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Optoelectronics, IET

Issue 3 • Date June 2012

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Displaying Results 1 - 5 of 5
  • Research on light-wave target detection and imaging by using NR-PC flat lens with active impurities

    Page(s): 121 - 126
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (614 KB)  

    The authors mainly use the two-dimensional finite-difference time-domain method to study the effection on image resolution of target detection and imaging when active impurities are introduced to negative refraction photonic crystals (NR-PC) flat lens. It is demonstrated that because of the influence of the mini-forbidden band and resonance excitation effect, high transmissivity will appear at the resonance frequency of 0.3068(a/λ) when the light wave goes through the NP-PC lens. Also, the results show that the refocused wave backscattered from a target is significantly stronger than the directly backscattered wave when no NR-PC flat lens is applied. Further studies demonstrated that the introduction of active impurities into NR-PC lens provides improved refocusing and image resolution. In conclusion, the authors' investigation optimises the performance of the focus-scanning scheme, and provides the basis for converting an idealised left-handed materials (LHM) lens into a physically realisable NR-PC flat lens. View full abstract»

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  • Compact and wide-band bismuth-based erbium-doped fibre amplifier based on two-stage and double-pass approaches

    Page(s): 127 - 130
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (278 KB)  

    In this study, a wide-band erbium-doped fibre amplifier (EDFA) operating in both C- and L-band wavelength regions is demonstrated based on two-stage and double-pass approaches. The amplifier employs two pieces of 21 and 46 cm long bismuth-based EDFs (Bi-EDFs) optimised for C- and L-band operations, respectively, which are pumped by 1480 nm laser diode and its performances are investigated in both parallel and linear configurations. Wide-band operation is achieved in both configurations that covers from 1525 to 1620 nm. Compared with the linear Bi-EDFA, the parallel Bi-EDFA provides a higher attainable gain especially for small input signal. At input signal power of 30 dBm, the average gains of the parallel Bi-EDFA are obtained at approximately 20 dB with gain variation of 2.5 dB within the wavelength region from 1530 to 1605 nm. At the input signal power of 0 dBm, the average gains of approximately 10 dB with a gain variation of 2 dB within 1540 to 1620 nm region are obtained by both parallel and linear Bi-EDFAs. The noise figures for both configurations are maintained below 10 dB in the wavelength region from 1535 to 1620 nm. The noise figures are mainly because of spurious reflection in the cavity and high reflection of amplified spontaneous emission (ASE) from the end face. View full abstract»

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  • Optical code-division multiple-access embedded with a polarisation diversity scheme for radio-over-fibre transmissions

    Page(s): 131 - 139
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (685 KB)  

    This study presents a spectral polarisation-coding optical code-division multiple-access (SPC-OCDMA) system for radio-over-fibre (RoF) transmissions. The proposed system implements encoding and double-balanced detection processes using a polarisation diversity scheme to enlarge the transmitted radio frequency (RF) signal space. By combining the quasi-orthogonality of Walsh-Hadamard codes with arrayed waveguide grating (AWG) routers and a polarisation beam splitter (PBS), the proposed coder/decoder (codec) pair can encode-decode multiple Walsh-Hadamard code words and retain the ability of multiple access interference (MAI) cancellation. This study presents a series of investigations to evaluate the sensitivity of the proposed structure to the degree of matching in the state of polarisations (SOPs) of the transmitted light in the encoder and decoder, respectively. Results show that when the polarisation states are fully matched between the encoder and the decoder, the proposed system achieves a carrier-to-noise ratio (CNR) improvement of up to 3-dB compared with that obtained from a complementary spectral polarisation coding (SPC) system with a single-balanced detector. Numerical results demonstrate that maintaining the system with an orthogonal SOP for each radio base station (RBS) effectively reduces the phase-induced intensity noise (PIIN). View full abstract»

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  • Cost-effective 10 Gb/s polymer-based chip-to-chip optical interconnect

    Page(s): 140 - 146
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (518 KB)  

    Board-level optical links are an attractive alternative to their electrical counterparts as they provide higher bandwidth and lower power consumption at high data rates. However, on-board optical technology has to be cost-effective to be commercially deployed. This study presents a chip-to-chip optical interconnect formed on an optoelectronic printed circuit board that uses a simple optical coupling scheme, cost-effective materials and is compatible with well-established manufacturing processes common to the electronics industry. Details of the link architecture, modelling studies of the link's frequency response, characterisation of optical coupling efficiencies and dynamic performance studies of this proof-of-concept chip-to-chip optical interconnect are reported. The fully assembled link exhibits a -3 dBe bandwidth of 9 GHz and -3 dBo tolerances to transverse component misalignments of ±25 and ±37 mm at the input and output waveguide interfaces, respectively. The link has a total insertion loss of 6 dBo and achieves error-free transmission at a 10 Gb/s data rate with a power margin of 11.6 dBo for a bit-error-rate of 10-12. The proposed architecture demonstrates an integration approach for high-speed board-level chip-to-chip optical links that emphasises component simplicity and manufacturability crucial to the migration of such technology into real-world commercial systems. View full abstract»

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  • Integrated multimode interference coupler-based mach-zehnder interferometric modulator fabricated on a silicon-on-insulator substrate

    Page(s): 147 - 152
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (494 KB)  

    The authors propose the design of a 6000×40-μm Mach-Zehnder interferometric (MZI) electro-optic modulator fabricated on silicon-on-insulator (SOI) substrate based on a back-to-back cascade of two 1×2 multimode interference (MMI) couplers for the operating wavelength of 1.55μm. A signal modulation is achieved with the incorporation of a phase shifter in one of the two arms that connect two MMI devices together and the resultant extinction ratio achieved is in the excess of -25dB. Furthermore, the frequency response measurement also shows that the 3-dB frequency measured for our MMI-MZI device is greater than 6 MHz. View full abstract»

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Aims & Scope

IET Optoelectronics covers but is not limited to the following topics: Optical and optoelectronic materials; Light sources, including LEDs, lasers and devices for lighting; Optical modulation and multiplexing; Optical fibres, cables and connectors; Optical amplifiers; Photodetectors and optical receivers; Photonic integrated circuits; Nanophotonics and photonic crystals; Optical signal processing; Holography; Displays.

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IET Research Journals