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Lightwave Technology, Journal of

Issue 5 • Date May 2001

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Displaying Results 1 - 23 of 23
  • Rectangular pulse generation based on pulse reshaping using a superstructured fiber Bragg grating

    Publication Year: 2001 , Page(s): 746 - 752
    Cited by:  Papers (49)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    We present a technique for the shaping of short pulses based on the use of superstructured fiber Bragg gratings (SSFBGs). We apply this technique to demonstrate the generation of 20-ps rectangular pulses by phase and amplitude profiling of 2.5-ps soliton pulses. Numerical calculations validate our experimental findings View full abstract»

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  • Light coupling by a vortex lens into graded index fiber

    Publication Year: 2001 , Page(s): 753 - 758
    Cited by:  Papers (14)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    This paper reports a novel launch scheme for coupling light into the skew rays of a graded index fiber. This is accomplished by utilizing a diffractive optical element in conjunction with a single mode fiber to mode match a graded index fiber. Results are used to confirm the fact that the element does improve the coupling into the skew rays of graded index fiber. This approach offers an alternative to existing methods based on tilting and angular offsets for the conditioned launch problem View full abstract»

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  • Stability of synchronous intensity modulation control of 40-Gb/s dispersion-managed soliton transmissions

    Publication Year: 2001 , Page(s): 624 - 635
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (204 KB) |  | HTML iconHTML  

    The efficiency of transmission control of dispersion-managed solitons by means of in-line synchronous intensity modulation is numerically analyzed. We demonstrate that intensity modulation may lead to dramatic improvements in the transmission performance of 40-Gb/s dispersion-managed solitons. In particular, we identify the locations within the dispersion map where synchronous intensity modulation provides an efficient control of the pulse propagation. Namely, a stabilization of pulse energy fluctuations is achieved, with no need for additional in-line control by guiding filters. On the other hand, incorrectly placed intensity modulation may cause significant pulse instabilities View full abstract»

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  • Characterization of wavelength-selective fiber-optic devices using a modified phase-shift method

    Publication Year: 2001 , Page(s): 717 - 731
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    We present a novel measurement setup that can be used for the complete characterization of fiber Bragg gratings and wavelength selective fiber-optic devices. Our setup is based on the phase-shift method (PSM), which we have modified to include the measurement of polarization-induced effects such as polarization-dependant loss (PDL) and polarization-mode dispersion (PMD). We measure the spectral response of devices used in transmission and in reflection, the wavelength dependency of the group delays due to chromatic and polarization-mode dispersion, and the wavelength dependency of the polarization-dependent loss. Experimental results are presented and sources of error are discussed. Comparisons with the Jones matrix eigenanalysis method for the measurement of PDL and differential group delay due to PMD have been carried out View full abstract»

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  • Four-wave mixing in optical links using quasi-distributed optical amplifiers

    Publication Year: 2001 , Page(s): 636 - 645
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    We investigate efficiency of four-wave mixing (FWM) generation in quasi-distributed erbium-doped fiber (EDF) sections under general power evolution conditions. Measured FWM efficiencies are found to be in a good agreement with newly developed formulae applicable to waveguides with spatially and spectrally varying gain. Inoue's work describing FWM process in multiple amplified spans is generalized. A new theory of FWM generation in optical links amplified by a set of quasi-distributed nodes is developed and used to analyze multiple span L-band link View full abstract»

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  • Fiber Bragg grating period reconstruction using time-frequency signal analysis and application to distributed sensing

    Publication Year: 2001 , Page(s): 646 - 654
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (140 KB)  

    The period and length of a fiber grating structure can be reconstructed from its corresponding complex reflection coefficient using time-frequency signal analysis based on Wigner-Ville and spectrogram distributions. We provide an experimental demonstration of this synthesis technique on two fiber grating structures and obtain good agreement between the reconstructed values and those expected based on the parameters used in their fabrication. We then propose and numerically demonstrate how this technique can be applied to distributed strain (or temperature) sensing View full abstract»

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  • Multimode interference couplers with tunable power splitting ratios

    Publication Year: 2001 , Page(s): 700 - 707
    Cited by:  Papers (36)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    New, compact multimode interference couplers with tunable power splitting ratios have been realized. Experiments show large tuning ranges. Such couplers are needed to optimize ON-OFF ratios in interferometric devices and may find applications as extremely compact switches View full abstract»

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  • Approximate scalar finite-element beam-propagation method with perfectly matched layers for anisotropic optical waveguides

    Publication Year: 2001 , Page(s): 786 - 792
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB) |  | HTML iconHTML  

    The perfectly matched layer boundary condition for arbitrary anisotropic media is incorporated into the approximate scalar beam propagation method. The procedure is based on a finite-element method for three-dimensional anisotropic optical waveguides with off-diagonal elements in a permittivity tensor. In order to treat a wide-angle beam propagation, the Pade approximant operator is employed. To show the validity and usefulness of this approach, numerical results are presented for Gaussian beam propagation in free space and Gaussian beam excitation on a three-dimensional anisotropic optical waveguide View full abstract»

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  • Improvement of cascaded semiconductor optical amplifier gates by using holding light injection

    Publication Year: 2001 , Page(s): 614 - 623
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB) |  | HTML iconHTML  

    The cascadability of semiconductor optical amplifier (SOA) gates by using holding light injection is numerically and experimentally investigated. Our experimental results show that the signal bit error rate after two cascaded SOA gates will be larger than 10-9 without holding light injection; however 11 SOA gates can be cascaded with holding light injection. The results show that the number of cascaded SOA gates by using holding light injection can be strongly increased View full abstract»

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  • Spot-size conversion using uniform waveguide sections for efficient laser-fiber coupling

    Publication Year: 2001 , Page(s): 708 - 716
    Cited by:  Papers (6)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    Using numerically simulated results, it is shown that an efficient laser-to-fiber coupling is possible by incorporating a uniform spot-size converter (SSC) with two nonidentical but phase matched optical waveguides. Using a “diluted” waveguide with a low index contrast, the power coupling loss can be significantly reduced from 10.4 dB to only 1.15 dB and at the same time 1.0 dB alignment tolerances can also be improved to achieve ±1.8 μm. Besides the improved coupling, the beam divergence of the far-field is also reduced considerably to 9°, accompanied by a significant lowering of the reflected power from the fiber interface View full abstract»

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  • Signal bandwidth of general n×n multimode interference couplers

    Publication Year: 2001 , Page(s): 739 - 745
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    Analytical expression of signal bandwidth of general straight and tapered N×N multimode interference (MMI) couplers is presented. The signal bandwidth is characterized as a function of mode relative energy, mode propagation delay time, and mode pulse broadening in the multimode section of MMI coupler. The model is used to evaluate the signal bandwidth of specific couplers. Results indicate that the signal bandwidth decreases seriously with the increase of channel number and channel guide space. Compared with the straight MMI coupler, the tapered MMI coupler has an improved signal bandwidth View full abstract»

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  • Interferometer-less coherent optical range finder

    Publication Year: 2001 , Page(s): 666 - 672
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB) |  | HTML iconHTML  

    A new coherent optical detection technique employing coherent frequency-domain reflectometry and a novel optical frequency sensor is demonstrated for high-precision optical path-length measurements. Using pulsed laser sources, an improvement of more than two orders of magnitude in spatial resolution over conventional optical coherent frequency domain reflectometry techniques is demonstrated. Varying degrees of spatial resolution ranging from several centimeters to a few hundred nanometers are achieved. High-precision distance measurement with long baseline is also presented View full abstract»

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  • Three-dimensional vector beam-propagation method for second harmonic generation analysis

    Publication Year: 2001 , Page(s): 780 - 785
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    A full vectorial three-dimensional beam-propagation method (BPM) based on the finite-element method is described for the analysis of second harmonic generation (SHG). Quasi-phase-matched SHG devices with periodically domain-inverted GaAlAs- and LiTaO3-based waveguides are analyzed. The influences of the shape of domain-inverted regions and of the inversion width on the conversion efficiencies are investigated in detail. The results of full-wave analysis are compared to those of approximate scalar analysis View full abstract»

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  • Operation principles of wavelength sensing using transparent properties of semiconductor optical diodes

    Publication Year: 2001 , Page(s): 655 - 665
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB) |  | HTML iconHTML  

    The wavelength-sensitive transparent properties of direct-bandgap semiconductor optical diodes (DBSODs) can be utilized for wavelength sensing. A simplified theory is used to describe the operation principles of such wavelength sensing schemes. The principles fan be applied to realize different measures, including sensing with or without pilot tone for single wavelength or multiple wavelengths. The simplified theory can also provide an easy way for estimating the wavelength resolution and accuracy. The wavelength resolution is demonstrated to be better than 0.01 nm by detecting the induced junction voltage for a fixed bias. The resolution is limited by the current resolution of the bias source to 0.03 nm when the wavelength is to be discriminated by transparent current detection. The feasibility and limitation of multiwavelength sensing using a single semiconductor optical amplifier are addressed both theoretically and experimentally. The limiting factors, including the power dependency and temperature stability, of the sensing schemes are also investigated View full abstract»

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  • A novel IP with MPLS over WDM-based broad-band wavelength switched IP network

    Publication Year: 2001 , Page(s): 596 - 602
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (92 KB) |  | HTML iconHTML  

    This paper presents a new technology for constructing IP over photonic systems. An IP with multiprotocol label switching (MPLS) over wavelength division multiplexing (WDM)-based broad-band IP network architecture and protocol is proposed and analyzed in this paper, which supports variable-length IP-like optical packet label switching and optical virtual path routing. This system tries to merge into one layer the functionalities of the wavelength switching, SONET mux/demux, and IP routing, and is sometimes known as the concept of optical MPLS. The label banding, forwarding/switching process, and node architecture of the proposed network are discussed and studied. A unique as well as important function of a lambda/label edge router (LER) is a flow assembly device that can encompass MPLS' forward equivalence classes, label stacking, and label switching path aggregation function. At the same time, a particular function of the core label switching router is wavelength merging. A fiber delay line is used to delay the data stream in order to process the label information and resolve contention. Transmission bit error rate measurements of the baseband data stream and back-to-back is also demonstrated to show its feasibility View full abstract»

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  • Wavelength tunability and polarization characteristics of twisted polarization beamsplitting single-mode fiber couplers

    Publication Year: 2001 , Page(s): 732 - 738
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB) |  | HTML iconHTML  

    The wavelength tunability and the polarization characteristics of twisted polarization beamsplitting fiber couplers are investigated experimentally and analyzed theoretically. The measured spectrum transmissions and polarization characteristics agree well with the theoretical results. The wavelength working as a polarization beamsplitter can be tuned in the 1.3-1.75 μm wavelength range without significant degradation. Splitting ratios for orthogonally polarized light are more than 20 dB and less than -20 dB View full abstract»

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  • Large-scale multiplexing of interferometric fiber-optic sensors using TDM and DWDM

    Publication Year: 2001 , Page(s): 687 - 699
    Cited by:  Papers (28)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB) |  | HTML iconHTML  

    This paper describes multiplexing schemes for interferometric fiber sensors based on time-division multiplexed and dense wavelength-division multiplexing using optical add/drop multiplexers. The results of an experimental arrangement, which is based on one of the architectures, is also presented. Topics include a discussion of the noise sources in the system, dynamic range, and a characterization of the distributed feedback fiber laser source noise. We show the crosstalk levels in the experimental arrangement to be between -47 and -76 dB depending on the mechanism involved. The multiplexing schemes demonstrate the potential to address at least 192 interferometric sensors through two fibers based on a system with six wavelengths with a phase resolution less than 20 μrad/√Hz. For application to sonar arrays, our analysis has shown that hydrophones multiplexed in this type of architecture would achieve ambient acoustic noise-limited pressure resolution with an in-water dynamic range up to 135 dB at frequencies up to 10 kHz. In general, these architectures would find application in systems requiring very large numbers of sensors with a minimum of telemetry cabling required View full abstract»

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  • Quasi-3-D beam-propagation method for modeling nonlinear wavelength conversion

    Publication Year: 2001 , Page(s): 772 - 779
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB) |  | HTML iconHTML  

    The two-dimensional (2-D) iterative finite difference beam-propagation method (IFD-BPM) is modified to model the cylindrically symmetric three-dimensional (quasi-3-D) second-order nonlinear wavelength conversion in quasi-phase-matched condition. The study shows that the difference between the 2-D and 3-D schemes is small for the guided waves but large for the nonguided beams. The comparison with experimental results shows that the quasi-3-D IFD-BPM is closer to reality than the 2-D scheme. In addition, simulation using the quasi-3-D IFD-BPM reveals that plane-wave and Gaussian-beam assumptions are not sufficient for estimating the nonlinear conversion and beam propagation in second-order nonlinear devices View full abstract»

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  • A performance analysis of an all-optical clock extraction circuit based on Fabry-Perot filter

    Publication Year: 2001 , Page(s): 603 - 613
    Cited by:  Papers (21)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    A performance analysis of an optical clock extraction circuit based on a Fabry-Perot filter (FPF) is presented. Two analytical methods, time-domain and frequency-domain analysis, are developed in this paper. Time-domain analysis shows that there is no phase jitter in the extracted optical clock if the free spectral range (FSR) of the FPF is exactly equal to the signal clock frequency. Based on this, we obtain an analytical expression for root mean square (rms) amplitude jitter of the extracted optical clock in time domain, in which we have taken the impacts of carrier frequency drift and carrier phase noise into account. When the FSR of the FPF deviates from the signal clock frequency, both phase jitter and amplitude jitter will occur in the extracted optical clock. In this situation, a more general frequency-domain method is developed to deal with the timing performance under the assumption that carrier phase noise is negligible. This method allows us to calculate both rms phase jitter and rms amplitude jitter of the extracted optical clock. Using the developed two methods, we present a detailed numerical investigation on the impacts of finesse of the FPF, carrier frequency drift, resonator detuning, carrier phase noise, and optical pulse chirp on the timing performance. Finally, the application of this circuit in multiwavelength clock recovery is discussed View full abstract»

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  • Efficient time-domain beam-propagation method for modeling integrated optical devices

    Publication Year: 2001 , Page(s): 759 - 771
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB) |  | HTML iconHTML  

    A new efficient technique that models the behavior of pulsed optical beams in homogenous medium, metallic and dielectric waveguides, is introduced and verified using both linear nondispersive and dispersive examples that have analytical predictions. Excellent accuracy results have been observed. The method is called time-domain beam-propagation method (TD-BPM) because it is similar to the classical continuous-wave BPM with additional time dependence. The explicit finite difference and the Du Fort-Frankel approaches were used to discretize the TD-BPM equation. Comparisons between these techniques are also given with the application of the perfectly matched layers as spatial boundary conditions to the Du Fort-Frankel. Then the TD-BPM was successfully applied to model a two-dimensional dielectric Y-junction. It is concluded that the new technique is more efficient than the traditional finite-difference TD method, especially in modeling large optical devices View full abstract»

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  • A novel structure for the intrinsic Fabry-Perot fiber-optic temperature sensor

    Publication Year: 2001 , Page(s): 682 - 686
    Cited by:  Papers (26)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (96 KB) |  | HTML iconHTML  

    A novel structure of the intrinsic Fabry-Perot interference (IFPI) fiber temperature sensor is presented. The sensor uses two different core diameter fibers and produces a reflective mirror by fusing uncoated bare fibers. This procedure not only solves the problem of controlling thickness and reflectance of the thin film but also provides easier and cheaper technologies for IFPI fiber sensors. Theoretical and experimental aspects of the intrinsic Fabry-Perot cavity are described. Both theoretical and experimental results from this novel structure show good agreement with those from the traditional Fabry-Perot fiber sensor View full abstract»

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  • An architecture for IP over WDM using time-division switching

    Publication Year: 2001 , Page(s): 589 - 595
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    This paper proposes an architecture for routing Internet protocol (IP) packets directly on optical networks. The use of label switching is assumed in the IP routers, while a new routing architecture is introduced to transport IP packets across an optical backbone network. The architecture is based on a two-tier multiplexing approach with wavelength division multiplexing (WDM) addressing the number of regional exchanges and time-division switching communicating among the hubs. Such an architecture not only has the advantages of simple network management and high efficiency with low latency; it also is scalable by addition of regional exchanges, hubs, and fibers View full abstract»

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  • Interrogation of low-finesse Fabry-Perot cavities based on modulation of the transfer function of a wavelength division multiplexer

    Publication Year: 2001 , Page(s): 673 - 681
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (284 KB)  

    A theoretical and experimental investigation is reported on a novel all-fiber technique for interrogation of interferometric low-finesse Fabry-Perot cavities. It is based on the modulation of the spectral transfer function of a wavelength-division multiplexer. Results are given when both serrodyne and sinusoidal modulation formats are considered View full abstract»

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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