The growing demand for mid-infrared broadband laser sources is driven by their critical applications in trace gas detection, free-space optical communication, and countermeasure technologies. Recent advances in supercontinuum generation have utilized waveguide-based near-infrared pumps and bulk mid-infrared sources. This paper presents a numerical simulation of pulse propagation and mid-infrared supercontinuum generation in a waveguide constructed from highly nonlinear chalcogenide glasses (As 2 Se 3 /As 2 S 3 ). The Generalized Nonlinear Schrödinger Equation is solved using the Split Step Fourier Method, allowing for a comprehensive analysis of how factors such as fiber nonlinearity, Group Velocity Dispersion (GVD), input power, pulse width, and both anomalous and normal dispersion pumping regimes influence the resulting supercontinuum bandwidth. A tapered waveguide model is employed to enable continuous and simultaneous tuning of both the GVD and Kerr nonlinearity. By pumping the waveguide with 230 fs secant hyperbolic pulses at a peak power of 4.0 kW, the simulation produces a mid-infrared supercontinuum extending across a broad wavelength range, from approximately 1–10 [Formula: see text]m. These results provide insights that are vital for optimizing mid-IR laser sources, which have the potential to enhance a wide array of optical applications.

As light propagates through the fiber, phase distortions are often introduced due to local variations of stress and temperature. These variations can impair the performance of a phase-shifted optical transmission system which utilizes QPSK or QAM transmission format. Semiconductor optical amplifiers (SOAs) can produce a phase conjugate signal using the four-wave mixing (FWM) process. Thus, using a SOA in the middle of a transmission link, it is possible to reduce the errors caused by phase distortions. This paper describes the FWM process in SOA and the results of a transmission experiment.

In this work, we investigate the two-photon absorption (TPA)-based quantum-dot semiconductor optical amplifier (QD-SOA) to simulate the encryption and decryption. Optical logic gates and pseudo-random binary sequence (PRBS) generators are realized using the TPA-based QD-SOA, and the encryption algorithm and key are based on these optical logic gates. The fast phase change due to the incorporation of TPA allows generation of keystream at high speed. Simulation results are carried out to show that encryption and decryption using PRBS based on optical logic gate are achievable.

Interest in mid-infrared broadband laser light sources has surged due to applications in trace gas detection, free-space communications, and countermeasures. Progress in supercontinuum generation leverages fiber-based near-infrared and bulk-optic mid-infrared pump sources. In this paper, the Generalized Nonlinear Schrödinger Equation has been solved, using the Split Step Fourier Method, to simulate the pulse propagation and mid-infrared supercontinuum generation, inside a fiber composed of highly nonlinear As 2 Se 3 /As 2 S 3 chalcogenide glass. The effect of various parameters, including fiber nonlinearity, Group Velocity Dispersion (GVD), input power and pulse-width, anomalous and normal dispersion pumping regime, etc. on the output supercontinuum bandwidth has been extensively studied. A tapered chalcogenide fiber is modeled to facilitate continuous simultaneous modification of the GVD and the Kerr nonlinearity parameter. Pumping the waveguides with 230-fs secant pulses at a peak power of 4.2-kW yields a mid-IR supercontinuum extending from [Formula: see text] to [Formula: see text] micrometers.

We propose schemes for binary adder, subtractor and parity checker using optical logic gates. These schemes could be useful for calculations using optical systems. Utilizing optical logic gates, we can achieve functions of binary adder, subtractor and parity checker of high-speed optical signals. Due to two-photon absorption in the wetting layer, quantum dot-semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA-MZI) can work as high data rate optical logic gates. The simulated result supports the idea that it is possible to realize all-optical binary adder, subtractor and parity checker at high optical signal rates.

This paper describes the recent advances in device designs and optical transmission applications of semiconductor optical amplifiers (SOA). The device advances described are quantum-dot-based SOA and photonic-integrated circuits using SOA. The use of nonlinear properties of SOAs in high-speed optical transmission is discussed.

A 30-GHz pulse-train is generated using the rational harmonic mode-locking technique, experimentally, using a Mach–Zehnder Lithium Niobate modulator. The width of the pulses is then reduced from 5.8-ps to 1.9-ps by incorporating nonlinear polarization rotation. This phenomenon arises due to the very high nonlinear behavior of the photonic crystal fiber (PCF) added to the ring laser cavity. Numerically solving the Generalized Nonlinear Schrödinger Equation provided insights into the pulse evolution behavior. The relative polarization angle and length of the PCF were varied to study their effects on the pulse-width.

Optical pulses at high repetition rates are generated using rational harmonic mode locking and saturable absorber made of graphene nanoparticles in a fiber laser. The pulse generation from the fiber laser is modeled by solving the Generalized Nonlinear Schrodinger Equation. The computation involved varying the various saturable absorption parameters, such as linear and nonlinear absorption coefficients. Experimentally stable pulse trains at 20 GHz and 50 GHz are generated with a pulse width of ∼ 2.7 ps. This result agrees with the simulation.

In this paper, we propose a scheme for high-speed all-optical Pseudo-Random Binary Sequence (PRBS) generator and use it for generating keystream for encryption. This PRBS generator design is based on Linear Feedback Shift Registers (LFSR) and optical XOR and AND gates. The optical logical gates are based on quantum dot-semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA-MZI). With two photon absorption (TPA) in quantum dot-semiconductor optical amplifier (QD-SOA), this kind of optical logic gates performs well when processing data in an ultra-fast timescale and therefore able to function as high speed PRBS generator. Result shows that it’s possible for this scheme to realize all-optical encryption and decryption at high process rate up to 320 Gb/s. We simulated different ways of generating keystream with schemes such as cascaded generator, parallel generator and alternating step generator. These generators use more than one LFSR. Result shows that the schemes we use can function as stable and complex keystream generators.

Mode locked fiber ring laser using graphene nanoparticles as saturable absorbers to compress the pulse width has been studied. An experimental method to demonstrate the generation of pulse train with 50 GHz repetition rate with an ultrashort pulse width has been demonstrated. This method uses a combination of rational harmonic mode-locking (RHML) and a saturable absorber in the fiber ring laser. The pulse width using saturable absorbers is shorter by about a factor of 2 compared to that without a saturable absorber. Pulse generation using fiber ring laser with a saturable absorber has been analyzed. The experimental results are in agreement with the results from the simulation.

The effect of two-photon absorption (TPA) on all-optical logic operation in quantum-dot semiconductor optical amplifier (QD-SOA) has been carried out. The rate equation was modeled with the TPA effect for the logic XOR gate, AND gate, and, for pseudo-random bit sequence (PRBS) generation. The output Q-factor (quality) has increased due to the implementation of TPA induced pumping. The results show that the quality of the output depends on the input pulse width and the speed of operation. The PRBS system has been shown to operate at 250 Gb/s and 320 Gb/s and the Q-factor decreases with an increase in pulse width.

Recent progress of high-speed all-optical logic gates based on dual semiconductor optical amplifiers (SOAs) has been reviewed in this article. These schemes include using quantum-dot semiconductor optical amplifier (QD-SOA) and two-photon absorption (TPA). Numerical simulation method was presented by solving the rate equations of gain dynamics in the SOA. Performance of all-optical logic operation is discussed by calculating the quality factor and plotting the eye diagram. Results show that the dual SOA scheme is a promising method for the realization of high-speed all-optical logic systems in the future.

We simulate supercontinuum generation for various shapes of a dispersion varying As2S3 waveguides on MgF2 substrate with air cladding. The supercontinuum generation is simulated for pulses of 2000 W peak power and 50 fs pulse width centered at 1.55 μm wavelength. For a uniform waveguide the generated spectrum is considerably narrower than that for a non-uniform waveguide. This is because the non-uniform waveguide allows a continuous phase matching of the generated waves through nonlinear interaction. We have demonstrated that a high coefficient of nonlinear refractive index is necessary for generating supercontinuum with large bandwidths. Larger supercontinuum bandwidth is predicted for waveguides with increasing As2S3 thickness along the propagation direction.

A scheme to generate 50 GHz pulse train using rational harmonic mode locking technique is proposed and studied experimentally. The modulation frequency is adjusted to achieve a 50 GHz pulse train which has a pulse width of 5.25 ps. Numerical simulation results show good agreement with the experimental results.

In this paper, we propose and experimentally demonstrate a mode locked fiber ring laser with the implementation of a photonic crystal fiber (PCF) to generate pulse train at high speed. This fiber ring laser combines rational harmonic mode locking based on a Lithium Niobate Mach-Zehnder modulator and nonlinear polarization rotation from a highly nonlinear PCF. By fine tuning of the modulation frequency and the polarization controllers in the cavity, a 30 GHz pulse train with pulse width 1.9 ps is generated. Without the PCF, the pulse width at 30 GHz from the rational harmonic mode locking is 5.8 ps. We also conduct numerical simulations of the pulse evolution, which shows good agreements of the experimental results.

We propose a scheme to realize all-optical logic operation in quantum-dot semiconductor optical amplifier (QD-SOA) based Mach-Zehnder interferometer (MZI) considering the effects of two-photon absorption (TPA). During propagation of sub-picosecond pulses in QD-SOA, TPA leads to an additional change in carrier recovery dynamics in quantum-dots. We utilize a rate equation model to take into account carrier refill through TPA and nonlinear dynamics including carrier heating and spectral hole burning in the QD-SOA. The simulation results show the TPA induced pumping in the QD-SOA can reduce the pattern effect and increase the output quality of the all-optical logic operation. With TPA, this scheme is suitable for high speed Boolean logic operation at 320 Gb/s.

We investigate all-optical logic operation in quantum-dot semiconductor optical amplifier (QD-SOA) based Mach-Zehnder interferometer considering the effects of two-photon absorption (TPA). TPA occurs during the propagation of sub-picosecond pulses in QD-SOA, which leads to a change in carrier recovery dynamics in quantum-dots. We utilize a rate equation model to take into account carrier refill through TPA and nonlinear dynamics including carrier heating and spectral hole burning in the QD-SOA. The simulation results show the TPA-induced pumping in the QD-SOA can reduce the pattern effect and increase the output quality of the all-optical logic operation. With TPA, this scheme is suitable for high-speed Boolean logic operation at 320Gb/s.

An axially non-uniform tapered As2S3 planar waveguide has been designed for mid-IR supercontinuum generation. The dispersion profile is varying along the propagation distance. Numerical results show this scheme significantly broadens the generated continuum, extending from ~1 μm to ~7 μm.

A fiber ring laser which implements hybrid mode locking technique has been proposed and experimentally demonstrated to generate pulse train at 20 GHz repetition rate with ultrashort pulse width. Graphene and charcoal nano-particles acting as passive mode lockers are inserted into a rational harmonic mode-locked fiber laser to improve the performance. With graphene saturable absorbers, the pulse duration is shortened from 5.3 ps to 2.8 ps, and with charcoal nano-particles, it is shortened to 3.2 ps. The RF spectra show that supermode noise can be removed in the presence of the saturable absorbers. Numerical simulation of the pulse transmission has also been carried out, which shows good agreement with the experimental results.