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Optical arbitrary waveform generation will allow waveforms to be synthesized at optical frequencies but with the flexibility currently available at radiofrequencies. This technique is enabled by combining frequency comb technology, which produces trains of optical pulses with a well-defined frequency spectrum, with pulse shaping methods, which are used to transform a train of ultrashort pulses into an arbitrary waveform. To produce a waveform that fills time, the resolution of the shaper must match the repetition rate of the original pulse train, which in turn must have a comb spectrum that is locked to the shaper. Here, we review the current efforts towards achieving optical arbitrary waveform generation and discuss the possible applications of this technology.

We experimentally demonstrate enhanced spectral broadening of femtosecond optical pulses after propagation through silicon-on-insulator (SOI) nanowire waveguides integrated with two-dimensional (2D) graphene oxide (GO) films. Owing to the strong mode overlap between the SOI nanowires and the GO films with a high Kerr nonlinearity, the self-phase modulation (SPM) process in the hybrid waveguides is significantly enhanced, resulting in greatly improved spectral broadening of the femtosecond optical pulses. A solution-based, transfer-free coating method is used to integrate GO films onto the SOI nanowires with precise control of the film thickness. Detailed SPM measurements using femtosecond optical pulses are carried out, achieving a broadening factor of up to ~4.3 for a device with 0.4-mm-long, 2 layers of GO. By fitting the experimental results with the theory, we obtain an improvement in the waveguide nonlinear parameter by a factor of ~3.5 and in the effective nonlinear figure of merit (FOM) by a factor of ~3.8, relative to the uncoated waveguide. Finally, we discuss the influence of GO film length on the spectral broadening and compare the nonlinear optical performance of different integrated waveguides coated with GO films. These results confirm the improved nonlinear optical performance of silicon devices integrated with 2D GO films.

In this paper, we concentrate on the higher-order nonlinear Schrödinger-Maxwell-Bloch system with the sextic terms, which could characterize the ultra-short optical pulses in an erbium-doped fiber. Proceeding from the existing Lax pair and one-fold Darboux transformation (DT), we build an N -fold generalized DT with one spectral parameter by means of the limit procedure, and on this basis determine the N th-order solutions of that system. The second- and third-order degenerate solitons are shown through the second-order and third-order solutions, respectively, and we also present the second-order degenerate breather through the second-order solutions. We obtain the eye-shaped rogue wave involving one hump and two valleys, rogue wave involving four valleys, as well as four-petaled rogue wave involving two humps and two valleys via the first-order solutions. Using the second-order solutions, we obtain the interaction between the two first-order rogue waves and show that the second-order rogue wave divides into three first-order rogue waves which are arranged in the triangle structure. Modifying that generalized DT, we work out the second-order and third-order mixed wave solutions, and then show the interactions between the first-order/second-order rogue wave and first-order breather.

Carrier-envelope phase stabilization 1 , 2 has opened an avenue towards achieving frequency metrology with unprecedented precision 3 , 4 and optical pulse generation on the previously inaccessible attosecond timescale 5 . Recently, sub-100-as pulse generation has been demonstrated 6 , approaching the timescale of the fastest transients in atomic physics. However, further progress in attophysics 7 appears to be limited by the performance of the traditional feedback approach used for carrier-envelope phase stabilization 8 , 9 , 10 . Here, we demonstrate a conceptually different self-referenced feed-forward approach to phase stabilization. This approach requires no complicated locking electronics, does not compromise laser performance, and is demonstrated with 12-as residual timing jitter, which is below the atomic unit of time. This surpasses the precision of previous methods by more than a factor of five and has potential for resolving even the fastest transients in atomic or molecular physics. Such shot-noise-limited comb synthesis may also simplify progress in current research in frequency metrology 11 , 12 . Scientists demonstrate a simple self-referenced feed-forward approach for stabilizing the carrier–envelope phase of femtosecond light pulses. Twelve attoseconds of residual timing jitter below the atomic unit of time is achieved, surpassing the precision of previous methods by more than a factor of five.

In this work, we study the evolution of an extremely short pulse in a dielectric crystal with carbon nanotubes containing an impurity with random parameters (energy level, electron hybridization energy). The dependence of the spatial characteristics of the pulse on the impurity parameters and the number of photons taken into account in the model is analyzed.

The spectral method was used to solve the problem of interaction of short optical pulses with PT‑symmetric photonic crystals under conditions of frequency singularity. It was shown that, at a small deviation from the exceptional point of spontaneous decay of PT-symmetric field modes, frequency singularities of the transmission and reflection coefficients of the structure arise. This leads to a significant narrowing of the pulse spectra and an increase in their amplitude and duration with unidirectional Bragg reflection.

Spin-polarized vertical-cavity surface-emitting lasers (spin-VCSELs) have emerged as promising candidates for next-generation high-speed photonic systems due to their unique polarization dynamics. Here, we numerically simulate the generation of high-repetition-rate polarized optical pulses in a solitary dual-state quantum-dot (QD) spin-VCSEL by applying return to zero pulse modulation of the pump ellipticity ( P ). Unlike conventional modulation schemes relying on current variation or optical injection, our approach exploits the inherent dependence of the lasing threshold on P . By maintaining a steady injection current and dynamically switching P between different ellipticities, we induce a controlled transition between the non-lasing and lasing states, effectively generating optical pulses with controlled polarization. This mechanism enables pulse repetition rates reaching up to 15 GHz, paving the way for novel ultrafast modulation schemes in spintronic photonic devices. Our findings open new perspectives for energy-efficient, semiconductor lasers-based, high-speed optical communication and neuromorphic photonic processing by taking advantage of spin-dependent nonlinear dynamics in VCSELs.

We have considered the problem of the evolution of two-dimensional few-cycle optical pulses inside a photonic crystal, which has a spatially modeled refractive index, from oriented carbon nanotubes. Based on Maxwell's equations, using the Coulomb calibration, an effective equation for the vector potential of the electric field of an extremely short pulse was written. Numerical simulation of the pulse dynamics in a medium with a spatially variable refractive index was carried out using a numerical scheme of the \"cross\" type. It was shown that the pulse propagation is stable in the considered medium. The pulse energy remains localized in a limited region of space, but dispersive spreading of the pulse shape takes place. The dynamics of the pulse was also considered as a function of the parameters of the photonic crystal (modulation depth and period of the refractive index); it showed that it is possible to control the speed of a group packet of a few-cycle optical pulse. The calculations were carried out at times up to 10 ps, which plays an important role in theoretical and applied research.

A study is performed of the propagation of electromagnetic waves in a medium with carbon nanotubes. An approximation that the random tilt of the tubes relative to the axis perpendicular to the wave vector of the momentum obeys a normal distribution and is sufficiently small was used. Effective equations for the vector potential of the electromagnetic field are derived. The dependence of the momentum field components on the dispersion of the distribution of the slope of carbon nanotubes is analyzed.

Quantum communications promise to revolutionize the way information is exchanged and protected. Unlike their classical counterpart, they are based on dim optical pulses that cannot be amplified by conventional optical repeaters. Consequently, they are heavily impaired by propagation channel losses, confining their transmission rate and range below a theoretical limit known as repeaterless secret key capacity. Overcoming this limit with today’s technology was believed to be impossible until the recent proposal of a scheme that uses phase-coherent optical signals and an auxiliary measuring station to distribute quantum information. Here, we experimentally demonstrate such a scheme for the first time and over significant channel losses, in excess of 90 dB. In the high loss regime, the resulting secure key rate exceeds the repeaterless secret key capacity, a result never achieved before. This represents a major step in promoting quantum communications as a dependable resource in today’s world.A proof-of-principle experiment on twin-field quantum key distribution is demonstrated. The key rate overcomes the repeaterless secret key capacity bound limit at channel losses of 85 dB, corresponding to 530 km of ultralow-loss optical fibre.