Showing papers in "Electronics Letters in 1996"
TL;DR: The authors report the empirical performance of Gallager's low density parity check codes on Gaussian channels, showing that performance substantially better than that of standard convolutional and concatenated codes can be achieved.
Abstract: The authors report the empirical performance of Gallager's low density parity check codes on Gaussian channels. They show that performance substantially better than that of standard convolutional and concatenated codes can be achieved; indeed the performance is almost as close to the Shannon limit as that of turbo codes.
3,032 citations
TL;DR: A method for the reduction of peak-to-average transmit power ratio of multicarrier modulation systems, called selected mapping, is presented, which is appropriate for a wide range of applications.
Abstract: The authors propose a method for the reduction of peak-to-average transmit power ratio of multicarrier modulation systems, called selected mapping, is presented, which is appropriate for a wide range of applications. Significant gains can be achieved by selected mapping whereas complexity remains quite moderate.
1,812 citations
TL;DR: A group III nitride based separate confinement heterostructure (SCH) single quantum well (SQW) structure, with an active layer thickness as small as 1.5 nm, was fabricated in this paper.
Abstract: A group III nitride based separate confinement heterostructure (SCH) single quantum well (SQW) structure, with an active layer thickness as small as 1.5 nm, was fabricated. It shows the shortest lasing from semiconductor lasers by current injection at room temperature to date. Line width is as little as 0.15 nm.
458 citations
TL;DR: In this article, the formation of stable soliton-like pulses in optical fibres with a periodic dispersion map was examined, and it was found that increased energy is required to launch a pulse of given width compared to the equivalent uniform fibre with equal path-average dispersion.
Abstract: The authors examine the formation of stable soliton-like pulses in optical fibres with a periodic dispersion map. It is found that increased energy is required to launch a pulse of given width compared to the equivalent uniform fibre with equal path-average dispersion. The stable pulse shapes in dispersion managed systems are significantly different to the hyperbolic secant solitons found in uniform fibres.
402 citations
TL;DR: In this article, two Bragg gratings with closely spaced center wavelengths are written either side of a splice between two fibres of different diameter, showing similar temperature sensitivities but different strain responses to an applied stress.
Abstract: A new technique for the simultaneous, independent measurement of temperature and strain using in-fibre Bragg grating sensors is proposed and demonstrated. Two Bragg gratings with closely spaced centre wavelengths are written either side of a splice between two fibres of different diameter. The gratings show similar temperature sensitivities but different strain responses to an applied stress. Maximum errors of /spl plusmn/17 /spl mu//spl epsiv/ and /spl plusmn/1/spl deg/ are reported over 2500 /spl mu//spl epsiv/ and 120/spl deg/C measurement ranges.
374 citations
TL;DR: In this article, the self-similarity properties of the Sierpinski antenna's fractal shape is exploited for designing new multiband and frequency independent antennas, based on which a multiband behavior over five bands is demonstrated.
Abstract: Experimental and computed results show a multiband behaviour over five bands for the new fractal Sierpinski antenna. Such a behaviour is based on the self-similarity properties of the antenna's fractal shape, which might open an alternative way for designing new multiband and frequency independent antennas.
335 citations
TL;DR: The 2D quaternion or hypercomplex Fourier transform is introduced in this paper to handle colour images in the frequency domain in a holistic manner, without separate handling of the colour components, and thus makes possible very wide generalisation of monochrome frequency domain techniques to colour images.
Abstract: The 2D quaternion, or hypercomplex, Fourier transform is introduced. This transform makes possible the handling of colour images in the frequency domain in a holistic manner, without separate handling of the colour components, and it thus makes possible very wide generalisation of monochrome frequency domain techniques to colour images.
329 citations
TL;DR: In this article, the authors reported simultaneous oscillation of 17 0.8 nm spliced wavelengths from a Fabry-Perot (FP) erbium doped fiber laser.
Abstract: The authors report simultaneous oscillation of 17 0.8 nm spliced wavelengths from a Fabry-Perot (FP) erbium doped fibre laser. Multiwavelength operation is made possible by inserting an intracavity etalon and cooling the erbium doped fibre at 77 K by liquid nitrogen. It is promising as the multiwavelength light source for wavelength division multiplexing (WDM) networks. Heterodyne measurement shows that two or three longitudinal modes exist in each wavelength.
269 citations
TL;DR: In this article, a selective scrambling technique was proposed for reducing the peak to average power ratio (PAPR) in QPSK-OFDM systems, while incurring negligible redundancy.
Abstract: A selective scrambling technique is proposed for reducing the peak to average power ratio (PAPR) in QPSK-OFDM systems, while incurring negligible redundancy. Formulation of an appropriate function for selecting between scrambled sequences is discussed, and simulation shows that scrambling reduces the PAPR of the OFDM signal to typically 2% of the maximum possible value.
245 citations
TL;DR: In this paper, a planar lens antenna based on aperture coupled microstrip patch elements with stripline delay lines is described, and features of this design are discussed, and results for transmission coefficient magnitude against frequency are presented.
Abstract: A planar lens antenna based on aperture coupled microstrip patch elements with stripline delay lines is described. Features of this design are discussed, and results for transmission coefficient magnitude against frequency are presented. The background for the development of this lens configuration is discussed in terms of a natural progression from frequency selective surfaces, and the inadequacies of simpler geometries are explained.
237 citations
TL;DR: By reducing the dark-spot density to <3/spl times/10/sup 3/ cm/sup -2, a device lifetime exceeding 100 h has been obtained for a ZnCdSe-ZnSSe -ZnMgSSe single quantum well separate-confinement heterostructure laser diode (LD) under room temperature continuous-wave operation with a constant light output power of 1 mW as mentioned in this paper.
Abstract: By reducing the dark-spot density to <3/spl times/10/sup 3/ cm/sup -2/, device lifetime exceeding 100 h has been obtained for a ZnCdSe-ZnSSe-ZnMgSSe single quantum well separate-confinement heterostructure laser diode (LD) under room temperature continuous-wave operation with a constant light output power of 1 mW The threshold current density is 533 A/cm/sup 2/ and the lasing wavelength is 5147 nm Considering the dark-spot density, we have concluded that the failure of this LD is not caused by degradation from macroscopic defects such as stacking faults, but by recombination enhanced defect reaction
TL;DR: In this article, the room-temperature operating characteristics of InGaAs/GaAs self-organised quantum dot lasers grown by molecular beam epitaxy were reported, and the emission wavelength was 1.028 µm and Jth = 650 A/cm2 for a 90 µm × 1 mm broad-area laser.
Abstract: We report the room-temperature operating characteristics of InGaAs/GaAs self-organised quantum dot lasers grown by molecular beam epitaxy. The emission wavelength is 1.028 µm and Jth = 650 A/cm2 for a 90 µm × 1 mm broad-area laser. Steady-state and time-resolved photoluminescence measurements confirm that lasing occurs through the e1-hh2 higher-order transition, and the spontaneous recombination time for this transition is ≃ 200 ps.
TL;DR: In this paper, a supercontinuum WDM source is successfully transmitted over a 40 km dispersion-shifted fiber using a 400 GHz channel-spaced arrayed-waveguide grating WDM MUX/DEMUX as well as a 100 Gbit/s-10 Gbps all-optical TDM all-over-the-place (TDM-DEMUX) source.
Abstract: 100 Gbit/s/spl times/10 channel (1 Tbit/s) optical signals from a single supercontinuum WDM source are successfully transmitted over a 40 km dispersion-shifted fibre using a 400 GHz channel-spaced arrayed-waveguide grating WDM MUX/DEMUX as well as a 100 Gbit/s-10 Gbit/s all-optical TDM MUX/DEMUX.
TL;DR: In this article, high-speed studies of oxide-confined, submilliampere threshold, oxide-constrained vertical cavity surface emitting lasers show modulation bandwidths > 16 GHz and very high modulation current efficiency factors occur at low bias but decrease as the modulation bandwidth and frequency of the relative intensity noise peak saturate at higher currents.
Abstract: High-speed studies of packaged, submilliampere threshold, oxide-confined vertical cavity surface emitting lasers show modulation bandwidths > 16 GHz. Very high modulation current efficiency factors occur at low bias but decrease as the modulation bandwidth and frequency of the relative intensity noise peak saturate at higher currents.
TL;DR: In this paper, an eight-channel flat spectral response arrayed-waveguide grating multiplexer with parabolic waveguide horns has been fabricated on a planar lightwave circuit (PLC).
Abstract: An eight-channel flat spectral response arrayed-waveguide grating multiplexer with parabolic waveguide horns has been fabricated on a planar lightwave circuit (PLC). A double-peaked intensity distribution is formed at the slab interface by the parabolic waveguide horn. A 1 dB bandwidth of 98 GHz, 3 dB bandwidth of 124 GHz and 20 dB bandwidth of 196 GHz are obtained for 200 GHz channel spacing. The crosstalk to neighbouring channels is less than –27 dB and the on-chip insertion losses range from 6.1 to 6.4 dB, respectively.
TL;DR: In this article, the implementation of an RF CMOS active inductor is described, where the inductor loss is reduced by applying gain enhancement techniques based on cascoding, and the proposed new inductors exhibit lower loss, high self-resonance frequency and wider inductive region.
Abstract: The implementation of an RF CMOS active inductor is described. The circuit is based on a recently proposed CMOS GIC. The inductor loss is reduced by applying gain enhancement techniques based on cascoding. The proposed new inductors exhibit lower loss, high self-resonance frequency and wider inductive region. An RLC bandpass filter response is realised to verify the performance of the simulated inductor.
TL;DR: In this article, alternating molecular beam epitaxy is used to form InGaAs quantum dots by utilizing the two-dimensional to three-dimensional Stranski-Krastanow growth transition.
Abstract: Alternating molecular beam epitaxy is used to form InGaAs quantum dots by utilising the two-dimensional to three-dimensional Stranski-Krastanow growth transition. The quantum dots are embedded in a separate confinement heterostructure to form laser diodes. Lasing is observed from excited states in the quantum dots from room temperature down to 80 K. Pronounced state-filling is observed in the quantum dot lasers at room temperature. As the temperature is decreased, the state-filling becomes less pronounced, which compensates for the bandgap increase and leads to lasers whose lasing wavelength is very weakly dependent on temperature.
TL;DR: In this paper, an adiabatic logic family is presented, which makes use of a CMOS positive feedback amplifier, and a gate is based on dual rail logic and a cascade of such gates only needs three power/clock lines to operate.
Abstract: An adiabatic logic family is presented, which makes use of a CMOS positive feedback amplifier. The gate is based on dual rail logic and a cascade of such gates only needs three power/clock lines to operate. The positive feedback amplifier ensures high noise immunity and takes part in the energy recovery process.
TL;DR: In this article, the authors proposed two new sources emitting in the mid-IR: type-II and type-I interband cascade lasers, and performed detailed gain calculations. And they showed that high radiative efficiencies are expected, since the phonon processes which dominate relaxation in the intersub-band quantum cascade laser are effectively eliminated.
Abstract: The authors propose two novel sources emitting in the mid-IR: type-II and type-I interband cascade lasers, and perform detailed gain calculations. High radiative efficiencies are expected, since the phonon processes which dominate relaxation in the intersub-band quantum cascade laser are effectively eliminated.
TL;DR: In this article, the effect of diametric load on the wavelength of the reflected light from a low-birefringence fiber Bragg grating was studied, and the experimental results showed very good correspondance with the theoretical predictions.
Abstract: The effect of diametric load on the wavelength of the reflected light from a low-birefringence fibre Bragg grating is studied. The effects of loads up to almost 90 N on a 2.5 cm length of fibre are examined. The experimental results show very good correspondance with the theoretical predictions.
TL;DR: A new iterative decoding algorithm for serial concatenation is proposed, and it is shown that the new coding scheme can yield a significant advantage with respect to turbo codes.
Abstract: Serial concatenation of convolutional codes separated by an interleaver has recently been shown, through the use of upper bounds to the maximum likelihood performance, to be competitive with parallel concatenated coding schemes known in the literature as ‘turbo codes’. The most important feature of turbo codes consists in their relatively simple, yet high performance, iterative decoding algorithm. The authors propose a new iterative decoding algorithm for serial concatenation, and show that the new coding scheme can yield a significant advantage with respect to turbo codes.
TL;DR: The authors propose an alternative scheme consisting in the serial concatenation of block or convolutional codes and evaluate its average performance in terms of bit error probability.
Abstract: Parallel concatenated coding schemes employing convolutional codes as constituent codes linked by an interleaver have been proposed in the literature as ‘turbo codes’. They yield very good performance in connection with simple suboptimum decoding algorithms. The authors propose an alternative scheme consisting in the serial concatenation of block or convolutional codes and evaluate its average performance in terms of bit error probability.
TL;DR: The authors advocate an exceedingly general numerical method for the calculation of P(/spl Delta//spl les/0) based on Gauss-Chebyshev quadratures, which combines simplicity with accuracy.
Abstract: The evaluation of error probabilities in digital communication systems is often amenable to computing a probability of the form P(/spl Delta//spl les/0), where /spl Delta/ is a random variable whose probability distribution is known. As an example, the pairwise error probability of coded modulations can be expressed in this form. The authors advocate an exceedingly general numerical method for the calculation of P(/spl Delta//spl les/0) based on Gauss-Chebyshev quadratures, which combines simplicity with accuracy.
TL;DR: In this paper, a 3/4 rate cyclic code was proposed for the reduction of the peak to average power ratio of multicarrier modulation, which can be applied for any number of carriers which is a multiple of four.
Abstract: A very simple 3/4 rate cyclic code is proposed for the reduction of the peak to average power ratio of multicarrier modulation. The proposed code may be applied for any number of carriers which is a multiple of four. It is shown that the peak to average power ratio can be reduced by more than 3 dB. Numerical computations fully support the result obtained.
TL;DR: In this paper, a fiber Bragg grating pressure sensor with enhanced sensitivity was demonstrated, using a grating housed in a glass bubble, which increased the pressure sensitivity and effectively reduced the thermal crosstalk.
Abstract: A fibre Bragg grating pressure sensor with enhanced sensitivity has been demonstrated, using a grating housed in a glass bubble. This configuration increases the pressure sensitivity and effectively reduces the thermal crosstalk by a factor of 4. A pressure resolution of 0.5% over a full measurement range of 14 MPa has been achieved. This concept could lead to a range of sensors using fibre gratings with mechanical amplifiers to enhance sensitivity.
TL;DR: The Smart Cut process has been applied for the first time to SiC, in order to form silicon carbide on insulator (SiCOI) structures as discussed by the authors, and these structures have been formed on polycristalline SiC and on silicon substrates.
Abstract: The Smart Cut process has been applied for the first time to SiC, in order to form silicon carbide on insulator (SiCOI) structures. These structures have been formed on polycristalline SiC and on silicon substrates.
TL;DR: In this paper, the combination of self-phase modulation and spectral filtering provides a fast intensity dependent loss in the cavity, which equalises the pulse energies and completely suppresses supermode competition.
Abstract: Harmonically modelocked fibre lasers suffer from supermode noise because the slow gain relaxation time cannot equalise the individual pulse energies. The authors show that the combination of selfphase modulation and spectral filtering provides a fast intensity dependent loss in the cavity, which equalises the pulse energies and completely suppresses supermode competition.
TL;DR: In this article, the authors used rational harmonic mode-locking with an erbium doped fiber laser to obtain a frequency of (nfosc+Δf) at 1.55 µm, where n corresponds to 5.5 MHz.
Abstract: Pulse trains with repetition rates as high as 80~200 GHz were obtained at 1.55 µm, using rational harmonic mode-locking with an erbium doped fibre laser. A fundamental repetition frequency (fosc) of 40 GHz was first generated by applying a 40 GHz modulation frequency to an LN intensity modulator in the fibre cavity, in which the longitudinal mode spacing (Δf) was 1.5 MHz. By rationally detuning the modulation frequency by Δf/n, the authors succeeded in obtaining a repetitive oscillation of (nfosc+Δf). The maximum frequency was 200 GHz, at which n corresponds to 5.
TL;DR: In this article, an optical add/drop multiplexer that enables full access to 16 individual wavelength channels has been fabricated on the planar lightwave circuit (PLC), which consists of four arrayed-waveguide gratings which are connected through 16 double-gate thermo-optic switches.
Abstract: An optical add/drop multiplexer that enables full access to 16 individual wavelength channels has been fabricated on the planar lightwave circuit (PLC). The device consists of four arrayed-waveguide gratings which are connected through 16 double-gate thermo-optic switches. The crosstalk characteristics of the optical switches have been improved by adopting a double-gate configuration. The on-off crosstalks from main input or add port to main output or drop port are less than -28.4 dB and the on-chip insertion losses are 7.8-10.3 dB, respectively.
TL;DR: In this paper, a scheme for modifying the spacing between the bands of the Sierpinski antenna is introduced, where the fractal structure can be perturbed to enable the log-period to be changed while still maintaining the multiband behavior of the antenna.
Abstract: A scheme for modifying the spacing between the bands of the Sierpinski antenna is introduced. Experimental results of two novel designs of fractal antennas suggest that the fractal structure can be perturbed to enable the log-period to be changed while still maintaining the multiband behaviour of the antenna.