Total Internal Reflection Condition Research Articles

Weak measurement of the Goos–Hänchen shift for a Hermite–Gaussian laser beam

We report on an experimental investigation of the Goos–Hänchen (GH) optical beam shift in the vicinity of the critical angle of incidence at an air–glass interface using a weak value amplification (WVA) technique for two mutually orthogonal first order Hermite–Gaussian (HG) modes (HG10 and HG01) of a light beam at 633 nm generated by a phase-only reflective spatial light modulator. We have developed a mathematical approach to visualize the beam shaping due to the WVA scheme of beam shifts for the HG modes. The study reveals the angle of incidence dependency of the GH shift in the total internal reflection condition. For both modes, a detailed study of the horizontal and transverse beam shift values with varied post-selection angles is also reported. In addition, a comparison of the beam shift values for both of the selected modes with the fundamental mode (HG00) has been demonstrated. We found a significant enhancement (about two to three times) in the beam shifts for the first order HG10 and HG01 modes compared to the fundamental mode (HG00). Our results clearly demonstrate the advantages of the HG modes of the light beam-exploiting WVA technique and thus may contribute significantly to this field and open up important applications in photonic manipulation and future technologies.

Hybrid waveguide based augmented reality display system with extra large field of view and 2D exit pupil expansion.

For a waveguide display device, the field of view (FOV) is a key parameter for evaluating its optical performance. To address this issue, we propose a hybrid waveguide system, which is composed of two projectors, two in-couplers, two half-mirror arrays and an out-coupler. We use two projectors to generate the left and right parts of the output image separately, which can increase the upper limit of the FOV significantly. Unlike conventional waveguide-based system, we use half-mirror arrays instead of folding gratings to realize 2D exit pupil expansion. By doing so, the total internal reflection condition can always be met during the pupil expansion process. To solve the difficulty in designing collimating optical system with large FOV, we propose a method of tilting the projection system. The hybrid waveguide system can realize a FOV of 88°(H) × 53°(V).

Sensitivity Enhancement of Hybrid Two-Dimensional Nanomaterials-Based Surface Plasmon Resonance Biosensor.

In this work, we designed structures based on copper nanosubstrate with graphene and two-dimensional transition metal dichalcogenides (TMDC) in order to achieve an ultrasensitive surface plasmon resonance biosensor. This system contains seven components: SF11 triangular prism, BK-7 glass, Chromium (Cr) adhesion layer, thin copper film, layers of one of the types of transition metal dichalcogenides: MoS2, MoSe2, WS2 or WSe2 (defined as MX2), graphene, sensing layer with biomolecular analyte. Copper was chosen as a plasmonic material because it has a higher conductivity than gold which is commonly used in plasmonic sensors. Moreover, copper is a cheap and widespread material that is easy to produce on a large scale. We have carried out both theoretical and numerical sensitivity calculations of these kinds of structures using the Goos–Hänchen (GH) shift method. GH shift is lateral position displacement of the p-polarized reflected beam from a boundary of two media having different indices of refraction under total internal reflection condition and its value can be retrieved from the phase change of the beam. The SPR signal based on the GH shift is much more sensitive compared to other methods, including angular and wavelength scanning, due to much more abrupt phase change of the SPR reflected light than its intensity ones. By optimizing the parameters of the SPR sensing substrate, such as thickness of copper, number of layers of 2D materials and excitation wavelength, we theoretically showed an enhanced sensitivity with a detection limit 10−9 refractive index unit (RIU).

Волоконно-оптичний малоінвазивний дифузний розсіювач на оптичному волокні для внутрішньотканинного лазерного впливу

The technical parameters of minimally invasive diffuse diffusers are analyzed in the article
 on the distal part of the polymer optical fiber. Prototypes were made
 diffuse diffusers made of polymer optical fibers manufactured by Mitsubishi Rayon
 Corporation (Japan) of different lengths: SC-20 with a diameter of 500 μm and SC-10 with a diameter of 250 μm
 by machining their reflective shell to apply inhomogeneities and
 changes in the conditions of total internal reflection.
 The conducted research created a basis for the introduction of new methods of creation
 minimally invasive diffuse diffusers in the distal part of the optical polymer fiber.

Resonant dielectric multilayer with controlled absorption for enhanced total internal reflection fluorescence microscopy.

Total internal reflection fluorescence microscopy (TIRF-M) is widely used in biological imaging. Evanescent waves, generated at the glass-sample interface, theoretically strongly improve the axial resolution down to a hundred of nanometers. However, objective based TIRF-M suffers from different limitations such as interference fringes and uneven illumination, mixing both propagating and evanescent waves, which degrade the image quality. In principle, uneven illumination could be avoided by increasing the excitation angle, but this results in a drastic loss of excitation power. We designed dedicated 1D photonic crystals in order to circumvent this power loss by directly acting on the intensity of the evanescent field at controlled incident angles. In this framework, we used dedicated resonant multi-dielectric stacks, supporting Bloch surface waves and resulting in large field enhancement when illuminated under the conditions of total internal reflection. Here, we present a numerical optimization of such resonant stacks by adapting the resulting resonance to the angular illumination conditions in TIRF-M and to the fluorescence collection constraints. We thus propose a dedicated resonant structure with a control of the absorption during thin film deposition. A first experimental demonstration illustrates the concept with a 3-fold fluorescence enhancement in agreement with the numerical predictions.

Quantization of Goos–Hänchen shift in monolayer graphene under partial and total internal reflection conditions

We theoretically investigate the Goos-Hänchen (GH) shifts of a reflected light beam from the dielectric interface containing a monolayer graphene sheet in the presence of an external perpendicular magnetic field. Using Kubo formalism we derive the expressions for the magneto-optical (MO) conductivities. Based on the angular spectrum analysis, we calculate and demonstrate that quantized GH shifts on the surface of graphene monolayer can be tuned by varying the intensity of the applied magnetic field and the beam incidence angle. We show that the GH shifts are quantized due to the Landau level (LL) quantization of the magneto-optical conductivities. In the vicinity of Brewster's angle the GH shift exhibit extreme positive or negative peaks around the magneto-excitation photonic energies in the terahertz regime. We discuss the dependence of the GH shifts on the strength of the magnetic field, the incidence angle, chemical potential, and the impinging frequency of the Gaussian beam. We also discuss the GH shifts for partial reflection (PR) and total internal reflection (TIR) conditions. We find that in the total internal reflection geometry, we have giant angular and spatial GH shifts in the vicinity of the Brewster angle as well as near the critical angle. The MO-modulated GH shift in graphene–substrate system provides a new mechanism to realize photonic devices in the terahertz region.

Bound states in the continuum based on the total internal reflection of Bloch waves.

A photonic-crystal slab can support bound states in the continuum (BICs) that have infinite lifetimes but are embedded into the continuous spectrum of optical modes in free space. The formation of BICs requires a total internal reflection (TIR) condition at both interfaces between the slab and the free space. Here, we show that the TIR of Bloch waves can be directly obtained based on the generalized Fresnel equations proposed. If each of these Bloch waves picks up a phase with integer multiples of 2πfor traveling a round trip, light can be perfectly guided in the slab, namely forming a BIC. A BIC solver with low computational complexity and fast convergence speed is developed, which can also work efficiently at high frequencies beyond the diffraction limit where multiple radiation channels exist. Two examples of multi-channel BICs are shown and their topological nature in momentum space is also revealed. Both can be attributed to the coincidence of the topological charges of far-field radiations from different radiation channels. The concept of the generalized TIR and the TIR-based BIC solver developed offer highly effective approaches for explorations of BICs that could have many potential applications in guided-wave optics and enhanced light-matter interactions.

PyFocus – A Python package for vectorial calculations of focused optical fields under realistic conditions. Application to toroidal foci

Focused optical fields are key to a multitude of applications involving light-matter interactions, such as optical microscopy, single-molecule spectroscopy, optical tweezers, lithography, or quantum coherent control. A detailed vectorial characterization of the focused optical fields that includes a description beyond the paraxial approximation is key to optimize technological performance as well as for the design of meaningful experiments and interpret properly their results. Here, we present PyFocus, an open-source Python software package to perform fully vectorial calculations of focused electromagnetic fields after modulation by an arbitrary phase mask and in the presence of a multilayer system. We provide a graphical user interface and high-level functions to easily integrate PyFocus into custom scripts. Furthermore, to demonstrate the potential of PyFocus, we apply it to extensively characterize the generation of toroidal foci with a high numerical aperture objective, as it is commonly done in super-resolution fluorescence microscopy methods such as STED or MINFLUX. We provide examples of the effects of different experimental factors such as polarization, aberrations, and misalignments of key optical elements. Finally, we present calculations of toroidal foci through an interface of different mediums, and, to our knowledge, the first calculations of toroidal foci generated in total internal reflection conditions. Program summaryProgram Title: PyFocusCPC Library link to program files:https://doi.org/10.17632/sybnhnxbrt.1Developer's repository link:https://github.com/stefani-lab/, https://pypi.org/project/PyCustomFocus/, https://pyfocus.readthedocs.io/ (user manual)Licensing provisions: MITProgramming language: Python 3.6Nature of problem: Full vectorial calculation of focused of optical fields under realistic conditions, such as high numerical aperture, incident beams modulated in phase and/or intensity, and focusing through an interface or a multilayer system.Solution method: PyFocus incorporates all the equations necessary to calculate the focused optical field and provides suitable integration methods. Setting up of the parameters, running calculations, plotting and saving results can be done by means of a graphical user interface or high-level functions.Additional comments including restrictions and unusual features: In addition to the Python source code, an MS Windows executable is provided.

Ellipsometry of thin films of biological objects under conditions of total internal reflection

An analysis of the ellipsometric parameters of the reflected light from the prism test material air system is carried out when circularly polarized light is incident on it under the conditions of the onset of the phenomenon of total internal reflection. At the onset of total internal reflection, the ellipsometry parameter shows high variability with the angle of incidence, in contrast to the parameter r0. It is shown that TIR occurs when the angle of incidence is not equal to the critical angle of the adjacent media for two different materials, these angles differ from each other. In the case of a film, the TIR phenomenon occurs at an angle equal to the critical angle at the prism-air interface and does not depend on the film material. The results obtained show the high efficiency of using the ellipsometric method together with circularly polarized incident radiation for diagnostics of thin films made of biological material.

Basic principles of information security monitoring in physical channels of optical access networks

The article presents theoretical information about the methods of information retrieval from optical fibers. The simplest analyzed method is the bending of the optical fiber when violating the conditions of total internal reflection. The functional dependence of the losses and the level of radiated power on the parameters and bending geometry of the optical fiber are given. In this case, the introduced losses are monitored in the monitoring system for detecting fiber bends. The structure, principles of operation, and trends in the development of monitoring systems are presented. The main technical characteristics of optical radiation detection devices are demonstrated.

Sensing of Surface and Bulk Refractive Index Using Magnetophotonic Crystal with Hybrid Magneto-Optical Response.

We propose an all-dielectric magneto-photonic crystal with a hybrid magneto-optical response that allows for the simultaneous measurements of the surface and bulk refractive index of the analyzed substance. The approach is based on two different spectral features of the magneto-optical response corresponding to the resonances in p- and s-polarizations of the incident light. Angular spectra of p-polarized light have a step-like behavior near the total internal reflection angle which position is sensitive to the bulk refractive index. S-polarized light excites the TE-polarized optical Tamm surface mode localized in a submicron region near the photonic crystal surface and is sensitive to the refractive index of the near-surface analyte. We propose to measure a hybrid magneto-optical intensity modulation of p-polarized light obtained by switching the magnetic field between the transverse and polar configurations. The transversal component of the external magnetic field is responsible for the magneto-optical resonance near total internal reflection conditions, and the polar component reveals the resonance of the Tamm surface mode. Therefore, both surface- and bulk-associated features are present in the magneto-optical spectra of the p-polarized light.

Optical bistability in reflection from multilayer metal-dielectric structure with Kerr nonlinearity

Both static and dynamic characteristics of light reflected from a specially designed multilayer metal-dielectric structure with Kerr nonlinearity have been studied in this work. Various regimes of nonlinear reflection from the structure have been demonstrated, including bistable switching between low and high reflection states, which occurs at low intensity of the incident light due to a significant enhancement in the optical field in the nonlinear layer under conditions of total internal reflection. This nonlinear structure has been proposed to use as an optically controlled intracavity laser modulator.

Wavelength and chemical potential dependence of optical beam shifts in graphene

We predict the spatial and angular Goos-Hänchen (GH) and Imbert-Fedorov (IF) shifts in partial (PR) and total internal reflection (TIR) conditions for fundamental Gaussian mode beams of a wide range of wavelength (400–1300 nm) impinging upon a graphene-coated dielectric surface. The GH and IF shifts turn out to be extremely dependent upon the chemical potential of graphene along with the wavelength of the incident light, thus enabling one to appropriately choose the operating wavelength and tune the chemical potential in the desired region to obtain maximum beam shifts in graphene. We also show that the typical features of the optical beam shifts are potentially linked with the optical conductivity of single-layer graphene. We expect the current study to be of fundamental significance in the field of optoelectronics and device industry based on graphene and other 2D materials.

Quantum weak measurement of Goos–Hänchen shift in monolayer MoS2

We report the direct experimental evidence of the Goos–Hänchen (GH) shift in monolayer molybdenum disulphide ( M o S 2 ) for a Gaussian beam via the quantum weak measurement scheme. We demonstrate the dependence of the GH shift in monolayer M o S 2 on the angle of incidence including the critical angle in the total internal reflection condition. We have also compared the results to the GH shift for single-layer graphene and plane glass–air interface. Our results may open up important applications of M o S 2 in optical devices and sensor industry.

Design of an ultra-thin, wide-angle, stray-light-free near-eye display with a dual-layer geometrical waveguide.

The field of view (FOV) of a geometrical waveguide display is limited by the total internal reflection (TIR) condition (related with the index of glass) and the stray light generated inside the waveguide. A novel concept of an ultra-thin, wide-angle, stray-light-free, optical see-through near-eye display (NED) with a dual-layer geometrical waveguide is proposed in this paper. In the dual-layer waveguide, the two waveguides have different structures and are responsible for two different FOVs which are spliced together to form the entire FOV. The stray light of the dual-layer waveguide is analyzed and an optimized structure to suppress the stray light is designed. An optimized coupling-in structure is designed and a progressive optimization method is proposed for optimizing the illuminance uniformity of the entire FOV across the exit pupil. A dual-layer waveguide with a total thickness of 3.0 mm and stray light of less than 1% is designed. The FOV is 62° in the pupil-expanding direction, and the diameter of the exit pupil (EPD) is 10 mm at an eye relief (ER) of 18 mm. A compact projection optic is designed and finally is integrated with the dual-layer waveguide.

Goos-Hänchen shifts of Gaussian beams reflected from surfaces coated with cross-anisotropic metasurfaces

The Goos-Hänchen (GH) shift of a Gaussian beam reflected from surfaces coated with a cross-anisotropic metasurface (CM) is theoretically investigated. It is revealed that, the CM coating has influence on the spatial GH shift as well as the angular one, only at the total internal reflection condition, where the incident angle θ is above critical angle θc. Moreover, near θc, a positive or negative larger peak spatial GH shift occurs while a pair of positive and negative peaks angular GH shifts appear, compared to the case of no coating, which are induced by the CM coating. Therefore, our results may provide a feasible method to obtain a larger GH shift, and open new possibilities for applications of the CMs.

On-Chip Diffraction-Free Beam Guiding beyond the Light Cone

On-chip channelless diffraction-free beam guiding enables dense integration of optical circuits in a reconfigurable manner, where total internal reflection, which is considered the cornerstone of guided-wave optics, is utilized to confine light in the out-of-plane direction. Here, we theoretically propose a physical mechanism to achieve on-chip channelless diffraction-free beam guiding beyond the light cone, utilizing the physics of bound states in the continuum. A bound state in the continuum with a tailored spatial dispersion plays an important role in cancelling both the in-plane diffraction and the out-of-plane scattering when the condition for total internal reflection is not satisfied. As a proof-of-concept verification, we experimentally demonstrate such an effect based on an all-dielectric platform using microwaves. The on-chip channelless diffraction-free beam guiding beyond the light cone also allows direct free-space coupling to such self-collimation modes. Our results may open up an avenue for exploring the physics and applications of guided-wave optics.

Electrodynamic analysis of light-assisted subnano-polishing of a quartz surface under conditions of total internal reflection by using surface profile optimization

The solution of the electrodynamic problem for determining the optimal configuration of the evanescent field formed near the rough quartz surface coated with an aqueous solution of sodium hypochlorite when illuminated from the side of quartz has been considered in order to ensure effective photochemical polishing of this surface to a sub-nanometer level of roughness. It was found that for a quartz surface profile in the form of triangular protrusions and troughs, which periodically repeat, the optimal conditions for photochemical polishing are achieved when the angle of incidence of light is critical and the height of the surface protrusions is small (up to 20 nm). It has been shown that in this case, the incident electromagnetic wave forms significantly higher values of the electric field in the protrusion region than in the trough region, creating optimal conditions for the subnano-polishing of this surface. Criteria are described for the possibility of using a regular profile in the form of protrusions and troughs of a triangular shape instead of a random surface profile characterized by a Gaussian correlation function when determining the optimal field parameters above the quartz surface.

Quantum weak measurement of Goos–Hänchen effect of light in total internal reflection using a Gaussian-mode laser beam

We report a detailed experimental demonstration of the Goos–Hänchen (GH) shift of light in total internal reflection condition for a Gaussian mode laser beam of 633 nm passing through an air-glass interface. The quantum weak measurement (QWM) technique has been exploited as a weak value amplification scheme to observe the amplified optical GH shift. The amplification of the GH shift depends on the angular deviation from the exact orthogonal position required for weak measurement. We have subsequently investigated the profiles of the beam pattern and their horizontal and vertical shifts in detail. We also show that the beam shift values obtained experimentally agree well with the theoretical results for a specific choice of angle of deviation from the orthogonal condition of weak measurement. Our results clearly demonstrate the advantages of the QWM technique for amplifying and detecting tiny optical beam shift effects and may provide important applications in precision metrology.

Surface Plasmon Resonance of Au Thin Films Modified By Catalyst Monolayer

In this talk, we present the results and modeling o the catalyst monolayer modification effects on plasmon resonance of Au thin films. The experiments are conducted using an attenuated total reflection arrangement in which p-polarized light is incident through a prism onto a thin (-400 A) Au film deposited on the mica substrate. (Kretschmann configuration [[1]]). The angle of incidence on the base of the prism is greater than the critical angle for the prism: electrolyte interface and SPs are excited by the evanescent wave generated under these conditions of total internal reflection. The excitation is manifested by a decrease in the intensity of reflected light. The Pd monolayer on Au were electrodeposited using procedure reported by Kolbe et al [[2],[3]], while the Pt submonolayer/monolayers were deposited on Au using Surface Limited Redox Replacement (SLRR) of Pb UPD monolayer [[4]]. The plasmon resonance frequency of Au(hkl), PdML/Au(hkl) and PtML/Au(hkl) and PtSML/Au(hkl) were investigated as a function of the applied potential in the range between -0.24 V to 0.4 V vs. SCE. The comparative analysis, between Au and catalyst monolayer modified Au(hkl) samples indicate that SP resonant frequency change is induced by both; surface charge and dipole moment of the surface as well as he adsorption of H on the catalyst monolayer surface in the UPD region. The latter effect is quantified using subtractive analysis between the Au and catalyst modified Au surface and solutions with different pH. In conclusion, we present a simple model describing the catalyst monolayer effect on plasmon resonance of Au films. [1] E. Kretschmann and H. Raether, Z. Natutforsch. 23a (1968) 2135. [2] L.A. Kibler, M. Kleinert, R. Randler, D.M. Kolb, Surface Science, 443 (1999) 19. [3] J. Tang, M. Petri, L.A. Kibler, D.M. Kolb, Electrochimica Acta, 51, (2005) 125 [4] K. Sasaki et al, Electrochim. Acta, 55, (2010) 2645.