This PDF file contains the front matter associated with SPIE Proceedings Volume 8767, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.

A systematic design process of slow light photonic crystal slab waveguides is presented with the aim of maximizing the storage capacity. Dispersion effects and propagation losses characteristics are included in order to increase the design accuracy. Our procedure allows the optimization of the structure at the same time by varying as many as ten design parameters. We show that storage capacities of almost 32bits at 40Gb/s and 65bits at 100Gb/s can be obtained.

The asymmetric Fano resonance lineshapes, resulting from interference between background and a resonant scattering, is archetypal in resonant waveguide grating (RWG) reflectivity. Resonant profile shift resulting from a change of refractive index (from fluid medium or biomolecules at the chip surface) is classically used to perform label-free sensing. Lineshapes are sometimes sampled at discretized “detuning” values to relax instrumental demands, the highest reflectivity element giving a coarse resonance estimate. A finer extraction, needed to increase sensor sensitivity, can be obtained using a correlation approach, correlating the sensed signal to a zero-shifted reference signal. Fabrication process is presented leading to discrete Fano profiles. Our findings are illustrated with resonance profiles from silicon nitride RWGs operated at visible wavelengths. We recently demonstrated that direct imaging multi-assay RWGs sensing may be rendered more reliable using “chirped” RWG chips, by varying a RWG structure parameter. Then, the spatial reflectivity profiles of tracks composed of RWGs units with slowly varying filling factor (thus slowly varying resonance condition) are measured under monochromatic conditions. Extracting the resonance location using spatial Fano profiles allows multiplex refractive index based sensing. Discretization and sensitivity are discussed both through simulation and experiment for different filling factor variation, here Δf=0.0222 and Δf=0.0089. This scheme based on a “Peak-tracking chip” demonstrates a new technique for bioarray imaging using a simpler set-up that maintains high performance with cheap lenses, with down to Δn=2×10^-5 RIU sensitivity for the highest sampling of Fano lineshapes.

Typical UHQ resonators, microspheres and microtoroids, lack the possibility of integration into lightwave circuits due to their planarity constrains. In this context, CMOS-compatible alternatives in the form of wedge resonators have been proposed. However, the mode retraction from the wedge cavity inhibits the possibility to side couple with integrated waveguides and therefore, halts the full integration within a planar lightwave circuit. In this work, we propose and demonstrate experimentally the complete integration of wedge resonators with vertically coupled dielectric bus waveguides. This coupling scheme permits to use arbitrary gaps, geometries and materials, enables simplified and precise control of the light injection into the cavity and opens the door to an industrial mass-fabrication of UHQ resonators.

We report the experimental investigation of image self-replication - Talbot effect with the use of 1- and 6 - fold rotational symmetry masks to create 3D intensity modulated light. These masks while having strong periodicity in azimuthal direction, are examples of multi-periodical and nearly periodical structures, respectively, along transverse XY directions. Since the Talbot image self-replication period in the axial direction depends on light wavelength and square of the structure periods, which are different in X-Y directions for 1-fold rotational symmetry mask, this gives a possibility to create the complex 3D light intensity distribution with different Talbot axial periodicity across the beam transverse plane. A cw single mode 532 nm, 100 mW laser beam was used in the experiment for formation of complex lattice beams. The observation of the transverse intensity patterns at multiple longitudinal positions will allow the construction of a whole 3D intensity distribution of the lattice beam. 3D intensity modulated light beams are promising for formation of crystalline and quasi-crystalline refractive index micro- and nano-structures in photorefractive materials.

The nonlinear characteristics of hydrogenated amorphous silicon nanowires are experimentally measured. A nonlinear coefficient, γ, with a high real part Real(γ)= 690W^-1m^-1, combined with a low imaginary part Im(γ)= 10 W^-1m^-1, resulted in a high nonlinear FOM of 5.5. Furthermore, systematic studies over hours of operational time under 2.2W of pulse peak power revealed no degradation of the optical response.

Low-loss hydrogenated amorphous silicon is employed for the fabrication of various planar integrated travelling wave resonators. Microring, racetrack, and disk resonators of different dimensions were fabricated with CMOS-compatible processes and systematically investigated. The key properties of notch filter ring resonators as extinction ratio, Q-factor, free spectral range, and the group refractive index were determined for resonators of varying radius, thereby achieving critically coupled photonic systems with high extinction ratios of about 20 dB for both polarizations. Racetrack resonators that are arranged in add/drop configuration and high quality factor microdisk resonators were optically characterized, with the microdisks exhibiting Q-factors of greater than 100000. Four-channel add/drop wavelength-division multiplexing filters that are based on cascaded racetrack resonators are studied. The design, the fabrication, and the optical characterization are presented.

Combination of nanometer-scale 3D structural analysis with optical characterization of the same material is a challenging task. Its results may be important for nanophotonics, materials science, and quality control. We have developed a new technique for complementary high-resolution structural and optical characterization followed by optical spectroscopic and microscopic measurements accompanied by reconstruction of the 3D structure in the same area of the sample. The 3D structure is reconstructed by combination of ultramicrotomic and SPM techniques allowing the study of the 3D distribution of implanted nanoparticles and their effect on the matrix structure. The combination of scanning probe nanotomography (SPN) and optical microspectroscopy makes it possible to direct estimate how the 3D structural characteristics of materials affect their macroscopic optical properties. The technique developed has been applied to the engineering of materials made from cholesteric liquid crystals and fluorescent quantum dots (QDs). These materials permit photochemical patterning and image recording through the changes in the dissymmetry factor of circular polarization of QD emission. The differences in the polarisation images and morphological characteristics of the liquid crystal matrix have proved to be correlated with the arrangement of the areas of homogeneous distribution and nonhomogeneous clustering of QDs. The reconstruction of the 3D structure of the liquid crystal matrix in the areas of homogeneous QD distribution has shown that QDs embedded into cholesteric liquid crystal matrices do not perturb their periodic planar texture. The combined optical/SPM/ultramicrotome technique will be indispensable for evaluating the effects of inorganic nanoparticles on the organisation of organic and liquid crystal matrices, biomedical materials, cells, and tissues.

Development of fast silicon photonics integrated circuit is mainly driven by the reduction of the power consumption. As a result, photodetectors with high efficiency, high speed and low dark current are needed to reduce the global link consumption. Germanium is now considered as the ideal candidate for fully integrated receivers based on SOI substrate and CMOS-like processes. We report on low power and high speed waveguide-integrated Ge photodetectors. Butt coupled lateral PIN structure photodiodes have been fabricated by Germanium selective growth and ion implantation at the end of silicon waveguide. Three types of photodiodes are reported, with dark current as low as 6nA at 1V reverse bias, optical bandwidth over 40GHz at zero bias and responsivity up to 0.8A/W at a wavelength of 1550nm. Such devices are suitable for data rate over 40Gbps and can be easily integrated with other photonic devices to fabricate wafer scale integrated circuits for datacom and telecom applications.

We report on the electro-refractive effect in Ge/SiGe multiple quantum wells grown by low energy plasma enhanced chemical vapor deposition (LEPECVD). The electro-refractive effect was experimentally characterized by the shift of Fabry-Perot fringes in the transmission spectra of a 64 μm long slab waveguide. A refractive index variation up to 1.3 × 10^-3 was measured with an applied electric field of 88 kV/cm at 1475 nm, 50 meV below the excitonic resonance, with a V_πL_π figure of merit of 0.46 V×cm. The device performances are promising for the realization of Mach Zehnder modulators in the Ge-Si material platform.

This work concentrates on the device characteristics and performance of Ge-on-Si p-i-n diodes for the use as absorption modulators. At first, the impact of temperature on electrical and on optical characteristics of these p-i-n diodes is investigated. Secondly, the feasibility of optical modulation using the Franz-Keldysh effect is demonstrated for temperatures up to 359 K. The Ge-on-Si p-i-n diodes are grown using a molecular beam epitaxy system. The layer structure includes a double Si/Ge-heterojunction and an intrinsic zone with a thickness of 500 nm. During the growth process several annealing steps are performed to reduce the dislocation density and incorporate tensile strain in the intrinsic zone. The dark current is proportional to the diode area and amounts to 40 mA/cm² at a reverse voltage of 1 V. An analysis of the temperature dependence of the dark current shows that it is dominated by generation/recombination of carriers probably at threading dislocations. The optical absorption spectra recorded show a shrinkage of the infrared cut off wavelength of about 0.6 nm/K. In addition the change of absorption at the direct bandedge with different applied biases, i.e. the Franz- Keldysh effect, is demonstrated for temperatures from 300 K to 359 K. With regard to modulation of an optical signal the on/off ratio is evaluated as function of the voltage swing. With a moderate voltage swing of 2 V the maximal absorption change is 300 cm^-1 and the optimal working regime shifts from 1625 nm at 300 K to 1665 nm at 337 K.

This work presents the limiting factors of fast Germanium p-i-n photodetectors for optical on-chip communication. The photodetectors are grown by molecular beam epitaxy on Silicon and Silicon on insulator substrates. On-wafer RF and optical RF measurements up to 40 GHz are performed at a wavelength of 1.55 μm. Different de-embedding procedures are used to obtain the amplitude and phase of the device impedance and the equivalent circuit description. An analysis of the reflection coefficient compared to the equivalent circuit explains the frequency characteristic and it is used to determine background doping of the intrinsic layer and the expansion of the space charge width. The optical bandwidth is measured for different bias voltages and background doping. The RC limitation of the detectors is shown and analyzed leading to adjusted parameters for high speed detectors at zero-bas.

In this article a selection of highlights of the TriPleX™ technology of LioniX is given. The basic waveguide technology is explained with recent benchmark measurements done by University California Santa Barbara (UCSB) and University Twente (UT-TE). In order to show the low loss transparency over a wide wavelength range three examples of applications in different wavelength regimes are described in more detail. These are the Integrated Laser Beam Combiner (ILBC) of XiO Photonics in the visible light, a ringresonator sensing platform of LioniX around 850 nm and a phased array antenna with an Optical Beam Forming Network in the 1550 nm band. Furthermore it is shown that the technology is easily accessible via Multi Project Wafer Runs for which the infrastructure and design libraries are also set up.

Application Specific Photonic Integrated Circuits (ASPICs) are considered key elements to make photonic systems or subsystems cheap and ubiquitous. ASPICs still are several orders of magnitude more expensive than their microelectronic counterpart: ASICS, which has restricted their application to a few niche markets. A novel approach in photonic integration is emerging that will reduce the R&D costs of ASPICs by more than an order of magnitude. It will bring the application of ASPICs that integrate complex and advanced photonic functionality on a single chip within reach for a large number of small and larger companies and initiate a breakthrough in the application of Photonic ICs. In this paper the process is explained. A significant number of designs has been realized the last 4 years, for a variety of applications in telecoms, datacoms, medical and sensing, from parties all over the world.

We have developed a CMOS-compatible Silicon-on-Insulator photonic platform featuring active components such as pi- n and photoconductive (MIM) Ge-on-Si detectors, p-i-n ring and Mach-Zehnder modulators, and traveling-wave modulators based on a p-n junction driven by an RF transmission line. We have characterized the yield and uniformity of the performance through automated cross-wafer testing, demonstrating that our process is reliable and scalable. The entire platform is capable of more than 40 GB/s data rate. Fabricated at the IME/A-STAR foundry in Singapore, it is available to the worldwide community through OpSIS, a successful multi-project wafer service based at the University of Delaware. After exposing the design, fabrication and performance of the most advanced platform components, we present our newest results obtained after the first public run. These include low loss passives (Y-junctions: 0.28 dB; waveguide crossings: 0.18 dB and cross-talk -41±2 dB; non-uniform grating couplers: 3.2±0.2 dB). All these components were tested across full 8” wafers and exhibited remarkable uniformity. The active devices were improved from the previous design kit to exhibit 3dB bandwidths ranging from 30 GHz (modulators) to 58 GHz (detectors). We also present new packaging services available to OpSIS users: vertical fiber coupling and edge coupling.

ePIXfab-The European Silicon Photonics Support Center continues to provide state-of-the-art silicon photonics solutions to academia and industry for prototyping and research. ePIXfab is a consortium of EU research centers providing diverse expertise in the silicon photonics food chain, from training users in designing silicon photonics chips to fiber pigtailed chips. While ePIXfab provides world-wide users access to advanced silicon photonics it also focuses its attention to expanding the silicon photonics infrastructure through a network of design houses, access partners and industrial collaborations.

Optoelectronic properties of Er³⁺-doped slot waveguides electrically driven are presented. The active waveguides have been coupled to a Si photonic circuit for the on-chip distribution of the electroluminescence (EL) signal at 1.54 μm. The Si photonic circuit was composed by an adiabatic taper, a bus waveguide and a grating coupler for vertical light extraction. The EL intensity at 1.54 μm was detected and successfully guided throughout the Si photonic circuit. Different waveguide lengths were studied, finding no dependence between the waveguide length and the EL signal due to the high propagation losses measured. In addition, carrier injection losses have been observed and quantified by means of time-resolved measurements, obtaining variable optical attenuation of the probe signal as a function of the applied voltage in the waveguide electrodes. An electro-optical modulator could be envisaged if taking advantage of the carrier recombination time, as it is much faster than the Er emission lifetime.

Semiconducting SWNT extraction was studied using an ultra-centrifugation method assisted by a conjugated polymer. It was demonstrated that the emission intensity can be highly improved and that in some conditions emission from one single nanotube chirality can be achieved. This optimized material was integrated on several photonic structures. The ability of nanotubes to emit light when drop-casted on a silicon waveguide was first demonstrated and its thermal stability was further investigated. We concluded over interesting integration ability on Silicon-On-Insulator (SOI) substrate, with coupling efficiency up to the order of 10%. The integration of SWNT on Bragg mirrors based cavity was also investigated. This is the first milestone towards a carbon nanotube based fully integrated LASER.

This work reports on the benefits and promising opportunities offered by white LED hybrid technology, based on a mixing perylene-based dyes in order to obtain a warm white light for frequency-down conversion. In a standard Ce:YAG-based white LED, the white light appears cold due to the weakness of red wavelength components in the emission spectrum. In order to obtain a warmer white, one possible solution is to add a red phosphor to the yellow one to move the chromatic coordinates properly, though the luminous efficiency drastically decreases due to the increased light absorption of the coating layer. It is generally believed that the low efficiency of warm white LEDs is the main issue today for LED-based lighting. Using photoluminescence of Lumogen® F Yellow 083, a perylene-based polymer dye commercialized by BASF, and adding a small quantity of another perylene-based dye, Lumogen® F Red 305 (BASF), we obtained high-efficiency warm white LEDs by yellow and red conversion from a standard 450 nm GaN/InGaN royal blue LED. Different weight proportions of dyes were dissolved in solutions with equal amounts of poly-methyl-methacrylate (PMMA) in ethyl acetate, then the LEDs were dip-coated in each solution and optically characterized. Record values of 8.03 lm of luminous flux and 116.11 lm/W of optical efficiency were achieved. Finally, the effects of both driving current, and pump wavelength on LED performances – such as chromatic coordinates, correlated color temperature, color rendering index (CRI), and optical efficiency – were investigated.

In the European projects EuroPIC and PARADIGM development of an InP based generic photonic integration technology is being undertaken to implement complex InP based application-specific photonic integrated circuits (ASPIC) with transmit and receive functionalities from a set of basic building blocks. The integration platform pursued at Fraunhofer HHI is building on semi-insulating substrate. Recently a variety of receiver-type PIC with up to 40 GHz bandwidth capability designed by external users was fabricated in multi-project wafer runs. Examples are demonstrated. Extension of this platform to include transmit functionalities is underway using an MOVPE based butt-coupling approach.

In this paper we show that using a DVS-BCB adhesive bonding process compact heterogeneously integrated III-V/silicon single mode lasers can be realized. Two new designs were implemented: in a first design a multimode interferometer coupler (MMI) – ring resonator combination is used to provide a comb-like reflection spectrum, while in a second design a triplet-ring reflector design is used to obtain the same. A broadband silicon Bragg grating reflector is implemented on the other side of the cavity. The III-V optical amplifier is heterogeneously integrated on the 400nm thick silicon waveguide layer, which is compatible with high-performance modulator designs and allows for efficient coupling to a standard 220nm high index contrast silicon waveguide layer. In order to make the optical coupling efficient, both the III-V waveguide and the silicon waveguide are tapered, with a tip width of the III-V waveguide of around 500nm. The III-V thin film optical amplifier is implemented as a 3μm wide mesa etched through to the n-type InP contact layer. In this particular device implementation the amplifier section was 500μm long. mW-level waveguide coupled output power at 20°C and a side mode suppression ratio of more than 40dB is obtained.

The 0.35μm HV-CMOS process technology utilizes several junctions with different doping levels and depths. This process supports complete modular 3V and 5V standard CMOS functionality and offers a wide set of HV transistor types capable for operating voltages from 20V to 120V made available with only 2 more mask adders [1]. Compared to other reported integration of photo detection functionalities in normal CMOS processes [2] or special modified process technologies [3] a much wider variety of junction combinations is already intrinsically available in the investigated technology. Such junctions include beside the standard n+ and p+ source/drain dopings also several combinations of shallow and deep tubs for both p-wells and n-wells. The availability of junction from submicron to 7μm depths enables the selection of appropriate spectral sensitivity ranging from ultraviolet to infrared wavelengths. On the other side by appropriate layouts the contributions of photocurrents of shallower or deeper photo carrier generation can be kept to a minimum. We also show that by analytically modelling the space charge regions of the selected junctions the drift and diffusion carrier contributions can be calculated with a very good match indicating also the suppression of diffusion current contribution. We present examples of spectral responsivity of junction combinations optimized for peak sensitivity in the ranges of 380-450nm, 450-600nm or 700-900nm. By appropriate junction choice the ratios of the generated photo currents in their respective peak zones can exhibit more than a factor of 10 compared to the other photo diode combinations. This enables already without further filter implementation a very good spectral resolution for colour sensing applications. Finally the possible junction combinations are also assessed by the achievable dark current for optimized signal to noise characteristic.

Integrated spot size converters (SSCs) are key components for efficient coupling between Photonic Integrated Circuits (PICs) and fibre-arrays. We report a compact SSC which is suitable for integration into dense arrays with a pitch down to 25 μm and compatible with our generic InP-based platform technology, which supports integration of SOAs and Electro Optical Modulators with a range of passive components. The small pitch supports coupling tens of on-chip optical waveguide ports to fiber arrays via a low-loss dielectric interposer chip. The density allows the design of a customized optical bus between the InP PIC and the interposer chip. The dielectric chip may simply expand to the pitch of a fiber array but also contain low-loss passive circuitry like delay-lines, high Q-filters and multiplexers. The latter enables the formation of a hybrid integration platform with our InP-based technology. Efficient coupling is obtained by adiabatically transforming the sub-micron modes of the InP waveguides to the 3 μm diameter mode of the interposer. We tested our SSCs by coupling to a lensed fibre with a mode field diameter of 2.5 μm. Coupling losses were found to be as low as 0.6 dB per fiber chip coupling for device lengths of a few 100 μm. We also measured the crosstalk from one input port to output ports adjacent to the targeted output port. We present simple design rules for reducing the crosstalk to neighbouring output ports below -50 dB. The quality and uniformity of the SSCs is demonstrated by fabrication of an 8 x 8 AWG demultiplexer between two SSC arrays placed at input and output ports. We measured an insertion loss between fibres of 4 dB for the central channel of the AWG, which is record low for an InP-based device.

In most integrated optics platforms device design is restricted to variations in the lateral dimensions, and a small set of etch depths. Sub-wavelength gratings (SWGs) in silicon-on-insulator enable engineering of refractive index in a wide range. SWGs exhibit a pitch smaller than the wavelength of light propagating through them, thereby suppressing diffraction and acting as a homogenous medium with an equivalent refractive index controlled by the duty-cycle. Here, we propose to not only engineer refractive index, but to control SWG dispersion. We use this concept to design ultra-broadband directional couplers (DCs) and multimode interference couplers (MMIs) with a fivefold bandwidth enhancement compared to conventional devices.

In this paper, we propose a theoretical model for an Interleave-Chirped Arrayed Waveguide Grating (IC-AWG), modifying the already existing formulation based on Fourier optics. With the IC-AWG is possible to achieve several functionalities in a single device, such as channel demultiplexing, polarization splitting and 90° optical hybrid operation. We also elaborate on the developed model to present a design procedure for the IC-AWG. Finally, the model validation through numerical simulations using real physical parameters obtained from manufactured devices available in the literature is performed.

Skin absorption properties, under diseases conditions, are modified due to the structural variations of chromophores and pigments. The measurement of such different absorptions can be a useful tool for the recognition of different skin diseases. In this study the design of a multi-resonant metamaterial-based sensor operating in the optical frequency range is presented. The sensor has been designed, in order to have multiple specific resonant frequencies, tuned to the skin components spectral characteristics. A change in the frequency amplitude of the sensor response is related to the different absorption rate of skin chromophores and pigments. A new analytical model, describing the multi-resonant sensor behaviour, is developed. Good agreement among analytical and numerical results was achieved. Full-wave simulations have validated the capability of the proposed sensor to identify different skin diseases.

Recent progress of low-loss silicon nitride waveguide in polymer is presented. The fabrication technology requires only low temperature (<200°C) processes and standard photolithography. These waveguides feature a large geometric aspect ratio, resulting in a strong waveguide birefringence. For the TM mode an average propagation loss of ~ 0.72 dB/cm is measured, while for the TE mode the value is ~ 0.96 dB/cm. Also demonstrated are uniform Bragg-grating filters and sampled grating filters. Since the waveguide modes are weakly guided and the majority of light field distributes in the polymer cladding, various optical properties of the polymer materials can be exploited. A thermally tunable waveguide Bragg grating is thus demonstrated, with wavelength tuning range above 57 nm for the TM mode and 49 nm for the TE mode, at a tuning power of ~ 220 mW.

In the last decade, Si based photonics has made major advances in terms of design, fabrication, and device implementation. But due to Silicon’s indirect bandgap, it still remains a challenge to create efficient Si-based light emitting devices. In order to overcome this problem, an approach is to develop hybrid systems integrating light-emitting materials into Si. A promising class of materials for this purpose is the class of semiconducting nanocrystal quantum dots (NCs) that are synthesized by colloidal chemistry. As their absorption and emission wavelength depends on the dot size, which can easily be controlled during synthesis, they are extremely attractive as building blocks for nanophotonic applications. For applications in telecom wavelength, Lead chalcogenide colloidal NCs are optimum materials due to their unique optical, electronic and nonlinear properties. In this work, we experimentally demonstrate the integration of PbS nanocrystals into Si-based photonic structures like slot waveguides and ring resonators as optically pumped emitters for room temperature applications. In order to create such hybrid structures, the NCs were dissolved into polymer resists and drop cast on top of the device. Upon optical pumping, intense photoluminescence emission from the resonating modes is recorded at the output of the waveguide with transmission quality factors up to 14000. The polymer host material was investigated with respect to its ability to stabilize the NC’s photoluminescence emission against degradation under ambient conditions. The waveguide–ring coupling efficiency was also investigated as function of the NCs concentrations blended into the polymer matrix. The integration of colloidal quantum dots into Silicon photonic structures as demonstrated in this work is a very versatile technique and thus opens a large range of applications utilizing the linear and nonlinear optical properties of PbS NCs at telecom wavelengths.

In this paper, we present the synthesis and the optical properties of 3D magneto-photonic structures. The elaboration process consists in firstly preparing then infiltrating polystyrene direct opals with a homogeneous solution of sol-gel silica precursors doped by cobalt ferrite nanoparticles, and finally dissolving the polystyrene spheres. Scanning Electron Microscopy (SEM) images of the prepared samples clearly evidence a periodic arrangement. Using a home-made polarimetric optical bench, the transmittance as a function of the wavelength, the Faraday rotation as a function of the applied magnetic field, and the Faraday ellipticity as a function of the wavelength and as a function of the applied magnetic field were measured. The existence of deep photonic band gaps (PBG), the unambiguous magnetic character of the samples and the qualitative modification of the Faraday ellipticity in the area of the PBG are evidenced.

Infrared wire-grid polarizers were fabricated consisting of a 500-nm pitch Al grating on a low toxic chalcogenide glass (Sb-Ge-Sn-S system) using the direct imprinting of subwavelength grating followed by a deposition of Al metal by thermal evaporation. To fabricate the subwavelength grating on a chalcogenide glass more easily, the sharp grating was formed on the mold surface. The fabricated polarizer with Al thickness of 130 nm exhibited a polarization function with a transverse magnetic transmittance greater than 60% in the 5–9-μm wavelength range, and an extinction ratio greater than 20 dB in the 4–11-μm wavelength range. The polarizer can be fabricated at lower costs and simpler fabrication processes compared to conventional infrared polarizers.

The motivation for integrated Silicon-based optoelectronics is the creation of low-cost photonics for mass-market applications. Especially, the growing demand for sensitive biochemical sensors in the environmental control or medicine leads to the development of integrated high resolution sensors. Here we present initial results in the integration and butt-coupling of a Si-based light emitting device (LED) [1-3] to a waveguide into a photonic circuit. Our first approach deals with the design, fabrication and characterization of the dielectric high contrast waveguide as an important component, beside the LED, for the development of a Si-based biodetection system. In this work we demonstrate design examples of Si₃N₄/SiO₂-waveguides, which were calculated using MATLAB, the effective index method (EIM) and the finite element method (FEM), with a 0.45μm thick and 0.7μm wide core which shows a high confinement factor of ~74% and coupling efficiency of ~66% at 1.55μm, respectively. The fabrication was done by plasma enhanced chemical vapour deposition (PECVD), optical lithography and reactive ion etching (RIE). Additionally, we characterized the deposited layers via ellipsometry and the etched structures by scanning electron microscopy (SEM). The obtained results establish principles for Si-based LED butt-coupling to a powerful optical waveguide-based interconnect with effective light absorption and an adequate coupling efficiency.

In this work we design and theoretically investigate optical switches based on long-range plasmonic directional couplers, which are controlled via the electro-optic effect of nematic liquid crystal layers. Employed numerical tools include a fully-anisotropic finite-element-method, the eigenmode-expansion method, and a rigorous finite-element based calculation of the liquid-crystal molecular reorientation. Both horizontal and vertical configurations are assessed, providing a comparison in terms of key-performance characteristics, such as coupling length, switching voltage, insertion losses, and crosstalk. These tunable plasmonic devices are envisaged as ultra-low power consumption switching elements in integrated platforms for optical inter-chip interconnects.

The Drever-Pound-Hall technique is a powerful tool to stabilize the laser frequency or to lock a cavity to a laser by controlling its length in the order of fraction of wavelength^1-3 . It had been widely applied as method to interrogate fiber optical cavity based sensors, as strain sensors or refractive index sensors, since it allows to reach very high sensitivity, especially in dynamic range, only theoretically limited by the laser shot noise^4-7 . In this paper we present a detailed analysis on the possibility to use the DPH technique for the simultaneous detection of detuning of two or more cavities each lying on a different output branch of a splitter, by interrogating them using only the single input channel of the splitter. More precisely, starting from a reflection configuration of the present technique, where the error signal to control the cavity length is extracted by the signal reflected by the cavity, we analyze all the possible configurations to simultaneously interrogate and discriminate the different cavities, using the same input channel to have not overlap and interference between the signals reflected by each of them. The interest of this kind of analysis resides in the possibility to design very compact and less invading sensors that requires bidirectional detection of the involved physical quantity or, the simultaneous and independent control of several parameters (like, for example, bidirectional strain sensors, that simultaneously detect the strain along two orthogonal directions, or magnetic field sensor able to determine the intensity of the field along perpendicular directions, or, refractive index sensor temperature calibrated⁸ ). Using a single interrogation/detection channel the sensor can be placed far away from the interrogation/detection apparatus and connected to the latest only by means of a single optical fiber, instead to have more signal detection channels.