Due to the Joule heating effect induced by the use of an assisting electric field, glass wafer temperature is experimentally found to increase synchronically with the flow of current during the process of field-assisted ion diffusion. A theoretical analysis demonstrates that the amplitude of the glass wafer temperature increase is dictated by competition between two factors, heat generation and heat dissipation. Heat generation and heat dissipation both become stronger as the glass wafer temperature increases. Studies have shown that the Joule heating effect can influence the waveguide manufacturing process profoundly, including aspects such as the stability of ion diffusion, theoretical modeling of the ion-diffusion process, and waveguide depth uniformity over the glass wafer.
A model based on the charge-density flux (CDF) is proposed for the electric-field-assisted (EFA) ion-exchange, which is suitable for various EFA ion exchanging processes. Theoretical analysis shows that the CDF model is equivalent to the voltage model when the local temperature change around the glass wafer is negligible when a constant voltage is applied to the ion exchanging process. However, our experiments show that the CDF model is more applicable than the voltage model because the constant-voltage scheme shows a positive feedback process and the local temperature rising is unavoidable in the ion exchanging process. Our further experiments also show that the EFA ion exchanging process can be conveniently characterized by the proposed CDF model with the monitored electrical current, no matter the EFA ion exchanging process is with a constant-voltage/current scheme, a mixed scheme, or even a scheme with random voltage change, while additional complicated measures will be required to characterize the EFA ion exchanging process with the traditional voltage model.
Traditional glass-waveguide-based electric-field-assisted ion-exchange model is characterized by the product of voltage
and time which is well known as the voltage model. In the voltage model, the modeling condition is mainly assumed to
be with a constant voltage (or a constant electric field) and temperature is considered to be a constant, diffuse depth is
mainly determined by voltage and time. However, our recent studies and experimental results show that there is a
thermally-induced warming effect in the ion-exchange, which leads to a change of local temperature in the glass
substrate which means the electrical current induced heating effect and the decrease of the local electrical resist with the
increase of the local temperature. In this paper, we analyze the influence of the temperature variation and introduce a
temperature-independent parameter to modify the traditional voltage model and solve the influence of ion-exchanging
temperature variation. Experiment results show that the voltage model with the temperature-independent parameter
modification is more applicable than the traditional one. We obtain a more precise result than traditional model in our
Optical splitter is one of most typical device heavily demanded in implementation of Fiber To The Home (FTTH) system.
Due to its compatibility with optical fibers, low propagation loss, flexibility, and most distinguishingly, potentially costeffectiveness,
glass-based integrated optical splitters made by ion-exchange technology promise to be very attractive in
application of optical communication networks. Aiming at integrated optical splitters applied in optical communication
network, glass ion-exchange waveguide process is developed, which includes two steps: thermal salts ion-exchange and
field-assisted ion-diffusion. By this process, high performance optical splitters are fabricated in specially melted glass
substrate. Main performance parameters of these splitters, including maximum insertion loss (IL), polarization
dependence loss (PDL), and IL uniformity are all in accordance with corresponding specifications in generic
requirements for optic branching components (GR-1209-CORE). In this paper, glass based integrated optical splitters
manufacturing is demonstrated, after which, engineering-oriented research work results on glass-based optical splitter are
Multimode Interference (MMI) based devices are widely used due to excellent performance. Here in this paper, a 1×2
multimode power splitter based on MMI is designed using three-dimensional beam propagation method (3D-BPM), and
then fabricated in glass using the Ag+-Na+ ion-exchange technique. The width of the input and output multimode
waveguides was 50μm and they were tapered to 75μm at the interface to the MMI region. The MMI region was also
quadratically tapered .First, Ag+-Na+ ion exchange was run in nitrate melt at 350°C.Then an electric field was applied at
300°C so that the silver ions continued their migration award. Under the wavelength of 1550nm, the measured results
showed that the propagation loss of multimode straight waveguide can be lower than 0.31dB/cm, and the insertion loss
and uniformity of the splitter were 4.28dB and 0.21dB, respectively. Parameters of the fabrication process and structure
of the device can be optimized to improve the performance of the device.
A detailed theoretical and experimental study of buried ion-exchanged waveguides is reported. The model of the ion
concentration distribution in Ag<sup>+</sup>-Na<sup>+</sup> ion exchanged glass, which is analyzed by numerical calculations, agrees well with
our experiments showing that after the first ion-exchange, a half oval-shaped ion concentration distribution can be
obtained in the substrate; and after the second ion-exchange, the radio-shaped ion concentration distribution presents.
These results may be used to establish the necessary correlation between the ion-exchange process parameters and the
A slot waveguide structure is used in the part of arrayed waveguides in AWG instead of silicon waveguides. It is filled
with high negative thermo-optic coefficient polymer in the narrow slot. The arrayed slot structure can remarkably reduce
the center wavelength shift when the temperature changes. In this study, we use the polymer WIR30-490 and ZP49 to be
filled in the slot. The thermo-optic coefficients of WIR30-490 and ZP49 are negative, and have the same order of
magnitude with silicon. In our simulations, by adjusting several variables of the slot structure, such as the width of the
slot between the pair of silicon wires, the width of the silicon waveguide, and the height of the silicon waveguide, we can
get the athermal condition of AWG for each polymer. Even if there is an acceptable error on fabrication, temperature-dependent
center wavelength shift of AWG can still be reduced down to 1 pm/°C. It makes the fabrication of athermal
silicon AWG possible.