We discuss the development of label-free, real-time and low-cost biosensors based on planar photonic bandgap (PBG)
structures. We propose a novel power-based readout technique where the PBG shift is indirectly tracked by simply
exciting the photonic sensing structure with a filtered broadband source and measuring the output power with a power
meter. Therefore, the use of either tunable lasers or spectrum analyzers to continuously acquire the transmission
spectrum of the structure, as done for other spectrum-based sensing techniques, is avoided. We have used this technique
both for the sensing of refractive index variations as well as for the label-free detection of antibodies, showing high
sensitivities and low detection limits, which demonstrate its high potential for the development of label-free, real-time
and low-cost photonic biosensors. Furthermore, the use of broadband sources and detectors for the readout of the
photonic sensors will also allow their integration, thus achieving a completely electrically accessed photonic biosensing
We present an extensive study of an Er doped Silicon Rich Silicon Oxide (SRSO) based material used for the realization of
optical waveguide amplifiers in which Si-nanoclusters (Si-ncls) are formed by thermal annealing. In particular we focus our
attention on the confined carrier absorption (CCA) mechanism within the Si-ncls and on the fraction of Er ions coupled to
them. Experimental data are used for accurate modeling of Si-ncls sensitized EDWAs (Erbium Doped Waveguide
Amplifiers) longitudinally pumped by visible broad area lasers.
Although the material requires further optimization to be effectively deployed, accurate numerical simulations of Si-ncls
sensitized EDWAs, based on this material and longitudinally pumped by visible broad area lasers at 660 nm, point out
significant benefits provided by the nanoclusters sensitization. Our model, based on the Finite Element Method, performs the
modal analysis of the guiding structure, and then allows to study the propagation of pump and signal electric fields along the
waveguide amplifier; the rate equations for the coupled Er/Si-ncls system account for their coupling ratio.
Numerical results, based on measured material parameters, point out that resonant pumping at 660 nm provides significant
benefits in terms of gain enhancement, with respect to standard EDWAs, even at low Er/Si-ncls coupling ratio. This feature
suggests that a careful design can lead to the realization of compact integrated amplifiers and lasers, compatible with CMOS
We present a multimode longitudinal pumping scheme for integrated rare-earth doped waveguide amplifiers which
allows an efficient use of low cost multimode pump sources. The scheme is based on evanescent pump light coupling
from a multimode low loss waveguide, which is gradually transferred to a single mode Si-nc sensitized Er<sup>3+</sup> doped active
core. Population inversion is ensured along the whole amplifier length, thus overcoming the main limitation of
conventional single mode pump butt-coupling in case of strongly absorbing active materials. Great flexibility in
controlling the pump power intensity values within the active core is also provided.
We propose this pumping scheme at 477 nm for Si-nanocluster sensitized Erbium doped waveguide amplifiers, in
which top pumping by LED arrays is limited by the low pump intensity values achievable within the active region.
The coupling between the multimode waveguide and the active core has been numerically studied for slab waveguide
structures using a 2D split-step finite element method.
Numerical simulation results, based on propagation and population-rate equations for the coupled Er<sup>3+</sup>/Si-nanoclusters
system, show that high pump intensities are indeed achieved in the active core, 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<sup>3+</sup>
concentrations is necessary.