ABSTRACT
We have used focused ion beam irradiation to progressively cause defects in annealed molybdenum silicide thin films. Without the treatment, the films are superconducting with critical temperature of about 1 K. We observe that both resistivity and critical temperature increase as the ion dose is increased. For resistivity, the increase is almost linear, whereas critical temperature changes abruptly at the smallest doses and then remains almost constant at 4 K. We believe that our results originate from amorphization of the polycrystalline molybdenum silicide films.
ABSTRACT
The growing interest for Fano resonators during the past decade is due to the narrow line shape observable in their optical spectra. The drastic phase shift occurring at the resonance yields a steep drop from a high to low amplitude. Fano resonances can be obtained by a combination of nanostructures. Such a system is extremely sensitive in terms of both geometrical parameters and environmental conditions. Here we study a complex arrangement of photonic crystal cavities and slot waveguides on a silicon chip. Our structure, composed of several cavities in parallel, has a particular response superimposing a shallow photonic bandgap and a resonance with a Fano line shape. It provides a low noise and a clear asymmetric resonance. We demonstrate it experimentally and show the potential of such a device for sensing. A sensitivity of 92 nm/RIU is measured.
ABSTRACT
We introduce a novel concept for an optical waveguide called a strip-loaded slot waveguide. It allows an extraordinary confinement of the field in a waveguide with an extremely tiny (vertical) cross section. Unlike conventional slot waveguides, the proposed configuration has potential for very low propagation losses. Its operation is demonstrated at telecommunication wavelengths and, in addition, it is fabricated by means of mass production compatible techniques: atomic layer deposition and nanoimprint replication. The possibility to fabricate the proposed structure with such low-cost techniques opens a new path for a variety of nanophotonics applications.
ABSTRACT
We present the theoretical study of a coupled cavity system yielding a Fano response on a fully on-chip silicon platform hybridized with an electro-optic polymer. This novel Fano system is based on a slot waveguide Bragg grating geometry, enabling a huge enhancement of the electro-optic properties due to slow light effects at the resonance. The modulator shows a high resonance tunability of 1.75 nm/V and a low switching power of 0.63 V. Such a versatile system shows the promise for various nonlinear and active devices only by using suitable cover material.
ABSTRACT
We investigate the feasibility of developing a one dimensional photonic crystal cavity on a TiO2 platform operating in the visible. The atomic layer deposition technique is used to finely adjust the parameters of the structure. We present the experimental demonstration of a nanobeam cavity with a quadratically tapered row of holes, in which a parabolic window is opened in order to facilitate the infiltration of gas, liquid, nonlinear material, or quantum emitters. The structure exhibits a photonic band gap between λ = 635 nm and λ = 690 nm and several resonances within the photonic band gap.
ABSTRACT
We investigate an in-line band pass filter, working both for TE and TM polarizations, based on a cross-slot waveguide merged with a Bragg grating and an optical cavity. Different types of cavities (C2- and C4-symmetric) are presented in order to optimize the filtering and make the device dependent or independent on the polarization. We show a strong light confinement in an extremely small volume, which offers an advantage for further sensing applications. Moreover, we show how the inclusion of a silicon nanowire in the cavity helps the guiding and increases the amplitude of the resonance. In this study we make use of both the Fourier Modal Method and the Finite Difference Time Domain method to perform the numerical simulations.
