Real-time observation of antigen-antibody association using a low-cost biosensing system based on photonic bandgap structures.

In this letter, we present experimental results of antibody detection using a biosensor based on photonic bandgap structures, which are interrogated using a power-based readout technique. This interrogation method allows a real-time monitoring of the association process between the antigen probes and the target antibodies, allowing the instantaneous observation of any interaction event between molecules. because etunable lasers and optical spectrum analyzers are avoided for the readout, a drastic reduction of the final cost of the platform is obtained. Furthermore, the performance of the biosensing system is significantly enhanced due to the large number of data values obtained per second.

Real-time and low-cost sensing technique based on photonic bandgap structures.

A technique for the development of low-cost and high-sensitivity photonic biosensing devices is proposed and experimentally demonstrated. In this technique, a photonic bandgap structure is used as transducer, but its readout is performed by simply using a broadband source, an optical filter, and a power meter, without the need of obtaining the transmission spectrum of the structure; thus, a really low-cost system and real-time results are achieved. Experimental results show that it is possible to detect very low refractive index variations, achieving a detection limit below 2×10(-6) refractive index units using this low-cost measuring technique.

Ion-exchanged Er3+/Yb3+ co-doped waveguide amplifiers longitudinally pumped by broad area lasers.

A multimode pumping scheme for Er(3+)/Yb(3+) co-doped waveguide amplifiers based on broad area lasers at around 980 nm is presented. The proposed amplifier is fabricated by ion-exchange (IE) technique on silicate and phosphate glasses. The highly efficient energy transfer from Yb(3+) to Er(3+) ions, combined with the use of low cost and high power broad area laser, allows the realization of high performance and cost-effective integrated amplifiers. The structure has been designed and numerically studied using a 3D finite element modelling tool, and over 3 dB/cm small signal gain has been predicted for an optimized amplifier. Preliminary characterization of an amplifier structure provides a first experimental evidence of the novel multimode longitudinal pumping.

Single-strand DNA detection using a planar photonic-crystal-waveguide-based sensor.

We report an experimental demonstration of single-strand DNA (ssDNA) detection at room temperature using a photonic-crystal-waveguide-based optical sensor. The sensor surface was previously biofunctionalized with ssDNA probes to be used as specific target receptors. Our experiments showed that it is possible to detect these hybridization events using planar photonic-crystal structures, reaching an estimated detection limit as low as 19.8 nM for the detection of the complementary DNA strand.

Study of an efficient longitudinal multimode pumping scheme for Si-nc sensitized EDWAs.

We present an efficient multimode longitudinal pumping scheme which overcomes the main limitations of single-mode longitudinal pumping as well as top pumping in Si-nanoclusters sensitized Erbium-doped waveguide amplifiers. The proposed configuration is based on evanescent pump light coupling from a multimode waveguide to a Si-nanoclusters sensitized Er(3+)-doped active core. Theoretical predictions, based on propagation and population-rate equations for the coupled Er(3+)/Sinanoclusters system, point out that the proposed pumping scheme can provide high pump intensity within the active core, also ensuring good uniformity of the population inversion along the waveguide amplifier. Although longitudinal multimode pumping by high power LEDs in the visible can potentially lead to low cost integrated amplifiers, further material optimization is required. In particular, we show that when dealing with high pump intensities, confined carrier absorption seriously affects the amplifier performance, and an optimization of both Si-nc and Er(3+) concentrations is necessary.