Anna Łukowiak

Photonic glass-ceramics: consolidated outcomes and prospects

Transparent glass-ceramics are nanocomposite materials which offer specific characteristics of capital importance in photonics. This kind of two-phase materials is constituted by nanocrystals embedded in a glass matrix and the respective composition and volume fractions of crystalline and amorphous phase determine the properties of the glass-ceramic. Among these properties transparency is crucial, in particular when confined structures, such as dielectric optical waveguides and optical fibers, are considered, and the number of papers devoted to this topic is continuously increasing. Another important point is the role of the nanocrystals when activated by luminescent species, as rare earth ions, and their effect on the spectroscopic properties of the glass-ceramic. The presence of the crystalline environment around the rare earth ion allows high absorption and emission cross sections, reduction of the non-radiative relaxation thanks to the lower phonon cut-off energy, and tailoring of the ion-ion interaction by the control of the rare earth ion partition. This last point is crucial and still object of intense experimental and theoretical studies. The composition of the glass matrix also impacts the properties of the rare earth ions located in nanoparticles. Moreover, some kinds of nanocrystals can play as effective rare earth sensitizers. Fabrication, assessment and application of glass-ceramic photonic systems, especially waveguides, deserve an appropriate discussion which is the aim of this paper, focused on luminescent glass-ceramics. In this work, a brief historical review, consolidated results and recent advances in this important scientific and technological area will be presented, and some perspectives will be outlined.

Optical pH detector based on LTCC and sol-gel technologies

This paper presents an investigation on using sol-gel thin film as a material for sensors application in LTCC (Low Temperature Co-fired Ceramics) technology. This material gives the opportunity to make new, low-cost highly integrated optoelectronic devices. Sensors with optical detection are a significant part of these applications. They can be used for quick and safe diagnostics of some parameters. Authors present a pH detector with the optical detection system made of the LTCC material. The main part of the device is a flow channel with the chamber and sol-gel active material. The silica sol-gel with bromocresol green indicator was used. As the absorbance of sol-gel layer changes with the pH value of a measured medium, the transmitted light power was measured. The pH detector was integrated with the electronic components on the LTCC substrate.

Active Sol-Gel Materials

Sol-gel technology has attracted considerable attention due to possibility of obtaining submicron and nano-sized materials. The method of silica and titania nanopowders and thin films obtaining will be presented. Also properties and prospective application of these materials will be express. Additionally, methods of obtaining nanomaterials with different grains shape and specific properties (submicron spherical silica powders, titania nanofibers) will be showed. One of the main advantages of the sol-gel technique is the easiness of doping of the obtained materials with various substances (inorganic, organic, biological). Materials activated this way possess several useful properties. For example, silica spherical matrices with metallic nano-islands on their surface will be presented. Such silver-doped silica powders display anti-microbial capabilities and can be used to obtain doped thin-film coatings e.g. for the production of bacteriostatic textiles. Moreover, materials obtained by the sol-gel method have found wide application in the area of sensors. Examples of optical sensors based on sol-gel derived thin films and optical fiber or planar wave-guide will be also presented.

1-D Photonic Crystals Fabricated by RF Sputtering Towards Photonic Applications

A great technological and scientific challenge is related to the fabrication of confined structures where the light is confined in systems with characteristic dimensions scale from micro to nanometers. The nanotechnology, that allows the study of innovative functional materials and gives advances in the miniaturization, has opened the way to the manufacturing of such structures and focalize the attention of new features of light-matter interaction (Ristic D et. al, Proc ICTON Tu. B 5.2:1–5, 2013). An example concerns planar microcavities, or one-dimensional (1-D) photonic crystals, which are the simplest photonic band – gap (PBG) devices exploitable to manage the spectroscopic properties of luminescent species such as rare earth ions (Valligatla S, Chiasera A, Varas S, Bazzanella N, Narayana Rao D, Righini GC, Ferrari M, Opt Express 20:21214, 2012) and quantum dots (Jasieniak J, Sada C, Chiasera A, Ferrari M, Martucci A, Mulvaney P, Adv Funct Mater 18:3772, 2008). The fundamental optical principle for the photonic crystals is, “localization of light” (John S, Phys Rev Lett 58:2486, 1987) so that combination of photonic crystals and nonlinear optics leads us towards new nonlinear optical devices (Ma GH, Shen J, Rajiv K, Tamg SH, Zhang ZJ, Hua ZY, Appl Phys B 80:359, 2005; Valligatla S, Chiasera A, Krishna MBM, Varas S, Narayana Rao D, Ferrari M, Righini GC, Int Conf Fiber Opt Photon 2012:W1C.2).