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We show that the authors of the preceding Comment [Schurmann and Serov, preceding Comment, Phys. Rev. A 100, 057801 (2019)10.1103/PhysRevA.100.057801] have not found a more general family of solutions of the generalized nonlinear Schrodinger equation (NLSE) with higher-order dispersions. Moreover, the necessary and sufficient conditions for the existence of the bounded traveling solutions presented by Kruglov (arXiv:1905.00960v1; arXiv:1905.00960v2) differ from the appropriate conditions in the preceding Comment. We have found (see the work by Kruglov) a regular method which yields the traveling-wave solutions of the generalized NLSE. This method differ from the approach presented in the preceding Comment. Moreover, our method yields a periodic bounded solution which is expressed in terms of elliptic Jacobi functions.

An exact solitary wave solution is presented for the nonlinear Schrodinger equation governing the propagation of pulses in optical fibers including the effects of second, third and fourth order dispersion. The stability of this soliton-like solution with sech2 shape is proven by the sign-definiteness of the operator and an integral of the Sobolev type. The main criteria governing the existence of such stable localized pulses propagating in optical fibers are also formulated. A unique feature of these soliton-like optical pulses propagating in a fiber with higher order dispersion is that their parameters satisfy efficient scaling relations. The main soliton solution term given by perturbation theory is also presented when absorption or gain is included in the nonlinear Schrodinger equation. We anticipate that this type of stable localized pulses could find practical applications in communications, slow-light devices and ultrafast lasers., 4 pages 3 Figures

The drying behavior of polyamide-imide (PAI)/graphene-oxide nanosheets (GO) in dimethylacetamide (DMAc) with and associated anisotropy development were determined using a real-time measurement system that tracks weight loss, thickness, in and out of plane birefringence. Initially optically isotropic cast films develop out of plane optical anisotropy at a critical solvent concentration. For PAI/DMAc solution the decrease of initial casting thickness lead to earlier onset of out of plane birefringence development caused primarily by increased depletion rate of solvent. Addition of GO content resulted in increased evaporation rate caused by reduction of hygroscopicity of DMAc in the presence of GO as shown by contact angle measurements. Planar orientation of nanosheets resulted in excellent helium-barrier properties even at very small GO concentrations.

We demonstrate an improved configuration of an all-fibre laser that incorporates three separate gain sections. This gives 5 nJ pulses that can be compressed to 200 fs and are suitable as a seed for a high power CPA system.

A repetition rate of 506 kHz is achieved in an all-fibre laser, mode-locked with a nonlinear amplifying loop mirror. The laser produces 7 nJ pulses with a broad 7.5 nm spectral width, compressible to 540 fs.

Optical parametric amplification is an important nonlinear process in photonic crystal fibres driven by the small effective area and the special dispersion characteristics of these fibres. Aside from its role in supercontinuum generation, parametric amplification can lead to efficient wavelength conversion, limited primarily by the uniformity of the diameter of currently available fibres. The related Bragg scattering process can be used for both wavelength conversion and optical switching, again limited by the physical characteristics of the fibres used.

The issue of how best to cleave PMMA microstructured polymer optical fibres (mPOF) is addressed. The impact of the following parameters on the cleaving process is considered: (i) temperature of the cutting blade, (ii) temperature of the platen holding the fibre, (iii) time allowed for thermal equilibration between fibre and platen, (iv) blade speed, and (v) blade condition. The strong influence of a temperature-dependent phase transition in the polymer on the cleaving process is established. Optically acceptable mPOF end-faces can be achieved but only over a limited range of cleavage conditions.

The ultrashort pulse measurement technique of frequency-resolved optical gating (FROG) has been used to characterize the propagation of picosecond pulses at wavelengths around 1550 nm in a variety of different optical fibers used in communications applications. In this paper, we review the use of the FROG technique for ultrashort pulse measurements, discussing in particular several practical issues of importance for accurate results at wavelengths around 1550 nm. We describe the use of FROG measurements to characterize pulse distortion in standard, dispersion-shifted, and erbium-doped optical fiber, and show how they provide direct measurements of complex intensity and phase evolution arising from the interplay of fiber nonlinearity and dispersion. We also discuss the application of the FROG technique to accurately measure the dispersive and the nonlinear parameters of optical fibers, and we present results for standard single-mode fiber in good agreement with specifications.

We present results from both theoretical and experimental studies of the noise characteristics of mode-locked superfluorescent lasers. The results show that observed macroscopic broadband amplitude noise on the laser pulse train has its origin in quantum noise-initiated ''phase-wave'' fluctuations, and we find an associated phase transition in the noise characteristics as a function of laser cavity detuning.

A series of experiments and numerical simulations have been carried out studying the transition between stable and unstable behaviour observed in a mode-locked argon laser when the cavity length is decreased from the optimum value associated with stable operation. Good qualitative agreement is found between the experiments and the numerical simulations, and the pulse characteristics in this regime are found to be determined by the interplay of the coherent atom - field interaction, the cavity detuning, the time-varying loss of the mode-locker and the recovery of the atomic inversion due to repumping.

Polarization modulation instability (PMI) has been utilised to generate amplitude modulated light pulses where the modulation frequency is continuously tuneable from 3.5 THz to 7.0 THz. The tuneability is achieved by varying the tension in a low-birefringent single-mode fiber which is wrapped around a spool.

Modulation instability can occur in the normal dispersion regime only via cross-phase modulation. In a high birefringence fiber, cross-phase modulation between the pump waves on the two principal axes of the fiber generates two modulation instability sidebands separated by a frequency which is primarily determined by the birefringence and dispersion of the fiber, with a secondary dependence on the pump power. The superposition of these sidebands can generate an amplitude modulated pulse with modulation frequencies of up to 16 THz.

We present approximate but nevertheless highly accurate similariton solutions to the generalized nonlinear Schr\"odinger equation (NLSE) with varying parameters describing pulses propagating in fiber amplifiers and lasers with normal and anomalous dispersion. We also derive the analytical similariton solutions of the NLSE for the case when the pulses have a rectangular or ``smooth rectangular'' shape and when they have a kink and antikink shape. Numerical simulations are in excellent agreement with these analytical solutions describing self-similar linearly chirped pulses showing that they can be observed in realistic fiber geometries.

Polymer optical fibres (POF) have historically focused on applications in data transmission over short distances, using highly multimode step-index or graded-index fibre designs. This paper will focus on a qualitatively different type of polymer fibres - microstructured polymer optical fibres (mPOF) - which allow a wider variety of fibre designs and optical properties to be achieved. Fibres with similar properties to conventional step- and graded-index POF can be made for data transmission applications, as well as single-mode fibres which can be used for grating inscription and gratingbased sensing. The use of microstructures can also be extended to longer wavelengths for the transmission of THz radiation, and both solid-core and hollow-core mPOF-based THz waveguides have been demonstrated. Finally, the development and extension of mPOF to form metal-dielectric structures for the manufacture of metamaterials using fibre-drawing methods will be discussed. Such drawn-metamaterials with electric and magnetic responses at THz frequencies have been demonstrated.

This talk discusses theoretical and experimental investigations of self similar solutions of the equation governing pulse propagation in optical fibre amplifiers. Several such similariton solutions have been discovered and experimentally realized in the last decade.

Cross-phase modulation has been harnessed to construct a modulation instability laser operating at 514.5 nm. The laser output consists of orthogonally polarized upshifted and downshifted sideband pulses separated in wavelength by 2.1 nm from the pump. The laser configuration has been found to generate a much more stable source of terahertz modulated light pulses than the single-pass configuration previously used to demonstrate modulation instability in the visible. The extra stability arises from the feedback, which provides a seed for the modulation, and hence a reduction in the pump power necessary compared with the single-pass configuration, which in turn reduces the Raman gain, and the asymmetry of the sideband amplitudes. The sideband pulses can be combined to generate a modulated envelope of 4-THz oscillations with a duration of 10-15 ps. >

We present an analytical solution for parabolic similaritons with saturation effects and new self-similar linearly chirped pulses generated in normal dispersion fibers with fast decaying gain, the Hyper-Gaussian pulse, suitable for low energy systems.

Self similar solutions of nonlinear partial differential equations have been found with applications in many areas of Physics. The techniques used to find these solutions have been recently been applied to develop solutions of the Nonlinear Schrodinger Equation (NLSE) governing optical pulse propagation, where they are known as similaritons. This talk will discuss not only the well known parabolic and hyperbolic similaritons but also self similar solutions appropriate to amplifiers with gain saturation, together with their applications in high power amplifiers, and similariton lasers.

This paper discusses recent experiments demonstrating dramatic improvements in the tunability and power output of fiber optical parametric amplifiers constructed utilising both conventional fibers and photonic crystal fibers.

We demonstrate 5Gb/s transmission in a microstructured PMMA fibre at visible wavelengths. The source used in this measurement is generated by sum frequency mixing a CW Nd-YAG laser with a modulated L Band signal.

Recent advances in the drawing of photonic crystal fibres have enabled the development of fibre optic parametric oscillators generating coherent light tunable over wide regions of the visible and near IR spectrum.

The generation of self-similar parabolic pulses (similaritons) has so far only been obtained in single-pass Raman amplifier configurations [1, 2], or in rare-earth doped fiber lasers [3, 4]. We report here the first demonstration of a mode-locked parabolic pulse fiber laser, which can potentially be run at any wavelength using Raman gain. This new all-fiber ring similariton laser scheme (cf. Fig. 1) has been designed using a full theoretical model. The output similariton pulses have a true parabolic shape, a linear chirp and an energy of 22nJ.

This paper discusses recent developments which have led to dramatic improvements in the performance of optical parametric amplifiers, utilising both highly nonlinear fibers and photonic crystal fibers.

We experimentally demonstrate the phase matching curve for the Four-Wave-Mixing effect of Bragg Scattering in two Highly-Nonlinear-Fibers with opposite sign 4th order dispersion coefficients. The experimental results are fitted to theoretical predictions with good agreement.

We demonstrate for the first time 10Gb/s error-free transmission through two differently micro-structured-multimode polymer fibers. Results show excellent transmission characteristics for these fibers and demonstrate that micro-structuring can significantly improve the bandwidth of multimode-polymer fibers.

Modulation instability generated by the coherent interaction of two polarization modes in a weakly birefringent optical fiber has been observed in the normal dispersion regime. In contrast to previous observations of cross-phase-modulation instability in the visible, the two generated sidebands have the same polarization, which is orthogonal to that of the pump, and their frequency shift is readily controlled by variation of the birefringence of the fiber. The frequency of the modulation and its qualitative features agree with those theoretically predicted.

The spectral and temporal characteristics of approximately 10-fs pulses from a self-mode-locked Ti:sapphire laser were found to exhibit large deviations from the predictions of current theories of mode locking. A simple model that takes into account coherent coupling between the circulating pulse and the gain medium gives results in good agreement with experimental observations.

The generation of self-similar parabolic pulses (similaritons) has so far only been obtained in single-pass Raman amplifier configurations [1–3] or in rare-earth doped fiber lasers [4–6]. We report here the first demonstration of a mode-locked parabolic pulse fiber laser, which can potentially be run at any wavelength using Raman gain. This new all-fiber ring similariton laser scheme [Fig.1] has been designed with the aid of a full theoretical model of its operation. The output similariton pulses of the laser have a true parabolic shape and a linear chirp.

A simple and accurate method is proposed for characterizing the chromatic dispersion of high air-filling fraction photonic crystal fibers. The method is based upon scalar modulation instability generated by a strong pump wave propagating near the zero-dispersion wavelength. Measuring the modulation instability sideband frequency shifts as a function of wavelength gives a direct measurement of the fiber's chromatic dispersion over a wide wavelength range. To simplify the dispersion calculation we introduce a simple analytical model of the fiber's dispersion, and verify its accuracy via a full numerical simulation. Measurements of the chromatic dispersion of two different types of high air-filling fraction photonic crystal fibers are presented.

The concept of self-similarity has been predicted theoretically and observed experimentally in an optical fiber amplifier [1]. Recently, self-similar propagation in laser oscillators with normal GVD has also been observed [2,3]. We report here a new all-fiber ring similariton laser scheme with Raman amplification (Fig.1) designed with the aid of a full theoretical model of its operation. The output similariton pulses of the laser have a true parabolic shape and a linear chirp.

We present a widely-tunable low-threshold all-fiber optical parametric ring oscillator that is resonant for the pump wavelength and the two sidebands. For some detunings, threshold can be achieved with as little as 0.7W peak power.

The spectrum of pulses from a mode-locked cavity dumped argon laser operated in the “coherent mode-locking” regime has been studied and found to exhibit a characteristic double-peaked structure is interpreted as arising from the coherent ringing of the electric field envelope of the pulse.

In 2001, the GONG+ instruments began acquiring solar magnetic field images (magnetograms) every minute. These observations offer a useful resource for the solar physics community. However, the quality of the magnetograms was reduced by a significant zero point error in the observations that varied across the solar image and with time. This precluded using the magnetograms for meaningful extrapolations of weak photospheric fields into the corona. The error was caused by the slow, asymmetric, locally varying switching of the LCD modulator (LCM) from one retardation state to the other. This generated a false magnetic field pattern as a result of different responses to weak instrumental linear polarization ahead of the LCM. The original modulator driver used a very simple design to excite the LCM. Liquid crystals like those in the LCM take different times to switch from one polarization state to the other than to return to the first polarization state. To eliminate the difference in switching times, a driver capable of varying its output during the change in LCM state was needed. A microcontroller-based design was chosen. The final driver design resulted in a factor of 100 improvement in the zero point error.

We describe a simple fiber optic fluorescence spectrometry system with a wide variety of biomedical applications. This low-cost, all-fiber system is portable, robust and has the capacity to acquire fluorescence spectra at rates up to 1 kHz. We demonstrate the capabilities of the system by presenting experimental measurements of action potentials in the di-4-ANEPPS stained heart and the concentration of GFP tagged bacteria.

The intensity and the phase of ultrashort pulses from a self-mode-locked Ti:sapphire laser operating in the vicinity of zero group-delay dispersion (GDD) have been completely characterized by the technique of frequency-resolved optical gating (FROG). For small values of negative GDD, the appearance of a dispersive wave in the pulse spectrum is manifested in the measured FROG trace, and pulse retrieval directly shows its association with a broad leading-edge pedestal. For positive GDD, we confirm previous experimental observations of picosecond pulses with large positive chirp and report a new operating regime in which the output pulses are of picosecond duration but are intensity modulated at 20 THz. The physical origin of this modulation is discussed by analogy with similar effects observed during pulse propagation in optical fibers, and the experimental results are compared with a model of intracavity four-wave mixing about the cavity zero GDD wavelength.

We report on the performance of an all-fiber widely-tunable photonic crystal fiber optical parametric oscillator. The output is continuously tunable from 588 to 675 nm and 784 to 924 nm.

Photonic crystal fibres have reinvigorated the study of parametric amplification in optical fibres through their special properties. Experimental results are presented for a range scalar and vector four wave mixing processes in photonic crystal fibres.

We report the generation of a 10 Gb/s source at 639 nm with applications in characterizing multimode plastic optical fiber systems, obtained via sum frequency generation in a PPLN crystal.

For the propagation of light in the normal dispersion regime in high birefringence fibers, the existence of cross-phase modulation instability depends critically on group-velocity mismatch between the eigenstates of polarization. In fact, the effect only occurs for non-zero group velocity mismatch. Under these circumstances, the spectral peaks predicted by the nonlinear wave equation occur at frequencies given by the usual phase-marching arguments. For this reason, the cross-phase modulation instability can be identified with four-wave mixing spectra previously observed in birefringen fibers. New experimental data reported in which the predicted cross-phase modulation instability and four-wave mixing spectra are observed by detecting the light exiting a highly birefringent pure fused silica core optical fiber pumped by intense laser pulses at 514.4 nm.

Cross-phase modulation in optical fibers has been used for complete characterization of ultrashort pulses by a modified frequency-resolved optical gating (FROG) measurement technique. This technique has been used for characterization of picosecond pulses at 1.5 µm with energy as low as 24??pJ, and the results are in excellent agreement with second-harmonic generation (SHG)–FROG characterization. The use of an optical waveguide gives measurement sensitivity comparable with that of SHG–FROG but without any temporal ambiguity in the retrieved pulse.

We present an experimental demonstration of a transparent optical switch using Bragg scattering frequency conversion in a nonlinear optical loop mirror.

We describe an all-fiber chi(3) optical parametric oscillator based on four-wave-mixing around the zero dispersion wavelength of a dispersion shifted fiber. We demonstrate a widely tunable (1300-1500 nm, 1600-1860 nm), high conversion efficiency output.

In this work we build upon a methodology that employs time-averaged nonlinear detection to measure the duty cycle (and thus the pulse duration) of a signal under test (SUT). The technique employed TPA in silicon APDs, while in our technique the TPA in the chalcogenide fibre forms the basis of the nonlinear detection. Our technique has the key advantage of being fibre-based that allows for a long interaction length, and therefore more nonlinear absorption, which allows for greater sensitivity in the nonlinear detection measurements.

50-nm optical wavelength conversion based on the potentially noise-free Bragg scattering process in an optical fiber is demonstrated experimentally. 2.5-Gb/s output waveforms and eye diagrams for the initial and converted signal are presented.

A fiber optical parametric oscillator based on modulation instability in the normal dispersion regime is described. A tuning range of over 560 nm with high conversion efficiencies has been experimentally achieved.

The intensity and frequency chirp of picosecond pulses from a self-seeded gain-switched Fabry-Perot laser diode have been directly measured using the technique of frequency-resolved optical gating. Measurements over an output sidemode suppression ratio (SMSR) range of 15-35 dB show that higher SMSR's are associated with an increasingly linear frequency chirp across the output pulses. This complete pulse characterization allows the conditions for optimum pulse compression to be determined accurately, and indicates that transform-limited, pedestal free pulses can be obtained at an SMSR of 35 dB.

The measurement technique of frequency-resolved optical gating is applied to determine the nonlinear switching characteristics of a passively modelocked figure-of-eight erbium-doped fiber laser. By completely characterizing the intensity and phase of the laser output pulses, the intracavity fields in the nonlinear amplifying loop mirror of the laser cavity are determined by numerical propagation using the nonlinear Schrodinger equation. Excellent switching of 95% can be achieved as a result of uniform phase characteristics developed by pulses propagating in the nonlinear amplifying loop mirror.

Two forms of vector modulation instability are observed in photonic crystal fiber. The strongly varying dispersion of these fibers result in complicated phasematching curves. We experimentally demonstrate the existence of broad regions of parametric gain.