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Photonics Technology Letters, IEEE

Issue 9 • Date Sept. 2005

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Displaying Results 1 - 25 of 85
  • Table of contents

    Publication Year: 2005 , Page(s): c1 - 1763
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    Freely Available from IEEE
  • IEEE Photonics Technology Letters publication information

    Publication Year: 2005 , Page(s): c2
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    Freely Available from IEEE
  • High-power optically pumped VECSEL using a double-well resonant periodic gain structure

    Publication Year: 2005 , Page(s): 1764 - 1766
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    We present the design and fabrication of an optically pumped vertical-external-cavity surface-emitting lasers with double-well resonant periodic gain structure. Each double-well consists of two 4-nm-thick InGaAs strained quantum wells. The double-well provides optimum overlap between the quantum wells and the antinodes of the standing wave of laser signal at high-power and high-temperature operation. The structure is more tolerant to variation of the growth, processing, and operating temperature for maintaining high modal gain. For a 230-μm diameter pump spot, over 4-W continuous-wave output with a slope efficiency of 39% is demonstrated at 30/spl deg/C without thermal rollover. View full abstract»

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  • VCSELs with a self-aligned contact and copper-plated heatsink

    Publication Year: 2005 , Page(s): 1767 - 1769
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (493 KB) |  | HTML iconHTML  

    Top-emitting, 850-nm vertical-cavity surface-emitting lasers with a self-aligned top contact and evaporated gold or plated copper heatsink were fabricated and characterized. Thermal resistance was reduced by 44%, and output power and bandwidth were increased by 38% and 12%, respectively. The fabricated devices exhibit a 3-dB modulation frequency bandwidth up to 16.3 GHz at 10 kA/cm2. View full abstract»

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  • A GaInAsP-InP double-ring resonator coupled laser

    Publication Year: 2005 , Page(s): 1770 - 1772
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (193 KB) |  | HTML iconHTML  

    A monolithic single-mode GaInAsP-InP double microring resonator coupled laser is demonstrated for the first time. The laser comprises two passive ring resonators, semiconductor optical amplifiers in the bus waveguides, and 3-dB codirectional couplers. The laser has an output power of 0.5 mW with a sidemode supression ratio of >35 dB. The tunability is demonstrated using integrated platinum resistors on top of the waveguides in the rings. View full abstract»

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  • Widely tunable coupled-ring reflector laser diode

    Publication Year: 2005 , Page(s): 1773 - 1775
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    A coupled-ring reflector (CRR), which is composed of two coupled rings both of which are coupled with a straight waveguide, is applied to a widely tunable laser diode. When the radii of two rings are slightly different, the peak reflection wavelength of the CRR can be widely tuned over a few tens nanometers by a small amount of refractive index change. It is shown that a few tens nanometers of tuning with a sidemode suppression ratio exceeding 45 dB both for adjacent cavity mode and for adjacent ring mode is achievable in the widely tunable CRR laser diode. View full abstract»

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  • Modes of multi-end-pumped nonplanar ring laser

    Publication Year: 2005 , Page(s): 1776 - 1778
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (679 KB) |  | HTML iconHTML  

    A novel multi-end-pumped nonplanar ring Nd:YAG laser with two-mirror cavity was demonstrated. A model was developed for attaining all beam loop modes of the laser cavity and calculating the mirror separation of each mode. With single-diode laser pumping, the operations of different modes at 1.064 μm were performed and the experimental results are in excellent agreement with the model. Using three laser diodes as the pumping sources led to over threefold increase in output power. View full abstract»

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  • The role of carrier transport on the current injection efficiency of InGaAsN quantum-well lasers

    Publication Year: 2005 , Page(s): 1779 - 1781
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (163 KB) |  | HTML iconHTML  

    A theoretical and experimental study demonstrates that the current injection efficiency of InGaAsN quantum-well (QW) lasers can be significantly affected by carrier transport in the separate confinement heterostructure (SCH) region. An offset QW design is utilized to show the impact of hole transport on the temperature dependence of the external differential quantum efficiency and above threshold injection efficiency. A reduction of the current injection efficiency is found for structures which have significant hole transport times in the SCH. View full abstract»

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  • Observation of temperature-independent longitudinal-mode patterns in violet-blue InGaN-based laser diodes

    Publication Year: 2005 , Page(s): 1782 - 1784
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (154 KB)  

    We present measurements on an aperiodic device-specific longitudinal-mode pattern in InGaN laser diodes. The characteristic shape of this pattern occurs only if the laser is driven slightly above threshold; in addition, it tunes with temperature at exactly the same rate as the cavity modes. By careful selection of the collection optics and averaging ten rapid scans over 15 min in a high-resolution Fourier transform spectrometer, we could exclude possible explanations like beating of mode families, self-pulsation, or external reflections. A naive simulation of the longitudinal modes profiting from their individual "gain profile" along the cavity suggests that we see the signature of quantum-well thickness fluctuations. View full abstract»

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  • Improved temperature performance of 1.31-μm quantum dot lasers by optimized ridge waveguide design

    Publication Year: 2005 , Page(s): 1785 - 1787
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (263 KB) |  | HTML iconHTML  

    We demonstrate the importance of the fabricated device structure for the external differential efficiency, threshold current density, and maximum operating temperature for ground state operation of a 1.31-μm quantum dot laser. The introduction of a shallow ridge etch design and selective electroplating of the gold bondpads is demonstrated to offer improved performance in comparison to a deep ridge etch design with thinner evaporated gold bondpads. View full abstract»

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  • Monolithically integrated multiwavelength grating cavity laser

    Publication Year: 2005 , Page(s): 1788 - 1790
    Cited by:  Papers (8)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (218 KB) |  | HTML iconHTML  

    A multiwavelength grating cavity laser is reported using a novel design for a multichannel light source based on an etched diffraction grating. Following the design, the compact eight-channel device capable of fine-tuning has been realized by monolithically integrating semiconductor optical amplifiers, various passive waveguides, and deeply etched grating, providing high butt-coupling efficiency, and low waveguide losses. As a result, the sidemode suppression ratio in excess of 45 dB over all channels was achieved. View full abstract»

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  • Measurements of coupling and reflection characteristics of butt-joints in passive waveguide integrated laser diodes

    Publication Year: 2005 , Page(s): 1791 - 1793
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (217 KB) |  | HTML iconHTML  

    Amplified spontaneous emission (ASE) spectra of passive waveguide integrated lasers have been studied to estimate the coupling efficiency and the reflectivity at the butt-joints between active and passive waveguides. A new method has been proposed for the analysis of ASE to extract the coupling efficiency and reflectivity at the butt-joints. This method was applied experimentally to estimate the coupling and reflection of the passive waveguide integrated lasers with different amounts of vertical misalignments of active and passive waveguides. View full abstract»

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  • Monolithically integrated grating cavity tunable lasers

    Publication Year: 2005 , Page(s): 1794 - 1796
    Cited by:  Papers (8)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    A novel grating cavity tunable laser is proposed and experimentally demonstrated. It is realized by monolithically integrating a semiconductor optical amplifier, a dispersive element, a phase-control section, and an etched diffraction grating in a single chip. Tuning operation is based on electrically controlled beam deflection provided by dispersive element and phase matching by phase-control section. With the electrical control, the wavelength tuning of 8.5 nm with a sidemode suppression ratio of about 35 dB has been successfully achieved. View full abstract»

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  • A theoretical model of a wavelength-locked Fabry-Pe´rot laser diode to the externally injected narrow-band ASE

    Publication Year: 2005 , Page(s): 1797 - 1799
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB) |  | HTML iconHTML  

    We propose a theoretical model of the wavelength-locked Fabry-Pe´rot laser diode (F-P LD) to the externally injected narrow-band amplified spontaneous emission. The model explains the dynamics of the wavelength-locked F-P LD. The simulation results with the proposed model show good agreement with the experimental results. View full abstract»

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  • Investigation of pulse pedestal and dynamic chirp formation on picosecond pulses after propagation through an SOA

    Publication Year: 2005 , Page(s): 1800 - 1802
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (209 KB) |  | HTML iconHTML  

    The authors investigate the propagation of picosecond pulses through semiconductor optical amplifiers using the measurement technique of frequency resolved optical gating. The work shows the generation of significant pulse pedestals and frequency chirp across the optical pulses, which initially have a duration of 2 ps. As the input peak power of the optical pulses is increased from 2.4 to 80 mW, the pulse pedestals increased by 20 dB and the chirp became significantly more nonlinear. The generated pedestals and the nonlinear output chirp may cause serious degradation in high-speed communications systems employing wavelength-division-multiplexing and optical time-division-multiplexing techniques. View full abstract»

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  • Theoretical analysis of gain-recovery time and chirp in QD-SOA

    Publication Year: 2005 , Page(s): 1803 - 1805
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (189 KB) |  | HTML iconHTML  

    We present a theoretical analysis of the gain recovery and chirp characteristics of quantum-dot semiconductor optical amplifier (QD-SOA). We have derived an analytical expression for the frequency chirp in QD-SOA. The values of chirp and gain recovery time (GRT) for various signal power levels are calculated by numerical solution of the rate equations. The simulation results show that the chirp value in QD-SOA is approximately one order of magnitude lower than that in a bulk SOA. The dependences of the GRT and the chirp on the pump power level are studied. View full abstract»

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  • Nitride-based LEDs with MQW active regions grown by different temperature profiles

    Publication Year: 2005 , Page(s): 1806 - 1808
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (109 KB) |  | HTML iconHTML  

    Nitride-based light-emitting diodes (LEDs) with multiple quantum-well active regions were separately prepared by metal-organic vapor phase epitaxy in different temperature profiles. Compared with conventional samples, the reduced reverse leakage current and improved electrostatic discharge characteristics of the LEDs can both be achieved using temperature ramping and temperature cycling methods. However, using the temperature ramping may degrade the optical properties of devices due to desorption of In atoms and/or impurity incorporation. With an emission wavelength of 465 nm, the 20-mA output powers measured were 5.5, 6.0, and 7.9 mW for temperature ramping LED, conventional LED, and temperature cycling LED, respectively. View full abstract»

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  • High-power GaN-mirror-Cu light-emitting diodes for vertical current injection using laser liftoff and electroplating techniques

    Publication Year: 2005 , Page(s): 1809 - 1811
    Cited by:  Papers (41)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    A large-area (1 × 1 mm) vertical conductive GaN-mirror-Cu light-emitting diode (LED) fabricated using the laser liftoff and electroplating techniques is demonstrated. Selective p-GaN top area was first electroplated by the thick copper film, and then an excimer laser was employed to separate the GaN thin film from the sapphire substrate. The luminance intensity of the vertical conductive p-side-down GaN-mirror-Cu LED presented about 2.7 times in magnitude as compared with that of the original GaN-sapphire LED (at 20 mA). The light output power for the GaN-mirror-Cu LED was about twofold stronger (at 500 mA). A more stable peak wavelength shift under high current injection was also observed. View full abstract»

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  • Enhanced luminescence from GaN-based blue LEDs grown on grooved sapphire substrates

    Publication Year: 2005 , Page(s): 1812 - 1814
    Cited by:  Papers (24)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (262 KB) |  | HTML iconHTML  

    Luminescence from GaN-based blue light-emitting diodes grown on grooved sapphire substrates was investigated using cathodoluminescence (CL) and electroluminescence (EL). The 60-nm-deep 2 (ridge) ×4 μm (trench) grooves along the <101~0> direction were created by BCl3-Cl2-based inductively coupled plasma reactive ion etching. Stronger CL and EL from the trench regions of the grooves in GaN and InGaN-GaN multiquantum-wells were observed, confirming its better crystalline quality over the trench regions, further supported by the EL mapping results. Epitaxial lateral growth was believed to initiate from the ridge regions to cover the trench regions at the foremost stage of GaN growth that is similar to the coalescence of islands. View full abstract»

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  • Metal-oxide-SiO2 composite ZnO lasers

    Publication Year: 2005 , Page(s): 1815 - 1817
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (350 KB) |  | HTML iconHTML  

    The use of metal-oxide-SiO2 composite to sustain random lasing in ZnO thin films is proposed. It is shown that the presence of stripe pattern in the metal-oxide-SiO2 composite is necessary to minimize lasing threshold and achieve directional emission. By controlling the concentration of the metal-oxide and stripe spacing, coherent lasing threshold and linewidth of ∼85 kW/cm2 and ∼0.4 nm, respectively, can be obtained from mirrorless ZnO thin-film waveguide lasers. View full abstract»

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  • Multiple-wavelength up-conversion laser in Tm3+-doped ZBLAN glass fiber

    Publication Year: 2005 , Page(s): 1818 - 1820
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (105 KB) |  | HTML iconHTML  

    In this letter, we report on a multiple-wavelength up-conversion laser in Tm3+-doped ZrF4--BaF2--LaF3--AlF3--NaF glass fiber pumped by an 1120-nm fiber laser. Single-wavelength, two-wavelength, and three-wavelength up-conversion lasers can be obtained by adjusting the distance between the coupler mirror and the fiber end, which is attributed to the frequency-filter effect in the etalon composed of the coupler mirror and the fiber end. The effects of the pump power on the performance of dual-wavelength laser were also discussed. View full abstract»

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  • High-power multiwavelength Er3+-Yb3+ codoped double-cladding fiber ring laser

    Publication Year: 2005 , Page(s): 1821 - 1823
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (175 KB)  

    A high-power simultaneous multiwavelength lasing in an Er3+-Yb3+ codoped double-cladding fiber (EYCDF) ring laser is demonstrated based on a wavelength-dependent filter through spatial mode beating within the multimode fiber section. We have investigated the relationship between the lasing wavelengths and the length of the EYCDFs. The experimental results indicate that both the number of lasing wavelength lines and the spacing between two adjacent lasing lines can be controlled by the changes of the lasing light polarization states. View full abstract»

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  • Stable single-frequency fiber ring laser for 25-GHz ITU-T grids utilizing saturable absorber filter

    Publication Year: 2005 , Page(s): 1824 - 1826
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    A stable single-frequency fiber ring laser is proposed that operates in a single mode for more than an hour by incorporating unpumped erbium-doped fiber (EDF) as a saturable absorber filter and optimizing the length of EDF used as gain medium. This laser can be continuously tuned to 25-GHz spacing that precisely matches the ITU-T grids by temperature control of etalon filter. This laser had a signal-to-source spontaneous emission ratio higher than 70 dB, and lasing frequencies of 361 channels was matched to ITU-T grids with excellent flatness. Frequency offset from the ITU-T grid was less than 0.14 GHz. The linewidth and the relative intensity noise value was less than 1.3 kHz and 130 dB/Hz (above 250 kHz), respectively. View full abstract»

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  • Narrow linewidth fiber laser for 100-km optical frequency domain reflectometry

    Publication Year: 2005 , Page(s): 1827 - 1829
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    A diode-pumped single-frequency piezoelectrically tuned fiber laser with narrow spectral linewidth has been used as a light source in applications for long-range coherent frequency-domain reflectometry. Frequency-modulated continuous-wave (FMCW) measurements of Rayleigh back-scattering and Fresnel reflection from a 95-km-long fiber have been demonstrated without the use of an optical amplifier. This is, to our knowledge, the longest distance measurement with FMCW. The high sensitivity and dynamic range of the long-range backscattering measurements benefit from the extremely long coherence length of the narrow linewidth fiber laser, which has been estimated to be 210 km in air. View full abstract»

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  • A novel hybrid silica wide-band amplifier covering S+C+L bands with 105-nm bandwidth

    Publication Year: 2005 , Page(s): 1830 - 1832
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (270 KB) |  | HTML iconHTML  

    We report a novel hybrid optical amplifier covering S+C+L bands with 105-nm total bandwidth using a silica fiber. The principle of amplification is based on the stimulated radiative transition of Er-ions for C-band and on the stimulated Raman scattering for S- and L-band, respectively. In this letter, we analyze the amplification characteristics for two types of active fiber mediums through numerical simulation. One is a silica fiber configured with Er-doped cladding and Ge-doped core and the other is a medium consisting of Er-doped fiber and dispersion-compensating fiber. By optimizing parameters such as fiber length and pump power, we newly achieve wide-band amplification with 105-nm bandwidth showing a flat gain characteristic over the entire S+C+L bands. 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.

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Meet Our Editors

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