Yongze Yu

Topological engineering of glass for modulating chemical state of dopants.

A novel approach to modulating the chemical state of dopants by engineering the topological features of a glass matrix is presented. The method allows selective stabilization of dopants on a wide range of length scales, from dispersed ions to aggregated clusters to nanoparticles, leading to various intriguing optical phenomena, such as great emission enhancement and ultra-broadband optical amplification.

Formation and selective micron-regional control of PbS quantum dots in glasses using femtosecond laser pulsation

The direct and effective synthesis of PbS quantum dots (QDs) in a solid-state matrix is of great importance in the production and application of PbS QDs photonic devices. The present article describes the direct precipitation of PbS QDs in an inorganic glass matrix by the irradiation of a femtosecond (fs) laser. It has been demonstrated that the formation of the QDs is strongly influenced by the thermal effect of the fs laser. The effect of the irradiation parameters and of Ag clusters on the precipitation of QDs has been investigated, in addition to the spatial distribution of the QDs in the irradiated area, and a mechanism is suggested. The confocal Raman spectra indicate that after irradiation the concentration of the QDs is the highest at the center. On the other hand, heat treatment of the irradiated sample has also been carried out to adjust the size, distribution and photoluminescence of QDs within the glass matrix. The electron probe microanalyzer (EPMA) has provided direct evidence for the large change in refractive index and for the ring-shaped structure formed on irradiation. Based on selective local control of the PbS QDs, a waveguide demonstration has been conducted to illustrate the feasibility of directly writing a PbS QDs waveguide with an fs laser in a glass matrix.

Space-selective precipitation of ZnO crystals in glass by using high repetition rate femtosecond laser irradiation

We report on three-dimensional (3D) precipitation of ZnO crystals inside a silicate glass by a 500 kHz femtosecond pulse laser. The precipitation and distribution of ZnO crystals in glass are confirmed and analyzed by Raman spectra and Raman mapping. Mirco- luminescence is observed in the laser modified region when excited by femtosecond pulse laser or Xenon lamp. The effect of laser average power on the precipitation of the ZnO crystals has also been investigated. The possibility of 3D optical data storage using the observed phenomena is demonstrated.

A chip-based microcavity derived from multi-component tellurite glass

Construction of a chip-based optical microcavity from multi-component glass has long been a significant fundamental challenge in the cross field of materials science and photonics. Here we introduced a scalable non-hydrolytic sol–gel method for deposition of multi-component glass film with high thickness and superior homogeneity. Prototypically, we demonstrated success in the fabrication of multi-component tellurite thick film, and construction of the tellurite microcavity on a silicon chip through a combined etching technology for the first time. The collaborative studies by using the steady-state spectrum, whisper gallery mode (WGM) resonance spectrum and electric field distribution firmly indicate that the obtained thick film and microcavity present excellent properties, pointing to their promising applications in integrated photonics.

Fabrication of microchannels by space-selective control of phase separation in glass

Microchannels have important scientific applications in many fields, because they enable precise control, manipulation, and analysis of fluid on a micrometer scale. Herein, we demonstrate an effective strategy for fabrication of microchannels, based on the space-selective phase separation in glass induced by a femtosecond laser. The proposed method shows its abilities in fabrication of three-dimensional microchannels with ∼5  mm length scale and a uniform cross section. Moreover, we also achieve the modulation of the morphology on the inner surface of microchannels by using objective lenses with various numerical-apertures. The physical mechanism of the phase separation and microstructure evolution is discussed. Our method provides new opportunities to fabricate microchannels with complex structures and multifunctional integration.

Grating-assisted generation of regular two-dimensional multicolored arrays in a tellurite glass.

A grating structure was inscribed in a tellurite glass after irradiation with high-repetition rate femtosecond laser pulses. High diffraction efficiency was obtained due to the large refractive index change, which was caused by the precipitation of Te crystals in the laser modified region. Two-dimensional multicolored arrays were generated by cascaded four-wave mixing (CFWM) together with the prefabricated grating structure, which showed much more superior than those induced by beam breakup.