scholarly journals PT-symmetry and supersymmetry: interconnection of broken and unbroken phases

2021 ◽  
Vol 477 (2254) ◽  
Author(s):  
Adipta Pal ◽  
Subhrajit Modak ◽  
Aradhya Shukla ◽  
Prasanta K. Panigrahi
Keyword(s):  
Complex Refractive Index ◽  
Refractive Index Profile ◽  
Optical Systems ◽  
Energy Spectra ◽  
Exceptional Point ◽  
Spontaneous Breaking ◽  
Trivial Shape ◽  
Scarf Potential ◽  
Bifurcation Behaviour ◽  
Symmetric Phase

The broken and unbroken phases of P T and supersymmetry in optical systems are explored for a complex refractive index profile in the form of a Scarf potential, under the framework of supersymmetric quantum mechanics. The transition from unbroken to the broken phases of P T -symmetry, with the merger of eigenfunctions near the exceptional point is found to arise from two distinct realizations of the potential, originating from the underlying supersymmetry. Interestingly, in P T -symmetric phase, spontaneous breaking of supersymmetry occurs in a parametric domain, possessing non-trivial shape invariances, under reparametrization to yield the corresponding energy spectra. One also observes a parametric bifurcation behaviour in this domain. Unlike the real Scraf potential, in P T -symmetric phase, a connection between complex isospecrtal superpotentials and modified Korteweg-de Vries equation occurs, only with certain restrictive parametric conditions. In the broken P T -symmetry phase, supersymmetry is found to be intact in the entire parameter domain yielding the complex energy spectra, with zero-width resonance occurring at integral values of a potential parameter.

Er3+/Yb3+ co-doped phosphate glass waveguides formed by the H+ ion implantation

2020 ◽  
pp. 2150099
Author(s):  
He Pan ◽  
Shuo-Qi Lin ◽  
Li-Jie Shen ◽  
Rui-Lin Zheng ◽  
Li-Li Fu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Energy Loss ◽  
Phosphate Glass ◽  
Refractive Index Profile ◽  
Planar Waveguides ◽  
Optical Systems ◽  
Glass Waveguides ◽  
Integrated Optical ◽  
Proton Implantation ◽  
Co Doped

The 400 keV proton implantation with a fluence of [Formula: see text] ions/cm2 was applied on the [Formula: see text] co-doped phosphate glass to fabricate a planar waveguide structure. The mode profile at the end face of the waveguide was measured by the end-face coupling technique. The energy loss profile of the energetic protons was calculated by the SRIM 2013. The refractive index distribution was simulated by the reflectivity calculation method. Based on these results, the formation theory of the planar waveguides was discussed through simulating the energy loss distribution and analyzing the reconstructed refractive index profile, which could be used for applications in the future integrated optical systems.

Regionally different optical systems in the compound eye of the water-flea Polyphemus (Cladocera, Crustacea)

1983 ◽  
Vol 217 (1207) ◽  
pp. 163-175 ◽  
Keyword(s):  
Regional Differences ◽  
Compound Eye ◽  
Focal Length ◽  
Complex Refractive Index ◽  
Optical Design ◽  
Optical Systems ◽  
Refractive Index Gradient ◽  
Water Flea ◽  
Central Type ◽  
Index Gradient

Polyphemus pediculus (L.) is a small (1 mm long) predatory crustacean that lives in bodies of standing freshwater. It has a single fused compound eye, which occupies most of its head. The eye comprises 130 ommatidia with five distinct types of crystalline cones. Four of these cone types were found to focus light by means of gradient index optics (lens cylinders). The edge ommatidia differ by having the focus displaced below the distal rhabdom tip. This was found to be correlated with their special type of rhabdom, which is characterized by its short, broad shape and the absence of a palisade. The central-type crystalline cone, contributing to a zone of acute vision, is functionally different from the other four cone types. The focusing on the rhabdom tip is in this case achieved by a prism, inside the cone, corrected for optical aberration with a complex refractive index gradient. The prism is interpreted as a way of compressing a long focal length into a short optical system, i. e. to enable high resolution in spite of the small size of the eye. Extreme regional differences in interommatidial angles were found to be the main reason for the different optical design between central and peripheral ommatidia.

scholarly journals Effect of electric field on optoelectronic properties of indiene monolayer for photoelectric nanodevices

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Deobrat Singh ◽  
Sanjeev K. Gupta ◽  
Igor Lukačević ◽  
Matko Mužević ◽  
Yogesh Sonvane ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electric Field ◽  
Density Functional ◽  
Complex Refractive Index ◽  
Transition Metal Dichalcogenides ◽  
Light Polarization ◽  
Optical Systems ◽  
Experimental Realization ◽  
Electronic And Optical Properties ◽  
Metal Dichalcogenides

AbstractIn recent years, layered materials display interesting properties and the quest for new sorts of two-dimensional (2D) structures is a significance for future device manufacture. In this paper, we study electronic and optical properties of 2D indiene allotropes with planar and buckled structures. The optical properties calculations are based on density functional theory (DFT) simulations including in-plane and out-of-plane directions of light polarization. We indicate that the optical properties such as complex refractive index, absorption spectrum, electron energy loss function (EELS), reflectivity and optical conductivity spectra are strongly dependent on the direction of light’s polarization. High values and narrow peaks in optical spectra introduce indiene to the field of ultra-thin optical systems. The effect of external static electric field on electronic and optical properties of indiene is also observed and discussed. We show that the band gap in buckled indiene can be effectively changed by applying the external electric field. The discoveries here expand the group of 2D materials beyond graphene and transition metal dichalcogenides (TMDs) and give valuable data for future experimental realization of new mono-elemental materials with conceivable applications in optical devices.

scholarly journals Dynamically encircling an exceptional point in anti-parity-time symmetric systems: asymmetric mode switching for symmetry-broken modes

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Xu-Lin Zhang ◽  
Tianshu Jiang ◽  
C. T. Chan
Keyword(s):  
Topological Structure ◽  
Optical Signal ◽  
Optical Systems ◽  
Exceptional Point ◽  
Mode Switching ◽  
New Wave ◽  
Asymmetric Mode ◽  
Starting Point ◽  
On Chip ◽  
Symmetric Systems

Abstract Dynamically encircling an exceptional point (EP) in parity-time (PT) symmetric waveguide systems exhibits interesting chiral dynamics that can be applied to asymmetric mode switching for symmetric and anti-symmetric modes. The counterpart symmetry-broken modes (i.e., each eigenmode is localized in one waveguide only), which are more useful for applications such as on-chip optical signal processing, exhibit only non-chiral dynamics and therefore cannot be used for asymmetric mode switching. Here, we solve this problem by resorting to anti-parity-time (anti-PT) symmetric systems and utilizing their unique topological structure, which is very different from that of PT-symmetric systems. We find that the dynamical encircling of an EP in anti-PT-symmetric systems with the starting point in the PT-broken phase results in chiral dynamics. As a result, symmetry-broken modes can be used for asymmetric mode switching, which is a phenomenon and application unique to anti-PT-symmetric systems. We perform experiments to demonstrate the new wave-manipulation scheme, which may pave the way towards designing on-chip optical systems with novel functionalities.

Optical Depth Profiling by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy: A New Approach

1996 ◽  
Vol 50 (9) ◽  
pp. 1187-1195 ◽  
Author(s):  
Sanong Ekgasit ◽  
Hatsuo Ishida
Keyword(s):  
Refractive Index ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Complex Refractive Index ◽  
Depth Profiling ◽  
Refractive Index Profile ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Index Profile

A new analytical technique for depth profiling using multiple-angle attenuated total reflection Fourier transform infrared spectroscopy has been developed. The analysis does not require prior knowledge of the profile of the complex refractive indices with respect to depth from the surface for the depth profiling calculation. This depth profiling analysis consists of two steps. First, the estimated complex refractive index profile is obtained by solving a set of linear equations of absorptance. Second, the reflectances from experiment are non-linearly fitted with those from exact optical theory. The estimated complex refractive index profile from the first step is used as a trial profile for the fitting. The converged complex refractive index profile from the fitting is then defined as the reconstructed complex refractive index profile of the film. The noise-added reflectances are used as experimental data to show the applicability of the new analytical approach.

Atomic Resolution in Crystal Aperture Stem

1990 ◽  
Vol 48 (1) ◽  
pp. 236-237
Author(s):  
J T Fourie
Keyword(s):  
Optical System ◽  
Spherical Aberration ◽  
Three Dimensional ◽  
Transmission Function ◽  
Optical Systems ◽  
Bragg Angle ◽  
Electron Optical System ◽  
Intimate Contact ◽  
Diffraction Effects ◽  
Design Aspect

The attempts at improvement of electron optical systems to date, have largely been directed towards the design aspect of magnetic lenses and towards the establishment of ideal lens combinations. In the present work the emphasis has been placed on the utilization of a unique three-dimensional crystal objective aperture within a standard electron optical system with the aim to reduce the spherical aberration without introducing diffraction effects. A brief summary of this work together with a description of results obtained recently, will be given.The concept of utilizing a crystal as aperture in an electron optical system was introduced by Fourie who employed a {111} crystal foil as a collector aperture, by mounting the sample directly on top of the foil and in intimate contact with the foil. In the present work the sample was mounted on the bottom of the foil so that the crystal would function as an objective or probe forming aperture. The transmission function of such a crystal aperture depends on the thickness, t, and the orientation of the foil. The expression for calculating the transmission function was derived by Hashimoto, Howie and Whelan on the basis of the electron equivalent of the Borrmann anomalous absorption effect in crystals. In Fig. 1 the functions for a g220 diffraction vector and t = 0.53 and 1.0 μm are shown. Here n= Θ‒ΘB, where Θ is the angle between the incident ray and the (hkl) planes, and ΘB is the Bragg angle.

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