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Photonics Technology Letters, IEEE

Issue 1 • Date Jan.1, 2010

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  • [Front cover]

    Publication Year: 2010 , Page(s): C1
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  • IEEE Photonics Technology Letters publication information

    Publication Year: 2010 , Page(s): C2
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  • Table of contents

    Publication Year: 2010 , Page(s): 1 - 2
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  • Wavelength Conversion of High-Speed Phase and Intensity Modulated Signals Using a Highly Nonlinear Chalcogenide Glass Chip

    Publication Year: 2010 , Page(s): 3 - 5
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (574 KB) |  | HTML iconHTML  

    We report all-optical wavelength conversion of high-speed differential phase-shift keyed (DPSK) and on-off keyed (OOK) signals using the nonlinear Kerr-effect in an optical chip. This was enabled by four-wave mixing (FWM) of the signal with a continuous-wave (CW) pump laser in a 7-cm-long dispersion-shifted planar rib waveguide in highly nonlinear As2S3 glass. Both conversion of 40-Gb/s DPSK and 160-Gb/s OOK signals by 33 and 15 nm, respectively, are shown. These are first demonstrations of signal processing by CW-pumped FWM in a chalcogenide waveguide, highlighting its capability to perform phase-preserving operations at high bit rates in chip-scale devices. View full abstract»

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  • Interleaver Using an Arrayed-Waveguide Grating-Lens-Grating Configuration for Spectrally Efficient Systems

    Publication Year: 2010 , Page(s): 6 - 8
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    We propose an optical interleaver using an arrayed waveguide grating-lens-grating cascade and a 3-dB coupler. It has a narrow channel spacing, high-order Gaussian passbands, and low chromatic dispersion. We demonstrate a 16.7-GHz version for spectrally efficient wavelength-division-multiplexed systems. View full abstract»

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  • Tunable Passively Q -switched Erbium-Doped Fiber Laser With Carbon Nanotubes as a Saturable Absorber

    Publication Year: 2010 , Page(s): 9 - 11
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (294 KB) |  | HTML iconHTML  

    An all-fiber tunable passively Q-switched erbium-doped fiber (EDF) laser is presented. Saturable absorbers are constructed by optically driven deposition of single-wall carbon nanotubes on fiber connectors. A low pump threshold of 11.1 mW is achieved. Self-mode-locking effect is also observed, and it could be suppressed by splicing an extra unpumped EDF into the laser ring cavity. The laser can be tuned by applying axial strain on the fiber Bragg grating which serves as a narrowband external mirror of the cavity. View full abstract»

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  • Self-Assembled Two-Dimensional Surface Structures for Beam Shaping of GaN-Based Vertical-Injection Light-Emitting Diodes

    Publication Year: 2010 , Page(s): 12 - 14
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (481 KB) |  | HTML iconHTML  

    Enhanced light extraction and beam shaping of GaN-based vertical-injection light-emitting diodes (VI-LEDs) employing biomimetic surface structures were demonstrated. The biomimetic surface structures were fabricated using self-assembled polystyrene nanospheres serving as a monolayer mask, and followed by anisotropic inductively coupled plasma reactive ion etching. The light output power of the VI-LEDs with the patterned structures exhibited an efficiency enhancement factor of 68% at a driving current of 350 mA, compared to those without any surface structures. The structures also resulted in a modified heart-shaped radiation pattern, which is preferable for backlight applications in flat panel displays. View full abstract»

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  • Polarization Control in Buried Tunnel Junction VCSELs Using a Birefringent Semiconductor/Dielectric Subwavelength Grating

    Publication Year: 2010 , Page(s): 15 - 17
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (490 KB) |  | HTML iconHTML  

    We present long-wavelength InGaAlAs-InP vertical-cavity surface-emitting lasers (VCSELs) with a buried tunnel junction (BTJ) and a well-defined polarization accomplished by a semiconductor/dielectric subwavelength grating (SWG). The grating is incorporated in the inner VCSEL cavity and exhibits an effective birefringence for polarizations parallel and perpendicular to the grating grooves. Theoretical modeling leads to distinct design rules for VCSELs with grating structure that deviate from the conventional design without grating. Due to the large polarization-mode separation, lasing activity is enabled only for one polarization mode. BTJ-VCSELs with properly chosen SWG parameters show predictable and full polarization stability. In addition, the relevant device parameters such as threshold current are comparable to conventional BTJ-VCSELs. View full abstract»

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  • Reduction of AlGaAs Heterostructure High-Index-Contrast Ridge Waveguide Scattering Loss by Sidewall Smoothing Through Oxygen-Enhanced Wet Thermal Oxidation

    Publication Year: 2010 , Page(s): 18 - 20
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (350 KB) |  | HTML iconHTML  

    We demonstrate the efficacy of oxidation smoothing of sidewall roughness in high-index-contrast AlGaAs heterostructure ridge waveguides via oxygen-enhanced nonselective wet thermal oxidation for reducing scattering loss. Single-mode waveguides of core widths between 1.5 and 2.2 ??m are fabricated using both the inward growth of a ~ 600-nm sidewall-smoothing native oxide outer cladding and, for comparison, encapsulation of an unoxidized etched ridge with a ~ 600-nm deposited silicon oxide cladding layer. On average, measured loss coefficients are reduced by a factor of 2 with the oxidation smoothing process. View full abstract»

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  • Silicon-Based Thermo-Optically Tunable Photonic Crystal Lens

    Publication Year: 2010 , Page(s): 21 - 23
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB) |  | HTML iconHTML  

    We report an extremely compact (30 ??m ?? 7 ??m) silicon-based 2-D thermo-optically tunable photonic crystal (PhC) lens operated at around telecommunication wavelength (1.55 ??m ) with transverse-magnetic-like polarization light. A honeycomb lattice array of high index silicon rods with 340 nm in thickness, 234 nm in diameter, and 338 nm in lattice constant were embedded in 3-??m-thick low index silicon dioxide. A 150-nm-thick NiCr micro-heater was placed directly on top of the PhC structure to provide localized heating to the silicon rod array. The localized heating causes refractive index change in silicon due to thermo-optic effect which results in change of the focal length of the PhC lens. The device was characterized with a tunable laser light source in the wavelength range of 1500 ~ 1580 nm. Tuning of focal length in this device was experimentally demonstrated by applying different current through the heater. Such experimental results showed good agreement with the simulation results. View full abstract»

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  • Microwave Generation Based on Optical Domain Microwave Frequency Octupling

    Publication Year: 2010 , Page(s): 24 - 26
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (370 KB) |  | HTML iconHTML  

    A novel approach to achieving microwave frequency octupling in the optical domain is proposed and demonstrated. The proposed system consists of two cascaded Mach-Zehnder modulators (MZMs) that are both biased at the maximum transmission point, with a tunable optical phase shifter connected in between to introduce a phase shift. An input microwave signal is applied to the MZMs with its power adjusted to ensure the two MZMs having an identical phase modulation index. A theoretical analysis that leads to the conditions for achieving frequency octupling is provided. The approach is verified by experiments. The phase noise performance and the frequency tunability are also experimentally investigated. View full abstract»

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  • 2R Regeneration of Time-Interleaved Multiwavelength Signals Based on Higher Order Four-Wave Mixing in a Fiber

    Publication Year: 2010 , Page(s): 27 - 29
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (228 KB) |  | HTML iconHTML  

    All-optical 2R regeneration of two-wavelength time-interleaved signals is demonstrated using higher order four-wave mixing in a fiber. In this regeneration scheme, a single fiber and a pump are shared by the two channels. The results show that interchannel crosstalk can be avoided when pulses in the two channels are time separated by more than ~3 times their pulsewidth. A possible power monitoring to determine suitable time-interleaving condition is also discussed. View full abstract»

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  • Mechanism Investigation of p-i-n ZnO-Based Light-Emitting Diodes

    Publication Year: 2010 , Page(s): 30 - 32
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (155 KB) |  | HTML iconHTML  

    Using a cosputtering technique to deposit P-ZnO : AlN film and using a vapor cooling condensation system to deposit n-ZnO : In and i-ZnO films on sapphire substrates, thin-film-type ZnO-based light-emitting diodes (LEDs) were fabricated. A Nd : YAG laser with a wavelength of 413 nm is utilized to identify the defect-related emissions of p-ZnO, i-ZnO, and n-ZnO films. The characteristics of i-ZnO layer of ultraviolet (UV) emissions were analyzed using temperature-dependent photoluminescence. The mechanism of the UV electroluminescence emission peak at 3.20 eV observed from the p-i-n ZnO-based LEDs were attributed to the low deep-level defects and the radiative recombination occurred in the i-ZnO layer. View full abstract»

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  • Proposal and Design of a Photonic In-Fiber Fractional Hilbert Transformer

    Publication Year: 2010 , Page(s): 33 - 35
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (129 KB) |  | HTML iconHTML  

    We numerically demonstrate that an asymmetrical fiber Bragg grating of uniform-period operated in reflection can provide the required spectral response for implementing an all-optical fractional Hilbert transformer. The device shows a good accuracy calculating the fractional Hilbert transform of the complex field of some typical input optical waveforms. The sensibility of the proposed device under different conditions was also analyzed. View full abstract»

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  • Novel Method of Generating QAM-16 Signals at 21.3 Gbaud and Transmission Over 480 km

    Publication Year: 2010 , Page(s): 36 - 38
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (380 KB) |  | HTML iconHTML  

    In this letter, we report on a novel method of generating a square quadrature amplitude modulation (QAM-16) signal at 21.3 Gbaud and its subsequent transmission over 480 km. The proposed scheme generates a QAM-16 signal by optically processing a quadrature phase-shift-keying signal using a phase-stabilized fiber interferometer. We also discuss the inherent advantages and limitations of optical and electrical generation methods of QAM-16 signals, and digital signal processing algorithms used in the experiment. View full abstract»

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  • High-Temperature Sensing Using Miniaturized Fiber In-Line Mach–Zehnder Interferometer

    Publication Year: 2010 , Page(s): 39 - 41
    Cited by:  Papers (15)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (301 KB) |  | HTML iconHTML  

    A miniaturized single fiber in-line Mach-Zehnder interferometer is proposed for high-temperature sensing. The interferometer has a microcavity in one of its arms, formed by removing part of the fiber core and cladding, while the other arm remains in the fiber core. Because the fiber core exhibits a temperature coefficient of refractive index which is different from that of air, the interferometer is sensitive to temperature variation. The microcavity structured interferometer also has excellent sustainability to high temperatures up to 1100??C . The system is compact, reliable and can detect the temperature at precise location. View full abstract»

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  • Filter-Free Optically Switchable and Tunable Ultrawideband Monocycle Generation Based on Wavelength Conversion and Fiber Dispersion

    Publication Year: 2010 , Page(s): 42 - 44
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (503 KB) |  | HTML iconHTML  

    In this letter, a novel filter-free scheme for all-optical ultrawideband monocycle generation based on wavelength conversion in semiconductor optical amplifier and group-velocity dispersion in single-mode fiber is proposed and experimentally demonstrated. The system is optically switchable in pulse polarity, and tunable in both pulsewidth and radio-frequency spectrum. View full abstract»

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  • Nonsingular Constant Modulus Equalizer for PDM-QPSK Coherent Optical Receivers

    Publication Year: 2010 , Page(s): 45 - 47
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    Adaptive electronic equalizers using the constant modulus algorithm (CMA) algorithm often converge to a singular coefficient matrix that produces the same signal at multiple outputs. We address this issue in the context of optical communications systems with polarization-division multiplexing and coherent receivers. We study, by computer simulation, the performance of multiuser CMA equalizer, an enhanced CMA equalizer initially proposed for use in wireless multiuser and later multiple-input/multiple-output communications systems. We show that the proposed adaptive electronic equalizer does not exhibit singularities and, therefore, is superior to the commonly used CMA equalizer. View full abstract»

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  • Design of Crystal-Type Multiport Optical Quasi-Circulator

    Publication Year: 2010 , Page(s): 48 - 50
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (122 KB) |  | HTML iconHTML  

    An alternative macrooptic design of crystal-type multiport optical quasi-circulator is proposed. A prototype of six-port optical quasi-circulator was fabricated and tested with insertion loss of 1.97 dB, and isolation of 39.6 dB. The advantages of this design include high performance, being polarization-independent , and resolved polarization-mode dispersion. In addition, the number of ports can be easily expanded. View full abstract»

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  • Orthogonal Basis Expansion-Based Phase Noise Estimation and Suppression for CO-OFDM Systems

    Publication Year: 2010 , Page(s): 51 - 53
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (122 KB) |  | HTML iconHTML  

    In coherent optical orthogonal frequency-division-multiplexing systems, the laser phase noise which induces common phase error (CPE) and intercarrier interference (ICI) is a major impairment to the system's performance. In this letter, we propose an orthogonal basis expansion-based phase noise suppression algorithm which can mitigate CPE as well as ICI effectively. The proposal can significantly reduce the bit-error-rate floor caused by ICI. View full abstract»

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  • Wavelength Tunable Laser Using an Interleaved Rear Reflector

    Publication Year: 2010 , Page(s): 54 - 56
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB) |  | HTML iconHTML  

    A novel integrated reflector concept for use in widely tunable semiconductor lasers is introduced. Two concatenated Fabry-Perot cavities with low partial reflections and different cavity lengths are interleaved to realize a wavelength-selective reflective element. Differential current injection in the interleaved cavities is used to tune the reflection peak. The reflector is integrated in an all-active multisection device. The laser tunes across 37 wavelength channels on a 100-GHz grid over a wavelength span of 30 nm. The linewidth of each mode is <7 MHz while the power deviation is <6 dB. View full abstract»

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  • Performance of Forward-Error Correction Code in 10-Gb/s RSOA-Based WDM PON

    Publication Year: 2010 , Page(s): 57 - 59
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (91 KB) |  | HTML iconHTML  

    We investigate the performance of the forward-error correction (FEC) code for the 10-Gb/s wavelength-division-multiplexed passive optical network (WDM PON) implemented by using reflective semiconductor optical amplifiers (RSOAs) with extremely limited modulation bandwidth and the electronic equalizers to compensate for the degradations resulting from the use of such RSOAs. We show that the error occurrences in this network strongly depend on the bit pattern and the burst errors are likely to occur. Thus, it is important to use the FEC code capable of correcting the burst errors such as Reed-Solomon (RS) code. In addition, since a significant penalty can be induced by the increased line rate resulting from the use of the FEC code, it is necessary to find the optimum redundancy required to minimize the bit-error rate. We also evaluate the tolerance to the chromatic dispersion of the proposed 10-Gb/s WDM PON implemented by using the RS code with the optimum redundancy. View full abstract»

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  • In Situ Interferometric Monitoring of Fiber Insertion in Fiber Connector Components

    Publication Year: 2010 , Page(s): 60 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (834 KB) |  | HTML iconHTML  

    We present an interferometric setup for in situ monitoring of fiber tip positions when inserting optical fibers for fixation in fiber connector components. It ensures an accurate fiber tip position at the fiber connector's front facet and across the fiber array in cases where postinsertion polishing is not possible. We demonstrate our technique by populating a plastic fiber connector for optical interconnect applications, and compare the fiber tip position measured in situ using our setup with the position measured off-line using a commercial white light interferometer, showing a deviation smaller than 5%. View full abstract»

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  • Special issue on nanowires

    Publication Year: 2010 , Page(s): 63
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    Freely Available from IEEE
  • IEEE Photonics Technology Letters information for authors

    Publication Year: 2010 , Page(s): C3
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    Freely Available from IEEE

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