Joan Manel Ramírez

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An integrated erbium-based light emitting diode has been realized in a waveguide configuration allowing 1.54 μm light signal routing in silicon photonic circuits. This injection device is based on an asymmetric horizontal slot waveguide where the active slot material is Er(3+) in SiO2 or Er(3+) in Si-rich oxide. The active horizontal slot waveguide allows(More)
Blue-green to near-IR switching electroluminescence (EL) has been achieved in a metal-oxide-semiconductor light emitting device, where the dielectric has been replaced by a Si-rich silicon oxide/nitride bilayer structure. To form Si nanostructures, the layers were implanted with Si ions at high energy, resulting in a Si excess of 19%, and subsequently(More)
The potential for application of silicon nitride-based light sources to general lighting is reported. The mechanism of current injection and transport in silicon nitride layers and silicon oxide tunnel layers is determined by electro-optical characterization of both bi- and tri-layers. It is shown that red luminescence is due to bipolar injection by direct(More)
Context. We have re-analyzed the X-ray spectra of the gravitational lensed high-redshift BAL QSO APM 08279+5255, observed with the XMM-Newton and Chandra observatories. Previous studies (Hasinger et al. 2002; Chartas et al. 2002) detected unusual, highly-ionized iron absorption features, but differed in their interpretation of these features, regarding the(More)
We demonstrate low-loss Ge-rich Si<sub>0.2</sub>Ge<sub>0.8</sub> waveguides on Si<sub>1-x</sub>Ge<sub>x</sub> (x from 0 to 0.79) graded substrates operating in the mid-infrared wavelength range at λ=4.6  μm. Propagation losses as low as (1.5±0.5)dB/cm and (2±0.5)dB/cm were measured for the quasi-TE and quasi-TM polarizations, respectively. A total coupling(More)
This work explores the use of Ge-rich graded-index Si<sub>1-</sub>xGex rib waveguides as building blocks to develop integrated nonlinear optical devices for broadband operation in the mid-IR. The vertical Ge gradient concentration in the waveguide core renders unique properties to the guided optical mode, providing tight mode confinement over a broadband(More)
This work reports the dynamical thermal behavior of lasing microspheres placed on a dielectric substrate while they are homogeneously heated-up by the top-pump laser used to excite the active medium. The lasing modes are collected in the far-field and their temporal spectral traces show characteristic lifetimes of about 2 ms. The latter values scale with(More)
In this Letter, we present the design, simulation (2D and 3D), fabrication, and experimental characterization of compact and fully etched focusing gratings for a horizontal slot waveguide based on a silicon nitride layer sandwiched between amorphous silicon and a silicon-on-insulator. The measured coupling losses are about 4 dB with a 3 dB bandwidth of 38(More)