The critical sensor: a new type of evanescent wave immunosensor

A new planar waveguide immunosensor has been developed in which adsorption at a surface, changing the refractive index contrast, is measured. In this ¿critical¿ sensor the change in the effective refractive index contrast is transducted to a shift of the critical reflection angle. The sensor's response after a specific binding of antigens to antibodies is discussed theoretically. In addition, an experimental sensitivity evaluation on the basis of several immunosensing experiments is presented. The obtained lower detection limit is 2 × 10¿2 nm in adlayer growth, equivalent to 12 pg/mm2 of analyte coverage. This sensitivity is comparable to the performance of the surface plasmon resonance sensors or the grating coupler sensors. However, the ¿critical¿ sensor has some advantages. These are mainly the ease of fabrication and adjustment prior to a measurement, and the fact for an experiment no metal layer has to be used

Fabrication of Polymeric Multimode Waveguides and Devices in SU-8 Photoresist Using Selective Polymerization.

Large cross section multimode waveguides have been realized in SU-8 using selective polymerization. SU-8 is a negative photoresist, which has shown good optical properties and it is mechanically and chemically stable. The fabricated waveguides have very smooth sidewalls and exhibit low optical losses. The fabrication method is simple and potentially very cost effective. N x N and 1 x N multimode power splitters have been realized using this fabrication technology

Low loss, high contrast optical waveguides based on CMOS compatible LPCVD processing: technology and experimental results

A new class of integrated optical waveguide structures is presented, based on low cost CMOS compatible LPCVD processing. This technology allows for medium and high index contrast waveguides with very low channel attenuation. The geometry is basically formed by a rectangular cross-section silicon nitride (Si3N4) filled with and encapsulated by silicon dioxide (SiO2). The birefringence and minimal bend radius of the waveguide is completely controlled by the geometry of the waveguide layer structures. Experiments on typical geometries will be presented, showing excellent characteristics (channel attenuation ≤ 0.1 dB/cm, IL ≤ 1.5 dB, PDL ≤ 0.2 dB, Bg ≤ 1×10-4, bend radius « 1 mm)

Optical gain of LaF3:Nd nanoparticle doped polymers for active integrated optical devices.

We report on rare earth doped LaF3 nanoparticles dispersed in PMMA and SU-8 photosensitive polymers. We observed optical gain after we applied these materials for waveguides. Experimental results on various samples will be discussed. We theoretically discuss the improvements that can be obtained and the possibilities of this new class of materials when applied to microring resonators

Ring resonator-based Tunable Optical Delay Line in LPCVD Waveguide Technology

Optical circuits providing a time delay to signals modulated on optical carriers are considered important for optical communication systems and phased array antennas. A continuously tunable optical delay line is demonstrated in low-cost CMOS compatible LPCVD planar waveguide technology. The device consists of three cascaded ringresonator all-pass filters with fixed circumference of 2 cm (delay of 0.12 ns and FSR of 8.4 GHz). The measured group delay ranges from 0 ns up to 1.2 ns with a bandwidth of 500 MHz and delay ripple smaller than 1 ps, which is in accordance with the calculations

Ring resonator-based single-chip 1x8 optical beam forming network in LPCVD waveguide technology

Optical ring resonators (ORRs) are good candidates to provide continuously tunable delay in beam forming networks (BFNs) for phased array antenna systems. \ud Delay and splitting/combining elements can be integrated on a single optical chip to form an OBFN. A state-of-the-art 1×8 OBFN chip has been fabricated in LPCVD waveguide technology.\ud It is designed with 1 input and 8 outputs, between which a binary-tree topology is used. A different number of ORRs (up to 7) are cascaded for each output.\ud In this paper, the principle of operation is explained and demonstrated by presenting measurements on the 1×8 OBFN chip

Phased array antenna steering using a ring resonator-based optical beam forming network

A novel beam steering mechanism for a phased array antenna receiver system is introduced. The core of the system is a ring resonator-based integrated optical beam forming network chip. Its principles are explained and demonstrated by presenting some measurement results. The system architecture around the chip is based on a combination of frequency down conversion, filter-based optical single sideband modulation and balanced coherent detection. It is proven that such an architecture has significant advantages with respect to a straightforward architecture using double sideband modulation and direct detection, namely relaxed bandwidth requirements on the optical modulators and detectors, reduced complexity and optical losses of the beam forming chip, and enhanced dynamic range

Optical beam forming for phased-array antennas

The activities of the Telecommunication Engineering (TE) group span the communications spectrum from copper cables, optical fibres, microwaves, radio and electromagnetic compatibility. Our research concentrates on optical signal processing and networks, mobile communications, microwave techniques and radiation from ICs and PCBs [1]. A considerable (and particularly interesting) part of it is related to optical beam forming for phased array antennas, using optical ring resonators.\ud In this article the theoretical basics and practical challenges of this interesting research topic will be summarized.\u

Photodefinition of channel waveguide in electro-optic polymer

Polymers with optically active nonlinear chromophores have been shown to have a promising future in low cost and high speed electro–optic device applications. However, a main question of concern is the photochemical stability of the chromophores for long term application. The chromophore TCVDPA with a benzene bridge between a tricyanovinyl acceptor and an amino donor has been reported to have high photochemical stability combined with high electro-optic activity. In the current work direct waveguide definition of the host polymer SU-8, a negative photoresist, containing this chromophore by masked UV exposure followed by development, has been demonstrated. This was possible by utilizing the chromophore low absorption window in the UV region that allows crosslinking of the host polymer by exposing to UV light followed by thermal curing

Novel ring resonator-based optical beamformer system and experimental results

A novel squint-free, continuously tunable beamformer mechanism for a phased array antenna system is proposed. It consists of filter-based optical single-sideband suppressed-carrier modulation, a fully integrated optical beam forming network using cascades of optical ring resonators as tunable delay elements, and balanced coherent optical detection. The proposed system brings advantages in optical bandwidth requirement, system complexity, and dynamic range, without introducing the problem of beam squint or limited tuning resolution. Some experimental results are presented in order to demonstrate the feasibility of the proposed concept