1,721,076 research outputs found
Generation of photon pairs in topologically protected guided modes
No full textWe present a theoretical study on the generation of photon pairs via spontaneous four-wave mixing in a waveguide array supporting topologically protected guided modes. Following a statistical approach, we introduce incremental levels of disorder in the waveguide positions and analyze the effects in terms of photon path correlations and generation efficiency. For moderate level of disorder, we show that the generated two-photon state as well as the generation rate is preserved. However, we find that for higher level of disorder quantum correlations are significantly affected, despite the fact that the linear properties of the topological mode are still protected
Grating couplers for guided Bloch surface waves
No full textPhotonic crystal ridge waveguides supporting guided Bloch surface waves (GBSWs) are a valuable and flexible platform for the development of integrated optical devices. However, coupling light into a GBSW from a single -mode optical fiber remains challenging. In this work, we study the main issues preventing the efficient excitation of GBSWs using grating couplers, and we present some solutions to increase the coupling efficiency. Our approaches do not require any additional fabrication step and can lead to a significant improvement compared to previous implementations. Further optimization along the lines illustrated in this work may allow one to achieve even larger coupling efficiency.(c) 2023 Optica Publishing Grou
Scalable and efficient source of entangled frequency bins
No full textWe present a scalable and efficient approach for the generation of frequency-bin encoded qudit states in photonic integrated devices. We exploit a series of coherently pumped resonators, each generating photon pairs in specific frequency bins via spontaneous four-wave mixing. The generated state can be described as a coherent superposition of the states that would describe the pairs generated in each ring separately. As the frequency bin separation is not fixed by the resonator free spectral range, small resonators having large finesse and pair generation rates can be used
Generation of hyper-entangled states in strongly coupled topological defects
No full textWe investigate spontaneous parametric downconversion (SPDC) in a waveguide array supporting two strongly coupled topological guided modes. We show that it is possible to generate photon pairs that are hyper-entangled in energy and path. We study the state robustness against positional disorder of the waveguides, in terms of Schmidt number (SN), fidelity, and density matrix. We show that quantum correlations are in general robust due to the peculiar interplay between structure topology and second-order nonlinear interaction
Resonant and nonresonant integrated third-order parametric down-conversion
No full textThird-order parametric down-conversion describes a class of nonlinear processes in which a pump photon can be down-converted into triplets of photons. It has been identified as a source of nonclassical light, with capabilities beyond those offered by better-established processes such as spontaneous four-wave mixing. Here we discuss the implementation of third-order parameter down-conversion (TOPDC) in integrated photonic systems. We derive equations for the rates of TOPDC in a nonresonant (waveguide) and resonant (microring) platform, such that the scaling with experimental parameters can be plainly seen. We find that generally nonresonant platforms should be pursued for spontaneous TOPDC (SpTOPDC), whereas resonant platforms are more suitable for stimulated TOPDC (StTOPDC). We present a sample calculation for TOPDC rates in sample systems with conservative and accessible parameters. We find that StTOPDC should be observable with the current fabrication technology, and that with some progress in the design of TOPDC platforms, integrated SpTOPDC too could be demonstrated in the near term
Generation of photon pairs by stimulated emission in ring resonators
No full textThird-order parametric downconversion (TOPDC) describes a class of nonlinear interactions in which a pump photon is converted into a photon triplet. This process can occur spontaneously or it can be stimulated by seeding fields. Here we show that stimulated TOPDC (StTOPDC) can be exploited for the generation of quantum correlated photon pairs. We model StTOPDC in a microring resonator, predicting observable pair generation rates in a microring engineered for third-harmonic generation, and we examine the peculiar features of this approach when compared with second-order spontaneous parametric downconversion and spontaneous four-wave mixing. We conclude that if the experimental difficulties associated with implementing StTOPDC can be overcome, it may soon be possible to demonstrate this process in resonant integrated devices
Bloch-surface-wave photonic crystal nanobeam cavity
No full textWe theoretically demonstrate a nanobeam cavity based on a photonic crystal ridge that supports localized Bloch surface waves (BSWs) propagating at the truncation interface of a periodic multilayer. Combining the appealing characteristics of a nanobeam cavity (such as flexible geometry, small footprint size, and an etching-free fabrication with the leading lithographic technologies) with the versatility of BSW (whose dispersion relation is finely tunable as compared to other surface waves), this structure may prove to be a customizable visible-to-IR platform, well suited for a number of applications ranging from optical sensing to the control of single-photon emission from embedded nanoemitters such as quantum dots or color centers
Bloch surface wave ring resonator based on porous silicon
No full textIn this work, we experimentally demonstrate confined modes in a Bloch surface wave (BSW) ring resonator. We fabricate and characterize a ring resonator with a radius R = 105 μm on a truncated periodic porous silicon multilayer. We show resonant modes around 1.5 μm with quality factors exceeding 103. These results suggest that this platform is promising to develop integrated optical resonators based on BSWs
Maximum-exponent scaling behavior of optical second-harmonic generation in finite multilayer photonic crystals
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