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We describe recent advances in the use of semiconductor optical amplifiers for all-optical signal processing of phase-based modulation formats. Four-wave mixing, which is inherently phase sensitive, is exploited in the techniques described.
We report a novel all-optical clock recovery technique for a BPSK OFDM superchannel. Four-wave mixing in SOAs strips the modulation from the superchannel sub-carriers, two of which beat in a photodiode to recover the clock.
We argue that the use of nonlinear semiconductor optical amplifiers for all-optical processing of phase encoded signals offers potential benefits. To illustrate the point, we demonstrate QPSK to 8PSK conversion and decomposition of QPSK to two BPSK outputs at new wavelengths by four-wave mixing.
Advanced modulation formats have become increasingly important as telecoms engineers strive for improved tolerance to both linear and nonlinear fibre-based transmission impairments. Two important modulation schemes are Duobinary (DB) and Alternate-mark inversion (AMI) [1] where transmission enhancement results from auxiliary phase modulation. As advanced modulation formats displace Return-to-zero...
We propose a novel scheme employing complementary data inputs to overcome the patterning normally associated with semiconductor optical amplifier based switches and demonstrate the scheme experimentally at 42.6 Gb/s. The scheme not only avoids introducing patterning during switching, but also compensates for much of the patterning present on the input data.
We demonstrate the first fully integrated all-optical XOR gate, running at 42.6Gb/s, which has on-chip delays and power splitters. Error-free operation is obtained.
We demonstrate all-optical pattern recognition using semiconductor optical amplifier logic gates. For the first time, target patterns up to 256 bits long were successfully recognised and located in 42 Gbit/s data.
We demonstrate all-optical pattern recognition using semiconductor optical amplifier logic gates. For the first time, target patterns up to 256 bits long were successfully recognised and located in 42Gbit/s data.
In this paper, we propose and demonstrate a novel all-optical pattern recognition system. The system is able to detect and locate a specified target pattern within an input data sequence at high line-rate. The key elements of the system are an all-optical XNOR logic gate and an all-optical AND gate, the latter forming part of a recirculating loop. Both these gates are based on semiconductor optical...
We propose a novel programmable pattern recognition system employing all-optical logic gates and experimentally demonstrate key functions at 42 Gbit/s. Gate count is independent of target length and the temporal position of the target is identified.
We review recent methods to increase the speed of the nonlinear optical response of semiconductor optical amplifiers (SOAs), including the use of filters and of an additional SOA in the 'turbo-switch' configuration. We also consider the effects of optimising parameters, such as the confinement factor and optical area, on the recovery rate.
We present two types of 42.6 Gbit/s all-optical non-return-zero (NRZ) to return-zero (RZ) format converters using semiconductor optical amplifiers (SOAs). The converters are based on cross-phase modulation (XPM) and cross-polarisation modulation (XPolM) in SOAs. Both format converters produce a correctly-coded, polarity- preserved RZ signal at the output and have the flexibility of variable NRZ input...
This paper reviews some of the most recent methods for increasing the speed of operation of all-optical switches based on semiconductor optical amplifiers (SOAs). We concentrate on two approaches; namely, methods to utilise the high-frequency tail of the nonlinear optical response of SOAs, and ways to reduce their gain recovery time.
We present for the first time error-free 42.6 Gbit/s all-optical NRZ to RZ format conversion using a single SOA. The RZ output is correctly coded, wavelength and polarity preserved, and has the flexibility of variable duty-cycle.
By measuring cross-gain modulation in a turbo-switch, we demonstrate that appropriate control of the optical power in this high-speed all-optical switch results in greatly reduced dependence on the input data pattern. We further show that the non-linear patterning may even be reversed for high internal powers.
We demonstrate error-free all-optical 40Gb/s wavelength conversion using nonlinear polarisation rotation in semiconductor optical amplifiers (SOAs). The high speed of the device is achieved by incorporating an SOA-based turbo-switch. The switching energy is 10fJ/pulse.
We investigate the dependence of the high-speed performance of bulk GalnAs semiconductor optical amplifiers (SOAs) on the dimensions of the active region. Corroborating experimental and modelling results predict a two-fold speed increase for optimised dimensions.
We describe the operating principle and performance of the 'turbo-switch', a new configuration of semiconductor optical amplifiers (SOAs) that gives an enhanced high-speed response for all-optical switching without compromising the optical signal-noise ratio. Error-free wavelength conversion is obtained at 170 Gb/s based on the use of an offset Mach-Zehnder interferometric filter incorporating a turbo-switch...
It is shown that interferometers containing quantum-dot semiconductor optical amplifiers can be effective for ultrafast cross-phase modulation and digital signal processing with low dependence on the specific random data pattern.
This paper correlates photodisplacement thermal wave characterization of ion implanted silicon wafers with the lattice information provided by Rutherford Backscattering Spectrometry.
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