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Showing papers on "Single-mode optical fiber published in 1987"


Journal ArticleDOI
TL;DR: In this paper, a lambda = 1.53 microm signal with +22 dB gain was achieved at 295 K in an Er(3+)-doped single-mode fiber using a Lambda = 514.5 nm pump source.
Abstract: Traveling-wave amplification of a lambda = 1.53 microm signal with +22-dB gain is achieved at 295 K in an Er(3+)-doped single-mode fiber using a lambda = 514.5 nm pump source. The optimum fiber length for maximum gain is determined experimentally. A limit in signal-to-noise ratio that is due to concurrent amplification of spontaneous emission is observed. By cooling the fiber to 77 K, the amplifier gain is increased to +29 dB as a result of depopulation of the lower laser level.

531 citations


Journal ArticleDOI
TL;DR: In this paper, the phase mismatch in the four-wave mixing process is clarified experimentally in a single-mode fiber transmission line at 825 nm wavelength, and the generated power of approximately 20 pW is measured successfully for input signal powers below 1 mW by the technique utilizing a heterodyne receiver and lock-in detector.
Abstract: The generation wave efficiency with respect to phase mismatch in the four-wave mixing process is clarified experimentally in a single-mode fiber transmission line at 825 nm wavelength. The generated power of approximately 20 pW is measured successfully for input signal powers below 1 mW by the technique utilizing a heterodyne receiver and lock-in detector. The calculated efficiency as a function of the equivalent frequency separation can well explain and reflect the results obtained experimentally. Furthermore, the efficiency at zero chromatic dispersion wavelengths of 1.3 and 1.55 μm is also discussed considering chromatic dispersion slope against wavelength.

393 citations


Journal ArticleDOI
TL;DR: In this paper, the authors experimentally observed transmission of negative pulses through a single mode optical fiber in conditions where self-phase modulation, due to self induced variations of silica refractive index, may be balanced by the positive group velocity dispersion (dVg/dδ#62;0).

305 citations


Journal ArticleDOI
TL;DR: This work has realized total electromagnetic mode confinement in a microscopic optical, Casimir-type, cavity and detected the resonant change of the molecular fluorescence time under short-pulse excitation due to a spontaneous-atomic-decay enhancement-inhibition process (Purcell effect).
Abstract: We have realized total electromagnetic mode confinement in a microscopic optical, Casimir-type, cavity and detected the resonant change of the molecular fluorescence time under short-pulse excitation due to a spontaneous-atomic-decay enhancement-inhibition process (Purcell effect). This corresponds to the first realization in optics of the resonant coupling of atoms with a single mode of the radiation field.

267 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the propagation of ultrashort (0.83 ps), intense dye laser pulses through a single-mode optical fiber and found that the parameters of this pulse closely correspond to those of the fundamental soliton solution of the nonlinear Schroedinger equation.
Abstract: The propagation of ultrashort (0.83 ps), intense dye laser pulses through a single-mode optical fiber is investigated. The input wavelength is tuned in the vicinity of the zero dispersion wavelength of the fiber. Although the input power is sufficient to generate solitons of up to the tenth order we do not observe the formation of high-order solitons. Instead, the input pulse breaks up temporally and spectrally after an initial stage of narrowing, and an ultrashort Stokes pulse is formed which shifts continuously to lower frequencies with increasing fiber length. The parameters of this pulse closely correspond to those of the fundamental soliton solution of the nonlinear Schroedinger equation. Using fiber lengths from a few meters up to 1 km the resulting pulse durations lie between 55 and 410 fs and the corresponding wavelengths between 1.36 and 1.54 μm. Numerical simulations solving a modified nonlinear Schroedinger equation including higher order dispersion and the Raman effect are in good agreement with the experimental results. It is shown that the principal soliton pulse shaping mechanisms are pulse narrowing and the soliton self-frequency shift.

259 citations


Patent
17 Feb 1987
TL;DR: In this article, a quadruple mode bandpass filter has at least one cavity resonating in four independent orthogonal modes simultaneously and the maximum number of transmission zeros is equal to the order of the filter minus two.
Abstract: A quadruple mode bandpass filter has at least one cavity resonating in four independent orthogonal modes simultaneously. Preferably, the filter has two cavities, one cavity being a quadruple mode cavity and the remaining cavity being either a single mode, dual mode, triple mode or quadruple mode cavity. By introducing a resonant feedback coupling into filters of the present invention, the number of transmission zeros produced by the filter is equal to the order of the filter. Previous filters have cavities resonating in either a single, dual or triple mode and the maximum number of transmission zeros is equal to the order of the filter minus two.

162 citations


Journal ArticleDOI
TL;DR: The applications of the Fabry-Perot interferometer to high capacity wavelength division multiplexed optical systems are discussed and the performances of several practical embodiments are described.
Abstract: The applications of the Fabry-Perot interferometer to high capacity wavelength division multiplexed optical systems are discussed. The performances of several practical embodiments, their anticipated role and ultimate performance limitations are described.

140 citations


Patent
William A. Reed1
02 Apr 1987
TL;DR: In this article, a single mode optical fiber is disclosed and the refractive index profile of the fiber comprises a depressed index or trench region in the cladding region, which can be adjusted by suitable adjustment of the position, width and index of the trench region.
Abstract: A single mode optical fiber is disclosed. The refractive index profile of the fiber comprises a depressed-index or trench region in the cladding region. By suitable adjustment of the position, width and index of the trench region, one or more fiber characteristics can be improved, relative to a similar fiber that does not comprise an index trench.

125 citations


Journal ArticleDOI
TL;DR: Using the coupling between a standard single-mode fiber and single higher-order modes in a high-index overlay waveguide, a wavelength-filtering device with a channel-dropping response is demonstrated.
Abstract: Using the coupling between a standard single-mode fiber and single higher-order modes in a high-index overlay waveguide, we demonstrate a wavelength-filtering device with a channel-dropping response. Two types of filter are described. One uses a thin overlay waveguide, giving a single tunable dropped band response in the 1.2-1.6-microm wavelength region with rejection greater than 20 dB and an insertion loss of about 0.5 dB. The other uses a thick overlay waveguide and gives a comb-filter response with a dropped channel spacing of 13 nm with 20-dB rejection and an insertion loss of between 1 and 4 dB.

121 citations


Journal ArticleDOI
D. Marcuse1
TL;DR: In this article, the authors consider a straight fiber with an infinitely extended radial parabolic-index profile and show that it exhibits mode conversion similar to that of the step-index fiber, provided that the comparison is made on the basis of corresponding mode spots instead of actual core radii.
Abstract: In this paper we discuss mode conversion in a straight fiber which maintains its circular cross section but whose radius a(z) increases monotonically with the length coordinate z so that it passes from the single-mode to the multimode regime. Our principal concern is with step-index fibers which are treated in the scalar approximation. We study conversion of power from the incident dominant mode to other core and cladding modes for several functions a(z) . The results of our calculations show clearly that the dominant mode is able to adapt itself to the changing fiber radius provided the change is gradual. For comparison, we also consider a fiber with an infinitely extended radial parabolic-index profile as an approximation to graded index fibers. We show that it too exhibits mode conversion similar to that of the step-index fiber, provided that the comparison is made on the basis of corresponding mode spot sizes instead of actual core radii.

116 citations


Journal ArticleDOI
TL;DR: Brillouin-gain spectra are measured for pure-silica core, GeO(2)-doped core, and P(2)O(5)- doped core single-mode fibers with different index profiles and the spectral shape of the Brillouin gain is found to be strongly related to the refractive-index profiles.
Abstract: Brillouin-gain spectra are measured for pure-silica core, GeO2-doped core, and P2O5-doped core single-mode fibers with different index profiles. A narrow-linewidth semiconductor laser operating at 828 nm is used as the pump light source. The spectral shape of the Brillouin gain is found to be strongly related to the refractive-index profiles. The Brillouin linewidths evaluated experimentally are 90 and 215 MHz for a step-index single-mode fiber and a graded-index single-mode fiber, respectively. The Brillouin Stokes shifts depend on the core/cladding dopant materials and their concentrations and range from 20 GHz for the P2O5-doped core fiber to 21.6 GHz for the pure-silica core fiber in the 0.8-μm-wavelength region.

Patent
15 Jun 1987
TL;DR: In this article, a fiber laser having a single mode fiber core of laser material is pumped by a high power coherent laser diode source by providing a multi-mode fiber around the single-mode core to define a pump cavity which propagates pump radiation while allowing the pump radiation to couple to the single mode core.
Abstract: A fiber laser having a single mode fiber core of laser material is pumped by a high power coherent laser diode source by providing a multi-mode fiber around the single mode core to define a pump cavity which propagates pump radiation while allowing the pump radiation to couple to the single mode core. Laser diode arrays and extended emitter laser diodes can be used to pump a single mode fiber by inputting the pump radiation into the multi-mode fiber surrounding the single mode fiber core. The milti-mode fiber has a much greater diameter than the single mode core.

Journal ArticleDOI
TL;DR: Using computer simulations, results indicate that both the cubic-dispersion term and the shock term of the nonlinear Schrödinger equation contribute to asymmetry in the pulse power spectrum and cause highly nonlinear chirp.
Abstract: Using computer simulations, we examine the effects of higher-order dispersive and nonlinear propagation processes on the spectral and time development of ultrashort, high-intensity pulses propagating in single-mode optical fibers having normal dispersion. Our results indicate that both the cubic-dispersion term and the shock term of the nonlinear Schrodinger equation contribute to asymmetry in the pulse power spectrum and cause highly nonlinear chirp.

Journal ArticleDOI
TL;DR: In this article, a theoretical model is presented concerning the influence of the waveguide structure on the maximum internal gain of a CW-operating 1.5-μm BH amplifier, including thermal effects.
Abstract: Gain, polarization sensitivity, saturation power, and noise characteristics of quaternary semiconductor laser amplifiers of the Fabry-Perot (FP) and traveling-wave (TW) types are reviewed. The status of antireflection coatings for TW amplifiers is presented. New results concerning the polarization sensitivity and output saturation power of a 1.5-μm buried-heterostructure (BH) amplifier are reported. A theoretical model is presented concerning the influence of the waveguide structure on the maximum internal gain of a CW-operating 1.5- μm BH amplifier, including thermal effects, and a comparison of this model with recent experimental results is reported. The influence of nonresonant losses on the noise factor of 1.5-μm amplifiers is discussed.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the compression characteristics of chirped pulses from gain-switched distributed feedback-laser diodes (DFB-LD) transmitting through highly dispersive media and clarified theoretically that the optimum dispersion value to obtain a minimum compressed pulse is proportional to the square of original pulsewidth.
Abstract: Picosecond optical pulse compression characteristics of chirped pulses from gain-switched distributed feedback-laser diodes (DFB-LD) transmitting through highly dispersive media are studied theoretically and experimentally. It is clarified theoretically that gain-switched chirped pulses can be compressed to about a 0.7-time bandwidth product by normal dispersion of the dispersive media and that the optimum dispersion value to obtain a minimum compressed pulse is proportional to the square of original pulsewidth. Through a dispersion, shifted single-mode fiber with -48-ps/nm normal dispersion at a 1.3-μm wavelength, gain-switched 30-ps (FWHM) pulses from a directly modulated 1.3-μm DFB-LD at a 4.4-GHz repetition rate have been successfully compressed to 6.4-ps optical pulses with a 0.86-time bandwidth product. Experimental results agree with the theoretical analysis.

Journal ArticleDOI
TL;DR: In this article, an ultrafast time-domain optical multi/demultiplexer utilizing the optical Kerr effect in two birefringent fibres concatenated with each fast axis crossed is proposed.
Abstract: An ultrafast time-domain optical multi/demultiplexer utilising the optical Kerr effect in two birefringent fibres concatenated with each fast axis crossed is proposed. Stable demultiplexing of an ultrashort 30 ps optical pulse train at 1.97 GHz from a gain-switched DFB LD has been successfully demonstrated using CW mode-locked Nd:YAG laser control pulses.

Patent
13 May 1987
TL;DR: In this article, the position, shape and material of the elongated member or the groove are determined in such a way that stress-induced birefringence produced in the core portion in accordance with a difference in thermal expansion coefficient between the substrate and the single mode optical waveguide is a desired value.
Abstract: In a single mode optical waveguide having a substrate, a cladding layer formed on the substrate, a core portion embedded in the cladding layer, and an elongated member for applying a stress to the core portion or a stress relief groove for relieving a stress from the core portion in the cladding layer along the core portion. The position, shape and material of the elongated member or the groove are determined in such a way that stress-induced birefringence produced in the core portion in accordance with a difference in thermal expansion coefficient between the substrate and the single mode optical waveguide is a desired value.

Patent
31 Mar 1987
TL;DR: In this article, a single frequency output in a semiconductor laser diode was proposed, where an anti-reflection coating was applied to the output pigtail to suppress Fabry-Perot type feedback.
Abstract: A mechanism for achieving single frequency output in a semiconductor laser diode is disclosed. In accordance with the invention, a conventional laser diode having an anti-reflection coating on its output facet is coupled to a single mode fiber output pigtail having an anti-reflection coating on its input facet. The anti-reflection coatings suppress Fabry-Perot type feedback which would normally be effective for a large number of wavelengths. The fiber includes a built-in distributed Bragg reflector grating, which grating is located just beyond the output fiber input facet. The grating supplies feedback that is effective only over a narrow wavelength band approximating the wavelength spacing between the actual longitudinal modes of the structure so that the laser produces only a single frequency output.

Journal ArticleDOI
TL;DR: In this paper, the performance characteristics of single-mode optical fiber tapers were investigated and it was shown that the dominant mode is preserved while traveling through the taper, from either direction, and the sensitivity of the excess loss to lateral and axial displacements for two coupled tapered sections is greatly reduced compared to that between two singlemode fibers.
Abstract: We investigate the performance characteristics of single-mode optical fiber tapers. These devices have a standard single-mode fiber geometry at one end and gradually increase in cross section so that the size of the core at the other end is comparable or greater to that of a multimode fiber. These tapers effectively expand the single-mode spot size and are envisioned as basic building blocks in a multitude of optical components. Analytical and experimental studies, at \lambda = 0.63 \mu m, show that the dominant mode is preserved while traveling through the taper, from either direction. The excess coupling loss between two tapers is less than 0.1 dB. The sensitivity of the excess loss to lateral and axial displacements for two coupled tapered sections is greatly reduced compared to that between two single-mode fibers. The sensitivity to angular displacement is increased but is within practical limits. For example, for an excess loss of 0.5 dB, the maximum allowed lateral displacement is 3.1 μm for taper coupling, while only 0.73 μm is allowed in the case of fiber coupling. An axial displacement of 291 μm for taper coupling produces 0.5 dB loss while a displacement of only 16.5 μm produces a 0.5 dB loss for fiber coupling. For the same loss, angular displacements of 0.42° for the tapers and 1.77° for the fiber are allowed.

Journal ArticleDOI
TL;DR: In this article, first-order soliton pulses of 77-250 fs duration have been generated in the wavelength region from 1.37 to 1.49 μm by transmitting dye laser pulses at 1.34 μm of 1 ps duration and peak intensity of ≊ 0.66 GW/cm2 through optical single mode fibers.
Abstract: First‐order soliton pulses of 77–250 fs duration have been generated in the wavelength region from 1.37 to 1.49 μm. These solitons are formed by transmitting dye laser pulses at 1.34 μm of 1 ps duration and peak intensity of ≊0.66 GW/cm2 through optical single mode fibers. Soliton narrowing and soliton self‐frequency shift are the dominant shaping mechanisms.

Patent
10 Jun 1987
TL;DR: In this article, a glass preform for use in the fabrication of a dispersion shifted single mode optical fiber is produced by a method for comprising steps of inserting a core member consisting of an inner core part made of a germanium-added quartz glass which optionally contains fluorine and an outer core part making of a quartz glass having a refractive index smaller than that of the inner core parts in a glass tube made of fluorine-added glass.
Abstract: A glass preform for use in the fabrication of a dispersion shifted single mode optical fiber is produced by a method for comprising steps of inserting a core member consisting of an inner core part made of a germanium-added quartz glass which optionally contains fluorine and an outer core part made of a quartz glass having a refractive index smaller than that of the inner core part in a glass tube made of a fluorine-added quartz glass having a refractive index smaller than that of the outer core part, heating the core member and the glass tube to collapse the glass tube and fuse them together to produce a glass perform. The glass preform comprises a core member consisting of an inner core part made of GeO 2 -SiO 2 glass or GeO 2 -F-SiO 2 glass and an outer core part made of F-SiO 2 glass and a cladding made of F-SiO 2 glass and provides a dispersion shifted single mode optical fiber having reduced attenuation of light transmission in the 1.5 μm wavelength band.

Journal ArticleDOI
TL;DR: The potential for using single-mode fiber optics to link two or more telescopes in a large optical to near-IR astronomical interferometer and the effects of dispersion, temperature, and birefringence on wide-bandwidth interference fringes are investigated.
Abstract: We have investigated the potential for using single-mode fiber optics to link two or more telescopes in a large optical to near-IR astronomical interferometer. On an optical bench, we observed the effects of dispersion, temperature, and birefringence on wide-bandwidth interference fringes using up to 30 m of single-mode fiber in each arm of a Twyman-Green interferometer.

Journal ArticleDOI
TL;DR: In this paper, the SBS gain depends on the ratio of the pump coherence length to the characteristic gain length of SBS as well as on the frequency separation between the two pump waves to SBS linewidth.
Abstract: Stimulated Brillouin scattering (SBS), excited by two pump waves in single-mode fibers, is investigated both theoretically and experimentally. Steady-state calculations, supported by experimental results, show that the SBS gain depends on the ratio of the pump coherence length to the characteristic gain length of the SBS as well as on the ratio of the frequency separation between the two pump waves to the SBS linewidth. These dependences are fully analyzed by following the evolution of the pressure wave that is generated by the SBS interaction. The competition between four-wave mixing and SBS is also considered.

Journal ArticleDOI
TL;DR: In this paper, the deformation of single-mode fibers resulting from a longitudinally applied static force has been measured experimentally by means of high resolution heterodyne interferometry and analyzed theoretically using the second-order theory of elasticity and the photoelastic effect.
Abstract: The deformation of single-mode fibers resulting from a longitudinally applied static force has been measured experimentally by means of high resolution heterodyne interferometry and analyzed theoretically using the second-order theory of elasticity and the photoelastic effect. Both the elongation of the fiber and the phase change of light propagating through the fiber have been measured as a function of tensile force. The values of the elastic constants measured for fibers with pure silica core and B 2 O 3 doped cladding are E = 6.41 \times 10^{10} N/m2for the Young's modulus, \delta = -4.0 for the nonlinearity constant of the longitudinal strain, and \beta = -2.3 for the nonlinearity constant of the transverse strain. For unit elongations up to 0.3 percent, no creep, hysterisis, or relaxation effects have been observed within a resolution of one part in 104.

Journal ArticleDOI
TL;DR: In this article, the authors used multilongitudinal mode lasers to investigate the polarization properties of long lengths of single-mode fiber cable and found that the individual longitudinal modes are >99 percent polarized after propagation through 54.6 km of cabled fiber; however, the different longitudinal modes have different states of polarization at the output.
Abstract: We have used multilongitudinal mode lasers to investigate the polarization properties of long lengths of single-mode fiber cable. We find that the individual longitudinal modes are >99-percent polarized after propagation through 54.6 km of cabled fiber; however, the different longitudinal modes have different states of polarization at the output. This difference is caused by polarization dispersion, and we estimate a propagation delay difference for the two principal states of polarization to be 0.42 ps in the 54.6 km of cabled fiber.

Journal ArticleDOI
TL;DR: In this article, the behavior of a cylindrical singlemode optical fiber piezoceramic phase modulator was investigated in the frequency range below resonance and the integral and differential phase modulation efficiencies were reported for different geometrical dimensions of the modulator and for various piezoelectric ceramic materials.
Abstract: The behaviour of a cylindrical single-mode optical fibre piezoceramic phase modulator was investigated in the frequency range below resonance. The integral and differential phase modulation efficiencies are reported for different geometrical dimensions of the modulator and for various piezoelectric ceramic materials. p ]The results obtained show that a phase-modulation depth in excess of ≪ can be easily achieved using commercially available piezoelectric cylinders, with driving voltage amplitude as low as 5 V.

Patent
13 Jan 1987
TL;DR: In this article, an all-fiber mode selector consisting of a single-mode optical fiber (100) and a double-mode optic fiber (110), each having a facing surface (144, 154) formed on one side of the cladding.
Abstract: An all-fiber mode selector comprises a single-mode optical fiber (100) and a double-mode optical fiber (110), each having a facing surface (144, 154) formed on one side of the cladding. The facing surfaces (144, 154) are juxtaposed in close facing relationship. The fibers are selected so that an optical signal propagating in the LP11 propagation mode of the double-mode optical fiber (110) propagates at substantially the same phase velocity as an optical signal propagating in the LP01 propagation mode of the single-mode optical fiber (100). The evanescent fields of the two fibers interact to couple optical energy from the LP" mode of the double-mode optical fiber (110) to the LPOI mode of the single-mode optical fiber (100) and vice versa.

Patent
09 Apr 1987
TL;DR: An optical fiber laser comprising a nearly pure fused silica glass, neodymium doped active core within a cavity in the form of a single mode optical fiber is described in this article.
Abstract: An optical fiber laser comprising a nearly pure fused silica glass, neodymium doped active core within a cavity in the form of a single mode optical fiber. The gain cavity is end pumped at a nominal wavelength of 0.8 microns and its length and neodymium concentration are adjusted to maximize pump absorption and minimize concentration quenching. Dichroic mirrors are preferably integrally formed on ends of the cavity and have reflection characteristics selected so that the laser has an output at a nominal wavelength of 1.06 microns.

Journal ArticleDOI
TL;DR: Pulse shortening by a factor of 2700x at 1.32 microm has been realized by means of a two-stage pulse compression and the largest overall compression factor using optical fibers yet reported is reported.
Abstract: Pulse shortening by a factor of 2700× at 1.32 μm has been realized by means of a two-stage pulse compression. In the first stage, 90-psec pulses from a cw mode-locked Nd:YAG laser were compressed to ∼1.5 psec by using a standard fiber–grating-pair configuration. Subsequent propagation of these pulses through ∼20 m of single-mode optical fiber with a minimum dispersion at 1.27 μm led to a final pulse width of 33 fsec. This represents the shortest reported pulse generated at 1.32 μm by using the technique described above as well as the largest overall compression factor using optical fibers yet reported.

Patent
22 Dec 1987
TL;DR: In this paper, a single-mode transmission optical fiber may have a bandwidth much greater than that necessary to transmit a desired predetermined maximum data rate, and it may be connected to a band-width limiting device (14, 14ʹ) comprising the serial combination of an input optical fiber (16,16ʹ), a mode converter (18,18ʹ,22) and multimode fiber (20,20ʹ).
Abstract: A single-mode transmission optical fiber may have a bandwidth much greater than that necessary to transmit a desired predetermined maximum data rate The single-mode fiber (11a, 11b) is connected to a band­width limiting device (14,14ʹ) comprising the serial combination of an input optical fiber (16,16ʹ), a mode converter (18,18ʹ,22) and multimode fiber (20,20ʹ) If the multimode fiber is capable of propagating two modes, for example, the mode converter converts the LP01 signal from the transmission fiber to the LP01 and LP11 modes These two modes propagate at different speeds through the multimode fiber Means (12,12ʹ,36) connected to the output end of the multimode fiber (20,20ʹ) detects the two modes If the time delay difference Δτ between the two modes is small with respect to the width of a pulse in the transmitted pulse train, the pulse train will be detected without distortion Transmission at a higher data rate causes Δτ to be large with respect to pulse width Thus, a transmitted pulse causes the generation of a false pulse, whereby operation at the higher data rate is impossible Also disclosed are methods of making suitable mode converters