JEOS:RP - Journal of the European Optical Society Rapid publications
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A new periodic interdigital structure - three dimensional realization based on two dimensional design
Get PDFA novel design concept of new periodic interdigital structure for total transmission is proposed from the perspective of electromagnetic (EM) field in this paper. The new structure is constructed in two-dimensional (2D) firstly by using the constructive interference of EM fields, and its transmission characteristic and band structure are calculated. Based on the calculated results, the interaction of the structure with EM fields is clearly demonstrated to provide a better physical understanding for the structure design. Meanwhile, the final three-dimensional (3D) implementation of the presented structure in actual printed circuit board is conducted for its potential applications. The maximum transmission frequency, bandgap and electric field distribution calculated by using the 2D structure and its final implementation all testify the validity of the realization process
Active Optics: deformable mirrors with a minimum number of actuators
Get PDFWe present two concepts of deformable mirror to compensate for first order optical aberrations. Deformation systems are designed using both elasticity theory and Finite Element Analysis in order to minimize the number of actuators. Starting from instrument specifications, we explain the methodology to design dedicated deformable mirrors. The work presented here leads to correcting devices optimized for specific functions. The Variable Off-Axis paraboLA concept is a 3-actuators, 3-modes system able to generate independently Focus, Astigmatism and Coma. The Correcting Optimized Mirror with a Single Actuator is a 1-actuator system able to generate a given combination of optical aberrations
UV-curable glassy material for the manufacture of bulk and nano-structured elements
Get PDFAn ultra violet (UV) -cured glassy material with less than 30% organic residues was fabricated by the fast sol-gel method. The material presents high thermal stability, good optical quality and high adhesive strength. It is suitable for optical bonding and, for manufacture of optical elements and micro-structured optical devices. Either soft-lithography or photo-lithography may be used for manufacture of the material while its curing can be thermal (few hours) or UV (few seconds). In this work we present the technology to fabricate optical elements at scales spanning the sub-micron to centimeter range. This technology enables mass-production of optical elements at low cost
Investigation of smooth wave fronts using SLM-based phase retrieval and a phase diffuser
Get PDFA phase retrieval technique using a spatial light modulator (SLM) and a phase diffuser for a fast reconstruction of smooth wave fronts is demonstrated experimentally. Diffuse illumination of a smooth test object with the aid of a phase diffuser (maximum phase shift, ΔΦ = 0.85π) results in a significant diversity in the intensity measurements which, in turn, is beneficial for a non-stagnating iterative phase reconstruction. The use of the SLM enables accurate and fast speckle intensity recording and active correction of misalignments in the setup. The effectiveness of the technique is demonstrated in the optical testing of lenses
Model for surface plasmon polariton mediated interaction between two dielectric-filled nanowaveguides
Get PDFWe propose an analytical model that describes the interaction between two apertures based on the excitation and propagation of surface plasmon polaritons. The model assumes no fitting parameters, and only requires coefficients that describe elementary processes occurring with a single aperture. We then use the model to predict both the far-field transmission and the near field intensity of two dielectric-filled cylindrical nanowaveguides separated by a varying distance. The choice of material and geometry for the nanowaveguides is based on a previous study where it was demonstrated that transmission of more than 40% can be achieved through isolated waveguides of diameter less than one tenth of the incident wavelength. In this current study, we found that both the transmission and the near field intensity of a nanowaveguide pair display an oscillatory behavior, however the oscillations in the near field intensity curve decay more rapidly. We compared the model predictions with results from three dimensional finite element simulations and the two are in excellent agreement. In addition, we analyzed the dependence of transmission on the polarization of the incident light and found that the interaction is negligible when the axis connecting the two waveguides is perpendicular to the polarization of the incident light
Local field enhancement of nano-structured metallic target irradiated by polarized laser beam
Get PDFThe local field enhancement is studied numerically in samples of metallic nanoparticles (NPs) randomly distributed over a metallic substrate. The sample was assumed to be irradiated by polarized laser beam. Based on dipole-dipole approximation (DDA), the electric field was calculated Two-dimensionally at the irradiated region. The results show that the optimized field enhancement is strongly depends on NPs characteristics, beam polarization and incident angle
Single scattering detection in turbid media using single-phase structured illumination filtering
Get PDFThis work shows a unique possibility of visualizing the exponential intensity decay due to light extinction, when laser adiation propagates through a homogeneous scattering edium. This observation implies that the extracted intensity mostly riginates from single scattering events. The filtering of this single light scattering intensity is performed by means of a single-phase structured illumination filtering approach. Results from numerical Monte Carlo simulation confirm the experimental findings for an extinction coefficient of μ_e = 0.36 mm^-1. This article demonstrates an original and reliable way of measuring the extinction coefficient of particulate turbid media based on sidescattering imaging. Such an approach has capabilities to replace the commonly used transmission measurement within the intermediate single-to multiple scattering regime where the optical depth ranges between 1 < OD < 10. The originality of the presented approach is that only one image is used (instead of three images usually employed in structured illumination) and that no monitoring of the incident intensity is required, simplifying the experimental procedure and set-up. Applications of the technique has potential in probing challenging homogeneous scattering media, such as biomedical tissues, turbid emulsions, etc, in situations where dilution cannot be applied and where conventional transmission measurements fail
All-optical silicon simplified passive modulation
Get PDFIn this paper we present an all-optical silicon based modulator suggested also for high power operation and for pulse picker application being used as part of fiber lasers system. The paper theoretically and experimentally investigates several new and important insights involving the dependence of the relative transmission on the pump pulse energy for different finesse values of the constructed cavity as well as the dependence of the response rate of the device to the pump wavelength due to coexistence of two physical recombination processes: fast surface effect and slow bulk recombination. To adapt the constructed silicon based cavity to be used in lasers applications, we aligned the pump and the signal beams to co-propagate through the device while the usage of a cavity allowed a low power pump to yield a significant extinction ratio at the output of the device
Parallel multichannel architecture for surface plasmon resonance sensors
Get PDFThe paper deals with an optical sensor based on the phenomenon of surface plasmon resonance. It proposes a new geometry of the measurement head which allows for measurements with both the change of the incident light angle and the change of the wavelength. The sensors proposed can also be used in parallel configurations, where they increase the functionality of the setup, allow for a greater precision of measurement, and eliminate such distracting factors as temperature change. The article presents the results of computer analyses of the sensor proposed, as well as the results of its experimental realization
Differential optics for illumination design in the presence of caustics
Get PDFAlternatively to using time-consuming Monte-Carlo simulations the irradiation at a target plane can also be calculated by differential optics methods. In the case of caustics, these methods yield to infinite irradiance and its results are not directly comparable to those of Monte-Carlo simulations. In this paper, a differential based algorithm for an on axis point source and a rotationally symmetric optical system is presented, which yields to the same results as a Monte-Carlo simulation. However, the differential optical methods are about three orders of magnitude faster than the latter one, thus allowing fast trial and error design of such kind of illumination systems. An applet is presented that uses sliders to change the shape of the lens and other properties of the illumination system whereas the irradiance profile is nearly immediately perceived. For beginners in the field, this does not only accelerate the design process itself but also the learning process is improved considerably. Some extensions and special cases are shortly discussed