This PDF file contains the front matter associated with SPIE Proceedings Volume 10027, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Large-scale optical switches are greatly demanded in building optical interconnections in data centers and high performance computers (HPCs). Silicon optical switches have advantages of being compact and CMOS process compatible, which can be easily monolithically integrated. However, there are difficulties to construct large ports silicon optical switches. One of them is the non-uniformity of the switch units in large scale silicon optical switches, which arises from the fabrication error and causes confusion in finding the unit optimum operation points. In this paper, we proposed a method to detect the optimum operating point in large scale switch with limited build-in power monitors. We also propose methods for improving the unbalanced crosstalk of cross/bar states in silicon electro-optical MZI switches and insertion losses. Our recent progress in large scale silicon optical switches, including 64 × 64 thermal-optical and 32 × 32 electro-optical switches will be introduced. To the best our knowledge, both of them are the largest scale silicon optical switches in their sections, respectively. The switches were fabricated on 340-nm SOI substrates with CMOS 180- nm processes. The crosstalk of the 32 × 32 electro-optic switch was -19.2dB to -25.1 dB, while the value of the 64 × 64 thermal-optic switch was -30 dB to -48.3 dB.

In this paper, the process difference between Si photonics and Si CMOS is discussed. Firstly, the substrate of Si photonics and the issues about electronic-photonic integration are commented . Lithography, etching and hydrogen annealing are then discussed in detail. Line edge roughness is thought to be the original source of scattering loss of waveguide. Hydrogen annealing is effective to reduce the sidewall roughness but has the risky of changing the profile of waveguide. Ion implantation and metallization for active photonics components can be easily transferred from the CMOS process recipes. Ge photodetector fabrication is challenging though it shares the same epitaxy equipment with the CMOS platform. Finally, a whole Si photonics process flow including passive and active components based on our 200 mm CMOS platform is presented.

The inverse Doppler effect in photonic crystal with negative refractive index had been proofed experimentally in our previous research. In this paper, we studied the spatial harmonics of Bloch wave propagating in such PhCs by FFT method. The lagging and front phase evolutions reveal that both backward wave and forward wave exist in these harmonics. Subsequently, we studied the double Doppler effect phenomenon that both the normal and inverse Doppler exist in one photonic crystal simultaneously by using the improved dynamic FDTD method which we made it suitable for dealing with moving objects. The simulative Doppler frequency shifts were consistent with the theoretical values. Our study provides a potential technology in measurement area.

In this paper, a polymer fiber was constructed by siphoning the xylene solution of a polymer into a capillary tube with 300 μm inner diameter. After the solvent evaporating, the polymer fiber was lighted by an external pump beam and the amplified spontaneous emission (ASE) of the polymer fiber is investigated. The emission spectra are recorded, and the intensity and the full width at half maximum (FWHM) as a function of pump power intensity are analyzed. The absorption coefficient of polymer F8BT is obtained from a polymer F8BT film with a thickness of 200 nm. For the high absorption of polymer, the pump beam can not penetrate the long F8BT fiber. The sketch up diagram and an optical photo show it in vividly. This fabrication method provides a cheap way for application of micro polymer fiber. Keywords: polymer fiber, amplified spontaneous emission, absorption coefficient

Optical waveguide is used in most integrated optic devices to confine and guide light in higher refractive index channels. The structures and materials of slot waveguides are reviewed in this paper. Coupled resonator optical waveguides (CROWs) can be used for a rotation sensor with compact size, low power consumption and low cost. The loss determines the ultimate sensitivity of CROW gyros. Resonator-based optical gyroscope’s sensitivity for measuring rotation is enhanced via using the anomalous dispersion characteristic of superluminal light propagation, which can be also generated by using passive optical resonators.

Surface plasmon microscopy (SPRM) usually employs high refractive index prism or high numerical aperture (NA) objective as coupling device to excite surface plasmon. Here we apply high NA oil-immersion objective considering k vector conditions of SPs and localization of SPs which provides better lateral resolution and less cross-talk between adjacent areas. However, performance of an objective based SPRM is often limited by the finite aperture of a physical objective which corresponds to sudden transition and limited bandwidth. Here we give a simplified model of the SPRM and numerically calculate how the sudden transition on the clear aperture edge causes inherent error. Notch filtering algorithm is designed to suppress the noisy ripples. Compared to the pupil function engineering technique, this technique makes both the sacrifice of NA and utilization of spatial light modulator unnecessary and provides a more compact system setup without decreasing the resolution and contrast.

Based on electromagnetic eigenequation in silver-coated microcylinder, we study its mode characteristics and sensing characteristics, including dispersion relation, quality factor (Q factor), sensitivity (S) and detection limit (DL). We find hybrid WGM-SPPs modes in energy distribution and mode coupling phenomenon in dispersion curve. In the vicinity of mode coupling point, hybrid TM-SPPs modes (or supermodes) have both high Q factor and high surface enhancement factor. Meanwhile the hybrid modes have high refractive sensitivity and figure of merit (FoM), which enables potential applications in chemical and biological sensing.

In this paper, we propose and numerically study a subwavelength grating based hybrid plasmonic waveguide. The metal layer on top of the waveguide enables unique features compared with conventional silicon based waveguide. Since the field distribution in this structure is different, traditional homogeneous medium approximation is not applicative. Therefore, we develop a new effective index calculation method. This method is suitable for metal-existing waveguide as well as structures with multiple medium. Effective index of this waveguide depends on grating period, duty ratio and width, respectively. By modifying duty ratio and period of the waveguide, the relationship between effective index and waveguide width can be concave function or convex function and the slope can be similar to TM mode of silicon based waveguide, which opens up possibilities for SPPs based applications.

Systems, based on aqueous suspensions of single walled carbon nanotubes, stabilized by surfactants, and having supramolecular ordering are studied by spectroscopy and polarized microscopy. Nonlinear optical behavior of the suspensions has been checked. A correlation between sizes of aggregate in suspension and nonlinear optical limiting parameters has been found. A nematic meso-phase based on suspension of carbon nanotubes has been obtained.

An asymmetric transmission device has been presented to realize high-performance one-way transmission at visible frequencies. This device consists of a pair of non-symmetric pyramid-shaped silicon gratings separated by a metal/dielectric multilayer structure (MDMS). Simulation results demonstrates that, compared with conventional Cr grating, MDMS with pyramid-shaped silicon gratings will greatly enhance the coupling and decoupling between the propagating waves in free space and the high frequency modes in MDMS, rendering an improved oneway transmission performance. The improved one-way transmission performance offered by our design may hold great potential in designing the optical isolator and polarizer for ultra-compact photonic integrated circuit.

We propose a novel 1×5 optical splitter (OS) for TE modes based on self-collimation effect in an air-hole silicon photonic crystal. The OS consists of two cascaded resonators which is formed with eight beam splitters. The theoretical transmission spectra of the OS is derived with multiple-beam interference theory. From our analysis of transmission spectra, it is found that the transmission spectra at five drop ports will reach the maximum values while the transmission spectra at two through ports reach zero for resonant frequencies. By scanning the radius of a beam splitter, the relationship between the radius and the reflectivity is obtained. Therefore, by changing the radii of the air-hole in eight beam splitters, we can manipulate the output light-intensity ratio at five drop ports to meet requirement. Theoretically, when reflectivity of beam splitters R₁=2/11, R₂=8/11, R₃=5/8, R₄=2/5, R₅=7/12, R₆ =6/7, R₇=1/2, R₈ =2/3, the light intensity ratio at five drop ports is 1:1:1:1:1. When R₁=2/7, R₂=6/7, R₃=1/2, R₄=2/3, R₅=1/7, R₆=6/7, R₇=2/3, R₈ =1/4, the light intensity ratio at five drop ports is 2:2:1:2:3. By means of finite-difference time-domain (FDTD) simulations, the numerical transmission spectra of OS can be figured out. The simulation results are consistent with the theoretical results. Considering micro processing technology of silicon materials is already available, this OS can be used in the photonic integrated circuits because of its small size, whole-silicon material and low insertion loss.

We present a localized surface plasmon resonance fiber optic biosensor based on an intensity interrogation mechanism. A layer of gold nano sphere is deposited on a fiber optic sensor probe which works as the sensing element and is immobilized on the sidewall of an unclad optical fiber via two different immobilization methods (amino silane method and layer by layer self-assembly method). Different self-assembly layers were also respectively investigated by using layer by layer self-assembly method to explore the optimum layer number. Experimental results reveal that PDDA/PSS/PAH layer self-assembly method provides the best LSPR response. We obtain a refractive index sensitivity as 6.57RIU^-1 in a RI range of 1.3266~1.3730. We also conduct real-time and label free monitoring of Ribonuclease B/Con A biomolecular interaction by using this sensor prototype and demonstrate it can perform qualitative and quantitative detection in real-time biomolecular sensing.

Au nanoparticle-coated In_0.2Ga_0.8As/GaAs bilayers have been released from GaAs (100) substrate through selective wet etching of AlAs sacrificial layer, which provides a solution to implant metal nanoparticles (NPs) in the inner wall of self-rolled-up III-V semiconductor microtubes. Scanning electron microscope (SEM) reveals that the diameter of Au nanoparticle-decorated In_0.2Ga_0.8As/GaAs microtube is only 2.4μm, 300nm smaller than that of traditional counterparts. This phenomenon can be explained by that the surface tension of NPs and the intrinsic strain relaxation of In_0.2Ga_0.8As/GaAs bilayers both affect the rolling process. In order to understand the diameter reduction in Au-assistant microtubes, room temperature (RT) Raman measurements have been employed to study the strain effects reflected by the GaAs longitudinal optical (LO) phonon mode shifts when compared LO mode of microtubes with as-grown planar. The spectrum showed that there were about 10 wavenumbers and 2.6 wavenumbers red-shifts of GaAs LO for Au-assistant and non-Au-assistant structures, respectively, from which we calculated that about 2.56% and 0.66% strain change occurred. Au nanoparticle enhanced Raman shift clearly. According to this study, an approach to reduce the diameter of rolled-up microtubes was demonstrated, and this method may provide viable solution to fabricate nanotubes in the application for Lab-on-a-chip system.

We have developed an innovated fabrication technology of Si, GaAs, and Ge nano-structures, i.e., we called defect-free neutral beam etching. The technology has been successfully applied to prototype the quantum nano-disks and nano-wires with ferritin based bio-templates. SEM observation verifies that the designed structures are prototyped. Photoluminescence measurements demonstrates high optical quality of nano-structures based on the technology.

InGaAsP/InP-air-aperture micropillar cavities are proposed to serve as 1.55-μm single photon sources, which are indispensable in silica-fiber based quantum information processing. Owing to air-apertures introduced to InP layers, and adiabatically tapered distributed Bragg-reflector structures used in the central cavity layers, the pillar diameters can be less than 1 μm, achieving mode volume as small as ~(λ/n)³, and the quality factors are more than 10⁴ - 10⁵, sufficient to increase the quantum dot emission rate for 100 times and create strong coupling between the optical mode and the 1.55- μm InAs/InP quantum dot emitter. The mode wavelengths and quality factors are found weakly changing with the cavity size and the deviation from the ideal shape, indicating the robustness against the imperfection of the fabrication technique. The fabrication, simply epitaxial growth, dry and chemical etching, is a damage-free and monolithic process, which is advantageous over previous hybrid cavities. The above properties satisfy the requirements of efficient, photonindistinguishable and coherent 1.55-μm quantum dot single photon sources, so the proposed InGaAsP/InP-air-aperture micropillar cavities are prospective candidates for quantum information devices at telecommunication band.

The coupling in a directional coupler (DC) has attracted lots of attention as a basic block for photonic integrated circuits. Most of previous work was focused on symmetric DCs consisting of two identical optical waveguides. In this case light power can be transferred from one waveguide to the other one completely when choosing the length L of the coupling region appropriately. Recently, an asymmetric DC (ADC) consisting of non-identical waveguides in the coupling region has been attracting more and more attention because of the versatility for various useful applications. ADCs can be formed by combining two ore more waveguides with different dimensions, shapes as well as bending radii for the core regions. In particular, silicon nanophotonics developed in the recent years provides a very good platform to make ADCs very useful and interesting. In this paper, we give a review for recent progresses of versatile ADCs on silicon, including the following three parts: (1) ADCs for power splitter used in microring resonators and Mach-Zehnder interferometers; (2) ADCs for realizing ultracompact and broadband PBSs; (3) ADCs for realizing mode (de)multiplexers.

An efficient Si-based laser is one of the most important components for photonic integrated circuits to break the bottleneck of data transport over optical networks. The main challenge is to create gain media based on group-IV semiconductors. Here we present an investigation of using low-dimensional Ge_1-xSn_x/Ge quantum-well (QW) structures pseudomorphically grown on Ge-buffered Si substrates as optical gain media for efficient Si-based lasers. Epitaxial growth of Ge_1-xSn_x/Ge QW structures on Ge-buffer Si substrate was carried out using low-temperature molecular beam epitaxy techniques. The light emission properties of the grown Ge_1-xSn_x/Ge QW structure were studied using photoluminescence spectroscopy, and clear redshifts of emission peaks were observed. Theoretical analysis of band structures indicates that Ge_1-xSn_x well sandwiched by Ge barriers can form type-I alignment at Г point with a sufficient potential barrier height to confine carriers in the Ge_1-xSn_x well, thereby enhancing efficient electron-hole direct recombination. Our calculations also show that the energy difference between the lowest Г-conduction subband and L conduction subband can be reduced with increasing Sn content, thereby enabling optical gain. These results suggest that Ge_1-xSn_x/Ge QW structures are promising for optical gain media to develop efficient Si-based light emitters.

Production of nanostructures consisting of semiconductor nanoparticles (NPs) is of interest for number of applications. Development of new methods of NPs' manipulation and aggregation of NPs into nanostructures with pre-defined geometry is also of considerable interest from the fundamental point of view. Under laser irradiation with properly chosen wavelengths excitonic excitations of semiconductor NPs will be induced. Electrodynamical interaction between excited NPs is rather universal and allows formation of wide variety of nanostructures both of homo- and heterogeneous content. Theoretical approach for study of interaction of NPs' ensembles with laser light includes dipole-dipole approximation for NPs' attraction. Experimental results are obtained for TGA stabilized CdTe QDs with the excitonic resonance at 520 nm. Six different samples of the same colloid solution were irradiated at wavelengths from 540 to 570 nm. Modifications of absorption spectra of solutions after irradiation was detected, being most prominent at 555 and 560 nm irradiation wavelengths. Analysis of spectra shows that up to 47% of QDs were assembled into pairs with 10 nm inter-QD distance. Therefore, possibility of precise QDs manipulation via laser-induced electrodynamical interaction is demonstrated.

The plasmonic enhancement and quenching of phosphorescence and fluorescence of the anionic (eosin) and cationic (rhodamine 6G) dyes have been studied in various environments: silver nanoparticles of silver hydrosol citrate in water, in polymer films and on the surface of nanoporous silica in order to determine the kinetic and spectral effects on the dye luminescence. Depending on the silver nanoparticles concentration both the enhancement and quenching of the dyes phosphorescence and fluorescence have been detected. The mechanism of interaction between the excited molecules and silver nanoparticles has been discussed.

Luminescence quantum yields (QYs) of gold nanoparticles including nanorods, nanobipyramids and nanospheres are measured elaborately at single nanoparticle level with different excitation wavelengths. It is found that the QYs of the nanostructures are essentially dependent on the excitation wavelength. The QY is higher when the excitation wavelength is blue-detuned and close to the nanoparticles’ surface plasmon resonant peak. A phenomenological model based on plasmonic resonator concept is proposed to understand the experimental findings. The excitation wavelength dependent of QY is attributed to the wavelength dependent coupling efficiency between the free electrons oscillation and the intrinsic plasmon resonant radiative mode. These studies should contribute to the understanding of one-photon luminescence from metallic nanostructures and plasmonic surface enhanced spectroscopy.

Optical detection of nanoparticle with ultra-high sensitivity plays an important role in bio- / nano- and their relative research fields. In our recently developed method, each single particle exhibits unique 4-lobes pattern both in the amplitude and phase images respectively, based on which we explored the possibility of resolution improvement by a particle pair. In this paper two polystyrene beads at the diameter of 100nm were employed with the gap distance ranging from 100-400nm. The amplitude and phase images of the particle pair were simulated by FDTD solver. The images are sensitive to geometrical parameters of the two particles, such as gap distance and direction. The simulation results lead to a resolution of 100nm.

Noble metallic nanoparticle exhibits unique optical properties in visible to near infrared band when its localized surface plasmon resonance is excited. For example a sharp absorption peak at 509nm for a gold nanoparticle at the diameter of 60nm. The plasmonic properties heavily depend on its geometrical structure. In this paper, we theoretically calculate the optical properties of a single nanoparticle with different structure such as solid and core-shell. The simulation results show that the core-shell structure can reach a much broader tunable band and in which the shell thickness plays a dominant role. Further by employing a core-shell pair, more flexible properties can be reached.

Color filters based on different Fabry-Perot structures are investigated extensively, and incident angle dependency is an important characteristic in practical applications. Here, we investigated a color filter incorporating a Fabry-Perot structure, discussing its reflective angular sensitivity related to refractive index of its dielectric material. By finite difference time domain(FDTD) theory, the refractive index of the dielectric material is found to influence the angular sensitivity greatly while the optical thickness keeps constant. The simulated results shows that the higher the dielectric layer’s refractive index is, the more angular insensitive of the reflection will be obtained and a good angular insensitive will achieved when the refractive index is larger than 2.1. Finally, samples with different dielectric layer are fabricated in experiment and the measured results verify influence of the refractive index of dielectric layer on the spectra angular sensitivity, which is helpful for the application of color filter in color display, image sensors and decoration.

Si micro-structures served as anti-reflection layer are widely employed in Si-based solar cells and detectors to enhance light harvesting. However, performance of these devices is suffered from the poor contact between the metal electrode and micro-structured surface. Conventional vacuum deposited metal electrode makes only superficial contact with the top of micro-structured surface and unable to fill the holes in the micro-structures. In this paper, instead, electroless nickel technique is applied to form low resistance ohmic contact. The surface micro-structures were fabricated by electrochemistry etching while the metal electrodes were deposited by sputtering and electroless pasting. Results show that only electroless nickel layer could fully fill the holes and achieve better ohmic contact than the sputtering ones before rapid annealing. Furthermore, a higher temperature rapid annealing process could improve the contact of all samples prepared by different ways. The specific contact resistance achieved by high alkalinity (pH=12) electroless nickel is 1.34×10^-1Ω·cm².

We use metal-assist chemical etching (MCE) method to fabricate nanostructured black silicon on the surface of C-Si. In our MCE process, a chemical reduction reaction of silver cation (Ag⁺) will happen on the surface of silicon substrate, and at the same time the silicon atoms around Ag particles are oxidized and dissolved, generating nanopores and finally forming a layer called black silicon on the top of the substrates. The nanopores have diameter and depth of about 400 nm and 2 μm, respectively. Furthermore, these modified surfaces show higher light absorptance in near-infrared range (800 to 2500 nm) compared to that of C-Si with polished surfaces, and the maximum light absorptance increases significantly up to 95% in the wavelength region of 400 to 2500 nm. The Si-PIN photoelectronic detector based on this type of black silicon, in which the black silicon layer is directly set as the photosensitive surface, has a substantial increase in responsivity with about 80 nm red shift of peak responsivity, particularly at near-infrared wavelengths, rising to 0.57 A/W at 1060 nm and 0.37 A/W at 1100 nm, respectively. Our recent novel results clearly indicate that nanostructured black silicon made by MCE has a potential application in near-infrared photoelectronic detectors.

In epitaxial lateral overgrowth (ELOG) of III-V semiconductor on nano-trench patterned Si substrates, the most important mechanism is aspect ratio trapping, which uses high aspect ratio nano-trenches to trap threading dislocations (TDs). A model based on the theory of dislocation is proposed to calculate proportion of blocking threading dislocations in ELOG of GaAs or InP on nano-trench patterned Si substrates. The model establishes relationship with the structure of nano-trenches and the proportion of blocking threading dislocations. It is found that, the blocking proportion is determined by thickness of the masks, width of the trenches and direction of the nano-trenches (the angle of opening orientations lies off the [110] direction). The blocking proportion gradually increases until 100% as aspect ratio increases with fixed trench direction; with the same aspect ratio, the blocking proportion firstly decreases from 0° to 45°, and symmetrically increases from 45° to 90°. It is worth noting that the blocking proportion abruptly reduces to 50% when the direction is 45°and the aspect ratio is more than 1; But it does not happen if the aspect ratio is less than or equal to 1. The reported experimental results are well consistent with the model. The model provides a method for optimization of nano-trench patterned substrates for more effectively blocking threading dislocations in III-V semiconductors.

Single photon sources are key devices for quantum communication and quantum computation. Recently, photonic nanowires with an embedded quantum dot have demonstrated to provide remarkable extraction efficiency due to the axial waveguide configuration and nanocavity function of nanowire. However, for thin nanowires, stable modes cannot be supported, resulting in very poor Purcell factor which is an important parameter of single photon sources. In this paper, a novel single photon source structure with a high Purcell factor is proposed and simulated. The structure consists of a GaAs nanowire embedded with an InAs quantum dot surrounded by Au. The enhancement of the Purcell factor is simulated by finite difference time domain (FDTD) method. Without Au shell, the Purcell factor quickly drops as the diameter of nanowire decreases. When the diameter is decreased to 50 nm, the nanowire cannot support any stable modes, resulting in a rather low Purcell factor of 0.009. After the Au shell is introduced, the Purcell factor is dramatically enhanced, and the enhancement ratio increases as the nanowire diameter decreases. The highest enhancement ratio of 1028 can be obtained at a nanowire diameter of 25 nm and Au shell thickness of 75 nm. The enhancement of the Purcell factor is attributed to the decrease of the cavity effective mode volume, which is inversely proportion to the Purcell factor. This work may offer a way to achieve single photon sources with an ultra-small size and ultrahigh Purcell factor.

The integration of Plasmonic Nano-Resonators (PNRs) to optical fibers tips with thin metallic claddings forming plasmonic slot nano-resonators (PSNRs) is presented. It is shown that the placement of the PSNR at the cut-off radius of the fiber tip for a specific wavelength where the group velocity tends to zero and light slows down leads to an optimization of field's enhancement. Enhancement factors greater than 3x10⁵ were calculated through Finite Element Method (FEM) simulations by placing the PSNR at the cut-off radius and by changing the geometrical characteristics in order to identify optimal conditions for loss minimization that can find many practical applications in nano-optics and sensing.

In this paper, we demonstrate the buried waveguides directly writing in LiNbO₃ crystal by a tightly focused femtosecond laser with repetition rate 75MHz, and the femtosecond laser was focused by the microscope objective of which NA is 0.65. Fabricating nine carved paths in LiNbO₃ crystal by moving three-dimensional electric translation stage at different speeds varying from 2mm/s to 10mm/s, controlled by a computer. Analyzing the structure of the end face of the directly writing region by laser Raman, which shows the large-scale defects are generated in the center of the etching region, densification induced by the thermal effect of high repetition rate femtosecond laser interaction of LiNbO₃ were generated below and down of the center of the etching region. Using a He-Ne laser focused by a microscope objective with NA 0.65 coupling to the end face of the prefabricated nine carved paths, which shows two waveguides are generated in the top and below of the inscribing region. Testing the insert loses of these waveguides with an optical power meter, the result shows that the insert loses of the waveguides fabricated at speed of 8~10mm/s is low to 3dB·cm^-1, and the insert loses was low to 1.5 dB·cm^-1 when the scanning speed is 9mm/s, moreover, the insert loses of the below region was low to the top region.

This paper presents a comprehensive study of light reflection modulation in graphene through external applied voltage and shows a strategy to realize both broadband and strong reflection enhancement. The influence of chemical potential, applied voltage and carrier concentration on reflection efficiency are investigated by numerical simulations. By employing an applied voltage, the maximum of difference of reflected coefficient can reach up to 30% for 3THz radian frequency. Thus, using external voltage to control optical reflection efficiency is testified to be reasonable and feasible based on graphene film. Furthermore, the reflection efficiency modulation can be realized at a wideband of frequency.