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Publications (11)7.48 Total impact

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    ABSTRACT: Polarisation-independent error-free 20 Gbit/s soliton data transmission over 12500 km with flat system Q dependence on distance, has been demonstrated using static filtering and a semiconductor polarisation-independent amplitude and phase modulator for soliton transmission control
    Electronics Letters 07/1995; 31(13-31):1090 - 1091. DOI:10.1049/el:19950753 · 1.07 Impact Factor
  • R.A. Saunders, J.P. King, I. Hardcastle
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    ABSTRACT: A Mach Zehnder (MZ) interferometer has been used as an optical discriminator to measure the time-resolved frequency chirp of an optical source
    Electronics Letters 09/1994; 30(16-30):1336 - 1338. DOI:10.1049/el:19940917 · 1.07 Impact Factor
  • J.P. King, I. Hardcastle, A. Hadjifotiou
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    ABSTRACT: A frequency shift keyed/intensity modulated (FSK/IM) optical transmitter is described which uses direct frequency shift keying of a laser and a Mach-Zehnder optical discriminator to produce a very low chirp intensity modulated source for high bit rate, high dispersion systems. The FSK/IM transmitter was demonstrated over a 200 km span of conventional nondispersion shifted fibre at 2.488 Gbit/s, with very low dispersion penalty, an error floor of better than 10<sup>-15</sup> BER, and a long term stability of better than 0.3 dB over 100 hours of operation. The performance and stability obtained make possible the introduction of repeaterless transmission over installed nondispersion shifted fibre links: system loss and dispersion requirements for spans of 200 km can be readily satisfied with sufficient margin for long term system viability
    Sources for Very High Bit Rate Optical Communication Systems, IEE Colloquium on; 05/1992
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    ABSTRACT: An optical receiver suitable for a 10 Gbit/s direct detection optical transmission system is described. It uses a pin diode, commercial GaAs MESFETs and hybrid construction techniques on a coplanar substrate. The measured sensitivity of the receiver is -20.4 dBm, which is the best reported sensitivity at 10 Gbit/s for a pin-FET optical receiver to date.
    Electronics Letters 02/1992; 28(2-28):120 - 122. DOI:10.1049/el:19920074 · 1.07 Impact Factor
  • Optical Fiber Communication Conference; 02/1992
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    ABSTRACT: An erbium-doped fibre amplifier (EDFA) has been used in a high performance transmission system, giving the highest reported sensitivity to date of -33.8 dBm (325 photon/bit) at 10 Gbit/s, for pumping at 1480 nm.
    Electronics Letters 12/1991; 27(23-27):2179 - 2180. DOI:10.1049/el:19911348 · 1.07 Impact Factor
  • I. Hardcastle, T. Large, F. Davis, A. Hadjifotiou
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    ABSTRACT: A 140 Mbit/s FSK heterodyne coherent transmission system is described having automatic frequency and polarisation acquisition and tracking. A receiver sensitivity of -57.4 dBm (88 photons/bit), using 7B8B block code, and -58.2 dBm (84 photons/bit), using biphase coding, has been obtained, only 3.4 and 3.2 dB away from the shot noise limit, respectively.
    Electronics Letters 09/1990; 26(18-26):1523 - 1525. DOI:10.1049/el:19900978 · 1.07 Impact Factor
  • I. Hardcastle, T. Large, F. Davis, A. Hadjifotiou
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    ABSTRACT: The use of frequency shift keying (FSK) modulation format reduces considerably the requirements on the performance of optical sources and leads to simple system implementation. Several laboratories have reported systems operating close to the quantum limit. The authors describe the design, implementation and evaluation of a practical 140 Mbit/s FSK heterodyne coherent transmission system with a balanced dual channel receiver, automatic carrier acquisition, tracking and endless polarisation control. The carrier acquisition, tracking and polarisation control are controlled by a built-in microprocessor giving the system flexibility and the ability to monitor the operation of these subsystems. A sensitivity of -57.4 dBm has been obtained, only 3.4 dB away from the quantum limit. System stability has been demonstrated over a period of 250 hours at an optical power level below sensitivity and an error floor shown to be lower than BER=3.5×10<sup>-14</sup>. This system therefore fulfils the requirements for transmission systems with span lengths on the order of 250 km. This enables previously unexploited markets for unrepeated transmission links to be addressed, opening a new era in the history of long haul communications
    Coherent Optical Communications, IEE Colloquium on; 07/1990
  • I. Hardcastle, A. Hadjifotiou
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    ABSTRACT: A balanced receiver for use in coherent transmission systems is described. It employs commercially available discrete components. A sensitivity of -57.2 dBm has been achieved in a 160 Mbit/s FSK heterodyne system, within 3.6 dB of the quantum limit.
    Electronics Letters 06/1990; DOI:10.1049/el:19900490 · 1.07 Impact Factor
  • I. Hardcastle, A. Hadjifotiou
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    ABSTRACT: The authors describe a receiver which is tailored in particular for coherent systems. A pair of low capacitance, high quantum efficiency InGaAs PIN detectors are incorporated to obtain performance near to the quantum limit. Inductive peaking is used to reduce high frequency noise. The circuit was simulated using both SPICE and COMPACT. Inclusion of a prototype front end into a 160 Mbit/s FSK Heterodyne system has resulted in a sensitivity within 3.6 dB to the quantum limit. It is concluded that discrete circuit techniques are capable of delivering high bandwidth, low noise balanced optical receivers. These make possible the implementation of coherent systems operating near the quantum limit with existing local oscillator power levels and linewidths. The use of high quantum efficiency, low capacitance detectors in the front end is fundamental to such systems
    Optical Detectors, IEE Colloquium on; 02/1990
  • A. Hadjifotiou, I. Hardcastle, D. Remedios
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    ABSTRACT: The capabilities of coherent detection for unrepeatered systems is outlined both in terms of components and subsystem performance and it is shown that the expected component improvements will make possible the realisation of coherent systems able to offer link lengths of around 300 km. As the component performance improves it is expected that the link length will increase by using either more efficient modulation formats or improving the initial `weakly coherent' systems
    Submarine Optical Transmission Systems, IEE Colloquium on; 04/1988