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Photonics Technology Letters, IEEE

Issue 11 • Date June1, 2013

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Displaying Results 1 - 25 of 31
  • Front Cover

    Page(s): C1
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    Freely Available from IEEE
  • IEEE Photonics Technology Letters publication information

    Page(s): C2
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    Freely Available from IEEE
  • Table of contents

    Page(s): 1001 - 1002
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  • Switchable Dual-Wavelength PM-EDF Ring Laser Based on a Novel Filter

    Page(s): 1003 - 1006
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (754 KB) |  | HTML iconHTML  

    A stable and switchable dual-wavelength polarization-maintaining erbium-doped fiber ring laser is proposed and demonstrated experimentally by using a novel filter, which is formed from dual-pass Mach-Zehnder interferometer incorporating a sagnac loop. By adjusting the polarization controllers, the output laser can be switched between single- and dual-wavelength. The wavelength spacing of the dual-wavelength can be tuned from 0.084 to 4.26 nm. Its 3-dB bandwidth and side mode suppression ratio are less than 0.015 nm and higher than 64 dB, respectively. In addition, the peak power fluctuation and wavelength shift are monitored to be less than 0.5 dB and 0.01 nm during an hour, respectively. The characteristics of the novel filter in experimental measurement accord with the result of theoretical analysis. View full abstract»

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  • CNT Film Fabrication for Mode-Locked Er-Doped Fiber Lasers: The Droplet Method

    Page(s): 1007 - 1010
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (443 KB) |  | HTML iconHTML  

    We present a new and simple method for the fabrication of carbon nanotube (CNT) films for fiber laser mode-locking. Using a microtip, we deposited a droplet of CNT/polymer suspension directly onto a fiber ferrule. Typical film thicknesses as low as 20 μm are measured. Thicker films are easily achievable through the deposition of additional droplets, which allow for fine tuning the transmittance of the film. Based on a 40-mg/ml CNT concentration film used in an Erbium-doped fiber laser, we obtain mode-locked pulses with a bandwidth of 10.2 nm and duration of 364 fs. View full abstract»

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  • Frequency- and Phase-Tunable Optoelectronic Oscillator

    Page(s): 1011 - 1013
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (890 KB) |  | HTML iconHTML  

    An optoelectronic oscillator (OEO) for the generation of a microwave signal with both tunable frequency and phase is proposed and experimentally demonstrated. In the proposed OEO, a single-sideband (SSB) polarization-modulated signal is generated by a polarization modulator (PolM) and a phase-shifted fiber Bragg grating (PS-FBG). The SSB polarization-modulated signal is then split into two parts. One part is sent to a photodetector (PD) and then fed back to the PolM to form the OEO loop. The other part is sent to an electronically tunable polarizer (ETP) and then applied to a second PD. The frequency tunability is achieved by tuning the wavelength of the optical carrier. The tunable phase is introduced by tuning the principal axis of the ETP. An experiment is performed, and a microwave signal with a tunable frequency from 6.6 to 13.1 GHz and a tunable phase from -180° to 180° is generated. The phase noise performance of the generated microwave signal is also evaluated, which is -101.9 dBc/Hz at an offset of 10 kHz. View full abstract»

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  • Silicon-Based Micro-Machined Infrared Emitters With a Micro-Bridge and a Self-Heating Membrane Structure

    Page(s): 1014 - 1016
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1109 KB) |  | HTML iconHTML  

    A micro-bridge membrane type (MBMT) infrared (IR) emitter is designed and fabricated to realize high IR radiation, low power consumption, and low thermo-mechanical stress. The suspended micro-bridge membrane, consisting of a heating layer and a self-heating support layer, is constructed in a silicon (Si) frame. A boron-doped poly-Si serves as the resistive heating layer to realize the IR radiation, and a heavily-boron-doped Si serves as the self-heating layer to absorb the backward IR radiation for storing the thermal energy and support the heating layer. The fabricated MBMT is thoroughly characterized by the electrical and optical measurements. The results reveal that MBMT emitters have higher photoelectric and mechanical performances than the closed membrane type emitters. View full abstract»

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  • Improved Field Emission Properties of Ag-Decorated Multi-Walled Carbon Nanotubes

    Page(s): 1017 - 1019
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1221 KB) |  | HTML iconHTML  

    A field emission is fulfilled by utilizing the vertically aligned carbon nanotubes (CNTs) decorating their external surface with Ag-nanoparticles. It is found that the average length and diameter of the CNTs are ~ 4.52 μm and 45 nm, respectively. We also coated Ag nanoparticles ~ 5 nm onto the nanotube surfaces and fabricated CNTs for field emission. The turn-on field and current density of the CNTs clearly indicate that the field emission of the coated-Ag is enhanced considerably. In this letter, the decoration of Ag nanoparticles effectively decreased the effective work function (Φeff) and turn-on field (Eto). View full abstract»

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  • Silicon Nitride Horizontal Air-Slot Microdisk Resonators With a Nanocrystal Si Emitting Layer

    Page(s): 1020 - 1023
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (630 KB) |  | HTML iconHTML  

    Silicon nitride (SiN) microdisk resonators with a 40-nm horizontal air slot and a nanocrystal Si (nc-Si) emitting top layer are investigated. The whole structure is fabricated using only a single deposition and lithography step, with the light-emitting layer self-aligned to excite the slot-mode within the air slot. The nc-si are excited via top-pumping using a UV laser diode, and the visible light emission from nc-Si is coupled into the whispering gallery mode (WGM) with the light concentrated in the air slot. The WGM resonances are observed via side-photoluminescence setup using a Si charge-coupled device. The feasibility of applying this structure as a biosensor is demonstrated, with an estimated surface sensitivity of 2.8 nm/nm. View full abstract»

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  • Phase Noise Suppression for Single-Sideband Modulation Radio-Over-Fiber Systems Adopting Optical Spectrum Processing

    Page(s): 1024 - 1026
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (924 KB) |  | HTML iconHTML  

    In this letter, the impact of the dispersion-induced phase noise (PN) on the transmitted signals in single-sideband (SSB) modulation radio-over-fiber (RoF) systems was investigated. We experimentally demonstrated that the fiber chromatic dispersion-induced phase mismatch between the two heterodyne optical tones will increase the error vector magnitude and phase error of the transmitted signal as the fiber transmission distance grows. We also proposed a phase adjustment technique employing an optical spectrum processor to suppress such PN, and an SSB modulation RoF system at 60 GHz with PN suppression was accomplished accordingly. View full abstract»

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  • Colorless and Preamplifierless Reception Using an Integrated Si-Photonic Coherent Receiver

    Page(s): 1027 - 1030
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

    We experimentally study the sensitivity limits of an integrated Si-photonic dual-polarization balanced coherent receiver co-packaged with transimpedance amplifiers. For 28 Gbaud PDM-QPSK and PDM-16QAM signals, we compare colorless and optical preamplifierless reception to the case where an optical preamplifier and optical filters are used before the receiver. Back-to-back receiver sensitivities are evaluated. After propagation over an SMF-28e+ EDFA amplified link and assuming a 3.8 × 10-3 FEC threshold, colorless/preamplifierless reception using the Si-photonic receiver allows for error-free transmission of 112 Gbps PDM-QPSK over 4800 km at a received power of -23 dBm and of 224 Gbps PDM-16QAM over 640 km at a received power of -17 dBm. Finally, a 16 × 112 Gbps PDM-QPSK WDM experiment is carried out. Using the Si-photonic receiver for colorless/preamplifierless reception of all channels, we achieve error-free transmission for all channels over 4160 km at a received power of -21 dBm per channel. Results reveal that the receiver provides excellent sensitivity while allowing us to save cost, footprint, and power if used in a colorless/preamplifierless scheme. View full abstract»

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  • Modulation-Free Frequency Stabilization Based on Polarization-Split Sagnac Loop

    Page(s): 1031 - 1034
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (678 KB) |  | HTML iconHTML  

    A novel frequency stabilization method for external cavity diode lasers by using an all-pass polarization-split Sagnac loop is proposed. This scheme uses a quarter waveplate to convert the incident beam to a circularly polarized beam, and a polarization beam splitter for the input and output of the Sagnac loop. The two beams with perpendicular polarizations counter-propagate in the loop and experience different absorption of the Rb cell; therefore, the Sagnac loop output beam is converted into elliptical polarization. The dispersion phase shift induced by Rb saturation absorption can be obtained by balanced polarization-divided detection of the Sagnac loop output beam. The experimental results showed the feasibility and merits of the new method. This scheme is simple, robust, low-cost, and has potential applications in atomic physics experiments. View full abstract»

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  • Bridging the Gap Between Kalman Filter and Wiener Filter in Carrier Phase Tracking

    Page(s): 1035 - 1038
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (323 KB) |  | HTML iconHTML  

    Data-aided carrier recovery based on phase-lock loop (PLL) is a popular scheme for tracking the phase of an incoming carrier affected by phase noise. Optimum tracking is achieved by a Kalman filter, that, with multilevel quadrature amplitude modulation (QAM), is implemented by a PLL with variable loop gain. This letter shows that a PLL with fixed gain achieves a performance that is close to the optimal one provided that the phase detector is optimized. Monte Carlo simulations for the mean-square phase error and the symbol error rate of a 256-QAM constellation are provided to validate the analysis. View full abstract»

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  • Tunable Distributed Feedback Quantum Cascade Lasers by a Sampled Bragg Grating

    Page(s): 1039 - 1042
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (820 KB) |  | HTML iconHTML  

    A novel complex-coupled distributed feedback quantum cascade laser emitting around λ ~ 4.7 μm is demonstrated by a sampled Bragg grating (SBG). The key superiorities are to utilize the +1st-order (positive first order) transmission of the SBG for laser single-mode operation, and use conventional holographic exposure combined with the optical photolithography technology to fabricate the sampled grating, which lead to improved flexibility, repeatability, and cost-effectiveness. Selective single-mode lasing with a mean side mode suppression ratio above 20 dB and wavelength coverage range of 87 nm is achieved by changing the sampling period. View full abstract»

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  • Robust Optical Fiber Using Single Negative Metamaterial Cladding

    Page(s): 1043 - 1046
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (873 KB) |  | HTML iconHTML  

    We introduce the idea of optical fibers made up of single negative metamaterial photonic crystal cladding with zero effective phase bandgap. Fiber characteristics are analyzed both at sub-wavelength and non sub-wavelength crystal dimension by varying cladding thickness and core radius. We find that in both cases they are robust with respect to incident angle, polarization of the light, crystal constant, and cladding irregularities. The fiber is found to behave like a step index fiber but the guided modes are leaky like Bragg fiber. It is shown that a fixed cladding thickness produces fixed loss around impedance matching frequency irrespective of crystal constant. View full abstract»

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  • Fabrication and Characterization of Light-Emitting Diodes Comprising Highly Ordered Arrays of Emissive InGaN/GaN Nanorods

    Page(s): 1047 - 1049
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (651 KB) |  | HTML iconHTML  

    A simple approach to fabricating ordered InGaN/GaN nanorod arrays light-emitting diodes (LEDs) with strongly directional light emission is reported. The far field radiation pattern of the nanorod arrays LEDs shows preferential emission in a ±10° cone about the surface normal and contained other features arising from diffraction associated with the periodicity of the nanorod array. The output power per unit in-plane emissive area at 300-mA drive current is three times larger than that of an equivalent planar LED. View full abstract»

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  • Distributed Strain and Temperature Measurement by Brillouin Beat Spectrum

    Page(s): 1050 - 1053
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (422 KB) |  | HTML iconHTML  

    A novel distributed strain and temperature measurement method based on Brillouin beat spectrum (BBS) in a complex index profile fiber are proposed. The BBS corresponds to the optical interaction of different acoustic modes. For a large-effective-area fiber (LEAF), the first peak of BBS is contributed by the first and second acoustic modes, while the second peak in BBS is contributed by the first and third accoustic modes. Through determining power changes in the peaks of BBS due to strain and temperature variation along a LEAF, the distributed strain and temperature can be measured by the homodyne Brillouin optical time-domain reflectometry (BOTDR) without scanning the Brillouin spectrum. The strain and temperature at the end of a 4.5-km LEAF are measured at 3-m spatial resolution in 140 s. View full abstract»

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  • Demonstrating Doubly-Differential Quadrature Phase Shift Keying in the Optical Domain

    Page(s): 1054 - 1057
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (877 KB) |  | HTML iconHTML  

    We report for the first time the experimental demonstration of doubly differential quadrature phase shift keying (DDQPSK) using optical coherent detection. This method is more robust against high frequency offsets (FO) than conventional single differential quadrature phase shift keying (SDQPSK) with offset compensation. DDQPSK is shown to be able to compensate large FOs (up to the baud rate) and has lower computational requirements than other FO compensation methods. DDQPSK is a simple algorithm to implement in a real-time decoder for optical burst switched network scenarios. Simulation results are also provided, which show good agreement with the experimental results for both SDQPSK and DDQPSK transmissions. View full abstract»

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  • Q-Switch All-Fiber Laser Pulsed by High Order Modes

    Page(s): 1058 - 1061
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (535 KB) |  | HTML iconHTML  

    In this letter, we demonstrate an all-fiber Q-switch laser in erbium-doped fiber using an intracavity loss modulator that controls the power transmitted by a cladding mode. The cladding mode is coupled by a pair of concatenated long period gratings; pulsed regime is achieved by dynamic attenuation of the power transmitted by the cladding mode, and attenuation is caused by lateral compression with a piezoelectric transducer. The pulse sequence can be controlled from a single shot up to repetition rates of 2 kHz. The laser performance is analyzed as a function of the pump power and emission frequency; pulses having a peak power of 4 W and a duration of ~80 ns can be generated with an absorbed pump of 100 mW. View full abstract»

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  • Low Temperature Gold-to-Gold Bonded Semiconductor Disk Laser

    Page(s): 1062 - 1065
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (981 KB) |  | HTML iconHTML  

    We present a gold-to-gold bonding method that combines features of surface activated bonding and capillary bonding. The process is performed at a relatively low temperature of 150°C and therefore allows the integration of materials with highly mismatched coefficients of thermal expansion. In this letter, the potential of this technique is illustrated by assembling a high-power flip chip semiconductor disk laser utilizing a chemical vapor deposition diamond heat spreader. The laser produces up to 14 W of output power at 15°C gain element temperature with a nearly diffraction-limited output beam. Further scaling of bonding area to wafer-level could make this method useful in the packaging of various optoelectronic and microelectronic components. View full abstract»

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  • Highly Reflective Fiber Bragg Gratings Inscribed in Ce/Tm Co-Doped ZBLAN Fibers

    Page(s): 1066 - 1068
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (465 KB) |  | HTML iconHTML  

    We report highly reflective fiber Bragg gratings (FBGs) photoinduced in the core of Ce/Tm co-doped ZBLAN fibers using a 248-nm excimer laser. We compare the characteristics of the FBGs inscribed in ZBLAN fiber to those produced in silica fiber. We also characterize the strain and temperature responses of ZBLAN FBGs and find that the wavelength can be strain- and temperature-tuned at rates that are 45% and 15% higher, respectively, compared to silica FBGs. View full abstract»

    Open Access
  • Hybrid Wireline and Wireless Transport System Based on Polarization Modulator

    Page(s): 1069 - 1072
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1578 KB) |  | HTML iconHTML  

    A polarization modulation and amplitude re-modulation scheme is proposed to achieve a hybrid wireline and wireless fiber optical transport system. With the assistance of a polarization beam splitter, the odd-order and even-order sidebands of an optical polarization modulated wireless signal can be separated colorlessly to achieve optical double frequency application and amplitude re-modulation scheme. The overall operation principle is experimentally demonstrated by up-converting a 625 Mb/s/20 GHz signal up to a 625 Mb/s/40 GHz signal. The transmission performance of the proposal is evaluated by communicating a hybrid 625 Mb/s baseband signal and a 625 Mb/s/14 GHz wireless signal over a 20 km single-mode fiber. The obtained error free transmissions and clear eye diagrams are great evidence to prove the practicality of this proposal. View full abstract»

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  • Modulation-Format-Independent Carrier Phase Estimation for Square M-QAM Systems

    Page(s): 1073 - 1076
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1693 KB) |  | HTML iconHTML  

    A modulation-format-independent or universal carrier phase estimation (U-CPE) technique is proposed for square 4-, 16-, and 64-ary quadrature amplitude modulation transmission systems for future elastic optical networks. The proposed U-CPE is based on a feedback architecture and eliminates the need to know the signal modulation format (MF) by using a cost function in the phase estimation update that is common to all square-shaped constellations. Compared with standard decision directed phase lock loop (S-DD-PLL) that requires the knowledge of the MF, the U-CPE method maintains close OSNR performance and linewidth tolerance. When MF is agnostic, the proposed U-CPE outperforms a modulation format oblivious (MFO)-DD-PLL in which QPSK decision rules are always used irrespective of actual MF of the signal. View full abstract»

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  • Monolithic Integration of a High-Speed Widely Tunable Optical Coherent Receiver

    Page(s): 1077 - 1080
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (703 KB) |  | HTML iconHTML  

    In this letter, a monolithically integrated widely tunable optical receiver is demonstrated. A sampled-grating DBR (SG-DBR) laser, an optical 90-degree hybrid, four high-speed uni-travelling-carrier photodetectors and microstrip transmission lines are integrated on a single InGaAsP/InP chip. A 42-nm tuning range and a 35-GHz detector bandwidth are achieved. Experiments show real-time reception of 40 Gb/s BPSK data. View full abstract»

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  • Amplification at 1400–1450 nm of the Large-Core Nd-Doped Fiber by White LED Pumping

    Page(s): 1081 - 1083
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB) |  | HTML iconHTML  

    A novel cost-effective fiber amplifier operating over 1400-1450 nm is developed based on pumping of a large-core Nd-doped fiber with a high-power white light-emitting diode (LED). An optical gain of 6 dB at 1400 nm is obtained by simultaneously exciting the multiple absorption bands in the visible wavelength of the Nd-doped fiber. 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