By Topic

Lightwave Technology, Journal of

Issue 7 • Date July 1998

Filter Results

Displaying Results 1 - 25 of 29
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mixed finite element beam propagation method

    Page(s): 1336 - 1342
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    An efficient mixed finite element (FE) beam propagation method (BPM) for three-dimensional (3-D) simulations is developed for integrated optic devices. Wide angle propagation is allowed by applying Pade approximants to the finite element operator. Mixed finite elements prevent spurious modes and accurately model waveguide corners allowing the adequate description of polarization effects. Furthermore, the finite element matrices are Hermitian leading to a unitary propagation scheme if lossless waveguides surrounded by metallic walls are assumed. In contrast to finite difference schemes energy conservation holds explicitly View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Enhanced wavelength tuning range in two-section complex-coupled DFB lasers by alternating gain and loss coupling

    Page(s): 1323 - 1328
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (120 KB)  

    A novel tunable two-section complex-coupled distributed feedback (DFB) lasers were demonstrated which exhibited an enhanced wavelength tuning range beyond 7 nm by current injection only. By a simple master-and-slave type of injection current control, either in-phase gain-coupling or antiphase loss-coupling mechanism can be activated, in such a way that one of the two Bragg modes around DFB stopband will become the lasing mode, and its wavelength can be simply and independently tuned by corresponding injection current. More then 45 dB side-mode suppression ratio (SMSR) over entire tuning range were obtained. Good system performance for 375 km transmission with butt-coupled III-V Mach-Zehnder (MZ) modulator at 2.5 Gb/s over nondispersion-shifted fiber was also demonstrated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A black box model of EDFA's operating in WDM systems

    Page(s): 1271 - 1275
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    A black box model is derived for an erbium-doped optical amplifier and is successfully applied to 1480 and 980 nm pumped devices operated under conditions which are typical for wavelength division multiplex (WDM) systems. It allows compound optical amplifiers with arbitrary passive optical circuitry (isolators, couplers, taps, and equalizing filters) to be modeled on the basis of “black box” characteristics. The gain model is based on an analytic solution for the effective two-level laser system, i.e., it is equivalent with the results of most numerical EDFA modeling tools. The model for amplified spontaneous emission (ASE) based on an equivalent ASE source in front of the amplifier can be applied over a wide range of operating points View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance characteristics and applications of hybrid multichannel ANI-VSB/M-QAM video lightwave transmission systems

    Page(s): 1171 - 1186
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    The performance characteristics and applications of hybrid multichannel amplitude modulation vestigal sideband (AM-VSB)/M-quadrature amplitude modulation (QAM) video lightwave transmission systems operating at either 1310 or 1550 nm are reviewed. These systems can transport up to 80 AM-VSB video channels and more than 30 64/256-QAM digital video channels over a standard single-mode fiber (SMF) using a single laser transmitter. Five main transmission impairment mechanisms for these systems are reviewed as follows: (a) clipping-induced impulse noise, (b) bursty nonlinear distortions, (c) multiple optical reflections, (d) stimulated Brillouin scattering, and (e) self-phase modulation. For AM-QAM video lightwave trunking applications, the in-line erbium-doped fiber amplifier (EDFA) selection is discussed using a frequency-domain simulation model. Such lightwave trunking systems can provide an AM carrier-to-noise ratio (CNR) greater than 50 dB with composite second order (CSO) and composite-triple-beat (CTB) distortions less than -65 dBc, and nearly error-free transmission (BER⩽10-9) for the 64-QAM channels with signal-to-noise ratio (SNR) of 30-dB or better. Comparison between 64-QAM and 256-QAM video channel transmission and the effect of the QAM channels on the AM-VSB channels are also presented. The implications of these results and others in hybrid multichannel AM-QAM video lightwave trunking systems are discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • All-optical address extraction for optical routing

    Page(s): 1129 - 1136
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    This paper describes the optical circuit that enables to extract address from a transmitted cell in an all-optical manner. Nonlinear optical loop mirrors (NOLM's) are used as all-optical switches in order to confirm the operation of the proposed circuit. The control pulses synchronized with address bits are generated from the transmitted cell. The address bits are successfully extracted without any electronic control circuit. The factors that limit an attainable bit rate are discussed. If we use NOLM composed of a 2-km-long fiber, 110 Gb/s is attainable for the 4 ps FWHM input pulse with RZ format View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the joint effects of fiber parametric gain and birefringence and their influence on ASE noise

    Page(s): 1149 - 1157
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    Parametric gain (PG) in optical fibers may substantially enhance amplified spontaneous emission (ASE) noise, especially in long-haul amplified links. We present new results that permit to accurately characterize the effects of PG on ASE noise, as well as the interplay of PG and ASE noise with fiber dispersion in both the anomalous and normal dispersion regions. In a recent letter, we introduced the concept of a PG transfer matrix, that allows the easy evaluation of ASE noise enhancement over chains of amplified fiber spans. In the same letter we showed that the transfer matrix can be expressed in analytical closed-form when a scalar (single polarization) fiber is assumed. In this paper we extend the analysis to a more realistic two-polarization fiber model that accounts for both linear and nonlinear polarization coupling effects. We show that the new transfer matrix does not have an analytical expression, but can be easily evaluated using standard numerical algorithms. ASE noise enhancement due to PG turns out to be slightly lower in a realistic birefringent two-polarization fiber than a single-polarization fiber. An interesting result is that the single polarization model yields a convenient approximation to ASE noise enhancement, that can be evaluated analytically View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design of high-frequency ZnO-coated optical fiber acoustooptic phase modulators

    Page(s): 1203 - 1211
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    In this paper, we present a theory of an optical fiber acoustooptic phase modulator using piezoelectric zinc oxide (ZnO) coating. The effects of changing device parameters in the acoustooptic resonator are investigated for transducer design. These results are entirely different from those of the well-known; planar device structure since every part plays an important role in the resonator structure. Optical phase modulation in the frequency region up to 1 GHz is also demonstrated. Multiple sharp resonance peaks with a maximum phase shift of 0.7 radians are observed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Integrated lightwave millimetric single side-band source: design and issues

    Page(s): 1276 - 1284
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    We report on a fully integrated lightwave single side-band (SSB) source optimized for millimeter-wave (20-40 GHz) transport over fiber with no chromatic dispersion penalty. The operation principle is first developed. A practical design is proposed and tolerances of multimode interference (MMI) couplers and electroabsorption (EA) modulators subcomponents are theoretically and experimentally examined. The phase tolerances of MMI couplers are in particular given for the first time for such a scheme. These results imply the achievement of fully integrated rugged SSB source without resorting to complex technology steps View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reproducible optical fiber tips for photon scanning tunneling microscopy with very small (<5°) cone angle

    Page(s): 1220 - 1227
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    Sharp optical fiber tips for photon scanning tunneling microscopes (PSTMs) have been fabricated by employing a new alternative technique for etching multimode optical fibers. The tip diameter is less than 30 mm, while the cone full-angle can be as sharp as 3°. To the knowledge of the authors, such tips are the sharpest reported up to now. Measurements, with 19 tips, of the evanescent wave decay distance produced by frustrated reflection of light on a same sample, show good reproducibility. Furthermore, the PSTM images, taken with the new tips, are very sharp and fit with images of the same sample obtained with an atomic force microscope (AFM) View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reliability of 1300-nm spot-size converter integrated laser diodes for low-cost optical modules in access networks

    Page(s): 1302 - 1307
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    This paper discusses the degradation behaviors and reliability of spot-size converter integrated laser diodes fabricated using the full wafer process with dry etching and metal organic vapor phase epitaxy (MOVPE). Failure criteria applicable to actual access networks were determined based on the degradation behavior exhibited in several aging tests, and device lifetimes were then estimated. The far-field patterns and wide-temperature operation required for low-cost system application scarcely changed during degradation, even after a 150% increase in threshold current. Within this degradation range, the device life for system application is estimated to be more than 105 h at 60°C and 10 mW View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-resolution, nonmechanical approach to polarization-dependent transmission measurements

    Page(s): 1285 - 1294
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    We have implemented an automated, nonmechanical approach to the measurement of polarization dependent loss (and, equivalently, gain). We use a deterministic fixed-states method to derive Mueller matrix elements from intensity measurements at specific polarization states. Voltage-modulated liquid-crystal variable retarders set the polarization states. Synchronous detection is employed to increase the signal-to-noise ratio (SNR) of the system and thereby allow measurement resolution to better than 0.001 dB. We present polarization-dependent loss measurements from 0.0016 to 0.56 dB at 1550 nm to verify performance View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Propagation loss measurements in semiconductor microcavity ring and disk resonators

    Page(s): 1308 - 1314
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    We report the measurement of cavity propagation losses in nearly single-mode semiconductor waveguide-coupled ring and disk microcavity optical resonators. Using a novel 10.5-μm-diameter ring resonator, we measure transverse electric (TE) and transverse magnetic (TM) field intensity losses in 0.35-μm-wide ring waveguide cavities in the 1.55-μm-wavelength region. We present the experimental results for nanofabricated AlGaAs-GaAs 10.5-μm-diameter ring and disk resonators to quantify cavity losses and to show the feasibility of these promising and robust submicron-scale devices View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multichip optical hybrid integration technique with planar lightwave circuit platform

    Page(s): 1249 - 1258
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    A two-step bonding technique for optical device assembly on a planar lightwave circuit platform was developed, which consists of a chip-by-chip thermo-compression prebonding step and a simultaneous reflow bonding step. The technique was used to realize multichip optical integration on the platform. The characteristics of the bonding technique were examined by investigating its strength and accuracy. The bonding accuracies in the horizontal and vertical directions were 1.1 and 0.8 μm, respectively, with high bonding strength. The technique was first applied to a 3 chip integrated transceiver module and the 136 fabricated modules exhibited good performance. The average coupling loss between the laser diodes and the waveguide was estimated to be 4.1 dB and stable characteristics were observed during 1200 cycle thermal shock tests between -40 and 85°C. Next, the two-step bonding technique was used for a 4 channel laser diode module on which 8 optical device chips were integrated and a low coupling loss was achieved of better than 4.2 dB which is as good as that of the 3 chip integrated optical modules View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multimode interference couplers for the conversion and combining of zero- and first-order modes

    Page(s): 1228 - 1239
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    Optical waveguide mode-combiners for fundamental and first-order modes, based on multimode interference (MMI) couplers are presented. These devices convert a fundamental mode into a transversal first-order mode and combine it in lossless fashion with a second fundamental mode. They can separate zero- and first-order modes in a common waveguide and allow the splitting and combining of zero- and first-order modes with nonuniform power splitting ratios. Realizations in InGaAsP-InP are demonstrated. These new components have successfully been integrated into all-optical switches and were found to have advantageous characteristics in all-optical devices View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A finite differences method for the reconstruction of refractive index profiles from near-field measurements

    Page(s): 1348 - 1353
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (108 KB)  

    A new method for the reconstruction of refractive index profiles of optical waveguides from the intensity profile of the fundamental mode, as measured with near field (NF) technique, is presented. In this procedure, an analytical expression of the index profile as function of some parameters such as the maximum index variation and depth is given. By a finite differences (FD) algorithm, the wave equation is solved in order to find the effective index and the intensity profile of the fundamental mode. The input parameters are then varied in order to minimize the difference between the measured intensity profiles and the calculated ones. An application of the method to the special case of planar Ti:Mg:LiNbO3 waveguides is presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A generalized approach to optical low-coherence reflectometry including spectral filtering effects

    Page(s): 1343 - 1347
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB)  

    In the interpretation of optical low-coherence reflectometry measurements, the reflectivity of the device under test is in general supposed to be with a slow dependency on optical wavelength. However, recent research aims at investigating strongly wavelength-dependent devices, such as fiber Bragg gratings and semiconductor lasers. In this paper, a general theory including spectral filtering effects is developed. It appears as a generalization of previously reported results only valid under special conditions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Influence of fiber nonlinearity on the phase noise to intensity noise conversion in fiber transmission: theoretical and experimental analysis

    Page(s): 1187 - 1194
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    Intensity noise resulting from the phase modulation to intensity modulation conversion of laser phase noise can be a major impairment in direct detection systems. In this paper, we investigate theoretically and experimentally the influence of fiber nonlinearity on the conversion of laser and optical amplifier phase noise to intensity noise by fiber transmission. Very good agreement of relative intensity noise (RIN) spectra at the output of a standard singlemode fiber between experimental data and theoretical predictions has been achieved. Results reveal that the fiber nonlinearity can enhance significantly the RIN magnitude and lead to a shift of the RIN dips toward higher frequencies, and consequently to a broader RIN spectrum at fiber output View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic digital holographic wavelength filtering

    Page(s): 1259 - 1270
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    This paper describes the theory and results of a new generic technology for use in optical telecommunications and wavelength division multiplexing (WDM): dynamic digital holographic wavelength filtering. The enabling component is a polarization-insensitive ferroelectric liquid crystal (FLC) spatial light modulator (SLM) in conjunction with a highly wavelength-dispersive fixed diffractive element. The technology has been used to perform demultiplexing of single or multiple WDM signals, dynamic erbium doped fiber amplifier (EDFA) gain equalization and channel management, and used to tune an erbium-doped fiber laser (EDFL) functioning as a high power, very narrow linewidth WDM source View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Theoretical analysis of system limitation for AM-DD/NRZ optical transmission systems using in-line phase-sensitive amplifiers

    Page(s): 1158 - 1170
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    This paper shows the theoretically derived performance of single channel, amplitude modulation/direct detection optical transmission systems using in-line optical phase-sensitive amplifiers (PSA's). The calculations take into account the degradation of the signal-to-noise power ratio (SNR) and intersymbol interference (ISI) due to the distortion of transmitted signal pulses. The SNR is analyzed by considering not only amplifier noise and fiber loss but also noise enhancement by four-wave mixing in the transmission fiber. The ISI is estimated by eye-pattern degradation of the transmitted signal numerically calculated using the nonlinear Schrodinger equation. The regenerative repeater spacing of in-line PSA systems limited by SNR and ISI can be expanded by approximately 3 to 10 times that of in-line EDFA systems, in the case of |D|⩽0.1 ps/mn/km dispersion fiber systems transmitting a 40-Gb/s signal View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mode mixing and power diffusion in multimode optical fibers

    Page(s): 1195 - 1202
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Mode coupling and power diffusion in multimode optical fibers is considered. In particular, the mechanisms responsible for the coupling are investigated and their characteristic lengthscales explored. An appropriate local coordinate system is introduced in which arbitrary curvatures may be considered. Through an asymptotic analysis, the mode coupling equations are shown to reduce to a nonconstant coefficient diffusive equation for the power coupling. This power coupling is shown to be strongly driven by the degenerate mode structure of the multimode fiber View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of end-pumped and electrooptically tuned Nd,Ti,MgO:LiNbO 3 microchip waveguide lasers

    Page(s): 1315 - 1322
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    An end-pumped and electrooptically tuned Nd,Ti,MgO:LiNbO3 microchip waveguide laser is studied by using the self-consistent model and the conformal mapping method. The complex atomic susceptibility is used to describe the laser gain and pump absorption by applying the fast Fourier transform beam propagation method (FFT-BPM) for simulation. Using the conformal mapping method, the index change distributions in the waveguide, caused by the applied electric field, were evaluated. The optimal configuration for the microchip waveguide laser with various cavity lengths was designed. The output performances of the end-pumped and electrooptically tuned Nd,Ti,MgO:LiNbO3 microchip waveguide lasers were simulated and investigated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Imperfect quarter-waveplate compensation in Sagnac interferometer-type current sensors

    Page(s): 1212 - 1219
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    We analyze scale factor errors associated with integrating imperfect quarter-waveplates into loop and in-line Sagnac interferometer fiber-optic current sensors. We show that relatively large imperfections in the quarter-waveplates can be tolerated in the loop version when the birefringence axes of the two quarter-waveplates are oriented 45° with respect to each other. For the in-line version, we demonstrate an electronic signal processing scheme that desensitizes the scale factor to imperfections in the quarter-waveplate View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semiconductor optical amplifier used as an in-line detector with the signal DC-component conservation

    Page(s): 1295 - 1301
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    We present in this paper a dc-coupled in-line optical detector based on a multisection semiconductor optical amplifier (SOA). The key principle is to use a voltage reference correlated with the bias voltage level by the way of a two-section or a three-section SOA. So, by means of the differential detection, the signal dc-component is kept with reduced sensitivity to temperature and bias current fluctuations. Experimental and theoretical results are presented when a two-section SOA is used and performance predictions when a three-section is employed. The obtained responsivity is -63 VNV at 40 mA and over -110 VNV at 50 mA when the input optical power, measured within the fiber, is -13 dBm. When the SOA is biased at 40 mA, the detection bandwidth is over 1 GHz when the input optical power is -4 dBm View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The Journal of Lightwave Technology contains articles on current research, applications and methods used in lightwave technology and fiber optics.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Peter J. Winzer
Alcatel-Lucent Bell Labs