Postmelting Encapsulation of Glass Microwires for Multipath Light Waveguiding within Phosphate Glasses

Abstract

Glass waveguides are the fundamental component of advanced photonic circuits and play a pivotal role in diverse applications, including quantum information processing, light generation, imaging, data storage, and sensing platforms. Up to date, the fabrication of glass waveguides relies mainly on demanding chemical processes or on the employment of expensive ultrafast laser equipment. In this work, we demonstrate an advanced, simple, low-temperature, postmelting encapsulation procedure for the development of glass waveguides. Specifically, silver iodide phosphate glass microwires (MWs) are drawn from splat-quenched glasses. These MWs are then incorporated in a controlled manner within transparent silver phosphate glass matrices. The judicious selection of glass compositions ensures that the refractive index of the host phosphate glass is lower than that of the embedded MWs. This facilitates the propagation of light inside the encapsulated higher refractive index MWs, leading to the facile development of waveguides. Importantly, we substantially enhance the light transmission within the MWs by leveraging the plasmon resonance effects due to the presence of silver nanoparticles spontaneously generated owing to the silver iodide phosphate glass composition. Employing this innovative approach, we have successfully engineered waveguide devices incorporating either one or two MWs. Remarkably, the dual MW devices are capable of transmitting light of different colors and in multipath direction, rendering the developed waveguides outstanding candidates for extending the functionalities of diverse photonic and optoelectronic circuits, as well as in intelligent signaling applications in smart glass technologies.

Figure 1

(a) Schematic representation of the glass MW drawing procedure from 0.3AgI + 0.7AgPO₃ splat-quenched glass that is depicted in the inset photograph. (b) Schematic representation of the MWs encapsulation within the host AgPO₃ glass. Indicative host glass prisms are depicted in the inset photograph.

Figure 2

(a) SEM images of the 0.3AgI + 0.7AgPO₃ splat-quenched glass. (b) Typical SEM image of a glass MW drawn from the splat-quenched glass. (c,d) Higher magnification images of the same glass MW. (e) SEM image of a curved MW. (f) SEM image of a single MW waveguide device upon encapsulation of the MW within the host glass. (g) Magnified area of the device. (h) Magnified area of the MW immersion point on the surface of the host glass.

Figure 3

(a) Optical microscope photo of a typical single MW waveguide device, in which the MW immersion point is visible. Waveguiding features of the green laser with lights-on (b), and under dark (c). (d) Picture of the same waveguide device under different angle, so that the output point is more visible. Waveguiding features of the blue laser with lights-on (e), and under dark (f). Waveguiding features of the red laser with lights-on (g), and under dark (h).

Figure 4

(a) Optical microscope photo of a multipath waveguide, in which two parallel MWs are incorporated. The arrows point out the two immersion points. (b) Red laser waveguiding throughout one of the incorporated MWs (left to right direction). (c) Red and green (right to left) laser waveguiding throughout the two parallel MWs. (d) Same as previous under dark. (e) Optical microscope photo of a multipath waveguide, in which the second MW is encapsulated diagonally with respect to the other. (f) Red laser transmission through the diagonally placed MW (bottom to right direction). (g) Red and green (right to left) light transmission through the diagonally and parallel placed MWs. (h) Same as previous under dark.

Figure 5

Optical absorbance (a), and Raman (b) of the employed glasses. STEM photo of the silver nanoparticles (AgNPs) within the host AgPO₃ glass (c), and the 0.3AgI + 0.7AgPO₃ MWs glass (d). (e) HAADF image of the agglomerated AgNPs within the MWs glass. (f) HRTEM-EDX elemental mapping of the same sample, along with the individual element spatial analysis for Ag (g), O (h), P (i), and I (j).