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Photonics Journal, IEEE This IEEE Publication is an Open Access only journal. Open Access provides unrestricted online access to peer-reviewed journal articles.

Issue 1 • Date Feb. 2011

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Displaying Results 1 - 16 of 16
  • Linearized Downconverting Microwave Photonic Link Using Dual-Wavelength Phase Modulation and Optical Filtering

    Publication Year: 2011 , Page(s): 1 - 12
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (800 KB) |  | HTML iconHTML  

    We describe a technique transmitting K-band microwave signals over an optical channel using electrooptic phase modulation at the transmitter followed by series phase modulation and bandpass filtering in the receiver to downconvert the transmitted signal to an intermediate frequency (IF). Unlike other downconversion methods, the method does not require a microwave mixer, high-speed optical photoreceivers, optically stabilized local oscillator, or active bias control at either phase modulator. We further show that the link can be linearized by using two wavelengths launched along orthogonal axes of a single lithium niobate phase modulator at the transmitter. We successfully demonstrate linearized downconversion of a 20-GHz microwave signal to a 250-MHz IF. The linearization method results in a 14-dB improvement in the spurious-free dynamic range compared with the nonlinearized case. View full abstract»

    Open Access
  • A WDM-PON-Compatible System for Simultaneous Distribution of Gigabit Baseband and Wireless Ultrawideband Services With Flexible Bandwidth Allocation

    Publication Year: 2011 , Page(s): 13 - 19
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1053 KB) |  | HTML iconHTML  

    In this paper, a novel and simple scheme to realize flexible access for gigabit wireline and impulse radio ultrawideband (IR-UWB) wireless services is proposed. The UWB signals are generated by multi-carrier upconverting and reshaping the baseband signals. The proposed system was experimentally demonstrated with the performances of 2.0-Gb/s data in both baseband and UWB formats after 46-km single mode fiber transmission and further 0.5-m wireless for UWB data. The flexibility of the system is confirmed by investigating the system performance at different data rates including 1.0 and 1.6 Gb/s. Optical wavelength independency and data-rate variability of UWB signal generation makes the system attractive for potential wireline and wireless applications in existing wavelength division multiplexing (WDM)-passive optical network (PON) systems. View full abstract»

    Open Access
  • Demonstration of OCDM Coder and Variable Bandwidth Filter Using Parallel Topology of Quadruple Series Coupled Microring Resonators

    Publication Year: 2011 , Page(s): 20 - 25
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (780 KB) |  | HTML iconHTML  

    The quadruple series coupled microring resonator (MRR) can realize a boxlike spectral response and lower adjacent channel crosstalk. Utilizing these features, we demonstrated the element of Optical Code Division Multiplexing (OCDM) coding circuit using two wavelength selective switches (WSSs) consisting of quadruple series coupled MRRs laid out in parallel topology and a phase shifter incorporated in the one arm between them. In addition, a digitally variable bandwidth filter was successfully demonstrated using the same circuit as the OCDM coder. View full abstract»

    Open Access
  • Efficiency Enhancement in Organic Light-Emitting Devices With a Magnetic Doped Hole-Transport Layer

    Publication Year: 2011 , Page(s): 26 - 30
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (383 KB) |  | HTML iconHTML  

    Magnetic field effects on tris-(8-hydroxyquinoline) aluminum-based organic light-emitting devices (OLEDs) by employing Fe3O4 as a magnetic dopant in the hole-transport layer (HTL) have been studied. The magnetic doped OLEDs exhibit efficient injection and transport of holes, and its performances are further enhanced after a magnetic field is applied. The enhancement of luminance and current efficiency of 20% and 24% has been obtained from the magnetic doped devices, while they are only 8% and 9%, respectively, for the nondoped devices under an applied magnetic field of 500 mT. Organic magnetoresistance induced by the magnetic doped HTL is the main origin of increased electroluminescence for the magnetic doped OLEDs. View full abstract»

    Open Access
  • Active Area Uniformity of InGaAs/InP Single-Photon Avalanche Diodes

    Publication Year: 2011 , Page(s): 31 - 41
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1501 KB) |  | HTML iconHTML  

    We present a detailed characterization of the active area uniformity of InGaAs/InP Single-Photon Avalanche Diodes (SPADs) from two different design iterations. Nonuniformity of the electric field within the device active area has been measured through 2-D scans of detection efficiency and timing response to a pulsed laser. Additionally, we measured the near-infrared luminescence emitted by hot carriers during the avalanche. The nonuniformity is stronger at lower excess bias, with much higher and nonuniform electric field at the edge of the active area than expected, and it is fainter at higher excess bias, due to the saturation of the avalanche triggering efficiency. The main drawbacks are that the detection efficiency is position dependent when the SPAD is not fiber pigtailed and that the temporal response is worse, because of the nonuniform delay in the avalanche build-up across the SPAD active area. View full abstract»

    Open Access
  • Modeling and Analysis of an 80-Gbit/s SiGe HBT Electrooptic Modulator

    Publication Year: 2011 , Page(s): 42 - 56
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1432 KB) |  | HTML iconHTML  

    We present a rigorous electrical and optical analysis of a strained and graded base SiGe Heterojunction Bipolar Transistor (HBT) electrooptic (EO) modulator. In this paper, we propose a 2-D model for a graded base SiGe HBT structure that is capable of operating at a data bit rate of 80 Gbit/s or higher. In this structure, apart from a polysilicon/monosilicon emitter (Width = 0.12 μm) and a strained SiGe graded base (Depth = 40 nm) , a selectively implanted collector (SIC) (Depth = 0.6 μm) is introduced. Furthermore, the terminal characteristics of this new device modeled using MEDICI are closely compared with the SiGe HBT in the IBM production line, suggesting the possibility of fast deployment of the EO modulator using established commercial processing. At a subcollector depth of 0.4 μm and at a base-emitter swing of 0 to 1.1 V, this model predicts a rise time of 5.1 ps and a fall time of 3.6 ps. Optical simulations predict a π phase shift length (Lπ) of 240.8 μm with an extinction ratio of 7.5 dB at a wavelength of 1.55 μm. Additionally, the tradeoff between the switching speed, Lπ and propagation loss with a thinner subcollector is analyzed and reported. View full abstract»

    Open Access
  • Tapered and Tip-Grounded Waveguide Electrooptical Microsensors

    Publication Year: 2011 , Page(s): 57 - 63
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (961 KB) |  | HTML iconHTML  

    A tip-grounded waveguide microsensor was proposed to overcome the difficulty of quantitative voltage calibration in electrooptical detection for integrated circuit (IC) test. On this basis, we optimized the thickness of the electrooptical material of the sensor to eliminate the influence of the circuit layout on the measured signals. The improved sensor in return made it possible to calibrate the voltage with known reference electric signals quantitatively. This method circumvented the uncertainty of the probe conditions of each measurement point. Finally, a calibration accuracy of better than 6% was obtained, which satisfied broad applications in the IC industry. View full abstract»

    Open Access
  • Tunable and Switchable Multiwavelength Passively Mode-Locked Fiber Laser Based on SESAM and Inline Birefringence Comb Filter

    Publication Year: 2011 , Page(s): 64 - 70
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (904 KB) |  | HTML iconHTML  

    A tunable and switchable multiwavelength passively mode-locked fiber laser by using a semiconductor saturable absorber mirror (SESAM) and an inline birefringence fiber filter is proposed and demonstrated. By properly rotating the polarization controllers (PCs), up to 7-wavelength mode-locked pulses in 3-dB bandwidth with 3.65-nm channel spacing are obtained. The wavelength switchable operation is determined by the characteristics of the comb filter used in the experiment. Taking advantage of an intensity-dependent loss mechanism caused by the nonlinear polarization rotation (NPR) effect, the mode competition is efficiently suppressed. In addition, the lasing locations of multiwavelength mode-locked pulses can be flexibly tuned via the wavelength-dependent loss mechanism. View full abstract»

    Open Access
  • Cavity Length Scaling of Quantum Cascade Lasers for Single-Mode Emission and Low Heat Dissipation, Room Temperature, Continuous Wave Operation

    Publication Year: 2011 , Page(s): 71 - 81
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1454 KB) |  | HTML iconHTML  

    Single-mode operation of Fabry-Perot quantum cascade (QC) lasers is achieved through the systematic shortening of the cavity length from 764 to 110 μm. The increased mirror loss is mitigated using highly reflective (HR) metallic facet coatings (R >; 95%). Ultrashort cavity QC lasers operate single mode with the best device having a mode-hop free current tuning range of 3.44 cm-1. Using combined heat-sink temperature and current tuning, the largest single-mode tuning range attained was 8.56 cm-1. The heat dissipation of a 110-μm ultrashort cavity QC laser is 0.23 W at 80 K and 0.43 W at 150 K. With a 500-μm cavity and both facets HR coated with reflectivities of ~95% and 75%, room-temperature continuous wave operation is realized with heat dissipation of 1.2-1.7 W. View full abstract»

    Open Access
  • Resonance Frequencies of Electrically Charged Nanoparticles

    Publication Year: 2011 , Page(s): 82 - 88
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (557 KB) |  | HTML iconHTML  

    We develop a procedure to analyze charged nanoparticle (NP) surface modes. Using the resonance condition derived by Rosenkrantz and Arnon, we obtain frequencies at which the electromagnetic (EM) radiation stimulates resonance over a wide range of modes. Our results confirm that the relation between the resonance frequencies and the excess surface charge can be described by a monotonically increasing function. Taking the derivative of this function, it is evident that the lower surface potentials have a greater influence on the resonance frequency. This effect decreases as the surface potential increases. Surface modes contribute to the surface energy of charged NPs, and for this reason, they can modify charged NP optical properties. We found that there is a strong dependence of the resonance frequencies on the electrically charged NP refractive index and surface potential. This dependence can play an important role in nonmetallic nanotechnological devices, such as attenuators and modulators in optical communication and optical detectors in biomedical sensors. View full abstract»

    Open Access
  • Optical Transmission Signal Phase Compensation Method Using an Image Rejection Mixer

    Publication Year: 2011 , Page(s): 89 - 99
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1435 KB) |  | HTML iconHTML  

    In the field of large-scale radio interferometers, there is a growing need for the photonic highly stable signal generation and distribution system. To maintain signal coherency of the distributed reference-frequency signal, the photonic phase compensation technique is indispensable. To address this issue, we have developed a new method to transmit a reference signal in the form of frequency difference between two coherent light waves. The proposed low-frequency signal optical transmission method is suitable for an optical transmission at a low frequency equal to or lower than 20 GHz, which optically enables a long-distance transmission by compensating a phase delay amount caused by the transmission. This method has external-influences resistance. The system can be applied to a signal transmission field with the objective of achieving high stability of the reference signal transmission, such as an interferometer, or the transmission or distribution of the highly stable signal according to, for example, the national frequency standard or applied to a field involving a problem of the transmission delay. View full abstract»

    Open Access
  • Broadband Extended Dynamic Range Analog Signal Transmission Through Switched Dual Photonic Link Architecture

    Publication Year: 2011 , Page(s): 100 - 111
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1409 KB) |  | HTML iconHTML  

    The design and experimental performance of a 40-GHz microwave photonic link scheme developed for broadband analog signal transmission that exhibits an increased input dynamic range compared with conventional microwave photonic links is presented. The scheme achieves an extension in the input power operating range by switching between two photonic links designed to operate at different input power levels, where the optical fiber provides the required delay for the switching operation. Although the extension in the dynamic range is noninstantaneous, the scheme has application in high-sensitivity receiver systems in a pulsed signal environment due to its feedforward gain control mechanism. This paper presents, through a realistic simulation study, the device parameter values required for optimized performance of a wideband (2-40 GHz) link with the noise figure, sensitivity, and dynamic range performance of each link and the composite link. A total "synthetic" dynamic range >;100 dB with a minimum detectable signal of -110 dBm at a 100-kHz noise bandwidth can be achieved for the 2-40-GHz frequency range operation. The simulation results compare well with experimental results obtained with a practical implementation of the dual link architecture. The design and operational details of the switching circuitry required are also presented. View full abstract»

    Open Access
  • Generation of Coherent Multicarrier Signals by Gain Switching of Discrete Mode Lasers

    Publication Year: 2011 , Page(s): 112 - 122
    Cited by:  Papers (12)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1631 KB) |  | HTML iconHTML  

    The authors demonstrate the generation of a highly coherent multicarrier signal that consists of eight clearly resolved 10.7-GHz coherent sidebands generated within 3 dB of the spectral envelope peak and with an extinction ratio in excess of 45 dB by gain switching a discrete mode (DM) laser. The generated spectral comb displays a corresponding picosecond pulse train at a repetition rate of 10.7 GHz with a pulse duration of 24 ps and a temporal jitter of ~450 fs. The optical spectra and associated pulses of the gain-switched DM laser are subsequently compared with a gain-switched distributed feedback (DFB) laser that generates a spectrum with no discernible sidebands and corresponding pulses with ~3 ps of temporal jitter. By means of external injection, the temporal jitter of the gain-switched DFB laser is then reduced to <; 1 ps, resulting in visible tones on the output spectrum. Finally, a nonlinear scheme is employed and initially tailored to compress the optical pulses, after which, the setup is slightly altered to expand the original frequency comb from the gain-switched DM laser. View full abstract»

    Open Access
  • Single-Layer Resonant High Reflector in TE Polarization: Theory and Experiment

    Publication Year: 2011 , Page(s): 123 - 129
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (952 KB) |  | HTML iconHTML  

    We present the fabrication and characterization of a guided-mode resonance-based high reflector operating in transverse-electric (TE) polarization. This reflector consists of a single periodic layer of amorphous silicon on a glass substrate. It is fabricated by silicon sputtering, holographic interference patterning, and dry etching. The measured reflectance exceeds 90% over a ~ 130-nm wavelength range with maximum reflectance of ~ 98% in a band centered at a ~ 1560-nm wavelength. The experimental spectrum approximates the theoretical spectral response of this fundamental minimal device. View full abstract»

    Open Access
  • Light Enhancement Within Nanoholes in High Index Contrast Nanowires

    Publication Year: 2011 , Page(s): 130 - 139
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (816 KB) |  | HTML iconHTML  

    We present systematic predictions for light enhancement in optical nanowires with nanoscale air holes in the core through numerical modeling. We show that the light intensity within such holes is strongly dependent on the hole size and refractive index of the host material and that light enhancement becomes significant only when the hole size is less than a critical value: 70 nm for silica and F2 nanowires and 50 nm for a As2S3 nanowire. High index As2S3 nanowires exhibit nearly eight times higher average mode intensity than silica glass for hole sizes of less than 10 nm. Such intensity enhancements open up new device opportunities; for example, filling nanoscale holes within silicon nanowires with silicon nanocrystals enables 30% enhancement of the nonlinear coefficient. View full abstract»

    Open Access
  • Characterization of Power-to-Phase Conversion in High-Speed P-I-N Photodiodes

    Publication Year: 2011 , Page(s): 140 - 151
    Cited by:  Papers (14)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1143 KB) |  | HTML iconHTML  

    Fluctuations of the optical power incident on a photodiode can be converted into phase fluctuations of the resulting electronic signal due to nonlinear saturation in the semiconductor. This impacts overall timing stability (phase noise) of microwave signals generated from a photodetected optical pulse train. In this paper, we describe and utilize techniques to characterize this conversion of amplitude noise to phase noise for several high-speed (>; 10 GHz) InGaAs p-i-n photodiodes operated at 900 nm. We focus on the impact of this effect on the photonic generation of low phase noise 10-GHz microwave signals and show that a combination of low laser amplitude noise, appropriate photodiode design, and optimum average photocurrent is required to achieve phase noise at or below -100 dBc/Hz at 1 Hz offset for a 10-GHz carrier. In some photodiodes, we find specific photocurrents where the power-to-phase conversion factor is observed to go to zero. View full abstract»

    Open Access

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IEEE Photonics is an online-only rapid publication archival journal of top quality research at the fore-front of Photonics.  Photonics integrates quantum electronics and optics to accelerate progress in the generation of novel photon sources and in their utilization in emerging applications at the micro and nano scales spanning from the far-infrared/THz to the x-ray region of the electromagnetic spectrum.

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Physics Department
University of Connecticut
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