Papers by Alejandro Martinez
2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII), 2013
ABSTRACT We report for the first time on a fluid sensor platform applying simultaneously confined... more ABSTRACT We report for the first time on a fluid sensor platform applying simultaneously confined electromagnetic and acoustic waves. Confinement is realized in a so-called phoxonic crystal, a specific version of a metamaterial. Metamaterials are engineered to achieve desired effects by incorporating structural elements of (sub-)wavelength sizes. The sensor platform is a solid plate featuring an array of holes arranged in a square lattice. A defect introduces local resonances and the resonance frequency has been found to depend on refractive index or permittivity and mass attached to the defect.
2008 5th IEEE International Conference on Group IV Photonics, 2008
We report the fabrication and characterization of both symmetric and asymmetric Mach-Zehnder inte... more We report the fabrication and characterization of both symmetric and asymmetric Mach-Zehnder interferometers (MZIs) with ring resonators (RRs) coupled to both MZI arms using silicon nanocrystals horizontal slot waveguides. Observed transmission dips are due to both MZI destructive interference and resonances of the coupled RRs. Since the slot is filled with a nonlinear material (silicon nanocrystals) the measured structures could
2009 IEEE/LEOS Winter Topicals Meeting Series, 2009
We report the simulation, fabrication and characterization of a new architecture of a 90deg phase... more We report the simulation, fabrication and characterization of a new architecture of a 90deg phase shifter of QAM-QPSK photonic vectorial modulators and demodulators based on ring resonators. The structure was fabricated with SOI technology and the ring resonator parameters were calculated and optimized for WDM specifications using a mathematic simulator. Futhermore this circuit was characterized by means of its optical
2005 International Topical Meeting on Microwave Photonics, 2005
AIP Advances, 2014
ABSTRACT We report on the optomechanical properties of a breathing mechanical mode oscillating at... more ABSTRACT We report on the optomechanical properties of a breathing mechanical mode oscillating at 5.5 GHz in a 1D corrugated Si nanobeam. This mode has an experimental single-particle optomechanical coupling rate of |g o, OM | = 1.8 MHz (|g o, OM |/2π = 0.3 MHz) and shows strong dynamical back-action effects at room temperature. The geometrical flexibility of the unit-cell would lend itself to further engineering of the cavity region to localize the mode within the full phononic band-gap present at 4 GHz while keeping high g o, OM values. This would lead to longer lifetimes at cryogenic temperatures, due to the suppression of acoustic leakage.
2006 IEEE MTT-S International Microwave Symposium Digest, 2006
A radio-over-fiber architecture for feeding WiFi (IEEE802.11a) or WiMAX (IEEE802.16) access nodes... more A radio-over-fiber architecture for feeding WiFi (IEEE802.11a) or WiMAX (IEEE802.16) access nodes is demonstrated. The technique is able to feed the nodes with the same signals simultaneously in the 5.5 and 41 GHz bands. This centralized architecture allows for easier channel accumulation in occupied-hot-spots environments and has no need for complex hand-over processes while the user is moving within the network, as all channels are available at all access nodes at any time
International Topical Meeting on Microwave Photonics MWP-02, 2002
ABSTRACT The transmission of a 155 Mbit/s 40 GHz modulated carrier through a 2.2 km SSMF link is ... more ABSTRACT The transmission of a 155 Mbit/s 40 GHz modulated carrier through a 2.2 km SSMF link is demonstrated using a technique for dispersion-tolerant optical harmonic generation of modulated microwave/millimeter-wave signals with simultaneous LO remoting, which employs a single laser and a single dual-drive Mach-Zehnder modulator.
2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278), 2002
A novel 2 N beams heterodyne optical beamforming architecture based on NxN optical butler matrice... more A novel 2 N beams heterodyne optical beamforming architecture based on NxN optical butler matrices. Daniel Madrid, Borja Vidal, Alejandro Martinez, Valentin Polo, Juan Luis Corral, Javier Marti IEEE MTT-S International Microwave Symposium Digest 3, 1945-1948, 2002. ...
IEEE MTT-S International Microwave Symposium Digest, 2005., 2005
In this paper, a Tx/Rx quadrature photonic vector modulator architecture is proposed. In transmit... more In this paper, a Tx/Rx quadrature photonic vector modulator architecture is proposed. In transmitting mode, an electrical QAM-modulated signal at microwave/millimeter-wave (mm-wave) frequencies is generated from the base-band in-phase (I) and quadrature (Q) components using two optical sources, one electrical tone and a dispersive media. Also in receiving mode, the original I and Q components are directly recovered from the
2005 International Topical Meeting on Microwave Photonics, 2005
The simultaneous wireline (600 MHz) and wireless (5.5 GHz) downstream transmission of Data Over C... more The simultaneous wireline (600 MHz) and wireless (5.5 GHz) downstream transmission of Data Over Cable Service Interface Specification (DOCSIS) signals through a 12 km optical fiber link is demonstrated. The DOCSIS signal wireless replica is generated employing an optical harmonic up-conversion technique. Successful full-duplex operation was achieved for both access types, including indoor wireless transmission.
IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313), 2002
A novel beamforming architecture based on optical Butler matrices is proposed and experimentally ... more A novel beamforming architecture based on optical Butler matrices is proposed and experimentally evaluated. The proposed architecture offers simultaneous multibeam generation capability and allows to double the number of beams (2N). Phase measurements of the proposed architecture at 40 GHz are presented showing
Optical Fiber Communication Conference and National Fiber Optic Engineers Conference, 2009
The use of silicon photonics as technological platform to implement ultra-high speed all-optical ... more The use of silicon photonics as technological platform to implement ultra-high speed all-optical switching devices for optical label processing and swapping in packet switches such as the Mach-Zehnder Interferometer is addressed.
8th IEEE International Conference on Group IV Photonics, 2011
We present the characterization of the nonlinear-dynamics of a CMOS-compatible horizontal-slot wa... more We present the characterization of the nonlinear-dynamics of a CMOS-compatible horizontal-slot waveguide with silicon-nanocrystals, where the temporal behavior of the phase and amplitude of the nonlinear response are simultaneously monitored. These results are complemented with four-wave-mixing measurements. I. INTRODUCTION
2006 European Conference on Optical Communications, 2006
ABSTRACT A highly-scalable photonic quadrature amplitude modulation architecture based on vector ... more ABSTRACT A highly-scalable photonic quadrature amplitude modulation architecture based on vector summation and dispersive delay lines, which can generate QAM signals directly from parallel digital words is proposed and experimentally demonstrated by generating a 3 Gbps¿8QAM¿39 GHz modulated carrier.
Physical Review B, 2014
ABSTRACT The interaction between phonons and photons is investigated theoretically in a phoxonic ... more ABSTRACT The interaction between phonons and photons is investigated theoretically in a phoxonic cavity inside a corrugated nanobeam waveguide presenting band gaps for both electromagnetic and elastic waves. The structure is made by drilling periodic holes on a silicon nanobeam with lateral periodic stubs and the tapered cavity is constructed by changing gradually the geometrical parameters of both the holes and stubs. We show that this kind of cavity displays localized phonons and photons inside the gaps, which can enhance their interaction and also promotes the presence of many optical confined modes with high quality factor. Using the finite-element method, we demonstrate that with appropriate design of the tapering construction, one can control the cavity modes frequency without altering significantly the quality factor of the photonic modes. By changing the tapering rates over the lattice constants, we establish the possibility of shifting the phononic cavity modes frequency to place them inside the desired gap, which enhances their confinement and increases the mechanical quality factor while keeping the strength of the optomechanic coupling high. In our calculations, we take account of both mechanisms that contribute to the acousto-optic interaction, namely photoelastic and interface motion effects. We show that in our case, these two effects can contribute additively to give high coupling strength between phononic and photonic cavity modes. The calculations of the coupling coefficient which gives the phonon-photon coupling strength give values as high as 2 MHz while photonic cavity modes display quality factor of 10${}^{5}$ and even values up to 3.4 MHz but with smaller photonic quality factors.
We consider the problem of designing waveguides in nanostructures presenting simultaneously a pho... more We consider the problem of designing waveguides in nanostructures presenting simultaneously a phononic and a photonic band gap. We specifically opt for designs in perforated silicon membranes that can be conveniently obtained using silicon-on-insulator technology. Geometrical parameters for simultaneous photonic and phononic band gaps are first chosen, based on the finite element analysis of a perfect phoxonic crystal of circular holes. A plain core waveguide is then defined, and simultaneous slow light and elastic guided modes are identified. Joint confinement of light and elastic waves with group velocities reduced by a factor of approximately 30 is predicted.
Metamaterials V, 2010
We prove theoretically that it is possible to build embedded reflectionless squeezers/expanders u... more We prove theoretically that it is possible to build embedded reflectionless squeezers/expanders using transformation optics. We illustrate the potential of this finding by proposing an application in which the squeezer is a key element: an ultra-short perfect coupler for high-index nanophotonic waveguides.
Photonic Crystal Materials and Devices X, 2012
ABSTRACT Sub-micron waveguides and cavities have been shown to produce the confinement of elastic... more ABSTRACT Sub-micron waveguides and cavities have been shown to produce the confinement of elastic and optical waves in the same devices in order to benefit from their interaction. It has been shown that square and honeycomb lattices are the most suitable to produce simultaneous photonic and phononic band gaps on suspended silicon slabs. The introduction of line defects on such "phoxonic" (or optomechanical) crystals should lead to an enhanced interaction between confined light and sound. In this work we report on the experimental measurements of light guiding through waveguides created in these kinds of two-dimensional photonic crystal membranes. The dimensions of the fabricated structures are chosen to provide a "phoxonic" bandgap with a photonic gap around 1550 nm. For both kinds of lattice, we observe a high-transmission band when introducing a linear defect, although it is observed for TM polarization in the honeycomb lattice and for TE in the square. Using the plane-wave expansion and the finite element methods we demonstrate that the guided modes are below the light line and, therefore, without additional losses beside fabrication imperfections. Our results lead us to conclude that waveguides implemented in honeycomb and square lattice "phoxonic" crystals are a very suitable platform to observe an enhanced interaction between propagating photons and phonons.
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Papers by Alejandro Martinez