This paper describes an idea of creating a liquid analyte sensor based on a one-dimensional (1D) photonic crystal - dielectric mirror - integrated on the optical fiber end face and creating a resonant cavity with the reversed structure. This geometry produces the evident resonances within the photonic band gap spectral region which are sensitive to refractive index changes inside the resonant cavity. The main idea is to use this arrangement as a sensor in Lab-on-a-chip (LOC) device with two single mode optical fibers (SMFs). An inlet and outlet is proposed for different liquid analyte delivery and in-situ monitoring of the refractive index change of the analyte.
Point-of-care diagnosis leads to integration of sensors, electrical and optical components in one device and stimulated the area of lab-on-a-chip (LOC) devices where all operations and analysis are realized on a single chip. In LOC applications, the optical components based on interference principles play also important role. The Mach-Zehnder Interferometer (MZI) is well-known photonic device from on-chip applications, especially used in the field of silicon photonics. We proposed design of symmetric MZI based on polymer IP-Dip. Prepared MZIs with interrupted gap in sensing arm were proposed for high sensitive refractive index change detection. The MZIs were realized by laser lithography and optically investigated of different concentration of sucrose/water solutions.
Progress in nanotechnologies accelerated the polymer based photonics, where simple and cheap solutions often bring comparable and sometimes also novel interesting results. Good candidates are polymer photoresists and siloxane materials with unique mechanical and optical properties. We present laser lithography as efficient tool for fabrication of different three-dimensional (3D) structures embedded in polydimethylsiloxane (PDMS) membranes. Presented concept of PDMS based thin membranes with 3D structures works as an effective diffraction element for modification of radiation pattern diagram of light emitting diodes and changes also the angular photoresponse of photodiodes. All these results were demonstrated on two types of 3D structures – spheres arranged in cubic lattice and woodpile structure.
The photonic crystals (PhCs) and photonic quasi-crystals (PQCs) have the considerable effect on enhancement of extraction efficiency and radiation pattern of light emitting diodes (LEDs). We present thin polymer membranes based on polydimethylsiloxane (PDMS) with PhC and PQC patterned surface for direct application on the LED chip. The patterned PDMS surface was achieved by embossing of liquid PDMS (Sylgard 184) on structured photoresist surface prepared by interference lithography. The patterned PhC and PQC modify the Lambertian radiation diagram of conventional LEDs. Radiation properties of LEDs were documented from far-field emission by goniophotometer measurements. Structure quality and symmetry was examined by atomic force microscope and related to the measured diffraction pattern of the PhC and PQC LEDs. The emitting LEDs were also investigated in the near field using the near-field scanning optical microscope. Presented results favor patterned PDMS membranes for the employment in LED emission improvement and with considerable effect on light diffraction.
This paper reports on optical measurements of GaP nanowire (NW) arrays with thin nanocrystalline ZnO layer. The GaP core was prepared by metal organic vapor phase epitaxy (MOVPE) and the ZnO shell by RF sputtering by different sputtering conditions. The NWs were grown from Au seeds created from very thin Au layer deposited on top of GaP substrate. Reflectance of different NWs structures covered by ZnO coating was measured in angular dependence in wide range of angles and compared. We experimentally show the reflectance suppression of the ZnO coated NWs in the wide range of angles.
This contribution presents implementation of one dimensional Fresnel structure in surface emitting part of the AlGaAs/GaAs multi-quantum well light emitting diode (LED).The structure consists in drilled lines distributed with square root of distance in order to obtain structures with different foci. First structure was prepared by electron beam lithography and etched directly in the emitting surface using reactive-ion etching. Second structure was prepared in the surface of thin PDMS membrane that can be stack directly on the emitting surface. The membrane is fabricated using dip in laser lithography combined with PDMS embossing. Implementation of such Fresnel structures leads in modification of LED far-field what was proved by goniophotometer measurements.
This contribution demonstrates surface modification of thin photoresist layers and polydimethylsiloxane (PDMS) surfaces with spatial resolution better than 20 nm. We provided few different 2D arrangements of surface patterning with aim to prepare 2D photonic structures with various symmetries in the thin S1828 photoresist layer using AFM lithography. Consequently, we used the imprinting technique for transferring the photoresist pattern to the PDMS membrane surface. Finally, prepared 2D photonic structures in photoresist and PDMS surfaces are characterized by AFM.
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