The Stratakis Lab

The Stratakis Lab

Ultrafast Laser Micro and Nano Processing Laboratory

Advanced Composite Glasses for Optoelectronics

Objective: This research topic aims at the development of advanced composite glasses for state-of-the-art optoelectronic applications by means of novel fabrication synthesis procedures.

Abstract: Over the years, the importance of inorganic oxide glasses in various fields of optoelectronics, photonics and solid state electrochemical technological applications has been demonstrated. A continuous scientific challenge lies on maximizing the functionality of novel glassy materials upon introducing new features, and thus expanding their potential towards next-generation applications and devices. Along these lines, this research activity focuses on the development of advanced composite glasses by means of two approaches. First, we have demonstrated in the ULMNP Laboratory a novel, low-temperature, post-glass melting encapsulation synthesis protocol for the incorporation of perovskite nanocrystals, 2D materials, and metallic nanoparticles within inorganic oxide transparent glasses. The developed protocol expands beyond the current state-of-the-art in terms of allowing the controlled and confined positioning of the functional crystals within the glass. Such aspect is not possible when conventional melting procedures are followed. Second, we take advantage of ultrafast laser processing techniques for the introduction of advanced photonic features within the bulk or on the surface of the developed composite glasses.

Perovskite Glasses (PV-Glasses): In the case of perovskite glasses, we have demonstrated the formation of highly luminescent and ultrastable perovskite patterns within phosphate glasses, upon following the simple low-temperature post-glass melting fabrication procedure and cw laser processing. The embedded micro-patterns exhibit remarkable photoluminescence stability while their periodicity can be varied according to the photonic application (Figure 1).

 

Figure 1: Schematic representation of the controlled incorporation of perovskite nanocrystals (PNCs) within inorganic oxide glass by means of low-temperature, post-glass melting encapsulation. The photoluminescence stability of the composite glass and the formation of a typical perovskite micro-pattern embedded within glass are also shown.

 

2D materials Glasses (2D-Glasses): Based on the same post-glass melting encapsulation synthesis, we have demonstrated the incorporation of 2D materials within phosphate glasses. This allows significant tailoring of the photoluminescence properties of the composite 2D-Glasses. Namely, robust B-exciton emission at room temperature in few layers of MoS2:Ag nanoheterojunctions was induced upon encapsulating MoS2 layers inside silver metaphosphate glass (Figure 2). The obtained remarkable B-exciton emission is attributed to enhanced exciton-plasmon coupling that takes place in silver nanoparticles-MoS2 nanoheterojunctions. Such findings provide a promising way towards tailoring the emission properties targeting application devices working with B-exciton emissions.

 

Figure 2: Schematic representations of the incorporated MoS2 flakes inside the transparent AgPO3 glass (left), and the mechanism illustrating the exciton-plasmon coupling (center). Room temperature PL emission of pristine AgPO3 glass, MoS2 on Si substrate, and incorporated MoS2 within AgPO3 glass (right).

 

Erasable periodic surface patterns: On a rather different approach, ultrashort pulsed laser processing is performed on the surface of pristine silver phosphate glass (AgPO3). The selection of AgPO3 glass offers a remarkable advantage in terms of allowing the fabrication of high regularity, erasable and rewritable periodic surface patterns (Figure 3). Remarkably, the developed write/erase/re-write process on the same glass area is based on a single laser beam, thus, rendering the silver phosphate glass an important candidate for waveguides and optical responsive memory components. The research outcome of this work was Editor’s choice in Appl. Phys. A (Dec 2018).

 

Figure 3: Schematic representations of the laser processing experimental setup, and the write/erase/re-write procedure of the high regularity periodic surface patterns on silver phosphate glass.

 

Erasable waveguides: Femtosecond laser processing is widely used for the fabrication of various photonic structures and waveguides. In this activity we expanded this method in terms of employing a single ultrafast laser source not only for the formation of waveguides within the phosphate glass substrate, but for the feasible erase and re-writing of these patterns by means of the same laser source (Figure 4). Our findings pave the way towards new photonic applications involving infinite cycles of write/erase/re-write processes without the need of intermediate steps of typical thermal annealing treatments.

 

Figure 4: Schematic representation of the erasable waveguiding effect along with the corresponding SEM images at the cross-section of the laser-processed silver phosphate glass.

 

Photochromic glasses: Photochromic glasses offer solutions in various types of temperature regulation, irradiation protection, and energy saving challenges that have become of particular importance. In this activity we employ the post-glass melting encapsulation protocol for the development of advanced composite photochromic glasses upon incorporating AgCl crystals within transparent phosphate glasses. The developed glasses exhibit remarkable photochromic features with brief response times that exceed the current state-of-the-art, while ongoing work focuses on maximizing the percentage of photochromic switching at various wavelengths (Figure 5).

 

Figure 5: UV irradiation of the AgCl-AgPO3 composite glass (left). Optical absorbance before and after various periods following UV irradiation (center), and photochromic switching response versus time (right).

 

Active projects: TheSmartMat.

Contact persons: Dr. Ioannis Konidakis, Dr. Emmanuel Stratakis.

Project members: Dr. Ioannis Konidakis, Mr. Marios Adamidis, Mr. Harris Goniotakis, Dr. Emmanuel Stratakis .

Projects members Alumni: Dr. Abdus S. Sarkar, Dr. Efthymis Serpetzoglou, Dr. Konstantinos Tsimvrakidis, Miss Anna Karagiannaki.

Collaborators: Dr. Ioanna Demeridou, Prof. George Kioseoglou .

Selected publications:

  1. “Laser-induced erasable and re-writable waveguides within silver phosphate glasses”, K. Tsimvrakidis, I. Konidakis and E. Stratakis, Materials 15, 2983 (2022).
  2. “Advanced composite glasses with metallic, perovskite, and two-dimensional nanocrystals for optoelectronic and photonic applications”, I. Konidakis, A. Karagiannaki and E. Stratakis, Nanoscale 14, 2966 (2022).
  3. “Probing the effect of a glass network on the synthesis and luminescence properties of composite perovskite glasses”. A. Karagiannaki, I. Konidakis, G. Kourmoulakis, I. Demeridou, J. Dzibelova, A. Bakandritsos and E. Stratakis, Opt. Mater. Express 12, 823 (2022).
  4. “Robust B-exciton emission at room temperature in few-layers of MoS2:Ag nanoheterojunctions embedded into a glass matrix”, A.S. Salam, I. Konidakis, I. Demeridou, E. Serpetzoglou, G. Kioseoglou and E. Stratakis, Sci. Rep. 10, 15697 (2020).
  5. “Highly luminescent and ultrastable cesium lead bromide perovskite patterns generated in phosphate glass matrices”, I. Konidakis, K. Brintakis, A. Kostopoulou, I. Demeridou, P. Kavatzikidou and E. Stratakis, Nanoscale 12, 13697 (2020).
  6. “Effect of composition and temperature on the second harmonic generation in silver phosphate glasses”, I. Konidakis, S. Psilodimitrakopoulos, K. Kosma, A. Lemonis and E. Stratakis, Opt. Mater. 75, 796 (2018).
  7. “Erasable and rewritable laser-induced gratings on silver phosphate glass”, I. Konidakis, E. Skoulas, A. Papadopoulos, E. Serpetzoglou, E. Margariti and E. Stratakis, Appl. Phys. A 124, 839 (2018).
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