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Lightwave Technology, Journal of

Issue 17 • Date Sept.1, 2010

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Displaying Results 1 - 25 of 28
  • [Front cover]

    Page(s): C1
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  • Journal of Lightwave Technology publication information

    Page(s): C2
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  • Table of contents

    Page(s): 2467 - 2468
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  • Highly Sensitive Miniaturized Refractive Index Sensor Based on Au-Ag Surface Gratings on a Planar Optical Waveguide

    Page(s): 2469 - 2476
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB) |  | HTML iconHTML  

    We present the theoretical study of a novel highly sensitive, miniaturized, integrated optic refractive index sensor based on a Au-Ag surface grating. The grating is considered to be made of alternate layers of equi-thick Au and Ag regions along the direction of propagation, on the surface of the waveguide. Due to the same thickness of both the metals, the surface plasmon polaritons (SPP) for both metals have their field maxima at the same transverse distance, leading to an increased modal overlap in the grating region and hence a reduced grating length. An exact coupled-mode-theory based on the local mode matching has been used to analyze the mode coupling between the guided mode and the SPP. It has been shown that the proposed design requires nearly one fourth of the grating length as compared to the corrugated metal grating for the same metal thickness. Further, for co-propagating mode coupling (LPG based sensor) the structure is found to be maximum sensitive at an optimum metal thickness, however, such an optimum metal thickness does not exist for counter-propagating coupling (FBG based sensor). View full abstract»

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  • Output Level Control of SOA Using On-Chip Heater for High Output Power Operation

    Page(s): 2477 - 2482
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (757 KB) |  | HTML iconHTML  

    A novel gain control scheme of semiconductor optical amplifiers (SOAs) using a heater-mounted SOA was investigated. In our proposal, a simple SOA gain control using an on-chip heater provides a high saturation output power over an entire gain control range of 10 dB. This scheme widely expands the usable power range in output level control of a 10 Gbps NRZ-OOK signal, compared to that of a conventional gain control operated by drive current. As a result, the heater-mounted SOA exhibited a large input power dynamic range (IPDR) of > 17 dB up to the output power of +8.0 dBm in level control operation. View full abstract»

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  • Total Internal Reflection Optical Switch in SOI With Defect Engineered Barrier Region

    Page(s): 2483 - 2491
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1011 KB) |  | HTML iconHTML  

    Total internal reflection optical switches offer a switching operation which can be wavelength insensitive, thermally stable and polarisation independent. The implementation of such a switch based upon carrier injection in silicon is difficult due to the long diffusion lengths of injected free carriers. In this paper experimental results are presented which show that a reflective type switching operation is obtainable if a barrier formed of defective silicon is used to reduce free carrier diffusion. View full abstract»

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  • Photonic True-Time Delay Beamforming Based on Polarization-Domain Interferometers

    Page(s): 2492 - 2498
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB) |  | HTML iconHTML  

    In this paper, we propose a novel photonic true-time delay beamforming system for phased array antennas. The system relies on tunable delay lines which are based on Mach-Zehnder delay interferometers (MZDIs) with tunable coupling ratio. As the MZDIs are implemented on the polarization domain, a single optical source and a single piece of polarization maintaining fiber are required. The proposed implementation is theoretically assessed and beam squinting is investigated by simulation. A proof-of-concept experiment that validates the operation principle of the proposed delay lines is presented. View full abstract»

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  • Tunable Wavelength Conversion by XPM in a Silicon Nanowire, and the Potential for XPM-Multicasting

    Page(s): 2499 - 2511
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1353 KB) |  | HTML iconHTML  

    Tunable wavelength conversion of a 10-Gb/s, return-to-zero on-off-keyed (RZ-OOK) signal has been carried out in a silicon (Si) nanowire waveguide (Si nanowire) using a pump-probe configuration and cross-phase modulation (XPM), followed by a tunable filter. This filter spectrally emulated the pass-band of a commercial 50-GHz DWDM arrayed waveguide grating (AWG). The tunability of the wavelength conversion process was demonstrated over a range of 20 nm, limited only by the amplifiers and the filter, while keeping the 10-9-BER receiver sensitivity penalty of the converted signal to a 0.5-dB maximum. A comprehensive model of wavelength conversion by XPM (XPM-WC) was developed, which took into account two-photon absorption, the Kerr effect, and free-carrier generation. The results of the model demonstrate good agreement with the experiment, especially with respect to the observed spectral broadening. The numerical model was also used to assess the dominant contribution among the various mechanisms within the context of XPM-WC, and to investigate the potential of multicasting by XPM in the nanowire. View full abstract»

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  • Tunable Optical Ring Resonator Integrated With Asymmetric Mach–Zehnder Interferometer

    Page(s): 2512 - 2520
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (810 KB) |  | HTML iconHTML  

    We demonstrate theoretically a tunable optical ring resonator incorporating an asymmetric Mach-Zehnder interferometer (MZI) and two phase shifters. The optimal resonance state of the ring resonator with different geometries can be achieved by tuning the two embedded phase shifters. Distinct intensity and phase responses and transmission spectra characteristics are newly observed by setting different structural parameters such as the asymmetrical path lengths of the waveguides and the coupling ratio of the directional couplers in the MZI. The performance characteristics related to the radius of the ring cavity and the propagation losses in the waveguides are also discussed. At optimal resonance, it is shown that sharp intensity response and tunable narrow-bandwidth spectra can be achieved especially for resonators with a highly asymmetrical configuration. Such device has a potential in sensing, switching and filtering applications. View full abstract»

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  • All-Optical Clock Recovery for 20 Gb/s Using an Amplified Feedback DFB Laser

    Page(s): 2521 - 2525
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB) |  | HTML iconHTML  

    We report all optical clock recovery based on a monolithic integrated four-section amplified feedback semiconductor laser (AFL), with the different sections integrated based on the quantum well intermixing (QWI) technique. The beat frequency of an AFL is continuously tunable in the range of 19.8-26.3 GHz with an extinction ratio above 8 dB, and the 3-dB linewidth is close to 3 MHz. All- optical clock recovery for 20 Gb/s was demonstrated experimentally using the AFL, with a time jitter of 123.9 fs. Degraded signal clock recovery was also successfully demonstrated using both the dispersion and polarization mode dispersion (PMD) degraded signals separately. View full abstract»

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  • Analysis of Laser Phase Noise Effect in Direct- Detection Optical OFDM Transmission

    Page(s): 2526 - 2536
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (969 KB) |  | HTML iconHTML  

    In this paper, we characterize the impact of laser phase noise (PN) in direct-detection optical OFDM (DDO-OFDM) and identify its many differences from those in coherent optical OFDM (CO-OFDM). The analytical models for the diverse PN effects, including power degradation, phase rotation term (PRT), and inter-carrier interference (ICI), are given in terms of critical system parameters with or without the small PN assumption. In particular, the analytical upper-bound of the ICI power with a simple form is also provided. We also present a bit error rate (BER) estimation approach which is proven to be reliable for an optical signal-to-noise-ratio (OSNR) penalty lower than ~ 2 dB. In addition, the PN tolerances, in terms of OSNR penalty, are also numerically analyzed and discussed with different QAM formats, data rates, laser linewdiths, and subcarrier numbers. View full abstract»

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  • OFDM versus Single-Carrier Transmission for 100 Gbps Optical Communication

    Page(s): 2537 - 2551
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (551 KB) |  | HTML iconHTML  

    We analyze the orthogonal frequency division multiplexing (OFDM) technique in long-haul next generation optical communication links and compare it with the well-established single-carrier (SC) data transmission using high-level modulation formats and coherent detection. The analysis of the two alternative solutions is carried out in the 100 Gbps scenario, which is commonly considered to be the next upgrade of existing optical links, with special emphasis on quaternary phase-shift keying (QPSK) modulations. The comparison between OFDM and SC takes into account the main linear and nonlinear impairments of the optical channel, e.g., group velocity dispersion (GVD), polarization mode dispersion (PMD), self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM), as well as the phase noise due to transmit and receive lasers, their relative frequency offset, other synchronization aspects, the overall complexity, the power and spectral efficiency, and the technological constraints. View full abstract»

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  • Scaling Guidelines of a Soliton-Based Power Limiter for 2R-Optical Regeneration Applications

    Page(s): 2552 - 2559
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (802 KB) |  | HTML iconHTML  

    In this work, we report scaling rules for the design of an all-fibered soliton-based power limiter for reamplification and reshaping (2R) regeneration process. In particular, we propose general guidelines to fix the optimum fiber length and initial power of the regenerator. We quantitatively point out the optical power limiting effect of the device enabling a significant reduction of the amplitude jitter of a degraded signal. Influence of the initial level of amplitude jitter is discussed and the results are compared with a self-phase modulation-based configuration working in the normal dispersion regime. Realistic numerical simulations in the context of 160 Gbit/s signals confirm that an efficient improvement of the signal quality can be achieved by means of such a device. View full abstract»

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  • Slow Light Propagation in Liquid-Crystal Infiltrated Silicon-On-Insulator Photonic Crystal Channel Waveguides

    Page(s): 2560 - 2571
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1629 KB) |  | HTML iconHTML  

    An SOI-based liquid-crystal (LC)-infiltrated photonic-crystal channel waveguide having rectangular air holes in a Silicon core is proposed-and has an average group index of 43 over a bandwidth of 1.02 THz, with vanishing group velocity dispersion, as well as reduced higher-order dispersion. The possible propagation losses due to coupling inefficiency are also investigated for the proposed structure. It is found that high transmission is obtained for a broad bandwidth from the output of the heterogeneous waveguide finally designed, which consists of an LC-infiltrated PhC slow waveguide surrounded by fast PhC regions on either side. The LC-infiltrated W0.7 PhC waveguide that has been designed for slow light propagation should be highly tolerant to fabrication errors-and has enhanced sensitivity in comparison with conventional PhC waveguides. View full abstract»

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  • 100 MHz Amplitude and Polarization Modulated Optical Source for Free-Space Quantum Key Distribution at 850 nm

    Page(s): 2572 - 2578
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (514 KB) |  | HTML iconHTML  

    We report on an integrated photonic transmitter of up to 100 MHz repetition rate, which emits pulses centered at 850 nm with arbitrary amplitude and polarization. The source is suitable for free space quantum key distribution applications. The whole transmitter, with the optical and electronic components integrated, has reduced size and power consumption. In addition, the optoelectronic components forming the transmitter can be space-qualified, making it suitable for satellite and future space missions. View full abstract»

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  • Polarization Beamforming PON Doubling Bidirectional Throughput

    Page(s): 2579 - 2585
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (644 KB) |  | HTML iconHTML  

    A low-complexity polarization multiplexed Passive Optical Network (PON) architecture based on Multiple Input Multiple Output (MIMO) polarization beamforming is experimentally demonstrated, achieving twice the throughput for both downstream and upstream transmissions. In addition, a novel dynamic power allocation scheme further improves the loss budget by up to ~1.8 dB in the downstream direction. View full abstract»

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  • Quasi-Light Storage: A Method for the Tunable Storage of Optical Packets With a Potential Delay-Bandwidth Product of Several Thousand Bits

    Page(s): 2586 - 2592
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (483 KB) |  | HTML iconHTML  

    We investigate and discuss the possibilities and limits of a method for the tunable storage of optical packets called Quasi-Light Storage (QLS). The QLS is simply based on a sampling in the frequency domain. Hence, it is independent of the data rate, the modulation and the wavelength of the optical packets. It works at room temperatures in standard fibers with off-the-shelf telecom equipment. As we will show in theory, the method has the potential to store packets with several thousand Bits of data from Zero to up to 100 ns. In the experiments we have stored several 8 Bit packets with a data rate of 1 Gbps for up to 100 ns, which corresponds to a delay-bandwidth product of 100 Bit. View full abstract»

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  • Enhancement of Input Power Dynamic Range for Multiwavelength Amplification and Optical Signal Processing in a Semiconductor Optical Amplifier Using Holding Beam Effect

    Page(s): 2593 - 2602
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (785 KB) |  | HTML iconHTML  

    We demonstrate a considerable enhancement of input power dynamic range (IPDR) for multiwavelength amplification and optical signal processing in a semiconductor optical amplifier (SOA) by using holding beam effect. The effect is used in SOA gain region at power level well below 10 dBm, which is much smaller than the required power as the setting at transparency wavelength. The IPDR is extended not only to high power range due to the reduction of nonlinear crosstalks, but also to low power range due to the compression of amplified spontaneous emission (ASE) noise. The technique is first applied to the amplification of wavelength-division multiplexed (WDM) channels using a continuous wave (CW) holding beam. The holding beam is particularly useful for the amplification of large number of channels thanks to the suppression effect of interactions among WDM channels. It is then carried out for one of extensively-used optical processing schemes, terahertz optical asymmetric demultiplexer (TOAD), for multiwavelength data format conversion without the need of an external CW light. The IPDR of TOAD reaches over 20 dB as control clock behaves simultaneously as the holding beam. We also present that the patterning effect and the impact of ASE noise on the converted signal are strongly dependent on the TOAD's switching window, which is optimized at 40% duty ratio for the largest IPDR. View full abstract»

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  • Synchronous Optical CDMA Networks Capacity Increase Using Transposed Modified Prime Codes

    Page(s): 2603 - 2610
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (374 KB) |  | HTML iconHTML  

    A novel spreading code-set based on the prime code (PC) families, referred to as `transposed modified prime codes (T-MPC)', is proposed for synchronous optical code-division multiple-access (OCDMA) networks. The new code-set is constructed algorithmically to enhance and simplify its implementation. The proposed code-set performance is compared with existing spreading code families in terms of correlations, bit-error rate (BER) and cardinality. The proposed optical spreading code family doubles the cardinality as compared to existing PC families. This also implies that greater number of users can be accommodated in the network. Since there is no longer a time-shift feature in T-MPC like in conventional modified prime codes (MPC), the code is not predictable and thus even more secure. However, the code structure is similar to MPC, thus its employment in a system running MPC will be nondestructive. The code is also compatible with low-weight MPC. The results indicate that the proposed code-set has properties to enhance the OCDMA network capacity remarkably. View full abstract»

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  • Narrow Linewidth DFB Lasers Emitting Near a Wavelength of 1064 nm

    Page(s): 2611 - 2616
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (691 KB) |  | HTML iconHTML  

    We report on the realization of narrow linewidth high power DFB diode lasers emitting near 1064 nm in stable longitudinal and lateral single mode. The linewidth is analyzed in dependence of the output power for lasers with cavity lengths of 1 and 2 mm by means of a heterodyne beat note technique. The minimum intrinsic linewidth is 22 kHz FWHM (full width at half maximum, at 100 μ s time scale) for an output power of 150 mW and a cavity length of 2 mm. The minimum total linewidth is mainly determined by technical noise and corresponds to 234 kHz FWHM at an output power of 70 mW. The influence of current noise on the linewidth is investigated and compared for different cavity lengths. Re-broadening at high output power is only observed for the contribution of technical noise to the linewidth. The intrinsic linewidth shows the theoretically expected 1/Pout-dependence at all power levels. View full abstract»

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  • Blank page

    Page(s): 2617 - 2618
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    Freely Available from IEEE
  • 2011 IEEE EDS Masters Student Fellowship

    Page(s): 2619
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    Freely Available from IEEE
  • OFCNFOEC 2011

    Page(s): 2620
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    Freely Available from IEEE
  • 2010 IEEE International Electron Devices Meeting (IEDM)

    Page(s): 2621
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    Freely Available from IEEE
  • Symposium on power semiconductor devices and ICs

    Page(s): 2622
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    Freely Available from IEEE

Aims & Scope

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

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Meet Our Editors

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