Small Group Velocity Dispersion Research Articles

High Sensitivity MZI Based on the Modular Interference With Small Group Velocity Dispersion Difference

High Sensitivity MZI Based on the Modular Interference With Small Group Velocity Dispersion Difference

Highly Nonlinear Composite-Photonic Crystal Fibers with Simplified Manufacturing Process and Efficient Mid-IR Applications

This paper reveals special design features of the proposed highly nonlinear circular-lattice-silicon-core and silica-doped-with-fluorine (1%) cladding-composite photonic crystal fiber (PCF) in the Mid-infrared region of the spectrum. A region of small negative group velocity dispersion (GVD), managed higher order dispersions (HODs), and unique nonlinearity of silicon have been used to demonstrate a supercontinuum broadening from 1500 nm to 4700 nm with consumption of low input power of 400 W over short fiber distances. It will be also shown that the fiber’s high-level engineered structure finally results in a simple manufacturing process compared with other designed nano-sized silicon PCFs. The designed fiber could have massive potential in gas sensing, soliton effect pulse compression, spectroscopy, material processing, etc.

Effect of the free parameters on the Biswas-Arshed model with a unified technique

The solitary dynamics of the Biswas–Arshed (BA) model without self-phase modulation are investigated in the present study. To compensate for the deserted small group velocity dispersion, the BA model includes higher-order spatio-temporal dispersion. The optical soliton solutions of the BA model are examined to use the unified strategy. The solutions to the BA model's nonlinear forms are rogue wave, periodic wave solution, periodic combined singular soliton, combined singular soliton, and periodic wave solution. The three-dimensional (3D) and two-dimensional (2D) graphs depict the dynamical physical appearance of the obtained solutions. We compared our results to those found in the existing studies. The 2D comparison chart additionally explored the consequences of the wave profile based on the values of the parameters k and δ. Finally, this technique can solve increasingly complex models, yielding a large number of soliton solutions.

Nonlinear pulse reshaping in a typically designed silicon-on-insulator waveguide and its application to generate a high repetition rate pulse train

A silicon-on-insulator (SOI) planar waveguide is designed with a small group velocity dispersion (β 2) ∼2.212 (ps2 m−1) and a quite high nonlinear coefficient (γ) of ∼360.57 (W−1 m−1). The designed waveguide is capable of reshaping a super-Gaussian input optical pulse into a parabolic pulse (PP), without any use of external gain. The same waveguide with a relatively longer length can also generate a triangular pulse (TP) by using a positive chirp at the input. In both cases, PP and TP are created at a much shorter optimum length (L opt) of a few millimeters when compared to previously reported works on normal dispersion optical fibers. The interaction of a pulse pair inside such an SOI waveguide is investigated, for the first time as per our knowledge to generate a high-frequency (∼4.8 THz) pulse train, while lower repetition rate (∼180 GHz) pulses are used at the input. This study as a whole enables potential device applications in the domains of tunable high frequency (THz) pulse generators, optical signal processing, and many more.

Investigation into the impact of the recovery time of a saturable absorber for stable dissipative soliton generation in Yb-doped fiber lasers.

In this study, we conduct a numerical evaluation of the impact of the recovery time of a saturable absorber (SA) on the output performance of an Yb-doped fiber laser operating in the dissipative soliton regime. Particularly, we evaluate the output pulse characteristics, such as the pulse width, spectral bandwidth, pulse peak power, and pulse energy depending on the change in recovery time. Applying a too-slow SA recovery time above a certain critical value is shown to make the output pulse unstable and broken. Furthermore, we demonstrate that there is an optimum recovery time range for stable dissipative soliton pulse generation, depending on the cavity dispersion and modulation depth of the SA. Further, we perform an additional numerical simulation of the pulse compression to demonstrate the relationship between the output dechirped pulse width and SA recovery time. The optimum approach for the generation of the shortest dechirped pulses in the dissipative soliton regime will be to construct a fiber laser cavity with a small normal cavity group velocity dispersion and use an SA with an appropriate recovery time.

Fractal Higher-order Dispersions Model and Its Fractal Variational Principle Arising in the Field of Physcial Process

This paper introduces the fractal version of the higher-order dispersion model for the construction of novel soliton solutions through fractal variational technology. Higher-order dispersion model theoretical study of the soliton propagation dynamics is known in the absence of self-phase modulation. In the context of negligibly small group velocity dispersion, this model involves higher-order spatio-temporal dispersion and can be a core component of the telecommunications industry. Using the variational approach, the model effectively produces bright and dark soliton solutions. Essential novel conditions guaranteeing the existence of suitable solitons have been developed. The 3D, 2D and contour graphs of the computed effects are seen in the collection of the relevant parameter values. This study shows the significance and immense latency of variational technologies to the derivative nonlinear Schrödinger equation (DNLSE).

Optical travelling wave solutions for the Biswas–Arshed model in Kerr and non-Kerr law media

This paper scrutinises the newly proposed Biswas–Arshed model for soliton propagation through optical fibres, with small group velocity dispersion and in the absence of self-phase modulation. Spatio-temporal dispersions of higher order are considered to balance with group velocity dispersion. First integral and functional variable methods are employed to recover solitary wave, shock wave, singular wave and singular periodic wave solutions for the two nonlinear forms of the model through Kerr law and power-law nonlinearity. The constraint relations are also figured for the manifestation of these optical solutions.

New optical solitons of Biswas-Arshed equation using different techniques

This paper scrutinizes the newly proposed Biswas-Arshed equation with Kerr and power law nonlinearities for soliton propagation through optical fibers, with small group velocity dispersion and in absence of self-phase modulation. Spatio-temporal dispersions of higher order are considered in compensation with group velocity dispersion. In this work, bright, dark, singular and bright-singular combo soliton solutions are retrieved using undetermined coefficients and Kudryashov's methods.

Optical singular and dark solitons with Biswas–Arshed model by modified simple equation method

This paper investigates the soliton dynamics of Biswas–Arshed model in the absence of self-phase modulation. This model contains higher order spatio-temporal dispersion in compensation with negligibly small group velocity dispersion. A dynamic integration scheme, modified simple equation method, is utilized in order to recover singular and dark soliton solutions to the two nonlinear forms of this model through Kerr law and power law of nonlinearity. Whereas a rational solution is also obtained as a by-product. Moreover, the dynamical characteristics of the obtained solutions are presented by 3D and 2D plots. Various constraint relations are also listed which ensures the existence of solitons.

Optical solitons and other solutions to Biswas–Arshed equation using the extended simplest equation method

In this article, we analyze the dynamics of soliton transmission to the newly proposed Biswas–Arshed model which is considered in the absence of self-phase modulation. To compensate the negligibly small group velocity dispersion, this model includes spatio-temporal dispersion of higher order. We utilize the extended simplest equation method to find new exact solutions of the Biswas–Arshed equation with the aid of computer algebraic system Maple. Hyperbolic functions solutions, trigonometric functions solutions, rational functions solutions are obtained. Comparison of our new results obtained in this article for the considered model with the other well-known results are also provided.

Dark and singular optical solitons to the Biswas-Arshed model with Kerr and power law nonlinearity

This paper analyzes the dynamics of soliton transmission to the newly proposed Biswas-Arshed model which is considered in the absence of self-phase modulation. To compensate the negligibly small group velocity dispersion, this model includes spatio-temporal dispersion of higher order. The extended (G′/G)-expansion method is employed to retrieve singular, dark and periodic singular soliton solutions for the two nonlinear forms of the model which are Kerr and power law. The constraint relations for the existence of these solitons are also reckoned.

Scalable mode division multiplexed transmission over a 10-km ring-core fiber using high-order orbital angular momentum modes.

We propose and demonstrate a scalable mode division multiplexing scheme based on orbital angular momentum modes in ring core fibers. In this scheme, the high-order mode groups of a ring core fiber are sufficiently de-coupled by the large differential effective refractive index so that multiple-input multiple-output (MIMO) equalization is only used for crosstalk equalization within each mode group. We design and fabricate a graded-index ring core fiber that supports 5 mode groups with low inter-mode-group coupling, small intra-mode-group differential group delay, and small group velocity dispersion slope over the C-band for the high-order mode groups. We implement a two-dimensional wavelength- and mode-division multiplexed transmission experiment involving 10 wavelengths and 2 mode groups each with 4 OAM modes, transmitting 32 GBaud Nyquist QPSK signals over all 80 channels. An aggregate capacity of 5.12 Tb/s and an overall spectral efficiency of 9 bit/s/Hz over 10 km are realized, only using modular 4x4 MIMO processing with 15 taps to recover signals from the intra-mode-group mode coupling. Given the fixed number of modes in each mode group and the low inter-mode-group coupling in ring core fibres, our scheme strikes a balance in the trade-off between system capacity and digital signal processing complexity, and therefore has good potential for capacity upscaling at an expense of only modularly increasing the number of mode-groups with fixed-size (4x4) MIMO blocks.

Extremely low‐loss hollow‐core bandgap photonic crystal fibre for broadband terahertz wave guiding

We demonstrate a simple polymer Topas-based low-loss hollow-core photonic crystal fibre for efficient guiding of terahertz radiation. The guiding properties are numerically investigated using finite-element method. It is shown that the proposed fibre exhibits extremely low average effective material loss of 0.017 cm−1, very small near-zero average group velocity dispersion of 0.263 ps/THz/cm with low total loss over 2–2.20 THz bands. Moreover, high air-core power fraction ∼94% having single-mode guiding is also reported for the optimum design parameters.

Characteristics of THz Pulse Propagation on Teflon Covered Two-Wire Lines

We report efficient direct coupling of THz dipole antenna pulses onto air spaced two-wire transmission lines and Teflon covered two-wire lines. The air spaced two-wire lines show TEM mode propagation with very small group velocity dispersion (GVD) and relatively low attenuation. The Teflon covered two-wire lines showed comparatively much higher attenuation and GVD. However, the Teflon covered two-wire lines show a very good guiding property when the lines are curved. Although the lines are circled only 5.0 cm in diameter, there is no additional attenuation compared to straight the lines.

A low-phase-noise 18 GHz Kerr frequency microcomb phase-locked over 65 THz.

Laser frequency combs are coherent light sources that simultaneously provide pristine frequency spacings for precision metrology and the fundamental basis for ultrafast and attosecond sciences. Recently, nonlinear parametric conversion in high-Q microresonators has been suggested as an alternative platform for optical frequency combs, though almost all in 100 GHz frequencies or more. Here we report a low-phase-noise on-chip Kerr frequency comb with mode spacing compatible with high-speed silicon optoelectronics. The waveguide cross-section of the silicon nitride spiral resonator is designed to possess small and flattened group velocity dispersion, so that the Kerr frequency comb contains a record-high number of 3,600 phase-locked comb lines. We study the single-sideband phase noise as well as the long-term frequency stability and report the lowest phase noise floor achieved to date with −130 dBc/Hz at 1 MHz offset for the 18 GHz Kerr comb oscillator, along with feedback stabilization to achieve frequency Allan deviations of 7 × 10−11 in 1 s. The reported system is a promising compact platform for achieving self-referenced Kerr frequency combs and also for high-capacity coherent communication architectures.

Prototype 250 GHz Bandwidth Chip to Chip Electrical Interconnect, Characterized With Ultrafast Optoelectronics

We have connected two optoelectronic chips with air-spaced two-wire transmission lines and have observed essentially undistorted transmission of 1.8 ps (FWHM) electrical pulses over propagation distances up to 200 cm. The lines consist of two 0.4 mm (or 0.5 mm) diameter copper wires with centers separated by 1.0 mm. The air spaced two-wire lines show transform-limited TEM mode pulse propagation with very small group velocity dispersion (GVD), and relatively low attenuation. Our achieved performance with a power loss of 5.8 dB/m approaches that needed for mm-wave and THz interconnects. The coupling was enabled by two tungsten probes with 1 μm diameter tips in near-contact (5 μm gap) with the coplanar transmission lines on the transmitting and receiving optoelectronic chips. The air spaced two-wire line's relatively small, measured pulse amplitude attenuation coefficient was 1.31 times larger than the theoretical prediction for the TEM mode. This discrepancy is considered to be primarily due to reduction of the Cu conductivity in the THz skin-depth layer.

Kerr frequency comb generation in overmoded resonators

We show that scattering-based interaction among nearly degenerate optical modes is the key factor in low threshold generation of Kerr frequency combs in nonlinear optical resonators with small group velocity dispersion (GVD). Mode interaction is capable of producing drastic changes in the local GVD, resulting in either a significant reduction, or an increase, in the oscillation threshold. Furthermore, we show that mode interaction is also responsible for majority of observed optical frequency combs in resonators characterized with large normal GVD. We present results of our numerical simulations together with supporting experimental data.

Laser duration and intensity limits in plasma backward Raman amplifiers

The shortest duration and the largest non-focused intensity of laser pulses produced by means of backward Raman amplification (BRA) in plasmas are calculated. These limits occur in moderately undercritical plasmas and are imposed by combined effects of moderately small group velocity dispersion and relativistic electron nonlinearity of the amplified pulses. The efficient BRA range covered by this theory is broader than one known previously. This can be useful for BRA of x-ray pulses in regular or compressed solids and ultra-powerful optical pulses in the lowest density solids.

Enhanced slow light propagation in photonic crystal waveguides using angular properties of scatter elements

Applicability of the angular properties of scatter elements as a tool to achieve improved slow light performance with small group velocity dispersion and large bandwidth in photonic crystal waveguides is investigated. A polyatomic photonic crystal waveguide, including two scatter elements with different geometrical shapes in each primitive cell, is proposed to investigate the feasibility of our method. Numerical results show that a versatile control of the dispersion relation of slow light modes, with large normalized delay-bandwidth products ranging from 0.2085 to 0.3394, can be obtained using a unique geometrical parameter.

Subwavelength slow-light waveguides based on a plasmonic analogue of electromagnetically induced transparency

We introduce a plasmonic waveguide system, based on a plasmonic analogue of electromagnetically induced transparency, which supports a subwavelength slow-light mode, and exhibits a small group velocity dispersion. The system consists of a periodic array of two metal-dielectric-metal (MDM) stub resonators side-coupled to a MDM waveguide. Decreasing the frequency spacing between the two resonances increases the slowdown factor and decreases the bandwidth of the slow-light band. We also show that there is a trade-off between the slowdown factor and the propagation length of the slow-light mode.