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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
optical adder an optical device capable of performing the function of arithmetic addition using binary signals. It can be constructed using a series of cascaded full adders where carry has to ripple through each full adder from least significant bit to most significant bit. It can also be constructed using cascaded layers. Each layer consists of a series of half adders. Carry also has to ripple through the cascaded layers. It is also known as digital adder. optical addition adding operation using light. Two incoherent light beams have intensities A and B, respectively. When two beams are combined, i.e., illuminating the same area, the resultant intensity is A + B. optical amplifier amplifier of electromagnetic waves at optical frequencies, usually by the process of simulated emission or nonlinear optics. See laser amplifier. optical beam beam of electromagnetic power at optical frequencies. optical bistability the property of certain nonlinear optical system to possess two possible output states for a given input state. In one typical example, the bistable optical device has the form of a third-order nonlinear optical material placed inside of an optical cavity, and the device can display two possible different transmitted intensities for certain values of the input intensity. optical bus an optical channel used for transmitting a signal from a source to one or more
Microwave Photonics
Published in Chi H. Lee, Microwave Photonics, 2017
A further important comment should be made at this point. The multifunctional EAT, with the internal feedback between the detection and modulation mechanisms, behaves similar to the well-known SEED (self-electro-optic device) element. Consequently, it can further be used to generate artificial optical and optoelectronic nonlinearities such as optical bistability [28], which gives rise to switching, logic, and memory effects. It has been shown that such a bistable characteristic may be useful for multiple GHz A/D conversion. The vertical EAT of Figure 1.12 is a device with a world record of switching energy and speed. The vertical EAT consists of an optical multilayer Bragg filter using a set of quarter wavelength semiconductor heterostructures such as GaAs/AlAs films. Please note that such a device is also a R-EAT. It should further be mentioned that besides bistability, the output versus input characteristics can also be monostable with controllable slope, which obviously is equivalent to a small signal optoelectronic gain.
Semiconductor Photonic Devices as Excitable Processors
Published in Paul R. Prucnal, Bhavin J. Shastri, Malvin Carl Teich, Neuromorphic Photonics, 2017
Paul R. Prucnal, Bhavin J. Shastri, Malvin Carl Teich
Soljačić et al. [72] proposed an analytical model along with numerical simulations for optical bistable switching in a nonlinear PC. Optical bistability in microcavities and nanocavities is of particular interest for its potential applications in all-optical transistors, switches, logical gates, and memory [73, 74]. Since then, there has been an active investigation of self-pulsing and excitability in two-dimensional (2D) PC resonators [22, 23, 75, 76] and in PC nanocavities [24, 77–80]. Both optical and electronic nonlinearities have been exploited to observe these phenomena. The latter is, however, difficult to achieve and observe due to the weak signals at play with fast time scales (picosecond to nanosecond). In the optical domain, third-order Kerr nonlin-earity plays a key role to achieve bistability and excitability. The key is to enhance this nonlinearity and reduce operation thresholds with tight confinement of light. Reducing both the optical volume and optical losses leads to a decrease of the bistability threshold since the latter scales as V/Q2 (where V is the optical mode volume and Q the cavity quality factor) [72, 73]. Both Yacomotti et al. [22] and Brunstein et al. [24] demonstrated class 2 excitability in a 2D PC. In class 2 excitability there are two distinct time scales at play: the fast one is responsible for the firing of the excitable pulse, and the slow one determines the full recovery to the quiescent state [22, 81]. In the 2D PCs, the fast and slow time scales are governed by the carrier recombination time and the thermal relaxation due to thermal diffusion, respectively.
Multistability and Fano resonances in a hybrid optomechanical photonic crystal microcavity
Published in Journal of Modern Optics, 2021
Sajia Yeasmin, Surabhi Yadav, Aranya B. Bhattacherjee, Souri Banerjee
One of the essential pre-requisite to design and fabricate tunable all-optical switching devices is the existence of optical bistability/multistability [48]. A high degree of nonlinearity prevails in our proposed system due to the optomechanical interaction and this may result in the possibility of optical multistability to exist if the system parameters are tuned properly. Figure 2(a) illustrates the optical bistability curve obtained by solving Equation (16) numerically. It is a plot of intracavity photon number as a function of incident pumping rate . It shows a typical hysteresis loop that the intracavity photon number follows as the incident pumping rate is increased or decreased. Transition from the off-state to the on-state takes place at the lower transition point (LIP) while transition from the on-state to off-state takes place at the upper transition point(UTP). Both the off-state and on-state are the stable solutions of Equation (16).
Optical switching and normal mode splitting in hybrid semiconductor microcavity containing quantum well and Kerr medium driven by amplitude-modulated field
Published in Journal of Modern Optics, 2020
Madhav Kumar Singh, Pradip Kumar Jha, Aranya Bhattacherjee
With the advancement of research in quantum optics, it has been demonstrated that optical nonlinearity at a single photon level demonstrates the potential for the implementation of ultra low power and high speed of all optical gates and switches for classical information processing [1–7]. Achieving single photon nonlinearities in solid-state systems usually relies on enhanced light matter coupling of some dipole allowed transition, where excitation can provide the required quantum anharmonicity [8–12]. Several experiments in the past focused on analysing optical nonlinearity and proposed its application for all optical switching [13,14]. For efficient all optical switching, there is a need for optical nonlinearity that can be achieved with low power light. It has been a goal of optical physicist to utilize light to control the transmission of another optical signal, and thus constructing all optical logic gates [15–24]. One of the ways to achieve such phenomena is via optical bistability, in which two distinct output optical powers can be achieved for the same input power [25]. Optical bistability has created a great deal of interest from both fundamental and applicative point of view, for instance, it can be used to implement optical logical elements for all optical information processing and optical transistors. There are many ways to control optical bistability such as quantum interference, squeezed light field and spontaneously generated coherence [26–36].