We present a new concept of three-dimensional (3D) polymer-based 1x4 beam splitter for wavelength splitting around 1550 nm. The beam splitter consists of IP-Dip polymer as a core and polydimethylsiloxane (PDMS) Sylgard 184 as a cladding. The splitter was designed and simulated with two different photonics tools and the results show high splitting ratio for single-mode and multi-mode operation with low losses. Based on the simulations, a 3D beam splitter was designed and realized using direct laser writing (DLW) process with adaptation to coupling to standard single-mode fiber. With respect to the technological limits, the multi-mode splitter having core of (4x4) μm2 was designed and fabricated together with supporting stable mechanical construction. Splitting properties were investigated by intensity monitoring of splitter outputs using optical microscopy and near-field scanning optical microscopy. In the development phase, the optical performance of fabricated beam splitter was examined by splitting of short visible wavelengths using red light emitting diode. Finally, the splitting of 1550 nm laser light was studied in detail by near-field measurements and compared with the simulated results. The nearly single-mode operation was observed and the shape of propagating mode and mode field diameter was well recognized.

In this paper, simple and highly sensitive plasmonic structures are analyzed theoretically and experimentally. A structure comprising a glass substrate with a gold layer, two adhesion layers of chromium, and a silicon dioxide overlayer is employed in liquid analyte sensing. The sensing properties of two structures with distinct protective layer thicknesses are derived based on a wavelength interrogation method. Spectral reflectance responses in the Kretschmann configuration with a coupling BK7 prism are presented, using the thicknesses of individual layers obtained by a method of spectral ellipsometry. In the measured spectral reflectance, a pronounced dip is resolved, which is strongly red-shifted as the refractive index (RI) of the analyte increases. Consequently, a sensitivity of 15,785 nm per RI unit (RIU) and a figure of merit (FOM) of 37.9 RIU${}^{-1}$ are reached for the silicon dioxide overlayer thickness of 147.5 nm. These results are in agreement with the theoretical ones, confirming that both the sensitivity and FOM can be enhanced using a thicker silicon dioxide overlayer. The designed structures prove to be advantageous as their durable design ensures the repeatability of measurement and extends their employment compared to regularly used structures for aqueous analyte sensing.

Highly reflective mirrors are indispensable components in a variety of state‐of‐the‐art photonic devices. Typically used, bulky, multi‐layered distributed Bragg (DBR) reflectors are limited to lattice‐matched semiconductors or nonconductive dielectrics. Here, we introduce an inverted refractive index‐contrast grating (ICG) as compact, single‐layer alternative to DBR. In the ICG, a subwavelength one‐dimensional grating made of a low‐refractive‐index material is implemented on a high‐refractive‐index cladding. Our numerical simulations show that the ICG provides nearly total optical power reflectance for the light incident from the side of the cladding whenever the refractive index of the grating exceeds 1.75, irrespective of the refractive index of the cladding. Additionally, the ICG enables polarization discrimination and phase tuning of the reflected and transmitted light, the property not achievable with the DBR. We experimentally demonstrate a proof‐of‐concept ICG fabricated according to the proposed design, using the technique of sub‐µm 3D laser lithography in which thin stripes of IP‐Dip photoresist are micro‐printed on a Si cladding. This one‐step method avoids laborious and often destructive etching‐based procedures for grating structuration, making it possible to implement the grating on any arbitrary cladding material.

In this paper, the fabrication method of waveguide structures and devices as ring resonators for different waveguide applications based on polymer material is presented. The structures were designed in computer-aided design (CAD) software and two-photon polymerization lithography system was used for preparation of desired devices. Morphological properties of prepared devices were investigated using scanning electron microscope (SEM) and confocal microscope. Finally, we performed measurement of optical spectrum characteristics in telecommunication wavelengths range. The results corresponds to calculated parameters. Final polymer devices are promising for lab on a chip and sensing applications due to unique elastic and chemical properties.