All-Optical Logic Based on Ultrafast Gain and Index Dynamics in a Semiconductor Optical Amplifier (original) (raw)
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All-Optical Logic Gates: Designs, Classification, and Comparison
Advances in Optical Technologies, 2014
The paper reviews the current status and designs of all-optical gates. Various schemes with and without semiconductor optical amplifiers are discussed and compared. The optical gates are classified according to their design structures. It is divided into two major divisions that is, nonsemiconductor optical amplifier based gates and semiconductor optical amplifier based gates. In nonsemiconductor optical amplifier based gates, different schemes have been proposed to create non-linearity which is discussed. The semiconductor optical amplifier based gates of different design structures are discussed to show the probe pulse that is modulated in different ways to obtain results.
IEEE Journal of Selected Topics in Quantum Electronics, 2008
We present experimental investigations of the dynamical properties of semiconductor optical amplifiers (SOAs) and their impacts in all-optical signal processing using SOAs. We introduce ultrafast optical signal characterization techniques to fully characterize the gain and phase dynamics of SOAs. We elucidate a consequence of the slow carrier recovery as pattern-dependent phase fluctuation in wavelength conversion of ON-OFF-keyed signals. We also analyze the conversion of the phase fluctuation into amplitude fluctuation limiting the performance of all-optical XOR operation. Finally, the performance of all-optical wavelength conversion of differential phase-shift-keyed signals is presented with emphasis on regeneration of the phase information.
We explain how a semiconductor optical amplifier in a Sagnac-interferometric arrangement can be used for switching of 200 fs optical pulses. The switching principles are based on gain and index saturation dynamics on a sub-picosecond timescale. We have carried out pump and probe experiments to measure the ultrafast refractive index dynamics of a multi-quantum well InGaAsP-InGaAs semiconductor optical amplifier that is operated in the gain regime. The pump and probe pulses are cross-linearly polarized. We observe a phase shift of 200 degrees if the amplifier is pumped with 120 mA of current, but find that the phase shift vanishes if the injection current is increased to 160 mA. Our results indicate a contribution of two-photon absorption to the nonlinear phase shift that opposes the phase shift introduced by the gain. Finally, we observe that the phase shift comes up and disappears within a picosecond.
All-optical Digital Processing Through Semiconductor Optical Amplifiers
Semiconductor Technologies, 2010
Semiconductor Technologies 438 designated output port. The other packet is delayed or discharged. Therefore a complex photonic digital circuit, able to compare two boolean numbers, is mandatory (Andriolli et al., 2007). All-optical subsystems able to discriminate if an N-bit (with N1) pattern representing a boolean number is greater or lower than another one are not reported yet. Calculating the addition of boolean numbers is another important functionality to perform packet header processing. If some packets are routed to the wrong link or are mislabelled, they can be routed in circles without reaching the destination. These loops are a cause of network congestion and must be avoided. A Time-To-Live (TTL) field in the packet prevents the formation of loops. This field represents the maximum number of hops of a packet and it is decremented after each node. When the field value is zero, the packet is discharged (McGeehan et al., 2003). The implementation of this functionality requires an all-optical processing circuit able to perform the decrementing of the boolean number in the TTL field. This operation can be performed by means of an all optical full-adder applying the so called method of complements (Hayes 1998). Moreover the all-optical full-adder can find application in resolving the Viterbi algorithm in the Maximum-Likelihood Sequence Estimation (MLSE) (Forney 1973; Proakis 1996). This method requires performing fast additions. An all-optical implementation of this algorithm can improve its efficiency. Other two important functions are analog-to-digital conversion (ADC) and digital-to-analog conversion (DAC). ADC is a key functionality which, converting continuous-time signals to digital binary signals, enables them to be transmitted through the modern digital communication networks. Applications regard e.g. radar signals, high-definition video, realtime signal monitoring, ultra-fast dispersion compensation. Although it didn't receive the same attention as all-optical analog-to-digital conversion, DAC and/or multilevel codification in the optical domain has also been extensively investigated in order to implement some ultra-fast signal processing functions. These functions include, for instance, pattern recognition for header extraction (Saida et al., 2001), amplitude multiplexing for increasing spectral efficiency (Abbade et al., 2005) or label/payload encoding techniques (Abbade et al., 2006), and waveform generation for radar and display applications (Yacoubian & Das, 2003). The photonic digital processing is effective and attractive if it can be realised with integrated solutions. SOAs have shown to be attractive because of their compactness, stability, low switching energy and low latency. SOAs are reliable, relatively low cost devices which can be integrated within complex optical circuits with hybrid techniques (Maxwell, 2008; Lal et al., 2007; Kehayas et al., 2006 b). In this perspective, the possibility of using a single basic building gate for implementing all the complex logic functions is practical. In this chapter new schemes for the implementation of SOA-based reconfigurable logic gates, a photonic combinatorial network, a comparator, a full-adder, a digital-to-analog converter and an analog-to-digital converter will be presented. 2. Reconfigurable logic gates with a single SOA Scheme of all-optical logic gates are reported in literature, using nonlinear effects in optical fibers (
All-optical high speed logic gates using SOA
Optics Communications, 2012
In this paper a novel and simple structure for operation as a high speed optical logic gate based on bulk semiconductor optical amplifier (SOA) is presented. The gain dynamic and phase response of bulk SOA using rate equations including the dynamics of carrier heating (CH) and spectral-hole burning (SHB) numerically is investigated. By using the presented numerical method, operation of NOR gate is analyzed and we show that the NOR gate can operates at 1Tb/s. High speed logic gates based on bulk SOA can be realized by using the proposed structure.
Journal of the Korean Physical Society, 2016
The performance of an all-optical logic OR gate is numerically studied and simulated. This Boolean operation is realized by using a semiconductor optical amplifier (SOA) and a delayed interferometer (DI) based on two-photon absorption (TPA). The input pulse intensities are high enough so that the two-photon-induced phase change is larger than the regular gain-induced phase change. The study is carried out with the effect of the amplified spontaneous emission (ASE) taken into account in the simulation analysis. The dependence of the output quality factor (Q-factor) on the data signals and SOA's parameters is also investigated and discussed. The achieved results show that the OR gate is capable of operating at a data speed of 250 Gb/s with logical correctness and proper Q-factor.