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In this paper, we demonstrate the design, fabrication, and performance estimation of an integrated Bragg grating (IBG) filter having stressed Si3N4 periodic layer over silicon waveguide. The influence of stress-optic effect on the optical performance of the proposed IBG filter is experimentally verified. The proposed IBG filter is fabricated with the different number of grating periods and therefore offers different spectral properties. The proposed filters are designed for a set of target specifications; such as center wavelength, bandwidth, and extinction ratio. The optical performances including temperature sensitivity of the filters are numerically estimated in the absence and presence of stress and are compared with fabricated filter characteristics. The study reveals that the filter, which is designed using numerical simulation considering stress effect, shows the similar optical performance to the fabricated IBG filter. It is also found that the increase of the number of grating periods increases the extinction ratio with narrowing of spectral bandwidth. The IBG filter experimentally demonstrates maximum temperature sensitivity and extinction ratio of 90 pm/°C and 26 dB respectively. The proposed IBG filter offers compact footprint and improved characteristics in comparison to the previously reported filters and finds its potential application in sensing and optical communication. Therefore, the presented work highlights the potency of stress-optic effect in enhancing the capabilities of photonic devices. [ABSTRACT FROM AUTHOR]

Integrated photonics has been pursued on a large variety of materials and platforms over more than half a century. In recent decades, silicon has emerged as the preferred optical and substrate material. However, since many optical functionalities cannot be, inherently or conveniently, implemented on silicon-based devices, heterogeneous integration of other materials has been an inevitable constituent of silicon photonics from its inception. This paper reviews recent progress in the heterogeneous integration of dielectrics and compound semiconductors as the core optical material for ultracompact nonlinear integrated photonics, preferably on silicon substrates. Occasionally, important devices on native substrates of the core nonlinear material are also reviewed. The focus is on ultracompact photonic devices and circuits formed on submicron films of lithium niobate (LiNbO3), and the aluminium-gallium-arsenide (AlGaAs) and aluminium-gallium-nitride (AlGaN) families for second-order nonlinear processes, such as second-harmonic generation, and techniques to address phase-matching in them. Integration of second- and third-order nonlinear devices on the same chip appears to be a future trend, thus the related preliminary results are reviewed. A broader introduction to heterogeneously integrated photonics, shortcomings of conventional silicon photonics for application in nonlinear optics, as well as an overview of modeling second-order nonlinear integrated-waveguide devices are also provided for completeness. [ABSTRACT FROM AUTHOR]

This paper reports the experimental and theoretical assessments of the optical characteristics of recently introduced vertically coupled microdisk resonators made by the selective oxidation of AlGaAs multilayer structures. Experimental measurements show that the Q-factors are in the 103–104 range for diameters ranging from 75 to $300~\mu \text{m}$. To establish the origins of this limited performance, a coupled-mode-theory-based model of the single-access-waveguide-coupled resonator system was developed. It includes features which are specific to oxide-based vertically coupled resonators, namely, losses toward the slab waveguide lying under the resonator and a coupling region with an asymmetric and multilayer structure. Setting this simulation tool required the proposal and validation of a general criterion to select an appropriate set of decomposition permittivity profiles to be able to accurately model the characteristics of these more complex couplers using the coupled-mode-theory approach. This theoretical development is generic and can be now deployed to simulate any device which includes multiwaveguide couplers with arbitrary piece-wise-constant profile of the dielectric permittivity. Exploiting this particular development and experimental measurements of the disk sidewall roughness and of the coupling lengths, the calculated and experimental Q-factors are found to be in good agreement and allow establishing that the current performance is limited by the scattering losses and the slab leakage losses for small- and large-diameter devices, respectively. [ABSTRACT FROM AUTHOR]

Silicon waveguides integrated with doped dielectric gain media may allow the design of planar light sources with electronic control. In this paper, the effects of design geometries and nonlinear losses on the gain in crystalline silicon waveguides with erbium-doped regions are investigated. We show that by using multitrench geometries, the power confinement can be increased and higher gain-to-nonlinear-loss ratio achieved. Net gain can be improved as much as 0.38 dB/cm in multitrench waveguides compared to single-trench waveguides. [ABSTRACT FROM PUBLISHER]

In this paper, we use the Wigner function in order to determine the photon number statistics of a heralded single-photon source constructed from a photon-pair source using four-wave mixing in optical fibers. Having this result, we discuss the performance of a quantum key distribution system when this kind of single-photon source is employed. [ABSTRACT FROM AUTHOR]

In this paper, the propagation of optical pulses in photonic crystal waveguides (PCWs) near the edge of the guided band is numerically investigated. In the linear regime, it is shown that group velocity dispersion can significantly limit the maximum bit rate of the optical signal. On the other hand, better performance is obtained using soliton waves. Both bright and dark solitons can significantly increase the maximum bit rate that can be achieved in the nanosecond delay regime. The influence of higher order dispersion and optical loss is numerically investigated. The results indicate that near the band edge soliton propagation in PCWs can be stable, provided that the optical losses are kept low. This could open a path towards implementing compact nonlinear elements and delay lines in integrated form. [ABSTRACT FROM AUTHOR]