Fabricating 90 nm Resolution Structures in Sol-Gel Silica Optical Waveguides for Biosensor Applications

Bragg grating structure in a sol-gel silica waveguide is fabricated on the basis of nanoimprint lithography for biophotonic applications. The process realizes nonstandardized lithography in sol-gel silica at a high resolution for a relatively large area in the range of several micrometers with a resolution in the order of several nanometers. Here we demonstrate structures of 250 and 90 nm resolutions in a sol-gel silica optical waveguide for a large area that is not optimized to date. Bragg grating of a 250 nm periodic structure is realized for a 1 mm long area

Short hybrid polymer/sol-gel silica waveguide switches with high in-device electro-optic coefficient based on photostable chromophore

The highest electro-optic (EO) coefficient to date is achieved in short polymeric directional coupler switches based on hybrid EO polymer/sol-gel silica waveguides. Optimized poling conditions in such waveguides give a highest in-device EO coefficient of 160 pm/V at 1550 nm using highly efficient and photostable guest–host EO polymer SEO100. Adiabatic waveguide transitions from the passive sol-gel core to active EO polymer cores surrounding the sol-gel core are shown using EO polymer cores with a coplanar tapered structure. Switching voltages of 8.4 and 10.5 V are achieved for electrodes that are 2.1 and 1.5 mm long, respectively, which are half those of EO switches containing the chromophore AJLS102

Electro-optic polymers and modulators

The devices using Electro-optic (EO) polymers has been demonstrated for high-speed modulators and switching because of its low dispersion, coating quality, inexpensive process. EO polymers itself has been progressing since their first invention some two decades ago, and simultaneously devices using the EO polymers have been demonstrated, corresponding to want from commercial communication system. Since the middle of ninety, active devices have been realized because to fabricate all polymeric waveguide structure in EO polymers has been realized with help of costly dry etching system. All polymeric waveguide still suffer from (1) low optical throughput due to coupling losses; (2) high intrinsic optical loss in EO polymers; and (3) optical-waveguiding instability due to photochemical reaction in EO polymers. Therefore, inexpensive process to solve these problems is needed when the fabricated devices is used in the commercial communication system. In this study, I mention theoretical backgrounds, properties, and then process for device fabrication to solve these precious all polymeric approaches

Analysis and characterization of electro-optic coefficient for multi-layer polymers: dependence on measurement wavelengths

We report a significant improvement in the measurement accuracy of electrooptic (EO) coefficients for low-loss EO polymers on substrates of solgel silica and indium tin oxide (ITO). Initially, we apply the standard Teng and Man reflection ellipsometric method, which results in substantial variability in the measured EO coefficients across a wavelength spectrum with changes as small as <1 nm. This variance leads to unreliable EO coefficient values ranging from a few to 70 pm/V at the 1.31 and 1.55 µm wavelengths. By adopting a transmission method for our experiments, we effectively mitigate the dependence of the measured EO coefficient on the wavelength variance of 0.2 nm. As a result, this new approach enables a more accurate and reliable measurement of the EO coefficients. This breakthrough presents a significant step forward in the field of EO research, paving the way for further exploration into the behavior and properties of EO polymers. Additionally, our findings highlight the importance of selecting an appropriate measurement method in accordance with the unique properties of the material under investigation.Optics Express, 31(23), pp. 39239-39249; 202

Detection of organophosphorus compound based on a sol-gel silica planar waveguide doped with a green fluorescent protein and an organophosphorus hydrolase

In this letter, the authors report the real-time detection of an organophosphorus compound using a sol-gel silica planar waveguide doped with a green fluorescent protein and an organophosphorus hydrolase on a yeast-cell surface display. The waveguide was pumped at 488 nm, and it emitted green fluorescence at the far field. The green fluorescent light at 550 nm changed by 50% from the original power 1 min after application of the organophosphorus compound. The results enable the real-time detection of sarin and other biochemicals by using an in-line fiber sensor network

Sol-Gel Material-Enabled Electro-Optic Polymer Modulators

Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed

Novel Features of Eukaryotic Photosystem II Revealed by Its Crystal Structure Analysis from a Red Alga

Photosystem II (PSII) catalyzes light-induced water splitting, leading to the evolution of molecular oxygen indispensible for life on the earth. The crystal structure of PSII from cyanobacteria has been solved at an atomic level, but the structure of eukaryotic PSII has not been analyzed. Because eukaryotic PSII possesses additional subunits not found in cyanobacterial PSII, it is important to solve the structure of eukaryotic PSII to elucidate their detailed functions, as well as evolutionary relationships. Here we report the structure of PSII from a red alga Cyanidium caldarium at 2.76 resolution, which revealed the structure and interaction sites of PsbQ, a unique, fourth extrinsic protein required for stabilizing the oxygen-evolving complex in the lumenal surface of PSII. The PsbQ subunit was found to be located underneath CP43 in the vicinity of PsbV, and its structure is characterized by a bundle of four up-down helices arranged in a similar way to those of cyanobacterial and higher plant PsbQ, although helices I and II of PsbQ were kinked relative to its higher plant counterpart because of its interactions with CP43. Furthermore, two novel transmembrane helices were found in the red algal PSII that are not present in cyanobacterial PSII; one of these helices may correspond to PsbW found only in eukaryotic PSII. The present results represent the first crystal structure of PSII from eukaryotic oxygenic organisms, which were discussed in comparison with the structure of cyanobacterial PSII

Novel Features of Eukaryotic Photosystem II Revealed by Its Crystal Structure Analysis from a Red Alga

Photosystem II (PSII) catalyzes light-induced water splitting, leading to the evolution of molecular oxygen indispensible for life on the earth. The crystal structure of PSII from cyanobacteria has been solved at an atomic level, but the structure of eukaryotic PSII has not been analyzed. Because eukaryotic PSII possesses additional subunits not found in cyanobacterial PSII, it is important to solve the structure of eukaryotic PSII to elucidate their detailed functions, as well as evolutionary relationships. Here we report the structure of PSII from a red alga Cyanidium caldarium at 2.76 resolution, which revealed the structure and interaction sites of PsbQ, a unique, fourth extrinsic protein required for stabilizing the oxygen-evolving complex in the lumenal surface of PSII. The PsbQ subunit was found to be located underneath CP43 in the vicinity of PsbV, and its structure is characterized by a bundle of four up-down helices arranged in a similar way to those of cyanobacterial and higher plant PsbQ, although helices I and II of PsbQ were kinked relative to its higher plant counterpart because of its interactions with CP43. Furthermore, two novel transmembrane helices were found in the red algal PSII that are not present in cyanobacterial PSII; one of these helices may correspond to PsbW found only in eukaryotic PSII. The present results represent the first crystal structure of PSII from eukaryotic oxygenic organisms, which were discussed in comparison with the structure of cyanobacterial PSII