Search

Introduction: The recovery response characteristics of optical stopping-effect on the AsxS100-x system (20≤x≤40) film waveguides are investigated in detail. We analyzed the chemical bond structure of the samples. The hybrid orbital theory and energy bandgap theory are applied in order to establish the model of optical stopping and the recovery process.Purpose: Amorphous semiconductor chalcogenides are potentially useful materials for integrated nonlinear optical components offering low-phonon energies, ultra-fast broadband optical response times. These unique optical properties make them very interesting for integrated optical devices and all-optical signal processing. The article is devoted to consideration of usage As-S films as an active element of waveguide attenuators.Results: AsxS100-x thin-film waveguides demonstrated the slow recovery propagation process with the disappearance of the fast rising edge in the optical stopping-effect. It is shown that in the propagation channel of waveguide modes there is a competition between two processes of changes in optical losses (the fast creation of an external optical recording from the initiating irradiation and its optical erasure by a controlling optical mode). The slow process taking several seconds for full recovery, moreover meaning that the actions of the photon pumping and thermal disturbance are equal and opposite in direction. The time parameters of processes essentially depended on the composition of the films, on the flux density of the initiating external radiation and on the control mode in the film waveguide. We have established that the time constants for dynamic changes in the refractive index under external illumination are weakly correlated with similar characteristics of the stopping-effect.Conclusion: The article is devoted to consideration of usage As-S films as an active, and it was confirmed that the device exhibits useful switching functionality based on the photo-optical effect (light-controlled waveguide optical attenuators)., С помощью высокочувствительной волноводной методики исследованы динамические характеристики эффекта наведения внешним инициирующим излучением оптической записи с фотоиндуцированным возрастанием уровня поглощения (затухания) оптических волн в тонкопленочних волноводах на основе системы As-S, а также особенностей ее устранения при сопутствующем активном воздействии на облучаемый участок контролирующей оптической моды. Определены временные характеристики процессов наведения оптической записи и ее стирания в режиме волноводного распространения световой моды. Показано, что их временные параметры существенно зависят от состава пленок, от плотности потоков инициирующего внешнего излучения и контролирующей моды в пленочном волноводе., З використанням високочутливої хвилеводної методики досліджено динамічні ефек­ти наведення зовнішнім випромінюванням оптичного запису з фотоіндукова­ним збільшенням рівня поглинання (затухання) оптичних хвиль у тонкоплівкових хвилеводах на основі системи As-S, а також характеру її усунення при супутній ак­тивній дії на ділянку зовнішнього опромінення контролюючої оптичної моди. Ви­значені часові характеристики процесів створення зовнішнього оптичного запису і його стирання в режимі хвилеводного розповсюдження світлової моди. Показано, що згадані часові параметри істотно залежать від хімічного складу плівок, також від густини потоків ініціюючого зовнішнього випромінювання та контролюючої мо­ди в плівковому хвилеводі. Запропоновано використати досліджуваний ефект для створення інтегрально-оптичних атенюаторів.

This Feature highlights recent advances on mid-infrared thin-film waveguide technology and on-chip photonics facilitating next-generation label-free chem/bio sensor and assay platforms. Complemented by more recent advancements toward on-chip semiconductor waveguides, it is anticipated that label-free integrated mid-infrared sensing schemes will readily complement existing chem/bio sensor technologies in applications ranging from process monitoring and environmental analysis to biomedical diagnostics and point-of-care devices, acceptedVersion

Optical simulations of GaAs/AlGaAs thin-film waveguides were performed for investigating the dependence of the modal behavior on waveguide geometry and the resulting analytical sensitivity. Simulations were performed for two distinct mid-infrared wavelengths, thereby demonstrating the necessity of individually designed waveguide structures for each spectral regime of interest. Hence, the modal behavior, sensitivity, and intensity of the evanescent field were investigated via modeling studies at 1600 and 1000 cm−1, thereby confirming the utility of such simulations for designing mid-infrared sensors based on thin-film waveguide technology., publishedVersion

Diamond has excellent optical properties including broadband transmissivity, low self- absorption and a high refractive index, which have prompted its use in for optical sensing applications. Thin-film diamond strip waveguides (DSWGs) combined with tunable quantum cascade lasers (tQCLs) providing an emission wavelength range of 5.78-6.35 μm (1735-1570 cm-1) have been used to obtain mid-infrared (MIR) spectra of proteins, thereby enabling the analysis of their secondary structure via the amide I band. Three different proteins were analyzed, namely bovine serum albumin (BSA), myoglobin, and γ-globulin. The secondary structure of BSA and myoglobin has a major contribution of -helices, whereas γ-globulins are rich in β-sheet structures, which is reflected in the amide I band. A comparison of the spectra obtained via the combination of the tQCL and DSWG with spectra obtained using conventional Fourier transform infrared (FTIR) spectroscopy and a commercial diamond attenuated total reflection (ATR) element has been performed. It is shown that the main features evident in FTIR-ATR spectra are also obtained using tQCL-DSWG sensors., submittedVersion