does not affect the pulse width of the laser emission.
TL;DR: In this article, the modal birefringence caused by external forces in the Panda and the Side Tunnel fibers is calculated using the finite element method and it is shown that the modality bireringence is directly proportional to the radial distance from the fiber center.
Abstract: Stress-induced birefringence in single mode polarization maintaining optical fibers has been investigated using the finite element method. The modal birefringence caused by external forces in the Panda and the Side Tunnel fibers are calculated. It is found that the modal birefringence is directly proportional to the radial distance from the fiber center. As expected, the modal birefringence vanishes with the variation in the magnitude of the applied external loads. Key Words: Birefringence, Polarization, Panda Fiber, Side-Pit Fiber, Finite Element Method.
TL;DR: In this article, an error function is defined to estimate the discrepancy between the expected electric-field radial derivative at the core-cladding interface and that obtained by numerically integrating the wave equation through the use of Runge-Kutta method.
Abstract: Near field distribution, propagation constant and dispersion characteristics of nonlinear single-mode optical fibers have been investigated. Shooting-method technique is used and implemented into a computer code for both profiles of step-index and graded-index fibers. An error function is defined to estimate the discrepancy between the expected electric-field radial derivative at the core-cladding interface and that obtained by numerically integrating the wave equation through the use of Runge-Kutta method. All of the above calculations done under the ocean depth in which the depth will affect the refractive index that have a direct effect on all the optical fiber parameters. KeyWords: Nonlinear refractive index, Normalized propagation constant, Mode delay factor, Material dispersion, Waveguide dispersion.
01 Jun 1970
TL;DR: In this paper, a comparison between the performance of single-mode fiber guides and lens-like guides with parabolic index profiles is made, and a comparison is made between the two types of guides from several points of view: delay distortion, beam capacity per unit cross section, ability to negotiate bends and deterioration of transmission due to imperfections.
Abstract: A comparison is made between clad fibers and lens-like guides with parabolic index profiles, from several points of view: delay distortion, beam capacity per unit cross section, ability to negotiate bends, and deterioration of transmission due to imperfections. Parabolic index profile guides and single mode fibers with any profile (approximately rectangular, parabolic, etc.) are equally promising and attractive for long-distance optical trans-mission from several points of view, namely, capacity per unit cross section, delay distortion, and ability to negotiate bends. Nevertheless, their tolerance of imperfections is markedly different. Though insensitive to diameter changes, the multimode parabolic index profile guide is quite sensitive to systematic or random departure of refractive index profile from ideal. On the other hand, single mode guides are sensitive to random changes of both the index profile and the guide width. Both of them produce scattering loss.© (1970) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.