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Lightwave Technology, Journal of

Issue 2 • Date Feb. 2005

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Displaying Results 1 - 25 of 56
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • Journal of Lightwave Technology publication information

    Page(s): c2
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  • Table of contents

    Page(s): 469 - 470
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    Freely Available from IEEE
  • Guest Editorial Photonics Manufacturing

    Page(s): 471 - 473
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    Freely Available from IEEE
  • Wafer-based nanostructure manufacturing for integrated nanooptic devices

    Page(s): 474 - 485
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    The authors have developed a nanomanufacturing platform based on wafer-level nanoreplication with mold and nanopattern transfer by nanolithography. The nanoreplication process, which is based on imprinting a single-layer spin-coated ultraviolet (UV)-curable resist, achieved good nanopatterning fidelity and on-wafer uniformity with high throughput. Some manufacturing issues of the nanoreplication process, such as the impact of wafer and mold surface particles on nanoreplication yield, are also discussed. Nano-optic devices, such as, quarter-wave plates and polarizers, were manufactured with the nanomanufacturing platform. An average wafer-level optical performance yield of 86% was achieved. The developed technology is applied for high-throughput and low-cost manufacturing nanostructure-based optical devices and integrated optical devices. View full abstract»

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  • A novel fiber alignment shift measurement and correction technique in laser-welded laser module packaging

    Page(s): 486 - 494
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB) |  | HTML iconHTML  

    A novel measurement and correction technique employing an ultra-high-precision laser displacement meter (LDM) with a 20-nm resolution to probe the postweld-shift (PWS)-induced fiber alignment shifts in laser-welded laser module packaging is presented. The results show that the direction and magnitude of the fiber alignment shifts induced by the PWS in laser-welded laser module packaging can be quantitatively determined by four parameters: the lateral position (r), the position angle (α), the swing angle (θ), and the tilt angle (ψ). Further studies show that the deformation of the lateral shift and the position angle are the dominant mechanisms that determine the fiber alignment shifts induced by the PWS. This clearly indicates that the PWS can be quantitatively corrected timely by applying a single weld spot on the negative lateral shift and the position angle to compensate for the fiber alignment shifts. In comparison with previous studies of the PWS correction by a qualitatively estimated technique, this LDM technique has significantly provided an important tool for quantitative measurement and correction to the effect of the PWS on the fiber alignment shifts in laser-welded laser module packaging. Therefore, the reliable laser modules with high yield and high performance used in low-cost lightwave transmission systems may be developed and fabricated. View full abstract»

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  • Model for analyzing manufacturing-induced internal stresses in 50-GHz DWDM multilayer thin-film filters and evaluation of their effects on optical performances

    Page(s): 495 - 503
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB) |  | HTML iconHTML  

    The manufacture of a high-quality reliable thin-film filter (TFF) requires a detailed understanding of the stresses created within the device during fabrication. The ability to systematically approximate the internal stress effect on optical performance is of crucial importance to provide fabrication guidance and improve manufacturing yield. This paper analyzes the internal stress distributions in the substrate and thin-film layers of a 50-GHz TFF and examines the relation of these stresses to the filter's optical characteristics. A linear model along the thickness direction is introduced based upon Townsend's theory of multilayer structures. The analytical results for the key optical parameters are in good agreement with measurements on fabricated filters. This model analyzes the effects of process parameters, such as the substrate type, its coefficient of thermal expansion, and the final substrate thickness on the optical performance of the transmission spectrum center wavelength, transmission passband ripple and isolation, the chromatic dispersion, and polarization-mode dispersion. View full abstract»

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  • MEMS integrated submount alignment for optoelectronics

    Page(s): 504 - 509
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    One of the most expensive and time-consuming production processes for single-mode fiber-optic components is the alignment of the photonic chip or waveguide to the fiber. The alignment equipment is capital intensive and usually requires trained technicians to achieve desired results. Current technology requires active alignment since tolerances are only ∼0.2μm or less for a typical laser diode. This is accomplished using piezoelectric actuated stages and active optical feedback. Joining technologies such as soldering, epoxy bonding, or laser welding may contribute significant postbond shift, and final coupling efficiencies are often less than 80%. This paper presents a method of adaptive optical alignment to freeze in place directly on an optical submount using a microelectromechanical system (MEMS) shape memory alloy (SMA) actuation technology. Postbond shift is eliminated since the phase change is the alignment actuation. This technology is not limited to optical alignment but can be applied to a variety of MEMS actuations, including nano-actuation and nano-alignment for biomedical applications. Experimental proof-of-concept results are discussed, and a simple analytical model is proposed to predict the stress strain behavior of the optical submount. Optical coupling efficiencies and alignment times are compared with traditional processes. The feasibility of this technique in high-volume production is discussed. View full abstract»

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  • Yield analysis of optical MEMS assembly Process using a Monte Carlo Simulation technique

    Page(s): 510 - 516
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    We developed a statistical Monte Carlo technique for the performance estimation of optical microelectromechanical systems (MEMS) components taking into account the randomness nature of its assembly. The developed technique is applied on the 2×2 moving mirror optical MEMS switch as a typical example to study its performance under realistic passive-alignment conditions. The obtained results enable us to evaluate the assembly process capability and to analyze the performance sensitivity to different fabrication parameters. This enables us to establish a design for manufacturability technique for the optical MEMS components. View full abstract»

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  • Thin-film devices fabricated with benzocyclobutene adhesive wafer bonding

    Page(s): 517 - 523
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    In this paper, we present and elaborate on die to wafer bonding technology with benzocyclobutene (BCB). This technology allows to fabricate a variety of reliable waferbonded components in a fairly simple way using only standard cleanroom equipment. We demonstrate the fabrication of passive devices such as microring resonators, as well as active components such as lasers and LEDs. We show good performance of these devices by presenting measurements of their characteristics. Furthermore, these devices were subjected to damp-heat testing, demonstrating the good quality of the BCB-bonding procedure. Finally, due to the low thermal conductivity of BCB, thermal management needs some attention. We present an analysis of the thermal problem and suggest a possible solution. View full abstract»

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  • Novel hollow optical fibers and their applications in photonic devices for optical communications

    Page(s): 524 - 532
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    Novel photonic devices based on a new type of waveguide, hollow optical fibers (HOF), are described. Utilizing unique three layered structure of HOF, the central air hole, germanosilicate ring core, and silica cladding along with its adiabatic mode transformation capability we demonstrated versatile applications in short-haul, long-haul optical communications, and tunable wavelength selective devices. Detailed design parameters, fabrication arts of the fibers, and operation principles of the devices are discussed. View full abstract»

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  • Development of microoptical waveguide on microactuating platform technologies for reconfigurable optical networking

    Page(s): 533 - 542
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    This paper reports on new hybrid optomechanical technology for reconfigurable optical networking applications. Unique and versatile functions in the technology were provided by micrometer-scale fused-taper waveguides mounted on microelectromechanical actuating platforms. The proposed technology can endow new degrees of freedom to control spectral response and port-to-port output power of the throughput of multiport fiber-fused-taper devices. Applications in a reconfigurable optical switch, an interband router, and a high-power optical attenuator for optical networking are discussed. View full abstract»

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  • Fabrication of Germanosilicate glass optical fibers containing Tm2+ ions and their nonlinear optical properties

    Page(s): 543 - 550
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB) |  | HTML iconHTML  

    Germanosilicate glass optical fibers incorporated with the Tm2+ ions were fabricated to enhance optical nonlinearity by providing a strong reduction environment based on the solution doping technique in the modified chemical vapor deposition (MCVD) process. The incorporation of the Tm2+ ions into the fiber core was identified by the electron paramagnetic resonance (EPR) spectrum in the fiber preform, and the absorption and emission properties between 350 and 1600 nm of the Tm2+ ions in optical fibers and the fiber preform. A strong broad absorption band due to the Tm2+ ions appeared from 350 to ∼900 nm, and a broad emission from ∼600 to ∼1050 nm and the other emission from ∼1050 to ∼1300 nm, which were not shown in the Tm3+ ions, were found upon Ar-ion laser pumping at 515 nm. Both absorption and emission results confirm that the Tm2+ ions in the germanosilicate glass have the 4f-5d energy band from 350 to ∼900 nm and the 4f-4f energy level at ∼1115 nm. Also, the resonant nonlinearity at ∼1310 and ∼1530 nm due to the Tm2+ ions in the fiber was measured upon the 515 nm optical pumping by using a long-period fiber grating (LPG) pair method. The nonlinear refractive index n2 at ∼1310 and ∼1530 nm was found to be ∼4×10-15 m2/W, where 70% and 30% of the n2 are attributed to the nonradiative transitions and the radiative transitions, respectively. View full abstract»

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  • Noncontact optical fiber coating removal technique with hot air stream

    Page(s): 551 - 557
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    We will discuss a novel noncontact removal technique of optical fiber coating in continuous and uninterrupted manner with hot air stream. We observed the mean breaking tensile strengths of the optical fibers coated with the UV-cured protective polymer and stripped using noncontact removal method were 5.6 and 5.1 GPa, respectively. A high-speed camera with 10 000 frames/s frame rates was used to observe the sequential steps of the explosion and vaporization of optical fiber coating materials. View full abstract»

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  • Comparison of zoned microstructure fiber geometries for low-dispersion waveguiding

    Page(s): 558 - 566
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    This paper presents a comprehensive analysis of zoning in microstructure fiber (MSF) in which parabolic and Gaussian graded-index (GRIN) refractive-index profiles are compared in both continuous and zoned geometries. Ray trajectories were calculated using Fermat's principle of least time and the paraxial approximation. Optimization of the zoned MSF refractive-index profile revealed that a piecewise Gaussian refractive-index profile exhibits aberration of just 10-nm on-axis focal variation, compared with 40 nm in the zoned parabolic case. In addition, a quarter-period length of the Gaussian-zoned MSF has a 630-nm theoretical spot-size, thus offering efficient coupling between standard single-mode fiber and photonic-crystal devices. A preliminary analysis of a binary radially chirped Bragg fiber geometry is performed using an eigenmode expansion of Maxwell's equations. Its simpler geometry offers fabrication advantages, but its spot size is closer to 1.2 μm due to its 41-μm quarter-period focal length, and it suffers greater waveguide dispersion compared with the optimized zoned GRIN MSF geometry presented here. View full abstract»

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  • Active alignment of optical fibers to planar waveguides using a thermal-curing adhesive

    Page(s): 567 - 572
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB) |  | HTML iconHTML  

    This paper described a process that was developed for the active alignment of optical fibers to planar waveguides using a thermal-curing adhesive, in order to improve the performance and reliability of waveguide-based components. The process combines alignment at a temperature selected for adhesive curing with offline postthermal treatment of the aligned device that is suitable for volume manufacturing. A specially designed fiber-array holder and a waveguide-device holder were used to overcome the effects of temperature and stress on the alignment, simplifying the alignment from high temperature to room temperature. By studying the adhesive curing kinetics and the buildup of adhesive bonding strength, the alignment was tuned to balance performance and efficiency. Using this alignment process, fiber-to-waveguide couplings that provide low optical loss, strong bonding, and excellent reliability were achieved. View full abstract»

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  • Testing of high-power semiconductor laser bars

    Page(s): 573 - 581
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    A measurement system called laser bar prober for characterizing high-power semiconductor edge-emitting laser bars is described. The laser bar prober is fully automated to handle testing of large numbers of lasers, is multifunctional to measure various laser characteristics and is accurate in predicting performance of fully mounted lasers. The bar prober has been proven to be an effective instrument for screening lasers during manufacturing process as well as an indispensable tool for providing rapid feedback to the development of new laser structures. In this paper, the design of the laser bar prober is described and a few examples of its applications are given; in particular, a time-resolved technique to correlate the measurement data of a laser within a laser bar to those of a fully mounted laser is demonstrated. View full abstract»

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  • Inductance-controlled electroabsorption Modulator modules using the flip-chip bonding technique

    Page(s): 582 - 587
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    The wire-bonding technique is widely used for the connections between the electroabsorption (EA) modulator chips and the electrical signal transmission lines. However, the parasitic inductance of the bonding wire degrades the electrical characteristics of the EA modulator modules in a high-frequency region. In this paper, we theoretically analyze the influence of parasitic inductance on the base-band digital transmission and obtain the relationship between the EA modulator capacitance and the optimum lead inductance. For precise inductance control, we introduced the flip-chip bonding (FCB) technique and fabricated 40-Gb/s EA modulator modules. View full abstract»

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  • Lens-free optical fiber connector having a long working distance assisted by matched long-period fiber gratings

    Page(s): 588 - 596
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    Optical fiber connectors that had a long working distance and wide alignment tolerance were implemented by utilizing long-period fiber gratings (LPGs) written in double-cladding fiber. The power coupling between two separated pieces of fiber was accomplished through the inner cladding modes of both fibers. Assisted by the LPGs, approximately 450 μm was achieved for a 1-dB working distance, as well as about 3 mm of 3-dB working distance. When the separation between two fiber tips was 1.5 mm, the 3-dB lateral tolerance was measured to be about 30 μm, which was five times better than was the case when not utilizing the LPGs. By using the inner cladding mode of a dispersion-compensating fiber, it was possible to implement a fiber connector that was insensitive to the perturbations at the cladding surface of the fiber. The total insertion loss of the device at the maximum coupling was 2.06 dB, from which the loss purely induced by inserting the fiber gratings was analyzed to be smaller than 0.9 dB. The experimental results show strong feasibility for implementing a simple and cost-effective fiber connector that does not require any bulk optic elements. View full abstract»

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  • Realization of true-time-delay using cascaded long-period fiber gratings: theory and applications to the optical pulse multiplication and temporal encoder/decoder

    Page(s): 597 - 608
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    This paper proposes and demonstrates a technique for repetition-rate multiplication of an optical pulse train having an arbitrary period or pattern and the optical temporal encoding/decoding for the optical-code-division multiple-access (O-CDMA) system. The technique exploits the difference in the propagation speeds between the core and copropagating cladding modes of a fiber to obtain true-time-delay between the modes traveling in the core mode and the cladding mode, which can be used to achieve pulse multiplication. For the coupling to the cladding mode, long-period fiber gratings (LPGs) were used. A series of cascaded LPGs imprinted in a fiber with a specific separation has been employed to obtain a specific rate of pulse multiplication with a single input pulse. Second, by controlling the separations among the gratings, the temporal encoder/decoder for O-CDMA could be implemented. The principle and the applications of the proposed device are investigated in detail. The effect of the birefringence of fiber and fiber gratings on the system performance in the time and spectral domains is presented. The sensitivity of the cladding modes in a conventional fiber to the perturbations at the cladding has been overcome by replacing the conventional fiber with inner-cladding fiber. The properties and the benefits of using the inner-cladding mode are investigated. View full abstract»

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  • Laser cleaving of glass fibers and glass fiber arrays

    Page(s): 609 - 614
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    An ultraviolet (UV)-excimer-laser-based cleaving procedure for silica fiber has been developed that enables automated cleaving for high-volume production of fiber-optic assemblies. A selective ablation of the glass in the form of a small rectangular cavity serves as a fracture initiator when the fiber is put under stress. The position of the UV-excimer-laser-induced scratch is very precise. The system provides high-quality cleaves on single-fiber and ribbon configurations. The end angle of the cleaved optical fiber is measured using a noncontact optical interferometer system and was 0.85° for perpendicular cleavages. Insertion loss after splicing is in the range of 0.03 dB, which is compatible with mechanical-cleaved fibers. View full abstract»

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  • Effect of welding sequence on welding-induced-alignment-distortion in packaging of butterfly laser diode modules: Simulation and experiment

    Page(s): 615 - 623
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1112 KB) |  | HTML iconHTML  

    Controlling welding-induced-alignment-distortion (WIAD) and maintaining coupling efficiency is obviously the most challenging issue in assembling of fiber-optic components using laser welding. WIAD is the dominant barrier to having high packaging yields. Previous investigation has revealed that the WIAD in butterfly laser diode module packaging could be mitigated by properly choosing weld process parameters such as welding sequence. In this paper, the effect of welding sequence on WIAD is studied numerically by finite-element method (FEM) with a more realistic physics based laser welding model and experimentally by welding prototype butterfly packages. Results from both methods are compared. It is shown that the influence of welding process parameters on WIAD is significant and WIAD control is possible if proper welding sequence is employed. View full abstract»

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  • UV-induced index changes in Undoped Fluoride glass

    Page(s): 624 - 627
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    Undoped fluoride glass slides have been exposed to pulsed 193-nm ultraviolet (UV) irradiation. Their absorption changes have been measured to evaluate UV-induced index changes using Kramers-Kronig relation. A layer-peeling polishing technique was applied to characterize the local UV-induced index change of highly absorbing glass. Index changes up to 1.75×10-4 have been evaluated with this method in fluorozirco-aluminate glass. Fluoroaluminate and fluorozirconate glass showed only small index changes of about 2.0×10-6 and 2.6×10-6 at a wavelength of 1550 nm. View full abstract»

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  • Fabrication of electrically controllable microlens array using liquid crystals

    Page(s): 628 - 632
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB) |  | HTML iconHTML  

    Electrically controllable liquid-crystal (LC) microlens arrays have been fabricated using the process of anisotropic phase separation of the LC from its solution in a ultraviolet curable prepolymer. The focal length of nematic LC-based microlens arrays can be changed in milliseconds with an applied electric field. The ferroelectric LC microlens array exhibits the memory effect and modulates the transmitted light within a few microseconds, i.e., ∼1000 times faster than the nematic LC-based microlens. Having no internal substructures to scatter light, these devices offer high efficiency and high light throughput that is different from polymer-dispersed devices. View full abstract»

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  • Fabrication trends for free-space microoptics

    Page(s): 633 - 646
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    In this paper, we discuss likely trends for manufacturing of free-space microoptics, focusing primarily on diffractive and refractive components. A brief historical overview of microoptics fabrication is presented, followed by our predictions on the future of the field. Examples of future applications, technical challenges, and supporting technologies required for manufacturing of different types of microoptics are discussed. 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