For refractive index (RI) sensing, a unique cavity design of racetrack combined circular cavity (CC) constructed on metaldielectric- metal waveguide (W/G) is proposed. The best sensing performance can be achieved by using an optimized cavity design. We used the finite element method (FEM) to numerically assess the device design in this paper. Small changes in the device’s geometric parameter might cause a considerable shift in the device’s sensitivity (S) and figure of merit (F.O.M). The predicted device’s S and F.O.M are 1400 nm/R.I.U and 12.01, respectively. We believe that the sensing device described in this research can be used to recognize biological analytes on-chip.
In this work, we proposed a compact design of a tunable high-pass filter based on the one-dimensional photonic crystal waveguide. The device design is simple and cut-off wavelength can be tuned by a few geometric parameters. The spectral characteristics of the high-pass filter are calculated for the wavelength range of 1200 nm to 2000 nm. The numerical simulations suggest that the extinction ratio of >22 dB is obtained for the wavelength range lying in the photonic bandgap for the device footprint of 3.4 x 1 μm2. We believe that our findings are useful for the realization of photonic integrated circuit filters with miniaturized footprint.
In this paper, we presented a metal-insulator-metal (MIM) waveguide resonator design for filtering white light into individual colours. Six square micro-ring cavities of different sizes are side coupled to MIM bus waveguide. By careful selection of cavity size and distance between bus waveguide and micro-ring cavities, the resonator can selectively couple to intensity maxima of different photonic modes and, as a result, preferentially select any of the primary colours. The spectral characteristics of the resonator are studied by varying the geometric parameters using the finite element method (FEM).
We investigate the generation of closed-packed light rings with a minimum possible diameter using a combination of a light ring distribution generator and a diffractive beam splitter. As a light ring distribution generator, we use the wellknown S-waveplate and generate three different types of ring-shaped laser beams: an azimuthally polarized Gaussian beam, a first-order circularly polarized optical vortex beam, and a first-order linearly polarized optical vortex beam. Our modeling and experimental results show that the azimuthally polarized Gaussian beam is the best solution for splitting in comparison with the other types of beams. These results can be used in applications of high-throughput laser micro- and nanopatterning materials for the fabrication of microlasers by direct laser ablation of a thin film on glass that have great potential in optical communications and sensing applications.
We investigated subwavelength diffraction optical elements based on ring gratings. We conduct numerical simulation of creation and focusing of the second order radially polarized beam and pulsed radiation passed through the subwavelength diffraction grating. The formation of a shadow focal spot in the immediate vicinity of an optical element, amplification of the longitudinal component of the electric field and the inverse energy flow can arise near the optical axis of the element were shown.
We present a novel type of diffractive optical elements - a nonlinear spiral phase plate whose transmission function is described as exp(iφmn). The light field generated by the element has a spiral-shaped intensity and phase distribution, a non-uniform orbital angular momentum (OAM) distribution and spiral-shaped energy flow. Because of the non-linear azimuthal phase variation, the nonlinear spiral phase plates demonstrate angle-dependent distortion resistance properties. We believe that the proposed nonlinear spiral phase plates will be useful for the realization of OAM-Mode Division Multiplexing in optical communication systems as well as in the area of laser manipulation and laser-matter interaction for fabrication of unique chiral metasurfaces that can be used in optical communication systems too.
In this paper amplitude Fresnel zone plates with metal relief on silica glass is investigated. Simulation by frequencydependent finite-difference time domain method shows that all proposed designs of amplitude lenses can produce focal spots whose transversal size could overcome the diffraction limit (full width at half maximum of intensity is 0.38 – 0.46 of wavelength) and in several cases amplitude zone plates give tighter focal spot (full width at half maximum of intensity is 0.38 of wavelength) than phase zone plate.
We present a novel method of forming the phase diffractive optical elements (DOEs) by direct laser writing in thin films of aluminum with the help of the circular laser writing system "CLWS-200S". The quality of the aluminum films were investigated depending on the parameters of magnetron sputtering process. Circular phase diffraction gratings of Al2O3 on the quartz substrate with a period of 4 μm and 50% duty cycle were fabricated for the desired wavelength of 532 nm. In the visible wavelength spectrum, Al2O3 has a refractive index of 1.8 which is higher than the refractive index of quartz 1.5 that provides a significant refractive index contrast. As a result, this fact reduces the requirement of high aspect ratio of the diffractive element structures in the Al2O3 film as compared to the structures in quartz by 20%. This method of phase diffraction optical elements forming substantially reduces the time, fabrication steps, costs of production and significantly improves the quality of the elements in comparison with traditional process.
We manufactured and investigated narrow spectral selection filter with a defect layer. Design of the filter was performed based on results of modeling. The main idea of that filter is sandwich structure of 5 layers with high aspect ratio between refractive indices of two different layers and phase diffractive optical element in the central layer. The structure was manufactured for operation at wavelength of 532 nm. The ZnO (n=2.03) and TiO2 (n=2.67) thin films were chosen as materials for the designed sandwich structure. The thin films were deposited by the magnetron sputtering system “Caroline D12A”. The thickness of each ZnO layer is 50 nm, the thickness of each TiO2 layer is 65 nm. The central defective layer was fabricated with the help of a plasma-chemical etching system through a hard mask of chromium. The chromium hard mask was manufactured by direct laser writing. The central TiO2 layer was etched in a SF6 gas. Then the mask was removed by liquid chemical etching. The influence of the multilayer structure properties and parameters of defective layer on the spectral characteristics of the optical filter was investigated. This filter shows very narrow spectrum selection and high efficiency. The possibility of the use of such filters for selecting a narrow range of wavelengths that can find various applications in the field of information transfer and medical devices was shown.
The well-known Gerchberg-Saxton (GS) algorithm allows the reconstruction of an unknown wave front from known intensity distributions on a few planes of an optical system, for example, in the input plane and the focal plane. It is also the method of choice for the production of computer-generated holograms and calculation of the transmission function of diffractive optical elements (DOEs) generating so-called structured laser beams. Such ‘unconventional’ laser beams have unique features of an amplitude/phase/polarisation distribution, significantly extending opportunities for application of laser optics in many fields of modern science. Here, we propose a new modification of the basic GS algorithm that can be used to calculate a pure-phase transmission function of DOEs which generate complex intensity distributions with submicron features. DOEs designed in this way can be used in the field of laser fabrication of nano- and micropatterns, allowing the high-performance single-step fabrication of nanostructures for real applications in nanophotonics and optical manipulation.
In this paper, we consider methods of design and manufacture of diffractive optical elements (DOEs), generating socalled structured laser beams with predetermined amplitude/phase/polarisation distributions and perform transformation of those laser beams. Diffraction optics makes it possible to implement generation and control of the structured laser beams via single DOE and their combinations. We demonstrate several traditional methods that can be used to calculate a pure-phase transmission function of DOEs, both iterative and non-iterative. In addition, different technological processes for the manufacture of DOEs are used, including direct laser writing in thin films and lithography combined with plasma etching. The structured laser beams generated using DOEs provide new opportunities for large-scale highrate laser fabrication of nano- and microscale functional elements, as well as for the laser manipulation of microscale objects. The use of the structured laser beams in these applications (for example, radially/azimuthally polarised laser beams, optical vortex beams or beams with complex-shape transverse intensity distributions) allows advanced control..
We demonstrate a new type of circular Airy beams, the so-called azimuthally modulated circular Airy beams, generated by utilizing a diffraction element, whose transmission function is the sum of the transmission function of the element generating a “petal” pattern and the transmission function of the element generating a circular Airy beam. We experimentally investigate the propagation dynamics of such beams and demonstrate that their autofocusing and selfhealing properties are strongly dependent on the number of generated petals. These beams are a combination of a conventional circular Airy beam and vortex laser beams (or their superpositions). Using a spatial light modulator, we demonstrate that these beams have unique properties such as autofocusing, "nondiffractive" propagation and self-healing after passing through an obstacle. The experimental results are in good agreement with the simulation. We believe that these results can be very useful for lensless laser fabrication and laser manipulation techniques, as well as for development of new filament plasma multi-channel formation methods.
Sunlight can be used a source of light in buildings and automobiles, however infrared wavelengths in sunlight result in heating. In this work, Infrared Reflective Coatings are designed using thin films to transmit visible wavelengths 400~700 nm while reflecting infrared wavelengths above 700 nm. Three different design approaches have been used, namely single layer of metal, sandwich structure and multilayer design. Four metals (Ag, Au, Al and Cu) and two dielectrics (TiO2 and SiO2) are used in this study. Designs with Ag show maximum reflection of Infrared wavelengths in all designs. Sandwich structures of TiO2-Ag-TiO2 on substrate with 22 nm of thickness for each layer show the maximum transmission of 87% in the visible region and maximum reflection of Infrared wavelengths.
In this work, narrowband pass and broadband pass filters are designed based on TiO2-SiO2 multilayers. These filters are used in observing planetary nebulas and emission nebulas. They are designed by using open source software open filter and optimized by using needle synthesis method (addition of thin layers called needles and analyze transmission till the best result achieved). Also results were cross-checked by using matrix method. The transmission of these filters is in the range of 486-501 nm (Oxygen-III and hydrogen-β) with a maximum transmission of 95%. Also it has a second peak at 656 nm for hydrogen-α where transmission reaches 87%.
This paper presents the new architecture of 2-DOF (degree-of-freedom) drive mode and 1-DOF sense mode gyroscope with the concept of additional anchoring that retains all the advantages of the Dynamic Vibration Absorber (DVA) concept while being operated at high frequencies. These concepts allow reduction of the bandwidth by varying the coupling parameter during the design, thereby increasing the mechanical sensitivity. In the present design, the anchoring concept has been implemented by adding a central anchor for the sense mass. The steady state response and design concept have been devised using analytical modeling.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.