This PDF file contains the front matter associated with SPIE Proceedings Volume 7941, including the Title Page, Copyright Information, Table of Contents, Conference Committee listing, and Introduction.

By leveraging advanced wafer processing and flip-chip bonding techniques, we have succeeded in hybrid integrating a myriad of active optical components, including photodetectors and laser diodes, with our planar lightwave circuit (PLC) platform. We have combined hybrid integration of active components with monolithic integration of other critical functions, such as diffraction gratings, on-chip mirrors, mode-converters, and thermo-optic elements. Further process development has led to the integration of polarization controlling functionality. Most recently, all these technological advancements have been combined to create large-scale planar lightwave circuits that comprise hundreds of optical elements integrated on chips less than a square inch in size.

In order to maintain the overall optical performance in a step index rectangular waveguide, the complex index of refraction of the core and cladding material must be maintained throughout the cycle of the lithographic fabrication process. The percentage of the core and cladding material that is cured and the irradiance that cure took place directly affects the complex index of refraction of these materials. Siloxanes produced by Dow Corning have been selected to meet the requirements for embedded waveguides for circuit board applications due to their optical performance characteristics and their compatibility with current manufacturing techniques. The required total dose for a 50 μm thick layer of siloxane is 1200 mJ at an irradiance of 30 mW/cm². In order to utilize lower irradiance levels the total dose of the ultraviolet exposure must be characterized and calibrated. By measuring the changes in the absorption peaks of the materials using transmission data from ellipsometric techniques it is possible to define the percentage cure of the siloxane from different curing profiles. Ellipsometric techniques were also utilized to measure the complex refractive index of the materials cured using different profiles. It was found that the total dose required for a complete cure and the complex refractive index of these materials drastically changes with different irradiances and the profile for the total dose compared to the curing of the siloxane materials at all irradiances is logarithmic.

We report monolithic integration of chalcogenide glass(ChG)/iron garnet waveguides and racetrack resonators on silicon for on-chip nonreciprocal photonic devices applications. Using a two step growth strategy, we successfully integrated phase pure Bi_0.8Y_2.2Fe₅O₁₂ (Bi0.8YIG), Bi_1.8Y_1.2Fe₅O₁₂ (Bi1.8YIG) and Ce₁Y₂Fe₅O₁₂ (CeYIG) polycrystalline thin films on silicon with low fabrication thermal budgets. Strip-loaded ChG/Iron garnet waveguides and racetrack resonators were fabricated by thermal evaporation and lift off. The waveguide loss was systematically characterized by cutback and paperclip methods. For the first time, the optical transmission loss of polycrystalline Bi or Ce doped garnets were evaluated at communication wavelengths in waveguides. Polycrystalline CeYIG films show a saturation Faraday rotation of -830deg/cm and transmission loss of ~40dB/cm at 1550nm, which is promising for on-chip nonreciprocal photonic device applications. Such waveguide structures were successfully incorporated in GeS₂/Bi0.8YIG racetrack resonators which show well defined resonance spectrum at near infrared wavelength. The nonreciprocal phase shift (NRPS) and device figure of merit of the ChG/Garnet waveguides were simulated by numerical methods. Possible improvements and applications of such devices for integrated optical isolator applications are analyzed and discussed.

To overcome the difficult problem of the integration of magneto-optical materials with classical technologies, our group has developped a composite magneto-optical material made of a hybrid organic-inorganic silica type matrix doped by magnetic nanoparticles. Thin films of this material are obtained through a soft chemistry sol-gel process which gives a full compatibility with an integration on glass substarte. Due to an interesting magneto optical activity (Faraday rotation of 310°/cm) several magneto-optical functionnalities have been realized. A thin film of such composite material coated on a pyrex™ substrate acts as non-reciprocal TE/TM mode converter. An hybrid stucture made of a composite film coated on an ion-exchanged glass waveguide has been realized with a good propagation of light through a hybrid mode. Finally, the sol gel process has been adapted in order to obtain 3D inverse opals which should behave as magnetophotonic crystals. Transmittance curves reveal the photonic band gap of such opals doped with magnetic nanoparticles.

The successive ion layer deposition reaction (SILAR) technique has been applied to CdSe based systems to develop Type 1 heterostructures . In such structures, the CdSe core is covered by wider band gap semicondutors to improve the emission properties. Cores of different dimensions has been synthesised and two different shell structures have been addressed. The obtained particles have been characterised by TEM technique, while UV-Vis absorption and photoemission spectroscopy were used to characterise the optical properties of the particles in the colloidal solution. The obtained particles were also introduced in a ZrO₂ sol-gel matrix to fabricate photoluminescent waveguides, which were characterised also by spectroscopic ellipsometry.

Mode-lock lasers have been studied a lot in the past years for producing pulses as short as possible. These devices have mostly been realized in bulk optics and they are consequently cumbersome and sensitive to vibrations. There are only a few studies on integrated optics mode-lock lasers, though this technology is very promising because of its stability, compactness and the possibility to integrate several functions on a single chip. In this paper, we present an ion-exchange passively mode-locked laser in dissipative soliton operation. One of the key characteristics of this structure is its mechanical stability. Indeed, no bulk optics is needed because the saturable absorber is hybridized on the top of the waveguide in order to interact with the evanescent part of the guided mode. Indeed, the device that has been obtained is composed of an ion-exchanged single mode waveguide realized in a Neodymium doped phosphate glass. The laser feedback is produced by a Fabry-Perot cavity realized with two multilayers dielectric mirrors stuck on the waveguides facets. We implemented a bis(4- dimethylaminodithiobenzil)nickel (BDN) dye included in a cellulose acetate thick film, which presents a saturable absorber behaviour around 1.06 μm. With this structure, pulses with repetition rates of 3.3 GHz and a single mode output have been measured. Moreover, the use of an autocorrelation set-up allowed us measuring picosecond pulse durations.

We present current development efforts on hybrid photonic integration for new generation "faster and greener" Tb/scapacity optical networks. On the physical layer, we present the development of a versatile, silicon-based photonic integration platform that acts as a technology "blender" bringing together different material systems including III-V and silicon-based semiconductors. The platform is also used to implement the so-called O-to-O (optical-to-optical) functionalities by patterning low-loss passive components such as MMI couplers and delay interferometers. With these passive building blocks as well as the ability for hybrid assembly of active material, we demonstrate the fabrication of key optical transport and routing devices such as optical demodulators and all-optical wavelength converters. These devices can now be used to fabricate chip-scale 100 GbE transceiver PICs and Tb/s-capacity wavelength switching platforms.

The manipulation and routing of light-bullets in a VCSEL-like planar waveguide array is studied numerically. By partitioning the gold contact layer used for current injection into discrete and individually addressable segments, an electronically controllable and non-uniform gain profile is created. Light-bullets typically follow the gradient of the gain and are therefore completely controllable by manipulating the gain profile. In addition, by exploiting gain-mediated interactions between nearby light-bullets, the NAND and NOR gates are also constructed. Therefore, planar waveguide arrays with addressable gain profiles appear to be an ideal technology for optical routing applications as well as for photonic logic devices.

We present algorithmic details and applications of the reduced basis method as efficient Maxwell solver to nanophotonic applications including examples from mask optimization in photolithography and parameter retrieval in inverse problems, e.g., in optical metrology. The reduced basis method is a currently studied approach to the multiple solution of problems depending on a number of geometrical, material and source parameters. Such problems occur frequently in optimization tasks where parameters have to be adjusted in order to minimize some error functionals or in production environments where deviations from ideal structures have to be controlled.

We study both experimentally and numerically far-field radiation patterns of single metallic nanowires coupled to weak confined optical waveguides. The radiation pattern resulting from the interaction of the nanowire and the optical mode depends strongly on the mode properties (polarization and wavenumber) and on the antenna properties (material and size). To investigate these phenomena we compare the electric far-field distributions computed with different numerical methods (Green's tensor technique, rigourous coupled wave method, Fourier modal method). We also compare simulated results to experimental measurements obtained over a large spectral domain ranging from 400 nm to 1000 nm. This study should be useful for optimizing nanostructured photonic circuits elements.

Defect engineered photonic crystals, with sub-micron dimensions have demonstrated high sensitivity to trace volumes of analytes; however exact identification of analyte through spectroscopic signatures had not been demonstrated. We demonstrate a 300micron long photonic crystal slot waveguide device which combines slow light phenomenon in photonic crystal waveguides with large optical field intensity in a low index narrow slot at the center of the photonic crystal waveguide for highly sensitive spectroscopic detection of methane on-chip at 100 parts per million (ppm) or 0.2% permissible exposure limit. Photonic crystal slot waveguide provides a factor of 1000 reduction in interaction length compared to free-space infrared spectroscopy leading to enhanced optical absorption by analytes in the optical path. By measuring absorption differences in presence and absence of methane, near-infrared absorption spectrum of methane is determined.

The waveguide structure for the local evanescent array coupled (LEAC) biosensor is optimized theoretically with Beam Propagation Method (BPM) simulations. The LEAC biosensor has successfully demonstrated experimental results of a sensitivity of 16% /nm and a metrology limit of 14 pm. Considering the waveguide thickness detector position used in previous experiments are far from optimized values, the detection performance of the LEAC sensor can be significantly improved with the simulated optimal structure. With the optimized parameters, when the upper cladding is air the estimated metrology limit is 0.8 pm; with water as the upper cladding for real-time measurements in an intigrated microfluidic channel, the estimated metrology limit is 1.6 pm.

We report, intrinsic fiber optic carbon nanotubes coated sensor for the detection of ammonia gas at room temperature. Multimode step index polymethyl methacrylate (PMMA) optical fiber passive cladding is partly replaced by an active coating of single and multi-walled carbon nanotubes following the dip coating technique and the reaction with ammonia is studied by measuring the change in output intensity from the optical fiber under various ammonia gas concentrations in the range 0-500 ppm in step of 50 ppm. The sensitivity is calculated for different wavelengths in the range 200-1100 nm both for single and multi-walled carbon nanotubes coated fiber. Higher sensitivities are obtained as 0.26 counts/ppm and 0.31 counts/ppm for single-walled (average diameter 1.3 nm, 30 wt.% purity) and multi-walled (average diameter 10-15 nm, 95 wt.% purity) carbon nanotubes respectively. The role of diameter and purity of carbon nanotubes towards the ammonia sensing is studied and the results are discussed.

The far-field extraordinary optical transmission (EOT) of palladium (Pd) sub-wavelength hole arrays in the infrared region is used to detect hydrogen near the lower flammability threshold in air. Upon exposure to hydrogen, the Pd layer of the hole array expands, causing changes in the hole structure, and the Pd permittivity decreases. These two effects shift the main EOT transmittance peak of the Pd hole array to longer wavelengths. In this report, the effect of the Pd layer thickness on the redshift is analyzed by the rigorous coupled wave analysis technique and experimental observation. Our computational and experimental results show that the hole structural effect on the peak shift is dominant in the opaque region of the Pd layer transmission, whereas the Pd permittivity effect is dominant in the semi-transparent region. The optimum Pd layer thickness for hydrogen sensing is found to be at the boundary between the semi-transparent and the opaque regions of the Pd layer.

Our group has developed a silicon-based guided-wave optical accelerometer with a proof mass centered on a diaphragm. For this type of accelerometer, it is strongly suggested that sensitivity is related to waveguide position, diaphragm dimensions, and size and weight of proof mass. In this study, sensitivity dependences on waveguide position and diaphragm thickness were considered experimentally. Experimental results demonstrated that the highest sensitivity could be obtained for the waveguide at the diaphragm edge and is inversely proportional to the square of the diaphragm thickness.

We will show in this paper that a new approach combining Photonic crystal (PC) and nano-antennas (NA's) allows for an efficient addressing of NA using a wide Gaussian beam. First, we will present results from a phenomenological approach (coupled mode theory in the time domain) of this mixed device. We derive the key factors that govern the coupling processes and show that high Q PC structures are required for efficient coupling. The design rules for high Q PC structures providing resonant slow Bloch modes above the light line are presented, on the basis of FDTD simulation results. We will end the presentation with FDTD simulations of the mixed structure (PC+NA), confirming the prediction of the coupled mode theory. Preliminary technological realization will be presented, together with a discussion on potential applications for optical trapping.

We present a concept where GaAs chips with dilute nitride and quantum dot optoelectronics are hybrid integrated on a silicon-on-insulator (SOI) waveguide platform and packaged into low-cost modules using silicon as the packaging material. The approach aims to offer high energy efficiency, low cost and high bandwidth for optical interconnects operating at 1.2-1.3 μm wavelengths. It presents technologies that could bridge the gap between long and short range optical communication, which are presently based on incompatible wavelength ranges and waveguiding technologies (single vs. multimode).

Whispering gallery mode (WGM) disk resonators fabricated in single crystals can have high Q factors within their transparency bandwidth and may have application both in fundamental and applied optics. Lithium niobate (LN) resonators thanks to their electro-optical properties may be used in particular as tunable filters, modulators, and delay lines. A critical step toward the actual application of these devices is the implementation of a robust and efficient coupling system. High index prisms are typically used for this purpose. In this work we demonstrate coupling to high-Q WGM LN disks from an integrated optical LN waveguide. The waveguides are made by proton exchange in X-cut LN. The disks with diameters of about 5 mm and thickness of 1 mm are made from commercial Z-cut LN wafers by core drilling a cylinder and thereafter polishing the edges into a spheroidal profile. Both resonance linewidth and cavity photon lifetime measurements were performed to calculate the Q factor of the resonator, which is in excess of 10⁸.

Vectorial modal field profiles and the complex propagation characteristics of Surface Plasmon modes in optical and THz guided wave structures are presented by using a H-field based finite element method. It is shown here that by engineering the metal electrode mode selectivity in a Quantum cascade laser can be enhanced. Additionally, it is also shown that by introducing Teflon coating, the propagation loss of a hollow-core rectangular waveguide can be significantly reduced.

Plasmonic devices, based on surface plasmons propagating at metal-dielectric interfaces, have shown the potential to guide and manipulate light at deep subwavelength scales. In addition, slowing down light in plasmonic waveguides leads to enhanced light-matter interaction, and could therefore enhance the performance of nanoscale plasmonic devices such as switches and sensors. In this paper, we introduce slow-light subwavelength plasmonic waveguides based on a plasmonic analogue of electromagnetically induced transparency (EIT). Both the operating wavelength range and the slowdown factor of the waveguides are tunable. The structure consists of a periodic array of two metal-dielectric-metal (MDM) stub resonators side-coupled to a MDM waveguide. The two cavities in each unit cell have a resonant frequency separation which can be tuned by adjusting the cavity dimensions. We show that in the vicinity of the two cavity resonant frequencies, the system supports three photonic bands, and the band diagram is similar to that of EIT systems. The middle band corresponds to a mode with slow group velocity and zero group velocity dispersion in the middle of the band. Decreasing the resonant frequency separation, increases the slowdown factor, and decreases the bandwidth of the middle band. We also find that metal losses lead to a tradeoff between the slowdown factor and the propagation length of the supported optical mode. We use a single-mode scattering matrix theory to account for the behavior of the waveguides, and show that it is in excellent agreement with numerical results obtained with the finite-difference frequency-domain method.

We investigate on the interaction of surface plasmon modes with TEM, Fabry-Perot-like cavity modes in arrays of subwavelength slits filled with GaAs. A full control on the transmission process, which is mostly dictated by the geometrical parameters of the array, such as the slit length and width as well as the separation between the slits, is achieved and explained. The effects of the interaction of pure cavity modes and surface modes lead to the formation of an energy band gap, i.e. a spectral band where a drastic inhibition of transmission is induced by the coupling and backradiation of the smooth-interface, unperturbed surface plasmon. Strong field localization in sub-wavelength regions boosts also the nonlinear response of the structure. The mere assumption that the metal is nonlinear via Coulomb and Lorentz contributions, and the introduction of high-index, nonlinear media, such as III-V semiconductors, in the subwavelength channels opens a cross-coupling of TE and TM polarizations for both pump and harmonic signals and makes it possible to generate both TE- and TM-polarized fields. These fields are generated even under high-absorption conditions, and survive thanks to a phase locking mechanism that sets in between the pump and its harmonics.

Rectangular waveguide is a very promising structure for different applications. It has some unique characteristics that allow for wide range of application including slow and fast light, metamaterial, low loss energy transmission, and sensing. The resemblances and differences between this waveguide configuration and metal-insulator-metal (MIM) are discussed in this paper. A Description of the guided modes and their operating band is also given. We also studied the characteristics of the fundamental TM-like mode of this structure for the first time. Its potential application in sensing and low loss energy transporting is also demonstrated. The effect of the design parameters on the performance of the rectangular waveguide is illustrated for different application. Slow light and negative refraction effects using this waveguide design using TE-like mode is also demonstrated. Different designs are proposed using this structure for these different applications. Square shape design allow for polarization insensitive applications which is one of the unique characteristics of the configuration.

We review recent advances in subwavelength and diffractive structures in planar waveguides. First, we present a new type of microphotonic waveguide, exploiting the subwavelength grating (SWG) effect. We demonstrate several examples of subwavelength grating waveguides and components made of silicon, operating at telecom wavelengths. The SWG technique allows for engineering of the refractive index of a waveguide core over a range as broad as 1.5-3.5 simply by lithographic patterning using only two materials, for example Si and SiO₂. This circumvents an important limitation in integrated optics, which is the fixed value of the refractive indices of the constituent materials in the absence of an active tuning mechanism. A subwavelength grating fibre-chip microphotonic coupler is presented with a loss as low as 0.9 dB and with minimal wavelength dependence over a broad wavelength range exceeding 200 nm. It is shown that the SWG waveguides can be used to make efficient waveguide crossings with minimal loss and negligible crosstalk. We also present a diffractive surface grating coupler with subwavelength nanostructure, that has been implemented in a Si-wire evanescent field biological sensor. Furthermore, we discuss a new type of planar waveguide multiplexer with a SWG engineered nanostructure, yielding an operation bandwidth exceeding 170 nm for a device size of only 160 μm × 100 μm.

Long period gratings (LPGs) have been recently proposed as sensing elements of chemical/biological compounds, exploiting their sensitivity to the refractive index changes in the surrounding environment. One of the difficulties of their utilization for this purpose is their strong dependence also to strain and temperature effects. An intrinsic optical feedback able to eliminate these effects was developed by manufacturing on the same fiber the LPG and a fiber Bragg grating (FBG) which is immune from external refractive index changes and is influenced by strain and temperature. An accurate temperature measurement system is utilised to eliminate or in any case to reduce to a minimum the interferences coming from temperature changes. A KrF excimer laser is used to write both the gratings into the same photosensitive fiber. The period of the LPG and FBG gratings are 615 μm and 530 nm, respectively and the attenuation at their resonance wavelengths (1570 nm for LPG and 1534 nm for FBG) was of the order of 15-20 dB. The same source, a broadband superluminescent diode with emission peak at 1550 nm, is used to interrogate both the gratings. The transmission spectra is acquired by means of an optical spectrum analyzer (OSA) controlled by a PC and an in-house software identifies the attenuation band in the FBG and LPG transmission spectra and calculates the minimum values. A suitable thermostabilized flow cell with a volume of 50 μL containing the fiber with the two gratings, has been developed and characterized.

We describe the design of pixelated filter arrays for hyperspectral monitoring of CO₂ and H₂O absorption in the midwave infrared (centered at 4.25μm and 5.15μm, respectively) using resonant subwavelength gratings (RSGs), also called guided-mode resonant filters (GMRFs). For each gas, a hyperspectral filter array of very narrowband filters is designed that spans the absorption band on a single substrate. A pixelated geometry allows for direct registration of filter pixels to focal plane array (FPA) sensor pixels and for non-scanning data collection. The design process for narrowband, low-sideband reflective and transmissive filters within fabrication limitations will be discussed.

We report the non linear fluorescence real-time detection of methylboldenone, an androgenic anabolic steroid used illegally as growth promoter based on a resonant sensing chip: a double grating waveguide structure. The limit of detection of this synthetic steroid is two orders of magnitude lower than the Minimum Required Performance Limit required by the World Anti-Doping Agency. The immunoreagents have been have been immobilized onto the surface of the resonant sensor after being activated with phosphonohexanoic acid spacers. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of illegal dopants and food contaminants.

We experimentally engineer Nanojets produced by dielectric spheres by varying the illumination and observe the effect with a high-resolution interference microscope (HRIM). Converging and diverging spherical wavefronts and Bessel- Gauss beams are considered. We find that the diverging wavefront pushes Nanojets away from the surface of the sphere without change of the spot size. This allows earning several micrometers of working distance contrary to the Nanojet confined at the sphere's surface. When the radius of curvature of the incident wavefront is greater than about 5 times the sphere size, the Nanojet moves back to the sphere surface like it is found for plane wave incidence. On-axis Bessel- Gauss beam illumination with the central lobe covering the whole sphere leads to the same results as the plane wave case. Off-axis Bessel beam illumination can generate multiple-spot Nanojets. We demonstrate the separation of such spots of about 220 nm at 642 nm. This separation is smaller than the feature sizes defined by the diffraction limit at this wavelength. We discuss briefly applications of engineered Nanojets for nano-lithography and near-field sensing.

We propose a waveguide integrated plasmonic platform in order to deliver excitation power to and collect signal efficiently from a nanoantenna. The system consists of a silicon waveguide with an integrated nanoantenna and a fiber spot size converter. The nanoantenna is designed to have a broad resonance around 1.5 microns with an estimated surface enhanced Raman scattering (SERS) enhancement of 6 orders of magnitude and collection efficiency up to 80%. The device is fabricated on a silicon-on-insulator (SOI) wafer. The proposed and fabricated device can be used in applications such as on-chip SERS spectroscopy, infrared spectroscopy and gas sensing.

In this paper, we propose an integrated photonic sensor structure using triangular ring resonator (TRR), in which surface plasmon resonance (SPR) is combined for the enhancement of sensitivity. In our previous experimental work on TRR without SPR, we have shown that the Q-factor and the sensitivity of the resonance shift were approximately 7×10²and 8.4 nm/RIU, respectively, near 1550 nm. By employing a thin-metal layer for SPR at the total-internal-refection mirror in TRR, we have obtained significantly enhanced sensitivity of the resonance shift up to 55 nm/RIU maintaining similar Q-factor.

In this study, we investigated light transmission based on a metallic nano-lens for imaging applications. The nano-lens consists of multiple nano-rings formed in a thin metal film. Four types of nano-lens structures in a 50-nm thick gold film were simulated using rigorous coupled-wave analysis. Each nano-lens is designed to operate as a lens element that focuses transmitted light. The results show the focal power increasing with the ring number and the enhancement of achievable numerical aperture compared to that of conventional lenses.

The design and realization of chip-scale plasmonic devices have been considerably facilitated by computational electromagnetic simulations and sophisticated nanofabrication techniques. For rapid device optimization, numerical simulations should be supplemented by simple analytical expressions capable of providing a reasonable estimate of the initial design parameters. In this paper, we develop an analytic approach and derive approximate expressions for the transmittance of metal-dielectric-metal (MDM) waveguides coupled to single, double, and periodic stub structures. Our method relies on the well-known analogy between MDM waveguides and microwave transmission lines, and enables us to use standard analytical tools in transmission-line theory. The advantage of our analytic approach over the previous studies is in accounting for the plasmon damping due to Ohmic losses and reflection-induced phase shift at the stub end. We found that the analyzed waveguide configurations can exhibit the characteristics of nanoscale filters and reflectors. We validate our analytical model by comparing its predictions with numerical simulations for several MDM waveguides with different stub configurations. The proposed theoretical results are particularly useful to reduce lengthy simulation times and will prove valuable in designing and optimizing MDM-waveguide-based photonic devices.

Photonic sigma-delta modulators can directly digitize wideband signals with high resolution directly atthe antenna. In our first-order, single-bit architecture, the antenna signal is applied to a pair of Mach-Zehnder interferometers and oversampled using a CALMAR 10 GS/s mode-locked laser (MLL) with a pulse width of 10 ps. The measurements of the MLL pulse-to-pulse sample time uncertainty (time jitter) and the laser pulse amplitude uncertainty (amplitude jitter) are described. Considering the jitter to be the result of non-uniform random sampling we show that a normal distribution is a good noise model for both jitter mechanisms. The sigma-delta modulator and the decimation filtering process are described. Using asynchronous spectral averaging of the reconstructed signal's magnitude spectrum, an expression for the noise floor without jitter is developed and compared to simulation results as a function of the oversampling ratio (OSR) and record length using a 100 MHz signal bandwidth. The noise floor is then evaluated as a function of the time jitter power and amplitude jitter power for several OSRs.