Complex systems are a proving ground for fundamental interactions between components and their collective emergent phenomena. Through intricate design, integrated photonics offers intriguing nonlinear interactions that create new patterns of light. In particular, the canonical Kerr-nonlinear resonator becomes unstable with a sufficiently intense traveling-wave excitation, yielding instead a Turing pattern composed of a few interfering waves. These resonators also support the localized soliton pulse as a separate nonlinear stationary state. Kerr solitons are remarkably versatile for applications, but they cannot emerge from constant excitation. Here, we explore an edge-less photonic-crystal resonator (PhCR) that enables spontaneous formation of a soliton pulse in place of the Turing pattern. We design a PhCR in the regime of single-azimuthal-mode engineering to re-balance Kerr-nonlinear frequency shifts in favor of the soliton state, commensurate with how group-velocity dispersion balances nonlinearity. Our experiments establish PhCR solitons as mode-locked pulses by way of ultraprecise optical-frequency measurements, and we characterize their fundamental properties. Our work shows that sub-wavelength nanophotonic design expands the palette for nonlinear engineering of light.
The dynamics of two active nonlinear resonators coupled to a linear resonator is studied theoretically. Possible stationary states and its dynamical stability are considered in detail. The spontaneous symmetry breaking is found and it is shown that this bifurcation results in the formation of asymmetric states. It is also found that the oscillating states can occur in the system in a certain range of parameters. The results of the analysis of the stationary states are confirmed by direct numerical simulations. The possibility of the switching between different states is also demonstrated by nu…
We report on the proposal and experimental realization of a spoof surface plasmon Fabry-Perot (FP) open resonator in a surface-wave photonic crystal. This surface-wave FP open resonator is formed by introducing a finite line defect in a surface-wave photonic crystal. The resonance frequencies of the surface-wave FP open resonator lie exactly within the forbidden band gap of the surface-wave photonic crystal and the FP open resonator uses this complete forbidden band gap to concentrate surface waves within a subwavelength cavity. Due to the complete forbidden band gap of the surface-wave photon…
A topologically protected ring-resonator formed in valley photonic crystals is proposed and fabricated on a silicon slab. The unidirectional transmission and robustness against structure defects of its resonant modes are illustrated. Coupled with topological waveguides, the topological ring is functioned as notch and channel-drop filters. The work opens up a new avenue for developing advanced chip-integrated photonic circuits with attributes of topological photonics.
We designed an on-chip transformative optic system of a metalens-photonic crystal resonator metasystem on a foundry compatible silicon photonic platform. By adjusting the on-chip metalens' focusing length and mode dimension, the insertion loss between the metalens and the photonic crystal resonator and waveguide structures are minimized through mode-matching. The micro-system does not involve any single mode silicon nanowire waveguide, and thus mechanically robust without any oxide claddings. The proposed microsystem is ideal for miniaturized chemical and biosensors operating in air or solutio…
We investigate analytically and numerically the formation of temporal localized structures in all photonic crystal fiber resonator. These dissipative structures consist of isolated or randomly distributed peaks in an uniform background of the intensity profile. The number of peaks and their temporal distribution are determined solely by initial conditions. They exhibit multistability behavior in a finite range of parameters. A weakly nonlinear analysis is performed in the neighborhood of the first threshold associated with the modulational instability. We consider the regime where the instabil…
Photonic molecules can be used to realize complex optical energy states and modes, analogous to those found in molecules, with properties useful for applications like spectral engineering and quantum optics. It is desirable to implement photonic molecules using high quality factor photonic integrated ring resonators due to their narrow atom-like spectral resonance, tunability, and the ability to scale the number of resonators on a photonic circuit. However, to take full advantage of molecule spectral complexity and tuning degree of freedom, resonator structures should have full symmetry in ter…
We describe a method that enables free-standing whispering-gallery-mode microresonators, and report spectral tuning of photonic molecules formed by coupled free and on-chip resonators with different geometries and materials. We study direct coupling via evanescent fields of free silica microtoroids and microspheres with on-chip polymer coated silica microtoroids. We demonstrate thermal tuning of resonance modes to achieve maximal spectral overlap, mode splitting induced by direct coupling, and the effects of distance between the resonators on the splitting spectra.
Fast and highly accurate method based on the Muller contour integral equations and a trigonometric-trigonometric Galerkin discretization technique is presented for spectral design and fine-tuning of clusters of whispering-gallery (WG) mode microdisk resonators and photonic crystal (PC) defect cavities. It is shown that degeneracy and near-degeneracy of natural modes as well as modes optical confinement in coupled resonator clusters are significantly influenced by the symmetry of the structure. Photonic molecules with greatly enhanced quality factors are designed by exploiting the symmetry of t…
Canonical Four-Wave-Mixing occurs in a resonator with only the required number of modes, thereby inhibiting competing parametric processes. The properties of the recently introduced photonic crystal parametric oscillator, Marty et al. Nat. Photonics, 15, 53 (2021), are discussed extensively. We compare the bichromatic design with other geometries of photonic crystal resonators. Based on a statistical study over more than 100 resonators and 10 parametric oscillators, robustness against fabrication tolerances is assessed, performances are evaluated in terms of average values and their dispersion…
We study photonic crystal fibers and ring resonators with topological features induced by Aubry- Andre-Harper modulations of the cladding. We find non trivial gaps and edge states at the interface between regions with different Chern numbers. We calculate the field profile and eigenvalue dispersion by an exact recursive approach. Compared with conventional circular resonators and fibers, the proposed structure features topological protection and hence robustness against symmetry-preserving local perturbations that do not close the gap. These topological photonic crystal fibers sustain strong f…
Optical bistability provides a simple way to control light with light. We demonstrate low-power thermo-optical bistability caused by the Joule heating mechanism in a one-dimensional photonic crystal (PC) nanobeam resonator with a moderate quality factor (Q ~ 8900) with an embedded reverse-biased pn-junction. We show that the photocurrent induced by the linear absorption in this compact resonator considerably reduces the threshold optical power. The proposed approach substantially relaxes the requirements on the input optical power for achieving optical bistability and provides a reliable way t…
Tight confinement of light in photonic cavities provides an efficient template for the realization of high optical intensity with strong field gradients. Here we present such a nanoscale resonator device based on a one-dimensional photonic crystal slot cavity. Our design allows for realizing highly localized optical modes with theoretically predicted Q factors in excess of 106. The design is demonstrated experimentally both in a high-contrast refractive index system (silicon), as well as in medium refractive index contrast devices made from aluminum nitride. We achieve extinction ratio of 21dB…
We outline the design for a photonic crystal resonator made in a hybrid Silicon/Lithium Niobate material system. Using the index contrast between silicon and lithium niobate, it is possible to guide and confine photonic resonances in a thin film of silicon bonded on top of lithium niobate. Quality factors greater than $10^6$ at optical wavelength scale mode volumes are achievable. We show that patterning electrodes on such a system can yield an electro-optic coupling rate of 0.6 GHz/V (4 pm/V).
In this paper, a new design of optical delay line based on coupled ring resonators in photonic crystals is proposed and analyzed by means of numerical simulation in CST Microwave Studio. The performance of the proposed photonic crystal ring resonator (PhCRR) based coupled resonant optical waveguide (CROW) is compared to: point-defect cavity based coupled cavity waveguides (CCW) in photonic crystal. microring resonator (MRR) based CROW. The suggested design addresses compactness issues of the MRR CROW while offering normalized delay values better than CCW and comparable to MRR CROW. The PhCRR C…
Unidirectional photonic edge states arise at the interface between two topologically-distinct photonic crystals. Here, we demonstrate a micron-scale GaAs photonic ring resonator, created using a spin Hall-type topological photonic crystal waveguide. Embedded InGaAs quantum dots are used to probe the mode structure of the device. We map the spatial profile of the resonator modes, and demonstrate control of the mode confinement through tuning of the photonic crystal lattice parameters. The intrinsic chirality of the edge states makes them of interest for applications in integrated quantum photon…
We report on a novel optofluidic system consisting of a silica-based 1D photonic crystal, integrated planar waveguides and electrically insulated fluidic channels. An array of pillars in a microfluidic channel designed for electrochromatography is used as a resonator for on-column label-free refractive index detection. The resonator was fabricated in a silicon oxynitride platform, to support electroosmotic flow, and operated at 1.55 microns. Different aqueous solutions of ethanol with refractive indices ranging from n = 1.3330 to 1.3616 were pumped into the column/resonator and the transmissio…
We present the design and fabrication of photonic crystal structures exhibiting electromagnetic bands that are flattened in all crystal directions, i.e., whose frequency variation with wavevector is minimized. Such bands can be used to reduce group velocity of light propagating in arbitrary crystal direction, which is of importance for construction of miniaturized tunable optical delay components, low-threshold photonic crystal lasers, and study of nonlinear optics phenomena.
Resistance thermometry provides a time-tested method for taking temperature measurements. However, fundamental limits to resistance-based approaches has produced considerable interest in developing photonic temperature sensors to leverage advances in frequency metrology and to achieve greater mechanical and environmental stability. Here we show that silicon-based optical ring resonator devices can resolve temperature differences of 1 mK using the traditional wavelength scanning methodology. An even lower noise floor of 80 microkelvin for measuring temperature difference is achieved in the side…
We demonstrate the generation of quantum-correlated photon pairs from a Si photonic-crystal coupled-resonator optical waveguide. A slow-light supermode realized by the collective resonance of high-Q and small-mode-volume photonic-crystal cavities successfully enhanced the efficiency of the spontaneous four-wave mixing process. The generation rate of photon pairs was improved by two orders of magnitude compared with that of a photonic-crystal line defect waveguide without a slow-light effect.
We report a circuit cavity optomechanical system in which a nanomechanical resonator is adiabatically embedded inside an optical ring resonator with ultralow transition loss. The nanomechanical device forms part of the top layer of a horizontal silicon slot ring resonator, which enables dispersive coupling to the dielectric substrate via a tapered nanogap. Our measurements show nearly uncompromised optical quality factors (Q) after the release of the mechanical beam.
We demonstrate waveguide-coupled titanium dioxide (TiO2) racetrack resonators with loaded quality factors of 2x10^4 for the visible wavelengths. The structures were fabricated in sputtered TiO2 thin films on oxidized silicon substrates using standard top-down nanofabrication techniques, and passively probed in transmission measurements using a tunable red laser. Devices based on this material could serve as integrated optical elements as well as passive platforms for coupling to visible quantum emitters.
We present a photonic reservoir computing, relying on a non-linear phase-to-amplitude mapping process, able to classify in real-time multi-Gbaud time traces subject to transmission effects. This approach delivers an all-optical, low-power neuromorphic dispersion compensator.
Coupled split-ring-resonator metamaterials have previously been shown to exhibit large coupling effects, which are a prerequisite for obtaining large effective optical activity. By a suitable lateral arrangement of these building blocks, we completely eliminate linear birefringence and obtain pure optical activity and connected circular optical dichroism. Experiments at around 100-THz frequency and corresponding modeling are in good agreement. Rotation angles of about 30 degrees for 205nm sample thickness are derived.
Current quantum cascade lasers based upon conduction band electron transitions are predominantly TM (electrical field normal to the epitaxial direction) polarized. Here we present a study of localized defect modes, with the requisite TM polarization, in connected square and hexagonal lattice two-dimensional (2D) photonic crystals for application as quantum cascade laser resonators. A simple group-theory based analysis is used to produce an approximate description of the resonant modes supported by defects situated at different high symmetry points within the host photonic lattice. The results …
Highly reproducible manufacturing of organic optical crystals with well-defined geometry and dimension is important to realize industrially relevant all-organic microelectronic and nanophotonic components, and photonic integrated circuits. Here, we demonstrate programmed shape and size alteration of perylene crystal resonators into disk and rectangular geometries using focused-ion beam milling technique. Due to highly reproducible nature of the employed technique, the fabricated smaller sized disk and rectangular crystal resonators displaying shape and size dependent optical modes are suitable…
Photonic systems based on microring resonators have a fundamental constrain given by the strict relationship among free spectral range (FSR), total quality factor (QT) and resonator size, intrinsically making filter spacing, photonic lifetime and footprint interdependent. Here we break this paradigm employing CMOS compatible Silicon-on-Insulator (SOI) photonic molecules based on coupled multiple ring resonators. The resonance wavelengths and their respective linewidths are controlled by the hybridization of the quasi-orthogonal photonic states. We demonstrate photonic molecules with doublet an…
We study the resonant transmission of light in a coupled-resonator optical waveguide interacting with two nearly identical side cavities. We reveal and describe a novel effect of the coupled-resonator-induced reflection (CRIR) characterized by a very high and easily tunable quality factor of the reflection line, for the case of the inter-site coupling between the cavities and the waveguide. This effect differs sharply from the coupled-resonator-induced transparency (CRIT) -- an all-optical analogue of the electromagnetically-induced transparency -- which has recently been studied theoretically…
We analyze the resonant linear and nonlinear transmission through a photonic crystal waveguide side-coupled to a Kerr-nonlinear photonic crystal resonator. Firstly, we extend the standard coupled-mode theory analysis to photonic crystal structures and obtain explicit analytical expressions for the bistability thresholds and transmission coefficients which provide the basis for a detailed understanding of the possibilities associated with these structures. Next, we discuss limitations of standard coupled-mode theory and present an alternative analytical approach based on the effective discrete …
We demonstrate a photonic RF Hilbert transformer for broadband microwave in-phase and quadrature-phase generation based on an integrated frequency optical comb, generated using a nonlinear microring resonator based on a CMOS compatible, high-index contrast, doped-silica glass platform. The high quality and large frequency spacing of the comb enables filters with up to 20 taps, allowing us to demonstrate a quadrature filter with more than a 5-octave (3 dB) bandwidth and an almost uniform phase response.
We demonstrate wideband integrated photonic circuits in sputter-deposited aluminum nitride (AlN) thin films. At both near-infrared and visible wavelengths, we achieve low propagation loss in integrated waveguides and realize high-quality optical resonators. In the telecoms C-band (1520-1580 nm), we obtain the highest optical Q factor of 440,000. Critical coupled devices show extinction ratio above 30 dB. For visible wavelengths (around 770 nm), intrinsic quality factors in excess of 30,000 is demonstrated. Our work illustrates the potential of AlN as a low loss material for wideband optical ap…
We report enhanced optomechanical coupling by embedding a nano-mechanical beam resonator within an optical race-track resonator. Precise control of the mechanical resonator is achieved by clamping the beam between two low-loss photonic crystal waveguide couplers. The low insertion loss and the rigid mechanical support provided by the couplers yield both high mechanical and optical Q-factors for improved signal quality.
We suggest a method for trapping photons in quasi one-dimensional waveguide or coupled-resonator lattices, which is based on an optical analogue of the Aharonov-Bohm cages for charged particles. Light trapping results from a destructive interference of Aharonov-Bohm type induced by a synthetic magnetic field, which is realized by periodic modulation of the waveguide/resonator propagation constants/resonances.
We report a simple technique in microwave photonic (MWP) signal processing that allows the use of an optical filter with a shallow notch to exhibit a microwave notch filter with anomalously high rejection level. We implement this technique using a low-loss, tunable Si3N4 optical ring resonator as the optical filter, and achieved an MWP notch filter with an ultra-high peak rejection > 60 dB, a tunable high resolution bandwidth of 247-840 MHz, and notch frequency tuning of 2-8 GHz. To our knowledge, this is a record combined peak rejection and resolution for an integrated MWP filter.
We build ring resonators to assess the potentialities of Kagome Hollow-Core Photonic Crystal Fibers for future applications to resonant rotation sensing. The large mode diameter of Kagome fibers permits to reduce the free space fiber-to-fiber coupling losses, leading to cavities with finesses of about 30 for a diameter equal to 15 cm. Resonance linewidths of 3.2~MHz with contrasts as large as 89\% are obtained. Comparison with 7-cell photonic band gap (PBG) fiber leads to better finesse and contrast with Kagome fiber. Resonators based on such fibers are compatible with the angular random walk …
We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filter…
The evanescent coupling from a photonic crystal resonator to a micron-thick optical fiber is investigated in detail by using a 3D-FDTD method. Properly designed photonic crystal cavity and taper structures are proposed, and optimal operating conditions are found to enhance the coupling strength while suppressing other cavity losses including the coupling to the slab propagating mode and to the higher-order fiber mode. In simulation, the coupling into the fundamental fiber mode is discriminated from other cavity losses by spatial and parity filtering of the FDTD results. The coupling efficiency…
An array of ring resonators specifically designed can perform as a topological insulator. We conduct simulations using both Tight-Binding Model (TBM) and Transfer Matrix Method (TMM) to analyze the transport properties of such optical structure, verifying the presence of robust topological edge states which is immune to disorder and defect. We have also made a comparison between these two methods, of which results suggesting that TBM is only applicable under weakly-coupling condition while TMM is more rigorous. Finally we compared the structure with common microring array and coupled resonator…
We introduce a numerical procedure which permits to drastically accelerate the design of multimode photonic crystal resonators. Specifically, we demonstrate that the optical response of an important class of such nanoscale structures is reproduced accurately by a simple, one-dimensional model, within the entire spectral range of interest. This model can describe a variety of tapered photonic crystal structures. Orders of magnitude faster to solve, our approach can be used to optimize certain properties of the nanoscale cavity. Here we consider the case of a nanobeam cavity, where the confineme…
The design and engineering of photonic architectures, suitable to enhance, collect and guide light on chip is needed for applications in quantum photonics and quantum optomechanics. In this work we apply a Faraday cage based oblique angle etch method to fabricate various functional photonic devices from 4H Silicon Carbide - a material that has attracted attention in recent years, due to its potential in optomechanics, nonlinear optics and quantum information. We detail the processing conditions and thoroughly address the geometrical and optical characteristics of the fabricated devices. Employ…
We develop a model for the coupling of quasi-normal modes in open photonic systems consisting of two resonators. By expressing the modes of the coupled system as a linear combination of the modes of the individual particles, we obtain a generalized eigenvalue problem involving small size dense matrices. We apply this technique to dielectric rod dimmer of rectangular cross section for Transverse Electric (TE) polarization in a two-dimensional (2D) setup. The results of our model show excellent agreement with full-wave finite element simulations. We provide a convergence analysis, and a simplifi…
We demonstrate the first compact photonic flywheel with sub-fs time jitter (averaging times up to 10 μs) at the quantum-noise limit of a monolithic fiber resonator. Such quantum-limited performance is accessed through novel two-step pumping scheme for dissipative Kerr soliton (DKS) generation. Controllable interaction between stimulated Brillouin lasing and Kerr nonlinearity enhances the DKS coherence and mitigate the thermal instability challenge, achieving a remarkable 22-Hz intrinsic comb linewidth and an unprecedented phase noise of -180 dBc/Hz at 945 MHz carrier at free running. The schem…
In the development of topological photonics, achieving three dimensional topological insulators is of significant interest since it enables the exploration of new topological physics with photons, and promises novel photonic devices that are robust against disorders in three dimensions. Previous theoretical proposals towards three dimensional topological insulators utilize complex geometries that are challenging to implement. Here, based on the concept of synthetic dimension, we show that a two-dimensional array of ring resonators, which was previously demonstrated to exhibit a two-dimensional…
In this letter we analyze an optical Fabry-Pérot resonator as a time-periodic driving of the (2D) optical field repeatedly traversing the resonator, uncovering that resonator twist produces a synthetic magnetic field applied to the light within the resonator, while mirror aberrations produce relativistic dynamics, anharmonic trapping, and spacetime curvature. We develop a Floquet formalism to compute the effective Hamiltonian for the 2D field, generalizing the idea that the intra-cavity optical field corresponds to an ensemble of non-interacting, massive, harmonically trapped particles. This w…
We report on the experimental observation of spontaneous creation and annihilation of temporal cavity solitons (CSs) in a coherently-driven, macroscopic optical fiber resonator. Specifically, we show that CSs are spontaneously created when the frequency of the cavity driving field is tuned across a resonance, and that they can individually disappear at different stages of the scan. In contrast to previous experiments in monolithic microresonators, we are able to identify these dynamics in real time, thanks to the macroscopic dimensions of our resonator. Our experimental observations are in exc…
We demonstrate the use of integrated micro-resonator based optical frequency comb sources as the basis for transversal filtering functions for microwave and radio frequency photonic filtering and advanced functions.
We demonstrate that the integration of a phase-change material (PCM) in one of the two microresonators of a photonic metamolecule, coupled to a bus waveguide, can lead to unidirectional Fano resonances and to the emergence of a unidirectional transmission window. The phase change is caused by light-induced heating and is accompanied by an abrupt increase in the extinction coefficient of the PCM resonator. Due to the photonic circuit asymmetry, the critical value of the input light intensity triggering the phase change is strongly dependent on the input light direction. The latter determines th…
Many novel properties of non-Hermitian systems are found at or near the exceptional points-branch points of complex energy surfaces at which eigenvalues and eigenvectors coalesce. In particular, higher-order exceptional points can result in optical structures that are ultrasensitive to external perturbations. Here we show that an arbitrary order exceptional point can be achieved in a simple system consisting of identical resonators placed near a waveguide. Unidirectional coupling between any two chiral dipolar states of the resonators mediated by the waveguide mode leads to the exceptional poi…
We report that $> 80%$ of the photons generated inside a photonic crystal slab resonator can be funneled within a small divergence angle of $\pm 30^\circ$. The far-field radiation properties of a photonic crystal slab resonant mode are modified by tuning the cavity geometry and by placing a reflector below the cavity. The former method directly shapes the near-field distribution so as to achieve directional and linearly-polarized far-field patterns. The latter modification takes advantage of the interference effect between the original waves and the reflected waves to enhance the energy-direct…
We demonstrate a two-dimensional photonic hypercrystal that shows enhanced spontaneous emission from its metamaterial component and light extraction through its photonic crystal property. Spontaneous decay rate is enhanced by a factor of 19.5 and light extraction from the HMM is enhanced by a factor of ~100.
