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Photonics Technology Letters, IEEE

Issue 16 • Date Aug.15, 2007

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Displaying Results 1 - 25 of 36
  • Table of contents

    Publication Year: 2007 , Page(s): 1189 - 1190
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    Freely Available from IEEE
  • Millimeter-Wave Signal Generation Using Two Cascaded Optical Modulators and FWM Effect in Semiconductor Optical Amplifier

    Publication Year: 2007 , Page(s): 1191 - 1193
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (157 KB) |  | HTML iconHTML  

    A novel method of optical generation millimeter-wave (mm-wave) signals employing two cascaded optical modulators and four-wave-mixing effect in semiconductor optical amplifiers is proposed. This approach is capable of generating signals of four times, eight times, and 12 times microwave source frequency with high spectral purity and stability. A mm-wave of 42 GHz (12times fundamental) with a 3-dB linewidth less than 30 Hz and a phase noise less than 83 dBc/Hz at 10-kHz offset is obtained. View full abstract»

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  • Multitap Complex-Coefficient Incoherent Microwave Photonic Filters Based on Stimulated Brillouin Scattering

    Publication Year: 2007 , Page(s): 1194 - 1196
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    We propose a novel scheme to implement multitap tunable incoherent microwave photonic filters with all-optical complex coefficients based on Brillouin signal processing of optical single-sideband signals. A six-tap filter is experimentally demonstrated to highlight the enhanced flexibility in the synthesis of frequency responses provided by complex coefficients, particularly in terms of tuning. View full abstract»

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  • Performance of Waveband MUX/DEMUX Using Concatenated AWGs

    Publication Year: 2007 , Page(s): 1197 - 1199
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (207 KB) |  | HTML iconHTML  

    Recently, we proposed a new waveband multi/demultiplexer that uses two concatenated arrayed-waveguide gratings. We fabricate the device using silica planar lightwave circuit technology and experimentally confirm its feasibility. The device was designed to accommodate 40 100-GHz-spaced C-band channels on the ITU-T grid and six input fibers simultaneously, that is, one chip can support 240 channels. View full abstract»

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  • Enhancement of Flip-Chip Light-Emitting Diodes With Omni-Directional Reflector and Textured Micropillar Arrays

    Publication Year: 2007 , Page(s): 1200 - 1202
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (781 KB) |  | HTML iconHTML  

    The flip-chip light-emitting diodes (FC-LEDs) with a conductive omni-directional reflector and textured micropillar arrays were investigated. The micropillar arrays structure was formed on the bottom side of sapphire substrate by dry etching process to increase the light-extraction efficiency. The light output power of the FC-LED was increased by 65% for a 3.2-mum textured micropillar on the bottom side of the sapphire substrate. Our work offers promising potential for enhancing output powers of commercial light-emitting devices. View full abstract»

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  • Multichannel Differential Group Delay Emulation and Compensation via a Phase Pulse Shaper

    Publication Year: 2007 , Page(s): 1203 - 1205
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (734 KB) |  | HTML iconHTML  

    We developed a differential group delay (DGD) emulator which is based on a high spectral resolution phase pulse shaper. DGD generation has been demonstrated for up to four wavelength channels independently and simultaneously, with DGD accuracy of approximately 1 ps for up to 400-ps DGD range. For each channel, DGD versus frequency profiles can be arbitrarily programmed to user specifications. Multichannel DGD compensation has also been demonstrated using the same setup. View full abstract»

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  • Coherent Optical Phase-Modulation Link

    Publication Year: 2007 , Page(s): 1206 - 1208
    Cited by:  Papers (41)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (155 KB) |  | HTML iconHTML  

    We demonstrate and characterize a new class of radio-frequency (RF)-photonic link for the linear transport of analog RF signals. Simultaneous and separate detection and digitization of optical in-phase and quadrature-phase signals is employed for linear phase demodulation in the digital domain. This is shown to allow significantly larger tolerance to imperfect physical implementation of the phase demodulating receiver. Digitizer-limited spur-free dynamic range improvement >12 dBldrHz2/3 is observed in our baseband demonstration. Modulation depths significantly exceeding unity are allowed and demonstrated. View full abstract»

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  • Arbitrary-Order Ultrabroadband All-Optical Differentiators Based on Fiber Bragg Gratings

    Publication Year: 2007 , Page(s): 1209 - 1211
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (231 KB) |  | HTML iconHTML  

    We introduce a general approach for designing ultrabroadband arbitrary-order all-optical (all-fiber) time differentiators based on the use of fiber Bragg gratings (FBGs). Specifically, we numerically demonstrate that an Nth-order time differentiator can be implemented using a single specially apodized highly dispersive linearly chirped FBG operated in transmission. A concatenated reflection phase-shifted FBG is also required for implementing any odd-order differentiator. Our numerical simulations show that accurate and efficient time differentiation of optical signals with bandwidths up to a few hundreds of gigahertz can be realized using readily feasible FBG structures. View full abstract»

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  • Hybrid Multicast Mode in All-Optical Networks

    Publication Year: 2007 , Page(s): 1212 - 1214
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (555 KB) |  | HTML iconHTML  

    Although serial multicast mode (SMM) can increase the multicast success ratio (MSR) more than parallel multicast mode (PMM), it suffers from the signal impairment and the extra delay caused by the optical loop. In this letter, a novel hybrid multicast mode (HMM), which combines PMM and SMM, is proposed to mitigate those issues. Moreover, an HMM-based two-level-buffered all-optical multicast module is also proposed to further mitigate the signal impairment in this letter. Finally, with the simulations, a conclusion can be drawn that HMM can get higher MSR and lower average delay than both PMM and SMM. View full abstract»

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  • Generation and Separation of Closely Separated Dual Baseband Channels for Provisioning of Independent Services in WDM-PON

    Publication Year: 2007 , Page(s): 1215 - 1217
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (309 KB) |  | HTML iconHTML  

    This letter presents a novel technique that enables simple provisioning of independent services in wavelength-division-multiplexed passive optical networks. The technique uses a single laser and modulator for generation and a periodic passive filter for separation of two closely separated baseband channels. We present experimental results of the bit-error-rate performance for the two 1.5-Gb/s independent service channels at a frequency separation of only 6 GHz. View full abstract»

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  • The Design and Optimization of an Ion-Exchanged Polarization Converter Using a Genetic Algorithm

    Publication Year: 2007 , Page(s): 1218 - 1220
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (571 KB) |  | HTML iconHTML  

    In this work, a genetic algorithm is used for the optimization of the design parameters of an integrated optical polarization converter on a glass substrate. The algorithm is applied to find the minimum possible length for the converter. The required asymmetry for the structure is realized with the aid of a cleaving process following the ion-exchange process. Simulation results show the possibility of realizing such a low-cost integrated converter. The obtained results demonstrate the importance of using such an algorithm in integrated optics problems where several design parameters such as the geometrical dimensions, the temperature, and the time duration are to be optimized. View full abstract»

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  • Greater Than 20-dB Supermode Noise Suppression and Timing Jitter Reduction Via CW Injection of a Harmonically Mode-Locked Laser

    Publication Year: 2007 , Page(s): 1221 - 1223
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (396 KB) |  | HTML iconHTML  

    Characterization of the timing and amplitude (AM) noise have shown a greater than 20-dB reduction of the supermode noise spurs from a harmonically mode-locked laser by continuous-wave optical injection. A reduction of the timing jitter and AM noise from 127 to 25 fs and 0.85% to 0.12% (10 Hz-100 MHz), respectively, is demonstrated. A reduction of the optical linewidth, implied by the reduction in the close-in phase noise, is also shown. View full abstract»

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  • Experimental Study of MLSE Receivers in the Presence of Narrowband and Vestigial Sideband Optical Filtering

    Publication Year: 2007 , Page(s): 1224 - 1226
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (218 KB) |  | HTML iconHTML  

    We report on experimental investigations of real-time maximum-likelihood sequence estimation (MLSE) in the presence of narrowband optical filtering, using 10.7-Gb/s nonreturn-to-zero ON-OFF keying and a fiber grating filter with 6.25-GHz bandwidth. Compared to standard threshold detection, the MLSE eliminates a 10-3 error floor due to narrowband optical filtering and results in DFB a <2-dB optical signal-to-noise ratio penalty at a 10-3 bit-error ratio. Furthermore, we demonstrate the ability of the MLSE to simultaneously compensate for narrowband optical filtering and chromatic dispersion. Finally, we investigate the influence of narrowband filter frequency detuning and show that the well-known effect of increased filtering tolerance given by the vestigial sideband effect observed in standard threshold detection, disappears in the presence of the MLSE. View full abstract»

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  • A Bidirectional WDM/TDM-PON Using DPSK Downstream Signals and a Narrowband AWG

    Publication Year: 2007 , Page(s): 1227 - 1229
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (310 KB) |  | HTML iconHTML  

    We present an innovative architecture to realize a single feeder bidirectional amplified wavelength-division-multiplexing/time-division-multiplexing passive optical network based on modified nonreturn-to-zero differential phase-shift keying (DPSK) downstream signals at 20 Gb/s and a narrowband arrayed waveguide grating (AWG). The AWG plays at the same time the role of channel distributor, simultaneous demodulator for all DPSK channels, and eliminates the need for chromatic dispersion compensation. A saturated semiconductor optical amplifier (SOA) provides bidirectional amplification to compensate the splitter losses. The remodulated upstream signals are obtained at 1 Gb/s by means of a reflective SOA. Experimental results show error-free operation on both downstream and upstream signal. View full abstract»

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  • Long-Haul Optically Uncompensated IMDD Transmission With MLSE Using the M-Method

    Publication Year: 2007 , Page(s): 1230 - 1232
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (153 KB) |  | HTML iconHTML  

    Recent experimental evidence with off-line processing has shown that intensity-modulation direct-dectection receivers using maximum-likelihood sequence estimation (MLSE) can successfully operate over a very long distance without any optical dispersion compensation. One hurdle towards the actual exploitation of the technology is the required complexity of the processor, which grows exponentially with distance. In this letter, we investigate the use of a complexity-reduction algorithm originally proposed for nonoptical communications, called the M-method. We show by simulation that over 400 and 700 km of G.652 fiber, at 10.7 Gb/s, the M-method allows us to operate with virtually no excess penalty with respect to conventional MLSE, while keeping track of only 32 and 128 trellis states, respectively, out of optimum full-fledged trellises requiring 512 and 8192 states, respectively. We investigate the robustness of the algorithm versus limited analog-digital resolution and confirm its effectiveness by testing it over experimental data at 10 Gb/s over 1040 km. View full abstract»

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  • A Novel Low-Cost Fiber In-Line-Type Bidirectional Optical Subassembly

    Publication Year: 2007 , Page(s): 1233 - 1235
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB) |  | HTML iconHTML  

    A novel low-cost fiber in-line-type bidirectional optical subassembly using a tilted fiber Bragg grating has been developed for fiber-to-the-home applications. We successfully realized a low-cost subassembly by reducing the number of components and simplifying the packaging process. The extinction ratio of 14.8 dB, receiver minimum sensitivity of -26.5 dBm at a bit-error rate of 10-12 and frequency response of 2.7 GHz were experimentally obtained. The electrical crosstalk between transmitter and receiver part was less than -86 dB up to 2.5 GHz. View full abstract»

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  • Optical Fiber Polarization Interferometer for Performance Improvement in Radio-Over-Fiber Systems

    Publication Year: 2007 , Page(s): 1236 - 1238
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    An extinction ratio tunable optical fiber polarization interferometer (OFPI) is proposed and implemented to increase the optical modulation depth in radio-over-fiber (RoF) systems by suppressing the optical carrier power. The extinction ratio of the OFPI can be simply tuned by adjusting the polarization state of the launched RoF signal. Experimental results illustrate that the receiver sensitivity and dynamic range of RoF systems are greatly improved using the proposed scheme. View full abstract»

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  • Proposal for All-Solid Photonic Bandgap Fiber With Improved Dispersion Characteristics

    Publication Year: 2007 , Page(s): 1239 - 1241
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (438 KB) |  | HTML iconHTML  

    We propose a novel design of all-solid photonic bandgap fiber (AS-PBGF). It is designed by introducing a new defect, several bigger high-index rods, in the cladding of a conventional AS-PBGF. Using the plane-wave expansion method and the full-vector finite-element method, we study the effect of introducing such bigger high-index rods. The numerical results show that both large normal and anomalous dispersion are induced within bandgap rather than near the edge of bandgap as conventional PBGF does. More importantly, the confinement loss of the LP01 modes around the wavelengths, where large normal and anomalous dispersion are induced, could be decreased by increasing the rings of high-index rods for the fact that these wavelengths are within the bandgap. View full abstract»

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  • Use of Fiber Bragg Grating Sensors for Determination of a Simply Supported Rectangular Plane Plate Deformation

    Publication Year: 2007 , Page(s): 1242 - 1244
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (347 KB) |  | HTML iconHTML  

    A measurement method has been developed to determine the full-field deformation of a simply supported plane plate under transverse load. The method utilizes strain information provided by a set of four fiber Bragg grating sensors mounted on the plate in a way that all sensors measure strains along one certain direction. The sensors were interrogated using a wavelength swept fiber laser. Utilizing the strain information and the first four terms of Navier solution of simply supported rectangular plate, the necessary parameters for determining the deflection could be computed. By substituting the values of x- and -y- coordinates of each position on the rectangle plate, the full-field deformation information can be obtained. Single-point loading tests were experimentally performed to verify the accuracy of the method. View full abstract»

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  • Performance Evaluation of Trellis Code Modulated oDQPSK Using the KLSE Method

    Publication Year: 2007 , Page(s): 1245 - 1247
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (155 KB) |  | HTML iconHTML  

    A direct detection optical differential quadrature phase-shift keying (oDQPSK) system with trellis coded modulation (TCM) is proposed and analyzed. From the results obtained for the symbol-error rate, it is observed that the proposed oDQPSK-TCM system can perform about 5 dB better than the uncoded oDQPSK system. Optical signal-to-noise ratio penalty due to first-order polarization-mode dispersion of the proposed oDQPSK-TCM system is evaluated and compared with that of unequalized as well as electrically equalized oDQPSK systems. View full abstract»

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  • Design and Operation of a Monolithically Integrated Two-Stage Tunable All-Optical Wavelength Converter

    Publication Year: 2007 , Page(s): 1248 - 1250
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (453 KB) |  | HTML iconHTML  

    We report on the design and testing of a novel two-stage wavelength-converter architecture, monolithically fabricated in indium phosphide. Two widely tunable integrated sampled-grating distributed Bragg reflector lasers are utilized on chip as probes in both converter stages. The architecture provides a first-stage tunable signal that is internal to the chip (lambdainternal), facilitating cascaded integration of wavelength-sensitive structures, or allowing wavelength conversion for cases where the input wavelength is equal to the output wavelength (lambdainput = lambdaoutput). Output wavelength tuning over 35 nm is shown, and error-free wavelength conversion for lambdainput = lambdaoutput is demonstrated for four wavelengths over a 20-nm range at 2.5 Gb/s. Dynamic range measurements show less than 2 dB of power penalty over a 15-dB variation in input power. View full abstract»

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  • 10-GHz 8.7-ps Pulse Generation From a Single-Mode Gain-Switched AlGaAs VCSEL at 850 nm

    Publication Year: 2007 , Page(s): 1251 - 1253
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB) |  | HTML iconHTML  

    We have successfully generated a 10-GHz 8.7-ps pulse train at 850 nm by using a gain switching technique with a high-speed AlGaAs-based vertical-cavity surface-emitting laser (VCSEL). The VCSEL, which operates in a single transverse mode by employing an aluminum oxide aperture, has a modulation bandwidth of 6.3 GHz and a relaxation oscillation frequency at around 11.7 GHz. An error-free 10-Gb/s return-to-zero data modulation was demonstrated by using the generated 10-GHz pulse train. View full abstract»

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  • Mode Coupling in Plastic Optical Fiber Enables 40-Gb/s Performance

    Publication Year: 2007 , Page(s): 1254 - 1256
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (307 KB) |  | HTML iconHTML  

    We report 40-Gb/s capability of 50-mum core plastic optical fiber using differential modal delay measurements and power penalty due to intersymbol interference computations. The results are explained via a comprehensive multimode fiber model that includes mode coupling (MC) and differential modal attenuation (DMA). We show that strong MC can enable 40-Gb/s transmission for reach in excess of 100 m even in the presence of irregularities in the refractive index profile that prevent 10-Gb/s performance without MC. Furthermore, we show that DMA effects are negligible and that the mode power distributions are not a good indicator of bandwidth. View full abstract»

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  • Bend Loss, Tapering, and Cladding-Mode Coupling in Single-Mode Fibers

    Publication Year: 2007 , Page(s): 1257 - 1259
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (169 KB) |  | HTML iconHTML  

    A new approach to the physical description and quantification of total bend loss in arbitrarily bent single-mode fiber is based on the coupling of the fundamental mode to cladding modes caused by curvature change. A criterion is derived that limits the maximum allowable rate of change of curvature to reduce bend loss to almost arbitrarily low levels regardless of the maximum curvature, provided only that the coating index is sufficiently smaller than the cladding index. This criterion is less demanding for pre- tapered fibers or fibers with a thinner cladding. View full abstract»

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  • Strain and Temperature Discrimination Using Concatenated High-Birefringence Fiber Loop Mirrors

    Publication Year: 2007 , Page(s): 1260 - 1262
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    In this letter, a new configuration for simultaneous strain and temperature discrimination is presented using two concatenated high-birefringence (Hi-Bi) fiber loop mirrors. The first loop mirror includes a Hi-Bi photonic crystal fiber, while the second one contains a length of internal elliptical cladding fiber. It is shown that by monitoring the wavelength and optical power of one of the peaks of the system spectral transfer function, it is possible to obtain information that permits the simultaneous measurement of strain and temperature. View full abstract»

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Aims & Scope

This letters journal addresses all aspects of the IEEE Photonics Society Constitutional Field of Interest with emphasis on photonic/lightwave components and applications, laser physics and systems and laser/electro-optics technology.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Dr. Seb J. Savory
University College London