Journal of Lightwave Technology

The ability to detect the presence or absence of optical signals on specific channels is used to prevent packet collisions in networks implementing the optical carrier-sense multiple-access with collision avoidance (CSMA/CA) protocol. This optical carrier-sense capability can be provided by a baseband carrier-sense circuit (BCSC), which directly detects the envelope of optical packets propagating ... View full abstract»

As an extension to a previous paper, this paper describes the optimization of a second-order, feedforward polarization-mode dispersion (PMD) compensation scheme by reducing its degrees of freedom (DOF) by two. The new design is optimal in the sense that the number of DOF used is the same as the minimal number of DOF required. Also derived is a set of constraint equations that govern the choice of ... View full abstract»

Physical and technical limits become important when trying to increase data transfer rates to tens of gigabits and higher for already installed optical cables. Polarization-mode dispersion (PMD) is one of the crucial transmission constraints, especially for aerial cables exposed to environmental stresses. Optical fibers in the laboratory and three aerial optical fiber cable links across the Swiss ... View full abstract»

This paper describes a study of the effect of polarization-dependent loss (PDL) on the signal-to-noise ratio (SNR) in optical communications systems, taking into account the effect of dynamic gain equalization. The paper shows that the PDL-induced SNR penalty is caused by two distinct mechanisms related to the two polarization components of the amplified spontaneous emission noise generated in eac... View full abstract»

In this paper, the formula of an optimal compensation vector, which is defined as an input polarization-mode dispersion (PMD) vector of the compensator, for second-order PMD compensation has been derived from the minimization of the root-mean-square (rms) pulse-broadening factor. The derived optimal compensation vector is a linear combination of frequency-averaged PMD vectors and output states of ... View full abstract»

This paper analyzes perturbations caused by nonlinear intrachannel effects and shows how to cancel them by symmetric configuration of transmission and dispersion-compensating fiber. From an analytical study of amplitude and timing jitter conditions are derived to reduce them effectively. Simulations are performed using different schemes of dispersion compensation and improvement and limits of rege... View full abstract»

This paper proposes a tuning technique to optimize the input power of a cross-phase modulation wavelength converter (XPM-WC). The focus is on an output signal whose wavelength is the same as the input signal. The optimum input power can be easily set by keeping the output signal (not converted signal) power constant. Input continuous-wave (CW) power should be increased or decreased with increasing... View full abstract»

This paper discusses the evaluation of the system outage probability caused by the temperature variation and statistically distributed chromatic dispersion of optical fiber in a high-speed (>40 Gb/s) optical network. This was to identify when the tunable dispersion compensator should be used at every channel. View full abstract»

In this paper, an intensive theoretical and experimental investigation is conducted on the dispersion-compensating Raman amplification module configured in double-pass geometry. An analytical model is developed to study the gain/pump efficiency improvement and the noise performance in a novel double-pass discrete-Raman-amplifier (DCRA) system. This paper demonstrates that the gain and pump efficie... View full abstract»

A hollow fiber with new cross section is studied by means of a numerical simulator for modal analysis based on the finite-difference time-domain method (FDTD). Results show that light can be confined into the core area due to six right angles of the hexagonal glass with high index, and the peak intensity is located in the low-index air region. Distribution of the transverse electric-field intensit... View full abstract»

The radiation-induced attenuation (RIA) in germanosilicate single-mode optical fibers was measured at 1.55 and 1.31 mm after a pulsed X-ray irradiation and at 1.55 mm during and after a steady-state g-ray irradiation. The influence of codoping the fiber cladding with germanium (Ge), phosphorus (P), and fluorine (F) on the sensitivity of Ge-doped core fibers was characterized. P-codoping makes it p... View full abstract»

Results from detailed numerical analyses of the modal characteristics of large-cross-section silicon-on-insulator-based rib waveguides are presented. They highlight for the first time that satisfying widely used design criteria is not sufficient to ensure single-mode behavior. In particular, the geometries that the design formulas predict should be single-mode are shown to support higher order ver... View full abstract»

A polymer-based integrated circular-polarization modulator (CPM) is demonstrated in this paper. Tilted poling is adopted to achieve polarization conversion in the electrooptic (EO) polymeric waveguide and then realize the power balance between transverse electric and transverse magnetic modes. Detailed analysis and experiments on polarization conversion are presented. The tensor nature of poled po... View full abstract»

This paper investigates rational harmonically mode-locked fiber ring lasers generating amplitude-stabilized fourth-order optical pulse trains at 13.91 GHz using a modulation signal frequency of 3.477 GHz. Pulse amplitude stabilization in terms of both amplitude equality and low amplitude noise is realized by using the nonlinear characteristics of a Mach-Zehnder intensity modulator in conjunction w... View full abstract»

Multichannel erbium-doped fiber amplifiers (EDFAs) are analyzed based on a rate-equation model. Forward pumping is considered and amplified spontaneous emission (ASE) as well as scattering loss are taken into account. An analytical approximation to calculate the amplification in high-power multichannel EDFAs is also introduced in this paper. Results for both the numerical and approximate analytica... View full abstract»

This paper compares two approaches for evaluating the amplitude and timing jitters of an Er-fiber laser mode-locked at 10 GHz. Using a low-noise oscillator as the clock drive for the mode-locking, relative amplitude jitter was measured as low as 0.0384% and timing jitter as low as 0.0153% (Δf=100 Hz-40 MHz). Applying the mode-locked pulse train in a photonic sampling experiment at 10 Gsample... View full abstract»

An angular spectrum of plane-wave representation is employed to calculate the discrimination between the fundamental and higher order transverse modes in step-index-guided vertical-cavity surface-emitting lasers. The effect of material composition and number of layer pairs in the distributed Bragg reflectors, as well as mode size and structure, are examined with the goal of optimizing the mode dis... View full abstract»

This paper proposes a tunable notch filter using a thermooptic long-period grating and investigates it theoretically. This notch filter is in the form of an integrated optical device and is based on a simple structure as compared with existing integrated optical notch filters. The thermooptic grating denotes a thermooptic index perturbation induced by periodic heaters. The attenuation of a resonan... View full abstract»

This paper proposes an accurate modeling technique of concatenated long-period fiber gratings (LPFGs). The proposed technique is then applied to the synthesis of LPFGs for the erbium gain equalization using both the simulated annealing and the steepest descent minimization technique. A piecewise-uniform LPFG is theoretically synthesized according to the inverted gain spectrum of a commercially ava... View full abstract»

A theoretical formalism is established for double-layer (DL) antireflection coating (ARC) on a one-dimensional (1-D) photonic crystal (PC). Conventional DL-ARC for a bulk is equally applicable for a 1-D PC when the bulk substrate index is replaced with the optical admittance, which can be obtained from the electromagnetic Bloch waves of the infinite 1-D PC. Numerical calculations are performed for... View full abstract»

Accelerated-aging studies of chirped Bragg gratings written in deuterium-loaded germano-silicate fibers were carried out using isothermal and continuous isochronal anneal methods. The master aging curve obtained from the isothermal decay is explained using the Arrhenius-rate-model-based equation. An empirical polynomial function was used to fit the continuous isochronal anneal data. The estimated ... View full abstract»

A tunable optical filter based on the axial strain of the fiber Bragg grating (FBG) is discussed. A wavelength range of 46 nm in compression and 10.5 nm in tension with negligible variations in reflectivity and bandwidth of the central Bragg wavelength reflectivity peak were obtained. The device consists of two fixed ferrules and one guiding ferrule. The difficulties with compressing the FBG were ... View full abstract»