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Lightwave Technology, Journal of

Issue 12 • Date Dec 1994

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Displaying Results 1 - 15 of 15
  • InGaAsP channel HFET's on InP for OEIC applications

    Publication Year: 1994 , Page(s): 2131 - 2138
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    A model for the calculation of the input noise of a high impedance photoreceiver is proposed, taking into account the contributions of low-frequency characteristics of the FET. Simulations based on this approach show that excess gate leakage current and low-frequency excess noise, usually observed in InGaAs channel FET's, strongly penalize the photoreceiver sensitivity for low to medium data rates. New InGaAsP channel HFET's have been developed and fabricated to solve those problems, dc measurements on 1×100 μm2 gate HFET's show good Ids-Vds characteristics with associated gate leakage currents lower than 200 nA. Promising ft of 18 GHz and f max of 40 GHz have been recorded on 0.5×200 μm2 gate transistors. Low-frequency gate and channel noise measurements demonstrate the suitability of InGaAsP channel HFET structure and technology for low noise applications. A hybrid pin-HFET high impedance photoreceiver has been assembled with a 1×150 μm 2 gate transistor. A very close agreement is found between photoreceiver input noise predicted by our model and experimental results. Record sensitivities of 34.8 dBm at 622 Mbit/s and -28.7 dBm at 2.5 Gbit/s are inferred from noise measurements, confirming the strong potential of InGaAsP channel HFET's for the fabrication of high sensitivity photoreceivers operating at moderate data rates View full abstract»

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  • S-SEED switching characteristics

    Publication Year: 1994 , Page(s): 2122 - 2130
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    S-SEED switching operation is studied, and an analysis technique introduced that produces a closed form expression relating the switching voltage to the input power contrast ratio and the responsivity characteristics of the device. A closed form equation for the switching time, and a general switching condition are derived as well. The analysis technique uses a single slope linear approximation to the responsivity curve, and is readily extended to a three epoch approach as well as an N-segment analysis scheme. Theoretical analysis is verified with a computer simulation using experimental data. A comprehensive model of the S-SEED with series and parallel resistors was also studied. It was found that the switching time could be reduced by as much as 24% over the purely capacitive model, and switching achieved with a minimum power ratio View full abstract»

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  • Threshold condition of DFB semiconductor lasers by the local-normal-mode transfer-matrix method: correspondence to the coupled-wave method

    Publication Year: 1994 , Page(s): 2092 - 2099
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    An analytical expression for the threshold condition of DFB semiconductor lasers is derived based on the local-normal-mode transfer-matrix method (TMM). The threshold condition is expressed in terms of an equivalent reflection coefficient of a DFB laser structure and a Bloch-wave propagation constant. It is shown that the TMM threshold condition can reproduce the one which is derived by the coupled-wave method (CWM) under certain conditions. It is also shown that the CWM can predict very accurately the spatially averaged values of the threshold modal gain and the detuning frequency which are obtained by the TMM if the coupling coefficient in the CWM is replaced by the TMM coupling coefficient View full abstract»

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  • Design of widely tunable semiconductor three-branch lasers

    Publication Year: 1994 , Page(s): 2100 - 2106
    Cited by:  Papers (4)  |  Patents (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    We describe the design and operating principles of the new, widely tunable, three-branch semiconductor Y3-lasers, which we have demonstrated recently. This multibranch tunable laser structure is formed by a cascade of Y-junctions and uses a geometrical tuning leverage to achieve wide-range discrete frequency tuning. Y3-lasers have demonstrated experimentally a tuning range of 45 nm (5.6 THz) and access to 50 frequency channels, with potential access to more than a 100 channels. Among the important issues discussed in this paper are the Y3-laser structure, mode selection of the Y3-laser filter, laser side-mode suppression, number of accessible channels, tuning range, and the tuning mechanism of the Y3-laser. A specific design example is also presented. The simplicity of Y3-laser fabrication and the powerful digital channel-access control make these lasers important electronically-tunable sources for multichannel wavelength-division-multiplexed (WDM) optical communication networks View full abstract»

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  • A new iterative method for the analysis of longitudinally invariant waveguide couplers

    Publication Year: 1994 , Page(s): 2056 - 2065
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    In this paper, a new iterative method to solve for the modal indices and field profiles of the supermodes of multichannel waveguide structures is proposed. This method combines the shift inverse power method with the simultaneous iteration method, and can be applied to any longitudinally invariant waveguide couplers problem very efficiently. Using this method, the characteristics of the leading supermodes can be obtained simultaneously. The validity and accuracy of this method are assessed by comparing to other existing methods for symmetric two-channel waveguide couplers. Results are in good agreement. Asymmetric two-channel and symmetric three-channel waveguide couplers are then considered to show the usefulness and versatility of the proposed method View full abstract»

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  • Near-infrared channel waveguides formed by electron-beam irradiation of silica layers on silicon substrates

    Publication Year: 1994 , Page(s): 2085 - 2091
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    Results are presented for channel guides formed by electron beam irradiation of silica layers formed on Si substrates by plasma-enhanced chemical vapor deposition. Electroplating is shown to be a simple method of fabricating the required surface mask. Optical insertion loss measurements performed at 1.525 μm wavelength show a strong dependence on the irradiation mask width, charge dose, and electron energy, and parameters for low propagation and coupling loss are identified. Optimum propagation losses are 0.4 dB/cm (TE), 0.75 dB/cm (TM). Spectral loss measurements are also presented for as-deposited and thermally annealed material, and it is shown that beneficial results are obtained by annealing before irradiation. The stability of irradiation-induced changes is also described View full abstract»

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  • Analysis of nonlinear grating couplers by singular perturbation technique

    Publication Year: 1994 , Page(s): 2049 - 2055
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB)  

    The properties of the nonlinear output and input grating couplers are analyzed by using the singular perturbation technique with the multiple space scales. We first introduce the perturbation parameter concerned with the nonlinear parameter and the grating depth. After the wave functions are expanded, the perturbation solutions to satisfy the equivalent boundary conditions are derived. From the solvability condition to have nontrivial solutions on each perturbation order, the nonlinear equations to describe the power leakage of the guided wave due to the second-order coupling to the first-order waves are obtained. The dependence of the radiated field and the input efficiency on the power are discussed numerically View full abstract»

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  • Simultaneous measurement of two strain components using 3×3 and 2×2 coupler-based passive demodulation of optical fiber sensors

    Publication Year: 1994 , Page(s): 2153 - 2161
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    This paper uses 3-3 and 2-2 coupler passive demodulation of combined Michelson and polarimetric optical fiber sensors to simultaneously measure axial and transverse strain components in a single optical fiber sensor. The separated Michelson and polarimetric signals are used with isothermal Michelson and polarimetric phase strain models to provide two independent equations describing the strain in the fiber. These equations provide enough information to simultaneously calculate axial and transverse strains in surface mounted sensors. Experiments performed on vibrating cantilever beams show good agreement with measurements made with resistance strain gauges View full abstract»

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  • Efficient solution of eigenvalue equations of optical waveguiding structures

    Publication Year: 1994 , Page(s): 2080 - 2084
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    A general numerical method is presented that is capable of extracting all the zeros of a complex equation. This method allows accurate determination of the complex propagation constants of general multilayer optical and microwave planar waveguides, the computation of energy states and their lifetimes of semiconductor heterostructures, and the roots of complex transcendental equations from other scientific disciplines. The method differs from previous approaches in that the time-consuming differentiation of the complex function is not required. Furthermore, the present method is not affected by the presence of complex poles and so can be used for the solution of meromorphic transcendental equations. In practice, the method is found to be much faster than other rigorous approaches View full abstract»

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  • Generation of optical phase-conjugate waves and compensation for pulse shape distortion in a single-mode fiber

    Publication Year: 1994 , Page(s): 2139 - 2146
    Cited by:  Papers (15)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    The generation of optical phase-conjugate waves and the application of optical phase conjugation (OPC) to optical communication systems is described. The method of pulse shape distortion compensation by OPC is outlined including distortion due to both fiber dispersion and the optical Kerr effect. The generation of a forward-going phase-conjugate wave in a third-order nonlinear medium is discussed and that by a nondegenerate forward four-wave mixing in a zero-dispersion single-mode fiber (SMF) is investigated. Suppressing the stimulated Brillouin scattering (SBS) of a pump wave in the fiber prevents saturation of the generation efficiency of the phase-conjugate wave even when the pump power exceeds the SBS threshold. In transmission experiments through a 200-km standard SMF with a 16-Gb/s intensity-modulated signal and a 5-Gb/s continuous-phase FSK (CPFSK) modulated signal, it is shown the applicability of OPC is modulation independent and that OPC effectively compensates for both chromatic dispersion and the optical Kerr effect View full abstract»

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  • Silicon compatible organic light emitting diode

    Publication Year: 1994 , Page(s): 2107 - 2113
    Cited by:  Papers (2)  |  Patents (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    As an effort toward a goal of monolithic optoelectronics for silicon (Si) chip-to-chip connections, we have fabricated organic light emitting diodes (LED's) using either heavily N-doped silicon (Si) as a cathode or P-doped Si as an anode. A thin silicon dioxide (SiO2 ) layer, thermally grown on Si before deposition of a polymer or a molecular organic layer, enhances the electron injection into the semiconducting emissive layer. Without the thin oxide layer, no light was observed from LED's made from either (2-methoxy, 5-(2'-ethyl-hexoxy)-1, 4-phenylene vinylene) (MEH-PPV) or 8-hydroxyquinoline aluminum (Alq). With the SiO2 layer,the internal quantum efficiencies as high as 0.02% and 0.5% have been observed for MEH-PPV and Alq, respectively, and the turn-on voltages were as low as 2.5 V and 8 V, again for MEH-PPV and Alq, respectively. From the LED response time measurement, we identified RC constant and the recombination time of transport-related traps as the speed limiting factors View full abstract»

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  • Probability density functions of optical polarization states: theory and applications

    Publication Year: 1994 , Page(s): 2147 - 2152
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    We introduce the concept of probability density functions of polarization states for a more systematical approach of depolarization and the evolution of polarization in optical fiber. This concept is useful when polarization is a random function of wavelength, time and/or distance, like in depolarizers and in low-birefringent optical fiber. We give three examples of such probability density functions and present three applications View full abstract»

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  • Prospects for silicon monolithic opto-electronics with polymer light emitting diodes

    Publication Year: 1994 , Page(s): 2114 - 2121
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (820 KB)  

    We have fabricated a monolithically integrated photodetector and amplifier in silicon bipolar technology and organic polymer light emitting diodes (LED's) using both poly (p-phenylene vinylene) (PPV) and its soluble derivative poly (2-methoxy, 5-(2'-ethyl-hexoxy)-1,4-phenylene vinylene) (MEH-PPV). Based on the individual capabilities of the photo-receiver and LED, we have begun to evaluate the feasibility of monolithic integration of opto-electronics for silicon chip-to-chip communication using both PPV-LED's and Si photoreceivers on Si chips. LED's made from PPV and its soluble derivative such as MEH-PPV are thought to be process-compatible with Si IC technology. However, as an additional requirement, the polymer LED's must emit large enough power to be detected by the receiver with an acceptable bit-error-rate (BER) View full abstract»

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  • Modal fields calculation using the finite difference beam propagation method

    Publication Year: 1994 , Page(s): 2066 - 2072
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    A method is described to construct modal fields for an arbitrary one- or two-dimensional refractive index structure. An arbitrary starting field is propagated along a complex axis using the slowly varying envelope approximation (SVEA). By choosing suitable values for the step-size, one mode is maximally increased in amplitude on propagating, until convergence has been obtained. For the calculation of the next mode, the mode just found is filtered out, and the procedure starts again. The method is tested for one-dimensional refractive index structures, both for nonabsorbing and for absorbing structures, and is shown to give fast convergence View full abstract»

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  • Explicit formulas of normalized radiation modes in multilayer waveguides

    Publication Year: 1994 , Page(s): 2073 - 2079
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    A new formulation for the normalization of radiation modes in one-dimensional lossless multilayer waveguide structures is derived using the transmission matrix method. In this formulation, an individual radiation mode is excited by two sources located at opposite ends of the two outermost regions of the waveguide. Proper choice of the absolute phase of one of the sources results in simple expressions for the normalized radiation modes. Calculation of radiation loss of grating-assisted directional couplers is used as an example to show the simplicity and usefulness of this method 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