This PDF file contains the front matter associated with SPIE Proceedings Volume 12229, including the Title Page, Copyright information, Table of Contents, and Conference Committee listings.

We report on polymer nanocomposite films with spectrum down-converting properties that can be transferred using pulsed laser deposition (PLD) on silicon avalanche photodiodes (APD) for responsive and fast UV sensing. The proposed spectrum down-convertors use two types of nanoparticles (NPs) embedded in a colorless polyimide matrix: semiconductor CdSe/ZnS core-shell quantum dots (QDs) and the QDs made of rare-earth (RE) doped lead halide perovskites CsPbX₃ (X stands for Br and Cl). These NPs have efficient down-conversion of UV radiation into visible and near-infrared (NIR) light matching spectral responsivity of Si APD with the photoluminescence quantum yield (PLQY) from 50 to 190%. Once an APD detects visible/NIR signal, it responds with an electronic gain <10⁶ and a response time of ~10 ns thus making rapid and strong UV sensing possible. Both types of NPs have strong absorption of UV and additionally protect the APD from degradation caused by UV radiation. CdSe/ZnS core-shell QDs convert UV spectrum in visible with a red peak at 631 nm using the down-shifting mechanism. The perovskite QDs doped with the ion of Yb³⁺ emitted in NIR with a peak at 980 nm due to the mechanism of down-conversion or quantum cutting. Both types of NPs were embedded in a polymer matrix and PLD deposited on a transparent substrate. We describe the results of characterization of the down-convertors using dynamic light scattering, X-ray diffraction, optical photoluminescence spectroscopy, and the photo-voltaic characteristics of silicon photodetectors integrated with the down-convertors.

Robust monitoring at a carbon capture and storage (CCS) site to detect, locate, and quantify CO₂ migration is necessary for providing early warning for an approaching well failure and potential gas leaking. We report on distribute chemical sensing via Raman spectroscopy in hollow core fibers (HoF) for direct gas detection via the percolation of gas into the fiber open core, leading to larger matter-light interaction and thus amplification of Raman signal. We present our experimental results on Raman detection in terms of concentration and uptake time for various HoF lengths with and without side microchannels. Guided by numerical studies, the optimized number of side holes lasers to possibly augment CO₂ penetration rate into the air-filled core was determined and channels were drilled with pulsed femtoseconds Ti-Sa laser. We also investigated splicing open joint collars for integrating HoFs with solid core fibers (SCFs), critical in any deep or large surface area coverage deployment, and fiber Bragg gratings (FBGs), valuable in enhancing SNR via backscattering while generating time-space signal mapping and temperature/pressure sensing for baselining. By interleaving HOFs, FBG and SCFs, the optical spectroscopy methodology could offer a path to overcome current roadblocks to gas storage wells, as specialized fiber optics will allow direct detection of gases, in wells with in-situ and low power measurements of concentration.

Laser sources in the mid-infrared (mid-IR) region are of great interest for use in military defense and scientific applications. Recent advancements in mid-IR fiber technology using materials such as ZBLAN and chalcogenide optical fibers open the potential to create novel mid-IR all-fiber lasers. A typical laser cavity design consists of a set of mirrors separated by the gain material. One technique for creating an all-fiber laser cavity is to create two fiber Bragg gratings (FBG) separated by a length of the fiber. Direct writing using femtosecond laser has shown to create a stable Fiber Bragg Grating that will survive under harsh environments. However, a detailed understanding of how mid-IR fiber’s refractive index (RI) varies with laser parameters is currently not well studied. In our work, we will present how the RI of ZrF₄-BaF₄- LaF₃-AlF₃-NaF (ZBLAN) and chalcogenide-based mid-IR fibers changes based on the laser power.

This study examined the influence of the composition of the core material, preform production technology and posttreatment with hydrogen on the optical stability of the all-silica optical fibers to UV radiation. Elaborated fiber coating, consisting of carbon and polyimide layers, allows hydrogen saturation at 250 °C but shows excellent hermeticity at room temperature. The comparative study of the optical fibers not saturated with hydrogen showed that silicas with both high and low content of hydroxyl groups are observed to have sufficient initial UV transparency and resistance to UV irradiation. More significantly is the occurrence of defects in the structure of silica causing absorption in the region of 200 - 400 nm as well as the presence of Si-H and Si-Cl groups, which act as precursors for defects with absorption peaks at 214 nm and 330 nm. The deposition method of a reflective cladding had a significant effect on the incidence of defects and Si-H groups in the fiber core. The most significant effect on induced loss was caused by hydrogen treatment of the fibers. The findings of this study provide strategies to optimize the production of optically transparent all-silica fibers for various spectral regions and significantly improve their stability under UV and gamma irradiation.

Digital volume reflection gratings are numerically constructed from digital transmission gratings recorded at different wavelengths. We study the effect of the grating thickness, wavelength, and incident angle on the performance of digital volume reflection holography. Point cloud is studied for random circular apertures in the object plane.

Phase retrieval imaging is widely significant in the scientific, optical engineering, and medical fields. The transport of intensity equation (TIE) has been extensively applied to phase retrieval imaging. In this paper, we investigate a technique for phase retrieval based on the TIE and TPE equations employing electro-optic materials such as liquid crystals to create optical path length difference through application of a bias voltage across the cell.

A binary encoding algorithm is presented for phase-shifting projected fringe profilometry. It does not require additional projections to identify fringe orders. The pattern used for phase extraction can be used for phase unwrapping directly. Fringes can be discerned even though the surface color or reflectivity varies with positions.

We present an n-type channel transparent field-effect transistor (FET) using a top-gate configuration on a sapphire substrate. ZnO:Li film was used as channel, and MgF₂ film - as gate insulator. Measurements showed that ZnO:Li films are ferroelectrics with spontaneous polarization Ps = 1–5 mkC/sm² and coercive field EC = 5–10 kV/sm. The dependences of drain-source current on drain-source voltage at various gate-source voltages in two antiparallel Ps states were measured and the values of field-effect mobility and threshold voltage were determined for two Ps states: a) μ = 1.5 cm²/Vs, Uth = 30 V; b) μ = 1.7 cm²/Vs, U_th =23 V. Thus, Ps switching leads to a change in FET channel parameters. Results can be used to create a bistable or, more precisely, digital FET.

There is great interest in materials for one-transistor capacitive memory elements (1T1C DRAM) based on a non-junction gate FET with high memory density. ZnO film is an interesting material for creating such memory, since dielectric properties of ZnO can be controlled by donor or acceptor impurity. The goal of this study is the investigations of the dielectric properties and mechanisms of charge carrier transport of ZnO and ZnO:Li films in wide frequency and temperature range to demonstrate the possibility of creating a memory element that combines a capacitor and a field-effect transistor. ZnO:Li dielectric layer can be used as channel of the FET and dielectric for capacitor. Proposed DRAM have good potential for memory applications because it has a high reading speed; the ratio of currents in states "1" and "0" is about 105 , and the holding time exceeds 10 ms.

In this study, highly Dy³⁺-doped germano-borate glasses for different dopant concentrations ranging from 20 to 30 mol% were fabricated and their physical, optical, and MO properties were investigated. The characteristic thermal parameters disclosed good thermal stability of <100 °C against crystallization in the studied glasses. In addition, the glasses showed a high optical transmission of ~ 85% in the NIR region of 1550 nm. A very large Verdet constant of approximately -5.36 rad/(T·m) at 1550 nm was obtained in the glass containing 30 mol% D_y2O₃. Therefore, this glass might be a promising MO material for applications in the NIR region.