| Apr 23, 2020 | |
Ultrashort laser pulses induce point defects in fused silica for anti-counterfeiting(Nanowerk News) Ultrashort laser pulses induced point defects in glass is always one of the hot topics in the field of laser processing materials. Point defects are closely related to density, refractive index, absorption and luminescence properties of glass. |
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| Along with the development of ultrashort laser, point defects related structure changes have enabled the preparation of functional photonic materials and devices in glass. | |
| Recently, the research group from Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences (CAS) reported tunable point defects in hydroxyl fused silica enabled by ultrashort laser pulses for anti-counterfeiting and functional module fabrication. | |
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| High-OH fused silica with a barcode. (Image: SIOM) | |
| The result was published in Optical Materials Express ("Tunable point defects in hydroxyl fused silica enabled by ultrashort laser pulses: photostimulated luminescence and functional module fabrication"). | |
| In their experiment, high, middle and low hydroxyl fused silica were subject to ultrashort pulsed laser irradiation. Three different kinds of point defects-SiE', ODC (II) and non-bridging oxygen hole center (NBOHC) were generated. Ultrashort laser pulses were proved to selectively destroy strained Si-O bonds and hydroxyl groups, thus enhancing the generation of SiE' and NBOHC. | |
| The researchers found that, as a luminous defect center, NBOHC creation density could be precisely regulated in a large range depending on hydroxyl content, laser power and pulse duration. Optimized by laser condition, high-OH fused silica could work as the extraordinary host for NBOHC, and NBOHC could give stable red photoluminescence. | |
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| (a) A schematic lab-on-chip system. Upper layer: Micro-sized defect arrays of NBOHC; lower layer: Functional module of channels, reservoirs, etc. (b) a fabricated arrays of micron-sized defects of NBOHC. (Image: SIOM) | |
| Based on ultrashort pulsed laser fabrication and defect manipulation technique, anti-counterfeiting and lab-on-a-chip applications were advocated on high-OH fused silica. | |
| This work provides a novel method for anti-counterfeiting in transparent materials, and also facilitate the application of point defects for biomedical assays based on lab-on-a-chip. |
| Source: Chinese Academy of Sciences | |
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