1,721,067 research outputs found
Optical regeneration using self-phase modulation and quasi-continuous filtering
No full textWe propose a scheme for 2R optical regeneration based on self-phase modulation in fiber and quasi-continuous filtering. Numerical simulations demonstrate the possibility of increasing the transmission reach from 3500 to more than 6000 km at 10 Gb/s using 100-km spans. Spectral broadening is shown to be small using this technique, indicating its suitability for wavelength-division-multiplexing regeneratio
Time-division-multiplexing using pulse position locking for 100 Gb/s applications
Full text linkRecently, there is a great interest in pushing communication technologies to 100 Gb/s. However, there are still many challenges to perform high speed (> 40 Gb/s) clock and data recovery, and data time-division-multiplexing (TDM). Here, we propose and numerically analyze an asynchronous optical packet retimer using parabolic or sinusoidal phase modulation and linear dispersion. This scheme is named pulse position locking (PPL). Numerical simulation shows that this scheme can effectively resynchronize input signals with arbitrary delays to the local clock, and reduce input jitter. The scheme can also be applied to TDM 10 Gb/s and 40 Gb/s signals to over 100 Gb/s
40 Gbit/s 1.55µm RZ transmission over 109km of non-dispersion shifted fibre with long continuously chirped fibre gratings
No full textWe report the first demonstration of 40 Gbit/s transmission over 109 km of standard fibre at 1.55µm with dispersion compensating linearly chirped continuous fibre gratings and a ~0.5 nm source wavelength tolerance, demonstrating the feasibility of fabricating such gratings for use at very high data rate
Dispersion compensated 10 Gbit/s transmission over 700km of standard single mode fibre with 10cm chirped fibre grating and duobinary transmitter
No full textUsing a 10 cm long chirped fiber grating for dispersion compensation and a reduced bandwidth phase alternating duobinary-encoded transmitter, 10 Gbit/s transmission up to 700 km of standard single mode fiber has been achieved. Positioning of the compensating grating at the middle of the link was found to improve the system performance considerably
An optical fibre rereadable radiation dosimeter for use at high doses and at elevated temperature
Full text linkA new type of radiation dosimeter for large radiation doses is described, which is based on silica fibre material. Conventional radioluminescence or thermoluminescence of silica produces emission in the blue region of the spectrum. However, in this new material irradiation, in conjunction with a heat treatment, generates a green emission band. The intensity of the green band can be monitored by either radioluminescence or thermoluminescence using a test dose. The signals are directly related to the total irradiation history of the material. The dosimeter is therefore rereadable. The production mechanism of the green emission centre requires a thermal processing stage, with an activation energy of 0.52 eV. Further, the dosimeter is effective at recording radiation during high-temperature exposure, to at least 400°C, with the subsequent dosimetry being performed below 200°C
Rectangular pulse generation based on pulse reshaping using a superstructured fiber Bragg grating
Full text linkWe present a technique for the shaping of short pulses based on the use of superstructured fiber Bragg gratings (SSFBGs). We apply this technique to demonstrate the generation of 20-ps rectangular pulses by phase and amplitude profiling of 2.5-ps soliton pulses. Numerical calculations validate our experimental finding
10Gbit/s transmission over 700km of standard single mode fibre with a 10cm chirped fibre grating compensator and duobinary transmitter
No full textThe advent of erbium-doped fibre amplifiers makes optical fibre transmission in the 1.55µm wavelength window very attractive. However, with the large amounts of standard non-dispersion shifted fibres (NDSF) already installed, high bit rate transmission is restricted by the large dispersion of these fibres at 1.55µm, unless compensating techniques are used. A number of approaches have been put forward to address this issue, such as dispersion compensating fibre, mid-point spectral inversion, dispersion-supported transmission, solitons, and chirped fibre Bragg gratings. Of these, fibre gratings are attractive as they are passive, linear devices, highly dispersive yet compact and relatively easy to fabricate in large numbers. In recent years, progress in the use of fibre grating-based compensation for 10 Gbit/s transmission has been rapid, with distances reported from 160km, 220km, 270km, 400km and most recently to 540 km. In this work, we demonstrate that 10 Gbit/s transmission up to 700 km of NDSF is achievable with a single 10 cm long chirped fibre grating in combination with a reduced bandwidth phase-alternating duobinary transmitter
Experimental demonstration of 10 Gbit/s, 4.7ps pulse transmission over 4300km in a low dispersion, loss compensating dispersion decreasing fibre
No full textWe describe recent results on the fabrication of low dispersion, loss compensating dispersion decreasing fibres and report their use in long distance, ultrashort pulse transmission experiments. Error-free propagation of 10 GBit/s, 4.7ps pulses over 4300km of such fibre is demonstrated illustrating the benefits of the reduced dispersion range achieved
Communication networks beyond the capacity crunch
Full text linkThis issue of Philosophical Transactions of the Royal Society, Part A represents a summary of the recent discussion meeting ‘Communication networks beyond the capacity crunch’. The purpose of the meeting was to establish the nature of the capacity crunch, estimate the time scales associated with it and to begin to find solutions to enable continued growth in a post-crunch era. The meeting confirmed that, in addition to a capacity shortage within a single optical fibre, many other ‘crunches’ are foreseen in the field of communications, both societal and technical. Technical crunches identified included the nonlinear Shannon limit, wireless spectrum, distribution of 5G signals (front haul and back haul), while societal influences included net neutrality, creative content generation and distribution and latency, and finally energy and cost. The meeting concluded with the observation that these many crunches are genuine and may influence our future use of technology, but encouragingly noted that research and business practice are already moving to alleviate many of the negative consequences
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