One-dimensional Photonic Lattices Research Articles

Discrete optical propagation in one-dimensional synthetic mesh lattice

Synthetic mesh lattice (SML) with temporally controlled potential is a versatile platform for realizing wave dynamics associated with physical areas of optics and quantum physics. Here, discrete optics in one-dimensional synthetic photonic lattice is investigated systematically, in which the light behavior is highly analogous to that in evanescently coupled one-dimensional discrete waveguides. Such a synthetic dimension is constructed with position-dependent periodic effective gauge fields based on the Aharonov–Bohm effect arising from the phase accumulation of the fiber loops. By tuning the phase accumulation and coupling coefficient of the coupler, the band translation and gap property can be modulated, which further results in the impulse and tailored Gaussian wave packet responses as well as Talbot recurrences. In addition, Bloch oscillations and Anderson localization can also be obtained when the phase accumulations are linearly changed and weakly modulated in a random manner, respectively. The periodic effective gauge fields configuration in our protocol enables SML to be a research platform for one-dimensional dynamically modulated elements or even non-Hermitian waveguides.

Topological and flat-band states induced by hybridized linear interactions in one-dimensional photonic lattices

We report on a study of a one-dimensional linear photonic lattice hosting, simultaneously, fundamental and dipolar modes at every site. We show how, thanks to the interaction between the different orbital modes, this minimal model exhibits rich transport and topological properties. By varying the detuning coefficient we find a regime where bands become flatter (with reduced transport) and, a second regime, where both bands connect on at a gap-closing transition (with enhanced transport). We detect an asymmetric transport due to the asymmetric inter-mode coupling and a linear energy exchange mechanism between modes. Further analysis show that the bands have a topological transition with a non-trivial Zak phase which leads to the appeareance of edge states in a finite system. Finally, for zero detuning, we found a symmetric condition for coupling constants, where the linear spectrum becomes completely flat, with states fully localized in space occupying only two lattice sites.

Rogue waves in disordered 1D photonic lattices

In this work, we study the phenomena of Rogue waves (RW) on one-dimensional (1D) photonic lattices presenting diagonal and non-diagonal disorder. Our results show the appearance of extreme events coming from the superposition of different, extended and localized, linear waves for weak disorder. We perform experiments on femtosecond laser written waveguide arrays having disorder in coupling constants, which is originated from a random waveguide distribution. Both, numerics and experiments, are in good agreement and show that RW are generically present in 1D lattices for weak disorder only, after a mandatory data filtering process.

Bound states in the continuum (BIC) accompanied by avoided crossings in leaky-mode photonic lattices

Abstract When two nonorthogonal resonances are coupled to the same radiation channel, avoided crossing arises and a bound state in the continuum (BIC) appears with appropriate conditions in parametric space. This paper presents numerical and analytical results on the properties of avoided crossing and BIC due to the coupled guided-mode resonances in one-dimensional (1D) leaky-mode photonic lattices with slab geometry. In symmetric photonic lattices with up-down mirror symmetry, Friedrich–Wintgen BICs with infinite lifetime are accompanied by avoided crossings due to the coupling between two guided modes with the same transverse parity. In asymmetric photonic lattices with broken up-down mirror symmetry, quasi-BICs with finite lifetime appear with avoided crossings because radiating waves from different modes cannot be completely eliminated. We also show that unidirectional-BICs are accompanied by avoided crossings due to guided-mode resonances with different transverse parities in asymmetric photonic lattices. The Q factor of a unidirectional-BIC is finite, but its radiation power in the upward or downward direction is significantly smaller than that in the opposite direction. Our results may be helpful in engineering BICs and avoided crossings in diverse photonic systems that support leaky modes.

Fano effect in a one-dimensional photonic lattice with side-coupled P T-symmetric non-Hermitian defects.

We theoretically study the transport properties in a one-dimensional photonic lattice influenced by the presence of side-coupled P T-symmetric non-Hermitian defects. The P T symmetry is manifested as the complex potentials on the defects and the complex defect-lattice couplings, respectively. These two mechanisms are found to induce the Fano effect in the transport processes, with the different characteristics of it. Next, if the complex potentials and defect-lattice couplings co-exist, the Fano effect will be achieved more efficiently. However, further enhancing either of them can weaken the Fano interference seriously. Our findings reveal the physical essence of the Fano effect on the P T-symmetric non-Hermitian defects, and the results can provide insights into the engineering and dynamical control of Fano resonances in non-Hermitian photonic structures.

Self-Organized, One-Dimensional Periodic Structures in a Gold Nanoparticle-Doped Nematic Liquid Crystal Composite.

Composite structures exhibiting a periodic arrangement of building blocks can be found in natural systems at different length scales. Recreating such systems in artificial composites using the principles of self-assembly has been a great challenge, especially for 1D microscale systems. Here, we present a purposely designed composite material consisting of gold nanoparticles and a nematic liquid crystal matrix that has the ability to self-create a periodic structure in the form of a one-dimensional photonic lattice through a phase separation process occurring in a confined space. Our strategy is based on the use of a thermoswitchable medium that reversibly and quickly responds to both heating and cooling. We find that the period of the structure is strongly related to the size of the confining space. We believe that our findings will allow us to not only better understand the phase separation process in multicomponent soft/colloid mixtures with useful optical properties but also improve our understanding of the precise assembly of advanced materials into one-dimensional periodic systems, with prospective applications in future photonic technologies.

Perfect localization on flat-band binary one-dimensional photonic lattices

The existence of flat bands is generally thought to be physically possible only for dimensions larger than one. However, by exciting a system with different orthogonal states this condition can be reformulated. In this work, we demonstrate that a one-dimensional binary lattice supports always a trivial flat band, which is formed by isolated single-site vertical dipolar states. These flat band modes correspond to the highest localized modes for any discrete system, without the need of any aditional mechanism like, e.g., disorder or nonlinearity. By fulfilling a specific relation between lattice parameters, an extra flat band can be excited as well, with modes composed by fundamental and dipolar states that occupy only three lattice sites. Additionally, by inspecting the lattice edges, we are able to construct analytical Shockley surface modes, which can be compact or present staggered or unstaggered tails. We believe that our proposed model could be a good candidate for observing transport and localization phenomena on a simple one-dimensional linear photonic lattice.

Imaginary modulation inducing giant spatial Goos–Hänchen shifts in one-dimensional defective photonic lattices

We investigate the spatial Goos–Hanchen (GH) shifts in one-dimensional defective photonic lattices by modulating the imaginary part of refractive index, namely, the imaginary modulation. The reflection spectra possess two singular points under imaginary modulation when the reflectance is infinite or vanishing. These two points correspond to the coherent-perfect-absorption-laser (CPA-LP) point and defect mode (MD) in the parameter space composed of the incident angle and refractive index. We show the spatial GH shifts are extremely giant in the vicinity of CPA-LP and MD as the phase of reflection coefficients dislocate. Moreover, the GH shifts are sensitive to the incident angle and the refractive index of defect. The sensitivity coefficients can reach as high as 106. The study may find potential applications in highly sensitive sensors.

Localization and Steering of Light in One-Dimensional Parity-Time Symmetric Photonic Lattices**Supported by the National Key Research and Development Program of China under Grant No 2017YFA0303700, the National Young 1000 Talent Plan, and the National Natural Science Foundation of China under Grants Nos 91321312, 11621091, 11674169 and 11474050.

We theoretically study the propagation dynamics of input light in one-dimensional mixed linear-nonlinear photonic lattices with a complex parity-time symmetric potential. Numerical computation shows simultaneous localization and steering of the optical beam due to the asymmetric scatter and interplay between Kerr-type nonlinearity and PT symmetry. This may provide a feasible measure for manipulation light in optical communications, integrated optics and so on.

Asimetrični nasuprot simetričnim defektima u jedno-dimenzionalnoj fotonskoj rešetki

Light propagation in one-dimensional photonic lattice is numerically analyzed. Two linear or nonlinear different widths asymmetric defects separated by a waveguide are located within the linear or nonlinear photonic lattice. We have found various types of localized modes located at the asymmetric defect position and at the waveguide between asymmetric defects. The results are compared with the ones obtained for light propagation in the system with the appropriate symmetric defects located within the linear or nonlinear photonic lattice.

Creating anyons from photons using a nonlinear resonator lattice subject to dynamic modulation

We study a one-dimensional photonic resonator lattice with Kerr nonlinearity under the dynamic modulation. With an appropriate choice of the modulation frequency and phase, we find that this system can be used to create anyons from photons. By coupling the resonators with external waveguides, the anyon characteristics can be explored by measuring the transport property of the photons in the external waveguides.

Non-diffracting states in one-dimensional Floquet photonic topological insulators

One-dimensional laser-written modulated photonic lattices are known to be particularly suitable for diffraction management purposes. Here, we address the connection between discrete non-diffracting states and topological properties in such devices through the experimental observation and identification of three classes of non-diffracting states. The first one corresponds to topologically protected edge states, recently predicted in Floquet topological insulators, while the second and the third are both bulk modes. One of them testifies a topological transition, although presenting topological features different from those of the edge states, while the other one results from specific band structure engineering.

Influence of disorder on generation and probability of extreme events in Salerno lattices.

Extreme events (EEs) in nonlinear and/or disordered one-dimensional photonic lattice systems described by the Salerno model with on-site disorder are studied. The goal is to explain particular properties of these phenomena, essentially related to localization of light in the presence of nonlinear and/or nonlocal couplings in the considered systems. Combining statistical and nonlinear dynamical methods and measures developed in the framework of the theory of localization phenomena in disordered and nonlinear systems, particularities of EEs are qualitatively clarified. Findings presented here indicate that the best environment for EEs' creation are disordered near-integrable Salerno lattices. In addition, it is been shown that the leading role in the generation and dynamical properties of EEs in the considered model is played by modulation instability, i.e., by nonlinearities in the system, although EEs can be induced in linear lattices with on-site disorder too.

Observation of dipolar transport in one-dimensional photonic lattices

We experimentally study the transport properties of dipolar and fundamental modes on one dimensional (1D) coupled waveguide arrays. By carefully modulating a wide optical beam, we are able to effectively excite dipolar or fundamental modes to study discrete diffraction (single-site excitation) and gaussian beam propagation (multi-site excitation plus a phase gradient). We observe that dipolar modes experience a larger spreading area due to an effective larger coupling constant, which is found to be more than two times larger than the one for fundamental modes. Additionally, we study the effect of non-diagonal disorder and find that while fundamental modes are already trapped on a weakly disorder array, dipoles are still able to propagate across the system.

The influence of a geometric defect on the light propagation through two one-dimensional nonlinear photonic lattices

The influence of a geometric defect on the light propagation through two one-dimensional nonlinear photonic lattices

Characterization of parity-time symmetry in photonic lattices using Heesh-Shubnikov group theory.

We investigate the properties of parity-time symmetric periodic photonic structures using Heesh-Shubnikov group theory. Classical group theory cannot be used to categorize the symmetry of the eigenmodes because the time-inversion operator is antiunitary. Fortunately, corepresentations of Heesh-Shubnikov groups have been developed to characterize the effect of antiunitary operators on eigenfunctions. Using the example structure of a one-dimensional photonic lattice, we identify the corepresentations of eigenmodes at both low and high symmetry points in the photonic band diagram. We find that thresholdless parity-time transitions are associated with particular classes of corepresentations. The approach is completely general and can be applied to parity-time symmetric photonic lattices of any dimension. The predictive power of this approach provides a powerful design tool for parity-time symmetric photonic device design.

Hanbury Brown and Twiss anticorrelation in disordered photonic lattices

We report measurements of Hanbury Brown and Twiss correlation of coherent light transmitted through disordered one-dimensional photonic lattices. Although such a lattice exhibits transverse Anderson localization when a single input site is excited, uniform excitation precludes its observation. By examining the Hanbury Brown--Twiss correlation for a uniformly excited disordered lattice, we observe intensity anticorrelations associated with photon antibunching--a signature of non-Gaussian statistics. Although the measured average intensity distribution is uniform, transverse Anderson localization nevertheless underlies the observed anticorrelation.

Design and fabrication of suspended Si3N4 nanobeam cavities

We report on the design, theoretical simulations and fabrication details of photonic crystal nanobeams (PhCNB) in air-bridge silicon nitride structures. The PhC nanobeams consist of a one-dimensional photonic crystal lattice of circular air holes. The design of structures that show band gaps for the waveguide modes will allow the creation of suspended photonic nanobeam cavities in a second step. The silicon nitride layer is deposited on top of a thermally oxidized silicon wafer with LPCVD followed by e-beam lithography and proper wet etching to release the suspended structures.

The influence of nonlinear and linear defects on the light propagation through linear one-dimensional photonic lattice

In this paper, the light beam propagation through one-dimensional photonic lattice, possessing one nonlinear defect and one linear defect, has been investigated numerically. Different dynamical regimes have been identified in terms of the distance between the two defects, position of the incident light beam, the width of linear defect, the values of nonlinearity and presence of the transverse kick. Strong localized modes on the defects, breathing and zig-zag modes in the area between defects have been observed. It has been concluded that the width of the linear defect placed next to the nonlinear one influences localization of the beam at the nonlinear waveguide. On the other hand, the nonlinear defect, regardless of the values of nonlinearity, have a small influence on the beam propagation in photonic lattice. It has been observed that the transverse kick of the initial beam leads to the distortion of localized structures. By launching the light beam towards defects, the reflection of light has been noticed. Presented results can be useful for different applications, such as blocking, filtering and routing of light beam through optical media.

Observation of beam deflection in one-dimensional photonic lattice in LiNbO3 crystal accompanied with self-focusing and self-defocusing nonlinearities

We numerically and experimentally investigated the deflection of a laser beam in a photo-induced one dimensional (1D) photonic lattice (PL) in a pure LiNbO3 crystal accompanied with self-focusing and self-defocusing nonlinearities, respectively. The results show that the probe beam will be self-focused or self-defocused when the sample temperature is increased or decreased. Moreover, the light beam deflects to the direction of heat flux if there exists an additional temperature difference between the two lateral sides of the sample. The probe beam forms a deflected discrete circle soliton in the PL when the sample temperature is increased from 25 °C to 45°C and the additional temperature difference is ±5 °C. Our simulation results are in agreement with the experimental observation.