This PDF file contains the front matter associated with SPIE Proceedings Volume 7218, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

The development of integrated optics components being able to work in the mid-infrared is of major interest for specific applications, such as the detection of pollutant gases for the environmental control or the detection of exoplanetary systems. Chalcogenide glasses being characterised by a unique property of transmission in the infrared are very promising materials for the realisation of such infrared micro-components. In order to realise and test channel waveguiding structures, we studied the deposition and the etching of chalcogenide films. Both ARROW and RIB waveguides were realised. In particular, all-chalcogenide RIB waveguides obtained by etching a Te-As-Se film deposited on an As-S bulk glass substrate were characterised at 10.6 μm.

Sr(Ti_0.6Fe_0.4)O₃ (STF) and Sr(Ti_0.7Co_0.3)O₃ (STC) room-temperature ferromagnetic oxides were grown epitaxially on LaAlO3(001), (LaSr)(AlTa)O₃ (001) and Si (001) substrates. Both materials were demonstrated to be magneto-optically active, and more optically transparent at 1550nm wavelength compared with other non-garnet ferromagnetic materials. As₂S₃/STF and As₂S₃/STC strip-loaded waveguides were fabricated on epitaxial STF or STC films grown on LSAT (001) substrates using thermal evaporation and lift-off processing. The absorption of STF at 1550 nm was measured by ellipsometry and by optical transmission spectrum measurements of the As₂S₃/STF waveguides, which gave similar results. A novel design for a Non-Reciprocal Phase Shift (NRPS) strip-loaded waveguide using chalcogenide glass (ChG) as the guiding layer is proposed. The NRPS and figure of merit of these waveguides are simulated. The ChG strip-loaded waveguide structure shows advantages both in fabrication and device performance according to the simulation results. Our study suggests the possibility of magneto-optical magneto-optical isolators monolithically integrated on a silicon platform.

We report on the first developments for a new approach of integrated photonic using optical evanescent coupling from organic microstructures to bundles of hybrid nanotubes (NT). Microstructures are organic disks acting as photon reservoirs, integrated on a photonic chip fabricated by micro-technologic processes. Biomimetic peptidic/ silica nanotubes are realized by molecular self-assembly allowing high aspect ratio. Such heterostructures have been included directly on the organic chip as an innovative solution based on nanotubes in situ chipapproach. The latter allowed us to obtain an adequate evanescent coupling localized between micronic-disks and bundles of nanotubes. As a result, we highlight a specific photonic propagation along various heterostructured- NT-bundles featuring distances beyond the centimeter and losses from 1.2 to 6.6 dB/cm. It presents an advantageous confinement of the optical mode marked with strong energy localizations between nanotubes.

Ion-exchanged devices on glass have been successfully used to realize passive and active integrated optic devices for sensor and telecom applications. Nowadays, research is focused on the reduction of the chip dimensions with an increase of the number of different function integrated. In this paper we present how the use of two stacked optical layers can allow realizing efficient and compact pump duplexer for ion-exchanged hybrid erbium doped waveguide amplifier. Indeed our complete theoretical study of the device shows that excess losses lower than - 0.1 dB and crosstalk lower than -20 dB can be achieved.

In this paper we review progress in optical gain clamped waveguide amplifiers for applications to optical communications. We demonstrate that compact waveguide devices may offer advantages compared to standard fiber amplifiers. In particular we focus on the application of gain clamping and optical burst switching networks where physical impairments may occur due to variation of the input power.

Slab waveguides were fabricated in tellurite glasses by means of nitrogen ion implantation, using a wide range of ion doses (from 5x10¹² to 8x10¹⁶ ions/cm²), in order to investigate their effects on the induced refractive index change. The results of the characterization, carried out by means of dark-line spectroscopy, show the presence of an optical barrier with a decrease of the refractive index at the end of range. Annealing post-implantation process was performed at different temperatures on higher doses (≥10¹⁶ ions/cm²) ion implanted slab waveguides and the characterization showed a decrease of the barrier effect probably due to a corresponding reduction of the defects inside the glass matrix.

The interfacing of an optical fiber and a photonic integrated circuit becomes more complex on a high refractive index contrast waveguide platform due to the large mismatch in mode size between the optical fiber mode and the waveguide modes in the integrated circuit. In this paper we review our work in the field of diffractive grating structures, in order to realize a high efficiency, polarization independent, large bandwidth optical interface with high index contrast waveguides fabricated on the silicon-on-insulator platform.

The area of integrated optical circuits has been undergoing rapid development and gaining a great deal of applications in fiber communications and optical interconnections. These applications bring a significant challenge to optical circuits such as increased circuit density and further miniaturized devices. Compact and high performance optical components are in great demand. This paper present our proposal to use Si based compact diffractive components for coupling, splitting, and reflection in integrated optical circuits. First, a novel subwavelength grating, binary blazed grating (BBG), is used as a high efficient vertical coupler from single mode fiber to Si waveguide. By using the strong polarization dependence of the BBG coupler, a polarization beam splitter (PBS) is proposed to split the polarizations of input light from fiber into two waveguides separately, during the coupling process. The coupling length is merely 14 μm. The extinction ratio is better than 20 dB for both polarizations over a 40 nm wavelength range and the coupling efficiencies for two polarizations are 58% and 50%, respectively. Second, a broadband and high efficient mirror based on the BBG is designed and fabricated. Up to 96% reflectivity over a wavelength rang of 1.2~1.7um was achieved both theoretically and experimentally. Finally, a nanoscale pillar waveguide is proposed as an ultra small nanotaper for mode conversion between fiber and submicron waveguide. It has been demonstrated that a 13 μm long taper is able to convert a mode size of 4 μm into 1 μm with an efficiency of 85%.

Due to the small coupling strength of waveguide grating couplers in low index contrast material systems such as polymers, the efficient coupling to single-mode waveguides via surface gratings represents a severe challenge. In this work, we demonstrate that the coupling strength of grating couplers in low-index difference waveguide systems can be strongly enhanced by the application of a thin high-index coating (HIC) on top of surface gratings. This allows reducing the grating coupler aperture size without sacrificing efficiency by up to more than an order of magnitude, which enables low-loss lateral tapering to single-mode waveguides.

We present the design and fabrication of a refractive polymer wedge that allows perfectly vertical coupling of light into a silicon waveguide, which is of interest for flip-chip bonding of vertical cavity emitting light sources on a silicon integrated circuit. The structure includes a conventional diffractive grating coupler that requires off-normal incidence to avoid second order Bragg reflections. The polymer wedge is thus used to refract vertically impinging light into an off-normal wave that couples into the underlying grating. The fabrication involves two steps: mold fabrication and imprint replication. Firstly negative wedge-shaped craters are etched into a quartz mold by Focused-ion-beam milling. Secondly the mold is used to imprint a UV-curable polymer onto a silicon chip containing waveguides and grating couplers, and so replicating the wedges. The characterization setup consisted of a fiber-to-fiber transmission measurement of a silicon waveguide equipped with a pair of grating couplers and polymer wedges. The obtained fiber coupling efficiency was equal to the efficiency of regular grating couplers and fiber positioned at an off-normal angle. The proposed fabrication method enables low cost integration of vertical cavity emitting light sources on silicon integrated photonic circuits.

Arrayed waveguide grating (AWG) devices play a crucial role in wavelength division multiplexing (WDM) networks and links. AWGs are key building blocks in multi-wavelength receivers and transmitters, wavelength routers, add-drop multiplexers and optical crossconnects. AWG size becomes a critical issue when they are used in higher complexity photonic integrated circuits. The last years have shown a steady reduction of AWG device dimensions in silica-on-silicon, silicon-on-insulator and InP-based technologies. Extremely compact AWGs with good performance are feasible and allow for a significant reduction in cost, when integrated with other components in photonic integrated circuits.

A photonic integrated circuit is designed containing a long grating with spiral geometry. Waveguide width and index modulation are studied as methods to form the grating structure. Both methods require an initial mask step for waveguide formation. In the case of width modulation the grating is formed in the same step as the waveguide, whereas a second mask step is required for index modulation. Thus width modulation removes the alignment tolerances associated with a two step process. The spiral geometry enables a long grating (~1 m) to be realized in a small area (1 cm²). The ability to form the grating in such a small area enables the use of current lithography mask / projection equipment. Thus, the requirements for mechanical/optical precision in a customized long fiber Bragg grating fabrication system is transferred to the precision of commercial lithography mask fabrication and projection equipment.

A new type of tunable guided-wave spectral slicing filter at the 1530nm wavelength regime is reported. The design allows the selection of equally spaced frequency channels and simultaneously produces nulls that are equally spaced between the selected channels. This makes it attractive for minimizing crosstalk in dense wavelength division multiplexing (DWDM) applications. The spectral selection of the filter is based on co-directional polarization coupling between transverse electric (TE) and transverse magnetic (TM) orthogonal modes in a waveguide by means of a static strain induced index grating. An etalon-like response results from the sparse arrangement of the grating sections as N individual coupling regions in tandem with equal spacing between their centers, yielding N-1 equally spaced nulls between adjacent selected frequencies. Adjustments of the resulting filtering function may be obtained by proper choice of coupling regions' lengths and spacing. Devices were fabricated using single mode channel waveguides formed by Ti diffusion on x-cut y-propagating LiNbO₃ substrates. Static strain from a periodically delineated surface film was used for making N = 6 polarization coupling regions. Electrode patterns centered about the optical waveguide and defined by liftoff were used to tune the filter electrooptically. Experimental results are in good agreement with design theory.

Hollow core photonic crystal fibers (HC-PCFs) find applications which include quantum and non-linear optics, gas detection and short high-intensity laser pulse delivery. Central to most applications is an understanding of the linear and nonlinear optical properties. These require careful modeling due to the multitude of lengthscales involved and non-standard variations in properties such as the mode-field distribution. Linear mode-solvers require many 100,000's of basis functions to resolve the field variations, and extra terms are often required in descriptions of nonlinear propagation. The intricacies of modeling various forms of HC-PCF are reviewed. An example of linear dispersion engineering, aimed at reducing and flattening the group velocity dispersion, is then presented. Finally, a study of short high intensity pulse delivery using HC-PCF in both dispersive and nonlinear (solitonic) regimes is given.

We develop a unified theory to analyze the modal properties of surface emitting chirped circular grating lasers. Based on solving the resonance conditions which involve two types of reflectivities of chirped circular gratings, this theory is both easy to understand and convenient to apply to different configurations of circular grating lasers. Though in a more concise format, this approach is shown to be in agreement with previous derivations which use the characteristic equations. With this unified analysis, the modal properties of circular DFB, disk-, and ring- Bragg resonator lasers are obtained, and the threshold gains, single mode ranges, quality factors, emission efficiencies, and modal areas of these types of circular grating lasers are compared.

The Goos-Hanchen (GH) shift is observed from phase transition of the reflected light. However, the reported Artmann's equation is difficult to apply to drastic phase change of the critical and resonance angles because this equation is solved by differential of the phase shift. Therefore, the GH shift can be obtained from the structure optimized by the finite-difference time-domain method. In the surface plasmon resonance (SPR) phenomenon, positive and negative lateral shifts may result from the variation of incidence angle. The GH shift is very important to exactly detect the output power of the micro-size SPR sensor. The accurate positive and negative lateral shifts of -0.49 and +1.46 μm are obtained on the SPR with the incidence angles of 44.4° and 47°, respectively.

Ag slab near-field superlens (NFSL) has been much attractive issue due to their application of nano-imaging by the resolution beyond the diffraction limits. Although it has the advantages as sub-wavelength imaging tools, Ag NFSL always suffers from image blurring due to the intrinsic absorption loss, which prevent the ideal reconstruction of nanoimaging. In this research, through the analysis of focal property using the FDTD, we recognized that the impedance mismatched Ag NFSL is useful as the phase corrected optical components in the near-field. As a result, the significant enhanced of visibility, depth of field, and resolving capability is achieved in the mismatched Ag NFSL imaging system.

A method is presented for generating M-ary signals by introducing direct digital driving combined with a single Multi-Electrode Mach-Zehnder interferometer. It is characterized by using two-level driving signals and thus eliminating the need for complex analog driving circuits. Example of generating square 16-QAM constellation is given. It is shown that using a total of 10 electrode segments achieves close-to-ideal performance.

Backscatter in integrated optical waveguides is responsible of losses and distortion of the spectral circuit response. In this contribution we present measurements of the backscattered power from medium and high index contrast waveguides and an equivalent circuit describing the statistical behavior of such effect is proposed. The measurements are carried out with a cavitometric technique allowing to space resolve the local backreflection distributed along the waveguide. The equivalent circuit is composed by an ideal waveguide with a central lumped reflector owning a random phase. We investigated the spectral response of simple circuits and ring resonators, both numerically and experimentally.

Compound semiconductors provide state-of-the-art performance in optoelectronics, while silicon-on-insulator (SOI) is an ideal platform for many passive functions in integrated optics. By combining them one can realise optical devices with high performance and low cost. This paper discusses the various applications and technologies for integrating InP chips with SOI waveguides. Bonding of lasers, SOA arrays and detectors for practical applications is described. Experimental results are given for visually aligned thermo-compression bonding and self-aligned flip-chip bonding with Indium bumps. Flip-chip bonding is reported directly on SOI chips, as well as on a separate silicon-optical-bench.

To meet market demand and enable the proliferation of camera phones for developing countries, manufacturers must be able to meet requirements for camera modules that are reduced in size and cost. Conventional camera-module technology is heading towards an asymptote, where the optics no longer scale with the required size, performance, and cost. Using wafer-level techniques and reflow compatible materials to manufacture the optics together with wafer-level chip scale packaging (WLCSP) of image sensors enables manufacturing of smaller-size, lower-cost, reflow-compatible camera modules. Focusing on VGA resolution, this paper will present a comparison between optical modules that were built using conventional technology and wafer-level technology.

The possibility of imaging objects at the resolution of smaller than the optical diffraction limit is of great interest to nanotechnologies and biotechnologies. In this paper, we present a novel near-filed nano-imaging device based on nanophotodetector(NPD) array, which is capable of addressing function. Multi-level Multi-electron(MLME) Finitedifference time-domain(FDTD) method is used to simulate the performance of NPD array. The simulation shows a highest obtainable resolution of 150nm for the light with 1.55μm wavelength. Various photolithography, e-beam lithography and etching back techniques have been developed to realize the NPD device. Up to 4x4 slab version NPD array with various resolutions have been successfully realized. The smallest pixel size is as small as 150nm.

Theoretical models of surface plasmon-polariton (SPP) refractive index sensors with Bragg grating and long period grating (LPG) are presented and comprehensively investigated for fiber and planar structures. The main principle of operation of these devices is based on high efficiency energy transfer between a guided mode propagating in a waveguide layer of the structure and counter- or co-propagating SPP supported by a metal layer separated from the waveguide layer by a buffer. The high efficiency energy transfer is realized by means of a properly designed Bragg grating or LPG imprinted in the waveguide layers of the structures or engraved on the top of the metal layer. These devices are compact, free from any moving parts and can be easily integrated into any fiber or planar schemes. Our simulations are made for telecom wavelengths in the 1500nm window.

We report on a real-time, non-invasive, and all optical microfluid temperature measurement technique using the surface plasmon resonance. The technique results in 0.03°C temperature resolution of liquid volumes as small as 20μL and thus may have applications in a myriad of fields including micro-fluidics, micro-chemistry, and biophysics. We also propose a technique for achieving a 25-fold increase in sensitivity. These all-optical measurements may be integrated into a fiber-optic systems providing great potential for use in emerging lab-on-chip and remote sensing technologies.

Plasmonic waveguides have shown the potential to guide subwavelength optical modes, the so called surface plasmon polaritons, at metal-dielectric interfaces. In particular, a metal-dielectric-metal (MDM) structure supports a subwavelength propagating mode at a wavelength range extending from DC to visible. Thus, such a waveguide could be important in providing an interface between conventional optics and subwavelength electronic and optoelectronic devices. Nonlinear processes such as second-harmonic generation (SHG) are important for applications such as switching and wavelength conversion. In this paper, we show that field enhancement in MDM waveguides can result in large enhancement of SHG. We first consider a structure consisting of a MDM waveguide filled with lithium niobate, which is sandwiched between two high-index-contrast dielectric waveguides. Such a structure forms a Fabry-Perot resonant cavity and can be designed to have a resonance at both the first and second harmonic. We show that this doubly resonant device results in more than two orders of magnitude enhancement in SHG compared to a uniform slab of lithium niobate. We also consider structures in which multisection tapers are used to couple light in and out of the MDM waveguide. We optimize the tapers so that their transmission efficiency is maximized at both the first and second harmonic. For such structures the field enhancement is due to the squeezing of the optical power from the wavelength-sized dielectric waveguide to the deep subwavelength MDM waveguide.

Multispectral imaging or imaging spectroscopy obtains spectral content of an object by dividing the image data, pixel by pixel, into wavelength (color) bands. The resulting 3D data cube (x, y, λ) allows materials to be identified by their pixel spectral content at multiple wavelengths in addition to their spatial characteristics. A new class of multispectral imaging systems are being developed that utilizes lithographically patterned dichroic filter arrays integrated with standard CCD and CMOS detector arrays. These new imagers offer the unique advantage of scalability to tens of Megapixel resolutions, compact size, and no moving parts. Our multispectral imagers are much simpler to manufacture in volume because the complexity is in the lithographically patterned dichroics rather than in the bulk optical system. The patterned dichroic filter arrays are fabricated utilizing standard microlithography techniques and can incorporate up to 10 different wavelength bands deposited onto a single substrate. Each channel is selectively patterned on the substrate with the dichroic filter coating applied using standard thin film coating techniques. The technique is repeated for all of the wavelength bands and then the final filter array is directly attached and aligned onto the CCD.

In this paper, we describe progress towards a multi-color spectrometer and radiometer based upon an active resonant subwavelength grating (RSG). This active RSG component acts as a tunable high-speed optical filter that allows device miniaturization and ruggedization not realizable using current sensors with conventional bulk optics. Furthermore, the geometrical characteristics of the device allow for inherently high speed operation. Because of the small critical dimensions of the RSG devices, the fabrication of these sensors can prove challenging. However, we utilize the state-of-the-art capabilities at Sandia National Laboratories to realize these subwavelength grating devices. This work also leverages previous work on passive RSG devices with greater than 98% efficiency and ~1nm FWHM. Rigorous coupled wave analysis has been utilized to design RSG devices with PLZT, PMN-PT and BaTiO3 electrooptic thin films on sapphire substrates. The simulated interdigitated electrode configuration achieves field strengths around 3×10⁷ V/m. This translates to an increase in the refractive index of 0.05 with a 40V bias potential resulting in a 90% contrast of the modulated optical signal. We have fabricated several active RSG devices on selected electro-optic materials and we discuss the latest experimental results on these devices with variable electrostatic bias and a tunable wavelength source around 1.5μm. Finally, we present the proposed data acquisition hardware and system integration plans.

We present multiaperture stationary spectrometers in planar optical waveguides. The devices are based on the spatial heterodyning technique, do not require moving parts, and use Fourier transformation for spectra retrieval. The design is based on arrays of waveguide interferometers with linearly increasing optical path delay. The spectrometers have increased optical throughput due to multiple input waveguides. We discuss design, fabrication, and first experimental results for these multiaperture spectrometers implemented in silicon-on-insulator (SOI) ridge waveguides.

In this paper, we present the development of a laser source for a LIDAR application. This sensor is proposed as a standby instrument to provide a way to measure some aircraft air data such as the air speed. Although such systems already exist, none of them are based on an optical measurement. Thus, the use of a LIDAR would provide a backup channel with different failure modes than existing systems. Our LIDAR system allows determining the air speed through Doppler measurement at a wavelength of 1.55 µm on aerosol particles present around the aircraft. The core of this device is a glass integrated optics continuous DFB laser. Its performances in term of single-frequency, stability, noise and linewidth are assessed in order to ensure the correct operation of the LIDAR system.

A refractive index sensor based on a three-layered polymeric waveguide was proposed and demonstrated. A high-index thin film in TiO₂ was placed on top of the waveguide in the sensing region, playing the role of strengthening the evanescent field to enhance the sensitivity of the sensor. The refractive index of the analyte applied to the surface of the sensor was estimated by observing the count of the polarimetric interference between the TE and TM polarizations, which is manifested as a periodic variation in the optical output of the sensor. For a fabricated sensor involving a 20 nm thick TiO₂ film, the sensitivity was found to be equivalent to 1.8x10^-3 RIU. It was found to be enhanced by increasing the thickness of the high-index overlay to a certain degree.

A planar optical waveguide with an input grating coupler was used as an affinity-based biodetection device. Nanoimprint lithography was used to integrate the grating patterns with low loss silicon oxynitride thin-film waveguides. A widely tunable laser source at 1550nm was used to characterize the device sensitivity to bulk medium changes, to thin film adsorption, and to streptavidin protein. For each test, a comparison was performed between the sensitivity of wavelength interrogation and the more standard angular interrogation approach. The effects of surface reflections on the measured coupling curves were observed and interpreted, with mitigation options being considered.

Ion-exchange in glass substrate has long been an enabling technology for optical waveguides device manufacturing. Thus, in the last years, hybridization of ion-exchanged glass waveguides components has become a promising method for functional integration. In that context, we propose a Integrated acousto-optic Polarization Analyzer Sensor (IPAS) made by ion-exchange in a glass substrate. The IPAS consists in two Y-junctions that give three different outputs. The first one is simply one output waveguides of the first Y-junction. The two other outputs are the waveguides following the second Y-junction. A piezoelectric plate is placed over the entrance waveguide of the second Y-junction. It creates an artificial anisotropy when it is excited electrically. For each one of the three output signals, a polarizer is inserted between the waveguide's end and a photodetector. The IPAS is a compact hybrid realization insensitive to vibrations and easy to realize. It is capable to determine, with adequate signal processing, the polarization state of a light beam. Experimental results are obtained with a single buried straight waveguide made by low birefringence Ag⁺↔Na⁺ ion-exchange. The measured polarization state is compared with a commercial polarization analyzer.

In a previous study, we have reported transmittance variations of sub-wavelength palladium hole arrays upon exposure to hydrogen. The main resonance peak of the microfabricated palladium hole arrays exhibiting the extraordinary transmission effect decreases when exposed to the lower flammability concentration of hydrogen in air. This variation in transmittance was attributed to a combination of two effects, namely, a change in the dimension of the array holes due to the expansion of palladium upon hydrogen absorption, and/or a change in the permittivity of the palladium layer upon formation of the palladium hydride phase. In this study, we examine the relative strength of the two effects by finite-difference- time-domain simulation. Our simulation results show that the transmittance variation upon exposure to hydrogen is predominantly caused by the lateral expansion of the palladium layer, which induced a decrease in the hole width of the array.

A new gas sensor was developed to enable visual indication of a contamination by specific gases like NO₂, SO₂, UV, etc. The sensor works with a combination of subwavelength structures and specific active dye thin film layers. The objective is to use the optical changes of the dye thin films after exposure and a custom designed subwavelength structure, a suited combination of both will produce a strong color change. The indication should be visible for the human eye. To enhance this visual aspect, we used a reference sensor sealed into a non-contaminated atmosphere. This work was realized within the PHODYE STREP Project, a collaboration of the 6th Framework Program Priority Information Society Technologies.

In this paper, the input-output coupler system using two and three Bragg gratings is implemented for optical communication wavelength, i.e. 1550nm, in path-folding and path-shifting type. The grating is designed with 45 degrees fringe slant angle to achieve normal direction input, output coupler. An additional grating at the output coupler makes the total system throughput increase 9% in comparison with two-grating input-output coupler system. With 5x5mm grating size, the total systems throughput can reach nearly 26% for two-grating and 35% for three-grating input-output coupler.