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 subcarriers, two of which beat in a photodiode to recover the clock.

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.

Two mechanisms that can make frequency conversion based on nonlinear mixing dependent on the phase of the input signal are identified. A novel phase-to-polarization converter that converts the orthogonal phase components of an input signal to two orthogonally polarized outputs is proposed. The operation of this scheme and a previously reported scheme at an increased symbol rate are simulated with semiconductor optical amplifiers (SOAs) as the nonlinear devices. Experimental results demonstrate the effectiveness of SOAs for nonlinear mixing over a wide range of wavelengths and difference frequencies and confirm the accuracy of the numerical model.

For the first time we demonstrate simultaneous suppression of phase distortion on two independent 10.7 Gbit/s DPSK modulated signal wavelengths using semiconductor optical amplifiers, realizing a compact phase sensitive amplifier with low power consumption.

Measurements of amplitude and phase dynamics of a concatenated SOA-EAM-SOA show 1/e amplitude recovery times as short as 2.6ps under optimal conditions, with longer 1/e phase recovery times (≥38ps). Due to the extremely fast amplitude recovery, the impulse response consists predominantly of a phase component only.

Dynamic phase and amplitude all-optical responses of silicon nanowires are characterized using a terahertz optical asymmetric demultiplexer (TOAD) based pump-probe scheme. Ultra-fast recovery is observed for moderate pump powers.

All-optical processing of phase encoded signals with nonlinear semiconductor optical amplifiers offers potential advantages. As examples, we demonstrate QPSK to 8PSK conversion and decomposition of QPSK to two BPSK outputs at new wavelengths.

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.

We propose and fabricate a two-bandgap SOA device integrated monolithically using a quantum well intermixing technique on an AlInGaAs-based multiple quantum well structure. With increased current injection into the wide bandgap section, the gain peak wavelength shows a shift to the blue and the gain at shorter wavelengths is significantly enhanced. The 3-dB gain bandwidth is extended with this two-bandgap SOA device, demonstrating the potential for realisation of wide bandwidth SOAs. Moreover, it is found that saturation output power depends on the direction of propagation, which may arise from a lower differential gain and/or a shorter carrier lifetime in the wide bandgap section.

In this paper we experimentally demonstrate an all-optical system incorporating a pair of hybrid-integrated semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometer (MZI) gates which translate RZ-OOK to RZ-DB or RZ-AMI at 42.6 Gbps. This scheme includes a wavelength conversion to arbitrary output wavelength and has potential for high level photonic integration, scalability to higher bitrates, and should exhibit regenerative properties.

Simultaneous conversion of the two orthogonal phase components of an optical input to different output frequencies has been demonstrated by simulation and experiment.A single stage of four-wave mixing between the input signal and four pumps derived from a frequency comb was employed.The nonlinear device was a semiconductor optical amplifier, which provided overall signal gain and sufficient contrast for phase sensitive signal processing.The decomposition of a quadrature phaseshift keyed signal into a pair of binary phase-shift keyed outputs at different frequencies was also demonstrated by simulation.

We describe a 42.6 Gbit/s all-optical pattern recognition system which uses semiconductor optical amplifiers (SOAs). A circuit with three SOA-based logic gates is used to identify specific port numbers in an optical packet header.

An all-optical XOR gate at 40 Gbit/s is demonstrated using ultrafast nonlinear interferometers (UNI) incorporating semiconductor optical amplifiers (SOAs), where no additional probe beam is required. The only inputs launched into the setup are the data A and B. The XOR logic of the data A and B is the sum of two components (A) over barB and A (B) over bar each of which is obtained from the output of UNI via cross-phase modulation in SOAs. The SOA switching pulse energy is lower than 33 fJ.

We propose a novel scheme employing complementary data inputs to overcome the patterning normally associated with semiconductor optical amplifier based gates and demonstrate the scheme experimentally at 42.6Gb/s. The scheme not only avoids introducing patterning during switching, but also compensates for much of the patterning present on the input data. A novel gate was developed for the experiment to provide the complementary signals required for the scheme.

We propose and numerically investigate for the first time a novel all-optical on-off-keying to alternate-mark-inversion modulation format converter operating at 40 Gbps employing a semiconductor optical amplifier (SOA)-based Mach-Zehnder interferometer (MZI). We demonstrate that this SOA-MZI operates as a pulse subtractor, and in the absence of patterning will produce perfectly phase inverted pulses regardless of the individual SOA phase excursions. We use a comprehensive computer model to illustrate the impact of patterning on the output phase modulation, which is quantified through the definition of the phase compression factor.

Two-color pump-probe measurements are used to study the carrier dynamics of InAs/GaAs quantum dots in a waveguide structure under reverse bias conditions. For the case of initially populating the ground state (GS), we find relaxation dynamics that include both absorptive and bleaching components in the excited state (ES) wavelength range. We reproduce the main features of this induced absorption dynamics using a simple model with an additional term for induced absorption at the ES due to carriers injected at the GS. The induced absorption dynamics includes multiple recovery timescales which can be attributed to phonon-assisted processes of GS/ES interaction.

We numerically investigate a novel 40 Gbps OOK to AMI all-optical modulation format converter employing an SOA-based Mach-Zehnder interferometer. We demonstrate operation with a 2 7 -1 PRBS and explain the phase modulation’s relationship with patterning.

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.

A pattern recognition system comprising three SOA-based logic gates locates programmable patterns of arbitrary length in 42Gb/s data. It will provide initial screening in an optoelectronic firewall being developed to protect future optical packet-based networks.