130,554 research outputs found
Design, fabrication, and characterization of deep-etched waveguide gratings
No full textOne-dimensional (1-D) deep-etched gratings on a specially grown AlGaAs wafer were designed and fabricated. The gratings were fabricated using state-of-the-art electron beam lithography and high-aspect-ratio reactive ion etching (RIE) in order to achieve the required narrow deep air slots with good accuracy and reproducibility. Since remarkable etch depths (up to 1.5 /spl mu/m), which completely cut through the waveguide core layer, have been attained, gratings composed of only five periods (and, thus, shorter than 6 /spl mu/m) have a bandgap larger than 100 nm. A defect was introduced by increasing the width of the central semiconductor tooth to create microcavities that exhibit a narrow transmission peak (less than 7 nm) around the wavelength of 1530 nm. The transmission spectra between 1460 and 1580 nm have been systematically measured, and the losses have been estimated for a set of gratings, both with and without a defect, for different periods and air slot dimensions. Numerical results obtained via a bidirectional beam propagation code allowed the evaluation of transmissivity, reflectivity, and diffraction losses. By comparing experimental results with the authors' numerical findings, a clear picture of the role of the grating's geometric parameters in determining its spectral features and diffractive losses is illustrated
Autoresonant harmonic generation in nonuniform crystals
No full textAn experiment of second harmonic generation in a nonuniform crystal is presented, and interpreted in terms of an autoresonant wave-mixing theory. A good agreement is found between numerical simulations, analytical solutions and experimental data
All optical switching in ultrashort photonic crystal couplers
No full textWe demonstrate the possibility of performing all optical switching in ultrashort photonic crystal couplers. The proposed structure exploits the AlGaAs Kerr nonlinearity to obtain an ultracompact power-controlled switch
Contactless Electromagnetic Interrogation of Quartz Crystal Resonators with Optimized Planar Spiral Coils
No full textFrequency addressing of nano-objects by electrical tuning of optical antennas
No full textWe first analyze the equivalent circuit parameters of linear wire optical nano-antennas in uniaxial anisotropic
media. We then exploit the electro-optic response of a bipolar nematic liquid crystal to demonstrate tuning of
an optical antenna using a low frequency external electric field as the control mechanism
Mid-Infrared Soliton and Raman Frequency Comb Generation in Silicon Microrings
No full textWe numerically study the mechanisms of frequency comb generation in the mid-
infrared spectral region from cw pumped silicon microring resonators. Coherent soliton
comb generation may be obtained even for a pump with zero linear cavity detuning, through
suitable control of the effective lifetime of free-carriers from multiphoton absorption, which
introduces a nonlinear cavity detuning via free-carrier dispersion. Conditions for optimal
octave spanning Raman comb generation are also described
Nonlinear bidirectional beam propagation method based on scattering operators for periodic microstructured waveguides
No full textBeginning with a recently proposed bidirectional beam propagation method based on scattering operators, we develop an accurate and efficient method for the analysis of periodic microstructured waveguides in a nonlinear regime. This novel numerical tool allows us to describe the role played by losses that are due to diffraction and the effects of the finite size of the beams in nonlinear optical devices with strong lateral confinement of the optical intensity. We demonstrate the effectiveness and the efficiency of our method with numerical examples
Role of the finite size of the pump beam for second harmonic generation in photonic crystals
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