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In this paper, we are going to exhibit the system performance using the single, double and three-electrode quantum-dot semiconductor optical amplifier as an intensity modulator (3E-QD-SOA-IM) of the adaptively modulated optical orthogonal frequency division multiplexing (AMOOFDM) signals in the intensity-modulation direct-detection passive optical network (IMDD-PON) systems. Moreover, to compare the bit-rate versus transmission distance of the proposed fiber link model when using both configurations multi-electrode semiconductor optical amplifier intensity-modulator (ME-SOA-IM) and multi-electrode quantum-dot semiconductor optical amplifier intensity-modulator (ME-QD-SOA-IM), to study the improvement of the transmission capacity, distance reach and power efficiency when applying the proposed configurations for optical access networks for distances ranging from 20 km up to 120 km. The three-electrode configuration solved the nonlinearity of the two-electrode configuration and offered a considerably wider range of optimum operating conditions to achieve up to 35 Gbps. Furthermore, the 3E-QD-SOA-IM showed a better performance over the 3E-SOA-IM over all the 120 km, and a 5 Gbps enhancement in the bitrate with a 20 dB less optical input power at 20 km.

Wavelength division multiplexing (WDM) is a very important technique to utilize the bandwidth of optical fiber; multiple channels can be transmitted in the same fiber cable at the same time, and each channel has individual wavelength. At different network node, it’s required to add or drop wavelength, wavelength converter process is a technique responsible for converting the wavelength of signal to other wavelength up or down from the original value. This paper has presented a proposed model to generate inverted and non-inverted wavelength conversion by using single wide band traveling wave semiconductor optical amplifier (WBSOA), based on cross-gain modulation. The investigation of conversion efficiency ( ) and quality factor ( ), versus pump power ranged value from −30 to 0 dB m, and input signal power is 0 dB m with data rate 25 Gb/s, are studied for up and down-wavelength conversion, “co-propagation” and “counter-propagation”, respectively. The simulation results indicate that, to get maximum conversion efficiency and maximum quality factor by using single WBSOA, the pump power should be located between −30 to −20 dB m for maximum conversion efficiency and equal to −10 dB m for maximum quality factor, that for up- and down-wavelength conversion, co-propagation and counter-propagation.

The use of optics in information processing, computation, and communication is well-established since last few decades. Electro-optic material has several applications in integrated optics, optical communication, and data processing. The modulator is generally used for the purpose of phase and amplitude modulation of an optical wave by electrical message signal. Again semiconductor optical amplifier (SOA) is an example of high-speed optical switch which requires a small electrical power to switch an optical signal. Add drop multiplexer and reflected semiconductor optical amplifier are special type of optical switches made of SOAs. Here in this paper authors propose an analytical study on recovering of biasing or modulating signal from the phase-modulated output of electro-optic modulator using semiconductor optical amplifier-based system.

Semiconductor optical amplifier-based polarization rotation is utilized in designing all-optical AND gate at 100 Gbps. The AND gate shows high extinction ratio (ER ∼ 15 dB), contrast ratio (CR ∼ 18 dB) and quality factor (Q-factor ∼ 16 dB). The effect of the amplified spontaneous emission noise on the performances is also investigated. The AND gate has relative eye opening (REO) varying from 93.52 to 97.1% for 10–30 dB unsaturated gain. Using the AND gate a majority voting gate is designed and analyzed and has Q ∼ 11.7 dB with REO ∼ 91%.

Light is established as a successful carrier in quantum optical computing and data processing, as photon always maintains the quantum phenomenon of a particle. In this connection it is always associated with definite wave function (eigenstate) and eigenvalues of energy, polarization, momentum, etc. Since last few years, different research works are seen in the field of quantum computing, where light is used as a carrier signal at different capacities, because of several hidden advantages of light. To do these, scientists used the optical/optoelectronic switches in proper method. In this paper, the authors have studied different applications of light in the area of quantum computing, where the stream of photon flow are modulated by the use of high-speed optical/optoelectronic switches. In this review study the applications of electro-optic Pockels cell-based switches, semiconductor optical amplifier (SOA)-based switches and photonic band gap crystal-based switches in the domain of quantum optical computing and information processing are included. These switches are high speed in nature and can act on the quantum state of light to make necessary changes. Here only some important areas in this field are covered, though there are a number of research outcomes which are not discussed because of space limitations.

In optical networks, header recognition systems (HRS) plays an important role in matching the incoming bits with local address. Conventional HRS is designed using XNOR gate followed by AND gate. AND gate operation further requires a wavelength converter and start bit generator for synchronization of XNOR with AND gate. In this paper, for the first time, 4 bit header recognition system, is presented using carrier reservoir semiconductor optical amplifier (SOA) based XNOR gate and conventional semiconductor optical amplifier (SOA) at 100 Gb/s. AND gate, wavelength converter, and start bit generator are replaced by conventional SOA by exploiting its slow gain recovery leading to gradual pulse power reduction, to detect bit pattern 1111 which denotes matching of input bits with local address. The unique sequence of 1111 will cause gain saturation in conventional SOA hence the fourth bit will be least amplified, therefore power of fourth bit will be used to determine match/mismatch case. The proposed scheme offers several advantages such as simpler design, require less number of active elements, reduced power consumption and processing time. Header recognition operation has been assessed and evaluated by various performance parameters such as quality factor, extinction ratio, eye opening factor. Obtained quality factor is further examined against critical parameters such as amplifier noise, data rate, transition time of carriers from CR to AR, population inversion factor, etc. The results demonstrate that the proposed HRS can perform pattern matching without AND gate at 100 Gb/s with accepstable performance parameters.

All-optical quantum logic gates with qubit data are the essential components in optical signal processing and computing. Quantum optical Toffoli gate is one of the most useful logic gates in the logic family which is extensively used to perform ultrafast optical digital operations. Here, in this paper, an all-optical scheme for realization of frequency encoded tristate Toffoli gate is proposed. Semiconductor optical amplifier based optical switches like frequency converters and add/drop multiplexers are used to implement the system. Also, a proper truth table and gate matrix of tristate Toffoli gate is developed. Tristate based optical logic operations not only increase the data handling capacity, it also increases the speed of different optical logic operations because of inherent parallelism of light. As frequency encoding principle is used to encode the qubits, so bit error problem can be ignored by the proposed system. The system is entirely all-optical in nature, so the system exhibits very high speed of operation (above tera hertz) with improved signal to noise ratio.

Broadband amplification in the O+E-band is very desirable nowadays as a way of coping with increasing bandwidth demands. The main issue with doped fiber amplifiers working in this band such as the bismuth-doped fiber amplifier is that they are costly and not widely available. Therefore, a wideband and flat-gain hybrid optical amplifier (HOA) covering the O+E-band based on a parallel combination of a praseodymium-doped fiber amplifier (PDFA) and a semiconductor optical amplifier (SOA) is proposed and demonstrated through numerical simulations. The praseodymium-doped fiber (PDF) core is pumped using a laser diode with a power of 500 mW that is centered at a wavelength of 1030 nm. The SOA is driven by an injection current of 60 mA. The performance of the HOA is analyzed by the optimization of various parameters such as the PDF length, Pr3+ concentration, pump wavelength, and injection current. A flat average gain of 24 dB with a flatness of 1 dB and an output power of 9.6 dBm is observed over a wavelength range of 1270–1450 nm. The noise figure (NF) varies from a minimum of 4 dB to a maximum of 5.9 dB for a signal power of 0 dBm. A gain reduction of around 4 dB is observed for an O-band signal at a wavelength of 1290 nm by considering the up-conversion effect. The transmission performance of the designed HOA as a pre-amplifier is evaluated based on the bit-error rate (BER) analysis for a coarse wavelength-division multiplexing (CWDM) system of eight on-off keying (OOK)-modulated channels, each having a data rate of 10 Gbps. An error-free transmission over 60 km of standard single-mode fiber (SMF) is achieved for different data rates of 5 Gbps, 7.5 Gbps, and 10 Gbps.

Picosecond optical pulses generation in a ring fiber laser with a semiconductor optical amplifier was investigated. Optical spectrum width is minimal at a fundamental resonant repetition frequency of 45 MHz, corresponding to a fiber resonator length of 4.5 m. As the frequency increases, the spectral width increases by an order of magnitude while the pulse duration decreases to 18 ps, and the power increases to 0.5 W. The power of picosecond optical pulses at the output of the semiconductor amplifier is 7 times higher than in the CW mode due to the carrier accumulation effect that occurs with short pump pulses.

In this paper, we have reported radio over fiber system with 30-tuple millimeter-wave generation using dual parallel Mach–Zehnder modulator and semiconductor optical amplifier. The optimum choice of Mach–Zehnder modulator parameters has resulted into generation of signal lightwave and pump signal with frequency separation of 10 . Four wave mixing effect in semiconductor optical amplifier results into 30-tuple millimeter-wave signal. The proposed scheme is applicable to radio over fiber system with multiple base stations. The multiple number of frequencies such as 50 GHZ, 100 GHz, and 150 GHz have been generated using 5 GHz radio frequency only. NRZ data at 2.5 Gbps was modulated and successfully transmitted via optical fiber. The impact of injection current on the sideband ratio and BER is investigated. The proposed scheme confirms quality reception of demodulated signal at a transmission distance of 20 km.