Achieving Optical Tri-Stability Through Periodic Metal-Dielectric Structure

Abstract

Through the modified transfer matrix method, the transmission properties of a one-dimensional coupled-resonator optical waveguide structure composed of metal layers and non-linear material layers is studied. Given proper incident frequency and structure parameters, an optical tri-stability has been achieved. The effect of loss has been considered.     

Optical Solitons in Fibers for Communication Systems

Abstract

A brief history of attempts to use solitons for optical fiber communications and of the technical developments toward making soliton transmission practical is reviewed. The main problems affecting long-distance soliton transmission, as well as techniques to solve them, are described. Recent developments concerning the use of dispersion management and some of the remarkable properties of dispersion managed solitons are also discussed.     

Full-Duplex Radio-over-Fiber System Based on a Novel Octupling mm-Wave Generation Scheme

Abstract

A novel mm-wave generation scheme based on two phase modulators and two unbalanced Mach-Zehnder interferometers is proposed. Compared with the conventional Mach-Zehnder modulator-based scheme, the phase-modulator-based scheme can work steadily without an electrical control circuit for the DC bias, and it has smaller insertion loss. A full-duplex radio-over-fiber system was investigated by simulation, and its performance is not affected by chromatic dispersion for both downstream and upstream transmission. A 40-GHz mm-wave is generated from a 5-GHz driving signal. The system performance is analyzed by using eye diagrams and bit error rate. Results demonstrate that the performance is still very good, even after a 50-km transmission.     

A Scalable Long-Reach Wavelength-Division Multiplexing Access Network Sharing Both Fiber Protection and Broadcasting Services

Abstract

A novel scalable wavelength-division multiplexing access network is proposed in this article. By newly designing the remote node, this network can not only support the long-reach transmission and broadcasting services, it can also have flexible scalability and the ability of sharing fiber protection. These make this network have great resilient capability. Also, this scheme still has the characteristic of Rayleigh backscattering mitigation and shared-seeding light of upstream signals. The simulation results indicate this network has good performance.     

Logic Gates Based in Asymmetric Couplers: Numerical Analysis

Abstract

In this work, we present a numerical investigation of the transmission and switching of fundamental solitons in asymmetric nonlinear directional couplers, constructed with dispersion decreasing fibers (DDF). In this configuration, the coupler consists of two separated parallel fibers, one with a DDF profile and the other with a constant profile. We obtained the characteristics of transmission, extinction ratio, and compression factor of the device.

The truth tables for the logic gates AND, OR, and XOR were obtained. We concluded that the device presenting a constant profile provided the best performance of the studied logic gates. Logic gates AND, OR, and XOR operating with extinction coefficient around 16.6 dB were obtained.     

Elliptically birefringent optical fiber transmission characteristics

Abstract

This paper presents a rigorous analysis of spun hi-bi (highly birefringent) fibers, loosely categorized as elliptically bi fibers, via the initial value problem approach. Two kinds of transmission problem are treated. In the single-eigenmode transmission regime, it is found that the major technological difficulty inherent to spun hi-bi fibers concerns excitation of the eigenmode, which strictly requires that the launched light be exactly oriented in conformity with one or the other local principal axes of the fiber and, meanwhile, that the ellipticity of the launched light be exactly equal to the eigen-ellipticity of the same fiber. In the second kind of problem that involves the interaction of two eigenmodes, a basic result is derived to show that an arbitrary polarization mode of excitation will reproduce itself in integer multiples of the local beat length. Such a kind of transmission regime is relieved of the excitation difficulty but, because of being severely length-sensitive, is inherently impractical from the application viewpoint.     

Polarization Mode Dispersion in High-Speed Optical Communication Systems

Abstract

We review the research progress concerning some fundamental issues related to polarization-mode dispersion (PMD) in high-speed fiber-optic transmission systems. We pay particular attention to issues such as the PMD-induced pulse broadening, PMD measurement and emulation, as well as PMD compensation. An electrical equalization technique based on a transversal filter and an optical technique based on a nonlinear chirped fiber Bragg gratings for PMD compensation will be discussed.     

Bidirectional Wavelength Reconfigurable Module Based on Tunable Fiber Bragg Grating and Remote Pump Amplifier

Abstract

This article presents a novel bidirectional wavelength reconfigurable optical network utilizing a remotely pumped erbium-doped fiber amplifier and tunable fiber Bragg gratings. The system is experimentally demonstrated at a 10-Gb/s per channel over 20-km fiber span that verifies the metro-network range system performance. The achieved power penalty is less than 1 dB when compared to the back-to-back transmission link. An example of practical application where the proposed module is used as an add/drop multiplexer and a remote node in the bidirectional wavelength division multiplexing passive optical network system is described.     

Theory of a FIR optical digital differentiator

Abstract

An optical realization of a proposed family of the finite impulse response (FIR) qth-order mth-derivative digital differentiators (under coherent operation), whose transfer functions are derived from the well-known numerical differentiation scheme (namely, the backward Taylor series expansion), using the amplified fiber optic transversal filters is presented. Several input pulse shapes, such as polynomials of various orders and the Gaussian and exponential pulses, are chosen as examples for illustration of the accuracy of the proposed optically realized differentiators. A mathematical model describing the dynamic (or transient) response of any optical discrete-time systems using the z-transform technique is proposed. The real-time performances of the proposed differentiators have been analyzed using both the steady-state and the dynamic analyses, Although the analysis is directed at fiber optic systems, the methodology and the results are applicable to other physical systems.     

Beyond 90-km Reach of a 16 × 2.5 Gb/s C/L-band Dense Wavelength-Division Multiplexing Metropolitan Network Based on Self-Seeded Reflective Semiconductor Optical Amplifiers

Abstract

This article reports the operation of a cost-effective, colorless, dense wavelength-division multiplexing metropolitan network based on self-seeded reflective semiconductor optical amplifiers. All reflective semiconductor optical amplifiers used in the experiments are packaged in commercial small form-factor pluggable modules. The proposal architecture is simple and symmetric thanks to utilization of two cyclic array waveguide gratings. Downstream link functions in the C-band wavelength range and the upstream link functions in the L-band wavelength range. By using erbium-doped fiber amplifiers to extend the reach, an error-free transmission over 90 km for 16 channels at 2.5 Gb/s was experimentally demonstrated for both directions, and an optical budget over 35 dB was obtained.     

Scattering as the cause of the blue coloration of KNbO3

Abstract

The extinction of blue KNbO₃ crystals has been derived from measurements of transmission as well as diffuse reflectance. The large differences between results obtained on both ways is attributed to scattering. This is supported by additional observations. Scattering is caused by so far not identified inhomogeneities of the material.     

Study of the Performance of an All-Optical Half-Adder Based on Three-Core Non-Linear Directional Fiber Coupler Under Delayed and Instantaneous Non-Linear Kerr Responses

Abstract

Recently, much attention has been given to the influence of the relaxation process of the non-linear response, because the usual assumption of instantaneous non-linear response fails for ultra-short pulses, and additional contributions coming from non-linear dispersion and delayed non-linearity have to be taken into account. This article presents a numerical analysis of the symmetric planar and asymmetric planar three-core non-linear directional fiber couplers operating with a soliton pulse, where effects of both delayed and instantaneous non-linear Kerr responses are analyzed for implementation of an all-optical half-adder. To implement this all-optical half-adder, eight configurations were analyzed for the non-linear directional fiber coupler, with two symmetric and six asymmetric configurations. The half-adder is the key building block for many digital processing functions, such as shift register, binary counter, and serial parallel data converters. The optical coupler is an important component for applications in optical-fiber telecommunication systems and all integrated optical circuit because of its very high switching speeds. In this numerical simulation, the symmetric/asymmetric planar presents a structure with three cores in a parallel equidistant arrangement, three logical inputs, and two output energy. To prove the effectiveness of the theoretical model for generation of the all-optical half-adder, the best phase to be applied to the control pulse was sought, and a study was done of the extinction ratio level as a function of the Δ > parameter, the normalized time duration, and the Sum and Carry outputs of the (symmetric planar/asymmetric planar) non-linear directional fiber coupler. In this article, the interest is in transmission characteristics, extinction ratio level, normalized time duration, and pulse evolution along the non-linear directional fiber coupler. To compare the performance of the all-optical half-adders, the figure of merit of the logic gates was used. All results were obtained numerically, considering a simple model for generation of an all-optical half-adder.     

A 10-Gbps × 12-Channel Pluggable Parallel Optical Transceiver Based on CXP Interface Specifications

Abstract

A novel 10-Gbps × 12-channel pluggable parallel optical transceiver is designed and fabricated. Compared with other optical transceivers, this transceiver emphasizes small size, high-density, low power consumption, and high transmission speed. Most importantly, its optical coupling structure is simplified to promote cost-effective large-scale production. This transceiver is electrically pluggable and consists of transmitter and receiver modules linked by parallel multi-mode fibers. Each module consists of a six-layered high-speed, high-density printed circuit board, the size of which is 30 mm × 18 mm × 1 mm, packaged with optoelectronic devices and corresponding control chips. The printed circuit boards not only provide a high-speed electrical connection between the I/O interfaces and high-speed chips, but they also supply power and ground planes to those chips. End-to-end error-free transmission at 10.3125 Gbps was obtained for a 2³¹ ? 1 non-return-to-zero pseudo-random bit sequence.     

NMR Evidence of Tautomerism for Some 1-Alkyl-3-Aryltriazenes

Abstract

For several 1,3-diaryl- and 1-alkyl-3-aryltriazenes, infraa red evidence of tautomerism I?II has been given;^1,2 in their ir spectra, in fact, these compounds generally show two separate N-H stretching bands. The relative intensities of these bands are influenced by the substituents,^1,2 It was recognized, how ever, that the tautomeric equilibrium constants K_T cannot be determined with accuracy by ir bands intensity measurements as the molar extinction coefficients of forms I and II are not known.¹     

Determination of refractive indices and thickness of absorbing crystalline thin films by using prism coupler

Abstract

An improved method has been implemented to study the refection of optical plane waves from anisotropic and absorbing films. The refection from anisotropic non-absorbing films and from isotropic non-absorbing films can be shown as some special cases. The method in this paper can be applied to almost all kinds of materials involved in optical films and integrated optics studies. Guided waves in the anisotropic and absorbing waveguides are determined, and the prism coupler method is employed to determine refractive indices and thickness of the anisotropic and absorbing films. The results show that when we only couple light beams into films with small effective indices, the effect of the absorption can be neglected.     

Synthesis algorithm of a multi-channel lattice-form optical delay-line circuit

A novel synthesis algorithm for multi-channel (M?2) lattice form optical delay-line circuit is presented in this paper. This circuit offers multi-port FIR optical filter with delay time of N Δτ (Δτ: unit delay time). Synthesis algorithm is based on division of total transfer matrix into unit blocks. Developed method confirms that 1×M optical delay-line circuit offers same transmission characteristics as 1×M FIR digital filter. Band-pass flat group delay type filter is considered as an example in this paper. It is also confirmed that proposed delay-line circuit can realize 100% power transmittance.     

Soft X-ray magnetic circular dichroism in Fe and Fe 0.50 Co 0.48 V 0.02 films: quantitative analysis of transmission

Magnetic circular dichroism (MCD) in X-ray absorption has been measured at the L _{2, 3} edges of Fe in ex-situ grown Fe and Fe _0.50 Co _0.48 V _0.02 films by means of the transmission method. A new approach is developed for fitting the observed transmittance, which describes the resonance lineshapes as (generalized) Fano profiles. Analytical integration of each single resonance allows a more reliable determination of the orbital and spin magnetic moments based on the MCD sum rules. The results are consistent with an increase of the Fe spin and orbital magnetic moment in Fe-Co alloys as obtained by other experiments and band structure calculations. Received 15 August 2000 and Received in final form 11 June 2001     

The F band of mixed ionic crystals as a function of temperature

Abstract

Experimental and theoretical study of the F absorption band were carried out in mixed ionic crystals as a function of temperature and molar composition. Both the point-ion and pseudopotential methods of Gourary–Adrian and Bartram–Stoneham–Gash, respectively, have been used to obtain the F band shift effect in KCl_1?x Br _x mixed crystals with molar fraction x and the temperature T of the crystal. The theoretical values were compared with the experimental ones, and a good agreement between experimental and theoretical calculations has been found.     

Feed-Forward- and Shared-Buffer-Based Optical Packet Switch Architecture

Abstract

This architecture incorporates wavelength-routed loop-buffer modules in the feed-forward configuration, and the buffering in these modules is recirculating in nature, using shared memory. The signal quality will deteriorate during each revolution, due to the insertion loss of the various optical components; therefore, it will impose a limit on the number of circulations that a packet can take in the buffer before its correct reception. Generally, this limit has not been considered in the past, but one should have to take care of it in the current scenario for the actual switching systems.