We have developed a fabrication procedure for growing photonic crystals in the lithographic defined microchannels, which enables easy integration with other planar optical components. This technique is based on the directed evaporation induced self-assembly of nanoparticles in the microchannels. Substrates with pre-patterned microchannels (30-100 μm wide) were dipped into solution of nanoparticles for several days. By controlling the evaporation rate, the meniscus contacting the microchannels will undergo evaporation-induced self-assembly. The capillary forces cause nanospheres to crystallize within the microchannels forming colloidal photonic crystals in the microchannels. Two types of colloidal particles, polystyrene and silica, have been employed to fabricate colloidal photonic crystals in the microchannels. Both types of colloidal particles were found to form large-area well-ordered colloidal single crystals in the microchannels. The optical reflection spectra from the (111) surfaces of the colloidal crystals formed by various sizes of nanoparticles have been measured. And the measured reflection peaks agree with the photonic bandgap calculated by the plane wave expansion method.

Using variable-angle spectroscopic ellipsometry, we measure the pseudo-dielectric functions of as-deposited and annealed SiO2/SiOx multilayers (MLs). The SiO2(2nm)/SiOx(2nm) MLs have been prepared under various deposition temperature by ion beam sputtering. The annealing at temperatures ≥ 1100°C leads to the formation of Si nanocrystals (nc-Si) in the SiOx layer of MLs. Transmission electron microscopy images clearly demonstrate the existence of nc-Si. We assume a Tauc-Lorentzian lineshape for the dielectric function of nc-Si, and use an effective medium approximation for SiO2/nc-Si MLs as a mixture of nc-Si and SiO2. We successfully estimate the dielectric function of nc-Si and its volume fraction. We find that the volume fraction of nc-Si decreases after annealing, with increasing x in as-deposited SiOx layer. This result is compared to expected nc-Si volume fraction, which was estimated from stoichiometry of SiOx.

The role of the size of amorphous silicon quantum dots in the Er luminescence at 1.54 μm was investigated. As the dot size was increased, the more Er ions were located near one dot due to its large surface area and more Er ions interacted with other ones. This Er-Er interaction caused a weak photoluminescence intensity despite the increase in the effective excitation cross section. The critical dot size, needed to take advantage of the positive effect on Er luminescence, is considered to be about 2.0 nm, below which a small dot is very effective in the efficient luminescence of Er.

The enhancement of the Er3+ ions photoluminescence (PL) emission at 1.54 μm in a Si and Er co-implanted aluminosilicate glass is investigated in details. Post-implantation annealing has been performed to recover the damage induced by the implantation process and to promote Si aggregation. It is shown that 1h treatment in N2 atmosphere is not sufficient to induce Si precipitation for the investigated temperatures, up to 500°C. Nevertheless, the most intense Er3+ PL emission at 1.54 μm is achieved at 400°C. Such emission has been investigated by pumping in and out of resonance. The results suggest that good energy transfer mediators could be small Si aggregates and not only crystalline clusters. The effective excitation cross section of Er3+ ions has been measured in the best performing sample yielding a value of ∼ 2 × 10−16 cm2, many orders of magnitude higher than the direct absorption cross section of Er3+ ions: about 10−21 cm2 in this glass. The structural and optical properties of this material are discussed and compared to those found for a standard silica substrate.

The structural properties of Si nanoclusters embedded in SiO2, produced by high temperature annealing of SiOx films, have been investigated by energy filtered transmission electron microscopy. The presence of amorphous nanostructures, not detectable by using dark field transmission electron microscopy, has been demonstrated. By taking into account also this contribution, a quantitative description of the evolution of the samples upon thermal annealing has been accomplished. In particular, the nanocluster mean radius and the density of amorphous and crystalline clusters have been determined as a function of the annealing temperature.

Ce3+ and Tb3+co-doped calcium aluminates luminescent material (Ca3Al2(OH)12: Ce3+, Tb3+) was synthesized at 453 K in hydrothermal system without any protective atmospheres. All the reactants used in the system were simple inorganic salts. The crystallinity and luminescent property of as-synthesized compound were investigated using X-ray diffraction and luminescence spectrometer. The compound formula was confirmed to be Ca3Al2(OH)12. The emission spectrum showed that only typical Tb3+ emission was observed and the emission from Ce3+ was almost not observed, which should be attributed to the energy transfer from Ce3+ to Tb3+ in the compound. The emission peaks at about 486 nm, 498 nm, 540 nm, 549 nm, 582 nm, 595 nm and 623 nm should be assigned to 5D4-7F6, 5D4-7F5, 5D4-7F4, and 5D4-7F3 transitions of Tb3+ ions. The weak emission peak at about 380 nm should be assigned to the emission of Ce3+ ions in the compound.

Red light emitting of Mn2+ doped Ba2ZnS3 phosphor powders have been synthesized by double-crucible method at different thermal treatments. XRD results indicate that the raw materials are completely sulfurized above 950°C, and the Ba2ZnS3: Mn2+ powders don't change its orthorhombic crystal structure with increasing doping concentration from 0 to 0.8 mol%. The photoluminescence of Ba2ZnS3: Mn2+ powders fulfilled the most efficient emission at the excitation wavelength λex=358 nm and showed the red emission light with peak wavelength λem=627nm at the doping concentration of Mn2+ ion between 0.2 and 0.8 mol%. The high-luminance red emission results from the 4T1 (4G)—6A1 (6S) transition in the Mn2+ ion. Ba2ZnS3: Mn2+ phosphors synthesized by double-crucible method have broad emission spectra (550nm∼750nm) with FWHM (full width at half maximum broadband) about 66nm. In our research, the Ba2ZnS3 doped with 0.4 mol% Mn2+ has the highest luminescent intensity as thermal treatment at 950°C for 16 hours and the CIE coordinate is x=0.66, y=0.33.

Organic electro-optic materials afford the realization of devices with terahertz bandwidths, providing bandwidths are not limited by resistive losses in metal electrodes. Recent realization of electro-optic coefficients (at telecommunication wavelengths) on the order of 200 pm/V permits construction of devices with operating voltage requirements of 1 volt or less. In like manner, substantial progress has been made in both understanding and improving thermal and photostability suggesting that organic electro-optic materials can meet Telacordia standards. However, one of the most intriguing advances afforded by organic materials is their processability including the ability to be integrated with diverse materials. This communication discusses both the systematic improvement, by theoretically-inspired rational design, of relevant material properties and the development of a variety of new processing methodologies, including soft lithography methods, for the fabrication of stripline, cascaded prism, and ring microresonator devices. The fabrication of flexible devices is also discussed.

Tunable laser action, in the visible spectrum, has been established using dye-doped, polymer-silica nanoparticle gain media. The silica nanoparticles, averaging about 12 nm in diameter, appear to be uniformly dispersed in the polymethyl methacrylate (PMMA) matrix, since the optical homogeneity of the gain medium is maintained. Using rhodamine 6G dye and 30% weight-by-weight (w/w) silica nanoparticles, laser action was established in the 567–603 nm range. At the peak wavelength (λ ∼ 580 nm) laser conversion efficiency is ∼63% at a beam divergence of 1.9 mrad (∼1.3 times the diffraction limit). The new solid-state nanocomposite gain media also exhibits a reduction in |∂n/∂T| because the thermo-optic coefficient of silica is opposite in sign to that of the PMMA polymer-host component.

We demonstrate that multilayers composed of nineteen alternating layers of tin sulfide and silica can function as omnidirectional reflectors. These materials exhibit omnidirectional reflectivity for a range of frequencies in the near infra-red (NIR) encompassing the 850 nm wavelength. A refractive index contrast of 2.7/1.46 is achieved, one of the highest values demonstrated until now in NIR photonic bad gaps. In addition, new nanoindentation procedures have been developed to measure mechanical properties of these fine laminate materials, and demonstrate that tin sulfide-silica multilayers are mechanically stable for practical applications.

Opal-based photonic band gap (PBG) crystals with multiple stop bands were prepared utilizing a sol-gel method. The fabricating procedure includes colloidal crystal syntheses, dispersion, sedimentation, coating, and thermal treatments. Each of the steps can affect the PBG properties, such as stop band locations and ranges. Different stop bands of the photonic crystals can be produced by controlling the particle sizes prepared by the colloidal crystal syntheses. A PBG crystal film with a certain stop band was formed using a particular size of the colloidal crystals coated on glass substrates. In this study, two layers of different particle sizes of PBG crystal were fabricated by different deposition conditions to demonstrate the feasibility of producing multiple stop bands. These conditions can affect the stack layers and structural regularity for forming the PBG layers. In addition, the stop band intensity of the PBG layer can be further improved by the step of thermal treatments. Results imply that multiple stop bands can be feasibly designed and produced as multiple PBG layers coating with a certain SiO2 particle size for each layer.

We report electro-optic performance of highly polar axis oriented Na0.5K0.5NbO3(NKN) films grown directly on Pt(100nm)/Ti(10nm)/SiO2/Si(001) substrates by rf-magnetron sputtering. Semitransparent gold electrodes (diameter Ø= 2 mm) were deposited ontop the NKN films by a thermal evaporation through the contact mask. Processing parameters have been specially optimized to obtain “electrosoft” NKN films with a non-linear fatigue-free P-E characteristics: low remnant Pr = 3.6 μC/cm2 and high induced polarization P = 26 μC/cm2 @ 522 kV/cm, and the coercive field Ec= 39 kV/cm. Electro-optical characterization of NKN/Pt/Si films has been performed using waveguide refractometry: a free-space coupling of a light beam into the thin-film waveguide modes. Intensity of TM- andTE-polarized light of 670 nm laser diode reflected from the free surface of NKN film and Au-cladding NKN/Pt/Si waveguide was recorded at zero and 30 V (100 kV/cm) bias electric field. Extraordinary and ordinary refractive indices as well as electro-optic coefficient have been determined by fitting these experimental data to the Fresnel formulas. Applying 160 V (530 kV/cm) across the parallel plate NKN capacitor (Ø= 2 mm, thickness 3 μm), modulation of the reflected light as high as 40% was achieved.

We report on a complete optical investigation on two-dimensional silicon-on-insulator (SOI) waveguide photonic crystals obtained by electron beam lithography and reactive ion etching. The dispersion of photonic modes is fully investigated both above and below the light-line by means of angle- and polarization-resolved micro-reflectance and attenuated total reflectance measurements.

The investigated samples consisted in a) large area (300 × 300 μm2) two-dimensional (2D) triangular lattices of air holes containing repeated line–defects; b) small area triangular lattices of holes with different number of periods and /or line defects integrated in a ridge type waveguide structure.

In the case of large area samples, variable-angle reflectance and ATR is measured from the sample surface in a wide spectral range from 0.2 to 2 eV both in TE and TM polarizations. The sharp resonances observed in the polarized reflectance and ATR spectra allow mapping of the photonic dispersion of both radiative and guided modes. Experimentally determined and compared to those calculated by means of an expansion on the basis of the waveguide modes.

In the case of ridge type waveguide-integrated photonic crystals, transmission is measured in the 0.9-1.7 eV spectral range by an edge-coupling technique. Transmission spectra exhibit significant attenuation corresponding to the photonic gaps along the Γ–M and Γ–K directions respectively, even when a small number of hole periods is integrated in the ridge waveguide. Good agreement is obtained by comparing the measured transmission spectra with the calculated photonic bands.

Plasma enhanced CVD produces carbon layers with various properties which are highly correlated to the different process parameters such as monomer structure, plasma type or plasma power. For example, the modification of monomer (CH4 to C4H10) or the plasma source and the increase of plasma power lead to an optical band-gap which runs from 0.9 to 4.3eV, a conductivity from 5·103 to 5·105S.m−1 and a refractive index from 1.47 to 2.76. Then, it is able to control the optical and electrical film properties from the external process parameters. This paper will thus be focused on the description of relation between deposition parameters, structural characteristics of material and film properties. These materials can then be used for optoelectronics applications.

Glasses rich in rare-earth ions have attracted a lot of interest due to their applications in optical isolators and optical amplifiers. Integrating optical isolators with various optoelectronic devices allows sources to be integrated with lower costs, easier alignment and longer lifetimes. Glasses rich in rare-earth ions have large Verdet constants, so large Faraday rotations. Among the rare-earth ions used in paramagnetic glasses, Tb3+ ions have largest Faraday rotation per ion and the glasses are transparent down to 1.6um. These glasses can also avoid the temperature incompatibility and lattice match problems which are encountered when magneto-optical garnets mare used for integration. The Tb3+doping is also widely used in optical amplifiers. In this paper we have explored the metastable phases present in the sputtered Tb-Al-Si-O system in order to fabricate paramagnetic films with the highest possible Faraday rotations, lowest optical losses and that are easily integrated with semiconductors. A broad peak was observed in the microdiffraction pattern around 2θ= 30deg. This peak corresponded with the close-packed Tb-O plane spacing (111 for FCC Tb4O7 or 002 for HCP Tb2O3), but it was an “amorphous” peak with a 5 deg FWHM. Amorphous films were obtained even when the Tb concentrations were very high. Since high concentrations of Tb are known to devitrify glasses, the discovery of a high-Tb concentrated glass is exciting.

We show that both the coupled photonic crystal slab and the single photonic crystal slab structure can function as an optical all-pass transmission filter for normally incident light. The filter function is synthesized by designing the spectral properties of guided resonance in the slab. We expect this compact device to be useful for optical communication systems.

SiON thin films were deposited by plasma-enhanced chemical vapor deposition method at 350 °C using N2O/SiH4 gas mixtures as precursors. As-deposited SiON films were annealed in different gas atmospheres (air, N2, and O2) and at different annealing temperatures (800 oC ∼ 1100 oC). Effects of annealing atmosphere on the Si-O, Si-N, Si-H, and N-H bonding characteristics in SiON films and their structural and optical properties have been investigated. Cross-sectional and planar microstructures were characterized by scanning electron microscopy and atomic force microscopy, and crystallinity was investigated by X-ray diffraction. Chemical bonding characteristics and optical properties SiON films were studied using fourier transform infrared spectroscopy and prism coupler. Xray diffractions showed no evidence of any crystals in all SiON films. The deposition rate strongly depended on the processing parameters such as radio frequency (rf) power, N2O/SiH4 flow ratio, and SiH4 flow rate. Deposition rate increased as N2O/SiH4 flow ratio increased and SiH4 flow rate increased. It was possible to obtain SiON films with surface roughness of about 1 nm and a high deposition rate of about 4 μm/h when the processing parameters were optimized as rf power of 200 W, N2O/SiH4 flow ratio of 3, SiH4 flow rate of 100 sccm. It was observed that the intensity and the shift of the Si-O stretch and Si-N peaks depended on the annealing atmosphere as well as the annealing temperature. The intensity of Si-O peaks increased in the samples annealed in oxygen atmosphere, but it decreased in the samples annealed in nitrogen atmosphere. The intensity of Si-N peak decreased in the samples annealed in oxygen atmosphere, but it increased in the samples annealed in nitrogen atmosphere. The position of Si-O peaks shifted from 1030 nm to 1140 nm in the samples annealed both in oxygen and in nitrogen atmosphere. It was also observed that the intensities of Si-H (∼2250 cm−1) and N-H (∼3550 cm−1) peaks decreased apparently as the annealing temperature increased in all annealed samples.

Hybrid Integration of passive and opto-electronic devices is emerging as a key technology of optical component, because it can increase functionality and reliability of optical device module, lowers the packaging cost and enables automated manufacturing. Main applications of hybrid integrated microphotonic devices are FTTH system and metro access network.

There are various technical issues in hybrid integration modules. It requires connecting an active device to a passive waveguide. The embedded functional devices such as grating, coupler, switch and filter are essential elements to improve optical performance of integrated devices. The package solution for low cost and small size is also required.

We have developed SSC LD(Spot Size Converted Laser Diode) and RMF PD(Reflection Mirror Facet Photo Diode) for connecting to planar waveguide. Simple and cost-effective silica PLC platform with terraced-silica, PLC grating and coupler have been developed. Using these technologies, we have made bi-directional diplexer, triplexer and ECL(External Cavity Laser).

Ordered colloids are of great scientific and practical interests. Liquid crystals offer enhanced ways of producing and stabilizing these complex structures. We therefore studied the rheological and electro-rheological properties of the structured colloids as a means of probing this stabilization. We found that the mechanical properties of the colloids and stability of their 3D structures can be controlled by the particles size and distribution. In addition, when an electric field is applied, we observed an increase in the apparent viscosity with saturation at high electric fields. This effect depends on the shear rate and temperature. The results are also compared with the published data for the viscosity measurements of pure liquid crystals and isotropic colloids. While we are only beginning to understand the details of these complex colloids we expect they will find a wide variety of applications.

Strong visible luminescence was observed in silicon nitride (SiNx) thin films grown by ion beam sputter deposition (IBSD) using nitrogen ion as a sputtering source. Nitrogen content (x) of the films was controlled by variation of the sputtering N2 ion flux and analysed by in-situ x-ray photoelectron spectroscopy (XPS). Relative sensitivity factors of Si and N peaks could be calculated by Rutherford backscattering spectroscopy. The photoluminescence (PL) spectra of the post-annealed samples showed visible luminescence at blue-green region. PL energy showed a blue-shift due to quantum confinement with decreased excess Si and intensity showed a maximum value near x = 1.1. These PL properties are well correlated with the formation of Si nanocrystals (nc-Si). We found that there is a great increase of PL energy of SiNx thin films compared with SiOx thin films, which indicate that the surface state of Si nanocrystals plays an important role to increase PL energy and intensity.