scholarly journals Ανάπτυξη αισθητήρων πλασμονίου οπτικών ινών γεωμετρίας U με την χρήση νανοσωματιδίων χρυσού

2018 ◽  
Author(s):  
Δημοσθένης Σπασόπουλος
Keyword(s):  
Refractive Index ◽  
Laser Irradiation ◽  
Dip Coating ◽  
Laser Tailoring

Στα πλαίσια της παρούσας διδακτορικής διατριβής αναπτύξαμε και μελετήσαμε μια πρωτότυπη, γρήγορη και χωρίς τη χρήση χημικών ή πολυμερών τεχνική κατασκευής LSPR-OFS, η οποία συνδυάζει οπτικές ίνες σε γεωμετρία U, νανοσωματίδια χρυσού και τη χρήση ακτινοβολίας παλμικών laser. Η τεχνική αυτή περιλαμβάνει δυο στάδια κατασκευής: Στο πρώτο στάδιο γίνεται η τροποποίηση της οπτικής ίνας σε γεωμετρία και ακολουθεί η ακινητοποίηση νανοσωματιδίων χρυσού πάνω της, με τη βοήθεια μιας τεχνικής εναπόθεσης μέσω εμβάπτισης (dip coating) της ίνας μέσα στο κολλοειδές διάλυμα των νανοσωματιδίων. Το αποτέλεσμα του πρώτου σταδίου είναι η δημιουργία ενός LSPR-OFS, που πρακτικά δεν είναι λειτουργικός, λόγω των εκτεταμένων συσσωματωμάτων που δημιουργούνται κατά τη διαδικασία της εναπόθεσης. Στη συνέχεια κατά το δεύτερο στάδιο της τεχνικής γίνεται ακτινοβόληση του αισθητήρα με τη βοήθεια παλμικών laser, που έχει σαν αποτέλεσμα το σπάσιμο των συσσωματωμάτων, το φασματικό στένεμα του LSPR φάσματος απωλειών και την ενίσχυση της πλασμονικής κορυφής. Ονομάσαμε την τεχνική που αναπτύξαμε ως «Διαμόρφωση σχηματισμών νανοσωματιδίων μέσω ακτινοβόλησης laser» (Tailoring Decorations by Laser Irradiation, TDLI).Οι LSPR-OFS που κατασκευάστηκαν με τη χρήση της TDLI τεχνικής μελετήθηκαν ως αισθητήρες μεταβολής του δείκτη διάθλασης (Refractive Index, RI) σε διαλύματα ζάχαρης και σε διαλύματα αλκοολών. Κατά τη διάρκεια βελτιστοποίησης της τεχνικής αναπτύχτηκαν πρωτόκολλα εναπόθεσης των νανοσωματιδίων πάνω στην ίνα και πρωτόκολλα ακτινοβόλησης των αισθητήρων. Τέλος μελετήθηκε μια σειρά παραμέτρων, όπως το μέγεθος των νανοσωματιδίων, η συγκέντρωση εναπόθεσης, το μήκος κύματος της ακτινοβολίας και η χρονική διάρκεια των παλμών. Τα αποτελέσματα των παραπάνω μελετών θα βοηθήσουν στην περαιτέρω ανάπτυξη αυτών των αισθητήρων και θα οδηγήσουν στην ευρεία χρήση τους και εκτός εργαστηριού.

scholarly journals Mode Sensitivity Exploration of Silica–Titania Waveguide for Refractive Index Sensing Applications

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7452
Author(s):  
Muhammad A. Butt ◽  
Andrzej Kaźmierczak ◽  
Cuma Tyszkiewicz ◽  
Paweł Karasiński ◽  
Ryszard Piramidowicz
Keyword(s):  
Refractive Index ◽  
High Performance ◽  
Near Infrared ◽  
Sol Gel ◽  
Cost Effective ◽  
Dip Coating ◽  
Infrared Wavelength ◽  
Refractive Index Sensing ◽  
Sensing Applications ◽  
Coating Method

In this paper, a novel and cost-effective photonic platform based on silica–titania material is discussed. The silica–titania thin films were grown utilizing the sol–gel dip-coating method and characterized with the help of the prism-insertion technique. Afterwards, the mode sensitivity analysis of the silica–titania ridge waveguide is investigated via the finite element method. Silica–titania waveguide systems are highly attractive due to their ease of development, low fabrication cost, low propagation losses and operation in both visible and near-infrared wavelength ranges. Finally, a ring resonator (RR) sensor device was modelled for refractive index sensing applications, offering a sensitivity of 230 nm/RIU, a figure of merit (FOM) of 418.2 RIU−1, and Q-factor of 2247.5 at the improved geometric parameters. We believe that the abovementioned integrated photonics platform is highly suitable for high-performance and economically reasonable optical sensing devices.

scholarly journals Research on the Response Characteristics of Vanadium Pentoxide Film to the Irradiation of Ultrafast Pulsed Laser

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2078
Author(s):  
Qianqian Shi ◽  
Guodong Zhang ◽  
Yuheng Wang ◽  
Yu Lan ◽  
Jiang Wang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Laser Irradiation ◽  
Vanadium Pentoxide ◽  
Modulation Depth ◽  
Ultrafast Laser ◽  
Stable Phase ◽  
Saturable Absorption ◽  
Third Order ◽  
The Third ◽  
Structural Responses

Vanadium pentoxide (V2O5) is the most stable phase among many transition metal vanadium oxides, and has already been widely used in many fields. In this study, the morphological, structural, and optical responses of V2O5 film to ultrafast laser irradiation was investigated. The third-order nonlinear optical properties of V2O5 film were measured by common Z-scan technique, and the results showed that V2O5 film has self-defocusing and saturable absorption characteristics. The third-order nonlinear absorption coefficient and nonlinear refractive index were calculated to be −338 cm/GW and −3.62 × 10−12 cm2/W, respectively. The tunable saturated absorption with modulation depth ranging from 13.8% to 29.3% was realized through controlling the thickness of vanadium pentoxide film. V2O5 film was irradiated by ultrafast laser with variable pulse energy, and the morphological and structural responses of the V2O5 to the laser with different energy densities were investigated. The irreversible morphological and structural responses of V2O5 films to ultrafast laser irradiation was analyzed using the phase-contrast microscope and Raman spectrum. The chemical structure change from V2O5 to V6O13 was considered the main reason for refractive index modification.

Changes of thickness and refractive index of silica sol-gel film by dip coating process

2014 ◽  
Vol 26 (7) ◽  
pp. 72005
Author(s):  
张日东 Zhang Ridong ◽  
严鸿维 Yan Hongwei ◽  
吕海兵 Lü Haibing ◽  
张尽力 Zhang Jinli ◽  
晏良宏 Yan Lianghong ◽  
...  
Keyword(s):  
Refractive Index ◽  
Sol Gel ◽  
Dip Coating ◽  
Silica Sol ◽  
Coating Process ◽  
Gel Film

Modification of refractive index in Ag/Na ion-exchanged glasses by vacuum-ultraviolet pulse laser irradiation

2001 ◽  
Vol 78 (13) ◽  
pp. 1844-1846 ◽  
Author(s):  
S. Ruschin ◽  
K. Sugioka ◽  
G. Yarom ◽  
T. Akane ◽  
K. Midorikawa
Keyword(s):  
Refractive Index ◽  
Laser Irradiation ◽  
Pulse Laser ◽  
Vacuum Ultraviolet ◽  
Pulse Laser Irradiation

Ellipsometric Imaging of Drying Sol-Gel Films

1988 ◽  
Vol 121 ◽  
Author(s):  
Alan J. Hurd ◽  
C. Jeffrey Brinker
Keyword(s):  
Refractive Index ◽  
Sol Gel ◽  
Dip Coating ◽  
Drying Process ◽  
Imaging Ellipsometry ◽  
Withdrawal Velocity ◽  
Coated Film ◽  
Sol Gel Films ◽  
Physical And Chemical ◽  
Dip Coated Films

ABSTRACTAlthough controlled dip-coating is an established way to apply high quality uniform coatings, the details of the coating and drying process have not been deeply studied. Depending on the physical and chemical state of the sol and the parameters of dipping (dipping angle and speed), a variety of thicknesses and porosities can be achieved [1]. For optical coatings, the refractive index and optical thickness can thereby be controlled.We have developed a method to view the drying front of a dip-coated film using broad beam ellipsometry [2], or “ellipsometric imaging.” In dip-coated films we take full advantage of the fact that a steady state is quickly reached where the drying line velocity matches the withdrawal velocity; however, the technique might also be used in unsteady situations such as spin coating. Imaging ellipsometry makes it possible to measure the refractive index and thickness profiles of both wet and dry films point-by-point in an entire image at once. These profiles provide important clues as to the relative importance of gravity, evaporation and other phenomena.

The Influencing Factors for the Thickness of Silica Sol-Gel Film by the Dip Coating Process

2014 ◽  
Vol 597 ◽  
pp. 165-169
Author(s):  
Jie Hong Lei ◽  
Ri Dong Zhang
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Refractive Index ◽  
Sol Gel ◽  
Dip Coating ◽  
Silica Sol ◽  
Coating Process ◽  
Power Functions ◽  
Withdrawal Speed ◽  
Gel Film

The porous sol-gel silica thin films were prepared on silicon substrate by the dip coating process. The surface roughness and microstructure of the film was measured by optical microscopy and AFM .Coating thickness and refractive index were measured by ellipsometry method. Influence of withdrawal speed and concentration of colloid was investigated for the thickness of silica. The relation of the thickness and withdrawal speed was fitted by the linear and power functions, and the results were analyzed and compared. It was found that the films with the same thickness prepared by different concentrations of colloid have different refractive indexes. The experimental results indicated that the thickness and refractive index of the film can be controlled by changing the withdrawal speed and colloid concentration.

Refractive Index Controlled Plasmon Tuning of Au Nanoparticles in SiO2-ZrO2 Film Matrices

2008 ◽  
Vol 8 (8) ◽  
pp. 3868-3876
Author(s):  
Sucheta De ◽  
Samar Kumar Medda ◽  
Goutam De
Keyword(s):  
Heat Treatment ◽  
Refractive Index ◽  
Au Nanoparticles ◽  
Sol Gel ◽  
Dip Coating ◽  
Uv Treatment ◽  
Final Heat ◽  
Molar Ratios ◽  
Glass Substrates ◽  
Heat Treated

Au-plasmon tuning has been accomplished by controlling the refractive index (n) of the embedding film matrix. The refractive index of the film matrices were controlled by changing the molar ratios of low (SiO2) and high index (ZrO2) components following sol–gel reactions. Thus, Au nanoparticles doped films were prepared from SiO2-ZrO2 inorganic–organic hybrid sols of variable molar ratios containing HAuCl4 following the dip-coating method. The film samples deposited on glass substrates were obtained after drying, UV-treatment, and subsequent heat-treatment at 500 °C in air. The nominal mol ratios of SiO2:ZrO2 were 1:0, 1:1, 1:2.3, and 1:4. 3 equivalent mol% Au–97% total oxide (SiO2 + ZrO2) was maintained in the final heat-treated films. FTIR studies confirmed good homogeneity of Si-Zr network in the Zr-containing films. The UV-treatment has been introduced to facilitate the decomposition of HAuCl4 in the hybrid matrix prior to the heat-treatment step. The main Au-plasmon peak, in the case of a SiO2 host (SiO2:ZrO2 = 1:0, n = 1.410), observed at about 546 nm, gradually red-shifted to 592 nm upon increasing the ZrO2 content (SiO2:ZrO2 = 1:4, n = 1.847). Transmission electron microscopy of the final heat-treated (500 °C) films showed existence of plate-like (triangular and hexagonal) Au nanoparticles (25–50 nm) along with relatively smaller nanoparticles of about 10 nm in size. X-ray diffraction patterns reveal that the Au nanoparticles have a (111) orientation.

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