Recently, there is growing interest in integrating alkali vapors with nanoscale photonic structures, such as nano-waveguides, resonators and nanoantennas. Nanoscale confinement of electromagnetic fields may introduce a longitudinal electric field component, giving rise to circularly polarized modes which are essential for diverse applications involving vapor and light, such as chirality and non-reciprocity. Hereby, we have designed, fabricated and characterized a miniaturized vapor cell that is integrated with optical waveguides that are designed to generate a peculiar circular-like polarization. Taking advantage of this phenomenon, we demonstrate a spectral shift in the atomic absorption signatures at varying magnetic fields, and significant isolation between forward and backward propagating waves in our atomic-cladded waveguide. Our results pave the way for the utilization of chip-scale integrated atomic devices in applications such as optical isolation and high spatial resolution magnetometry.
Strongly anisotropic media with hyperbolic dispersion can be used for claddings of plasmonic waveguides. In order to analyze the fundamental properties of such waveguides, we analytically study 1D waveguides arranged of a hyperbolic metamaterial (HMM) in a HMM-Insulator-HMM (HIH) structure. We show that hyperbolic metamaterial claddings give flexibility in designing the properties of HIH waveguides. Our comparative study on 1D plasmonic waveguides reveals that HIH-type waveguides can have a higher performance than MIM or IMI waveguides.
Terahertz communications is a promising modality for future short-range point-to point wireless data transmission at rates up to terabit per second. A milestone towards this goal is the development of an integrated transmitter and receiver platforms with high efficiency. One key enabling component is a planar waveguiding structure with wide bandwidth and low dispersion. This work proposes substrate-less all-dielectric waveguides cladded by an effective medium for low-loss and low dispersion terahertz transmission in broadband. This self-supporting structure is built solely into a single silico…
Erbium doped integrated waveguide amplifier and laser prevail in power consumption, footprint, stability and scalability over the counterparts in bulk materials, underpinning the lightwave communication and large-scale sensing. Subject to the highly confined mode and moderate propagation loss, gain and power scaling in such integrated micro-to-nanoscale devices prove to be more challenging compared to their bulk counterparts. In this work, stimulated by the prevalent success of double-cladding optical fiber in high-gain/power operation, a Ta2O5 cladding is employed in the erbium doped lithium …
Magnetic field free nonreciprocity in tapered atomic cladded nano waveguide
The Hebrew University of Jerusalem（耶路撒冷希伯来大学）；University of Stuttgart（斯图加特大学）；Institut für Mikroelektronik Stuttgart (IMS CHIPS)（斯图加特微电子研究所 (IMS CHIPS)）；Bar-Ilan University（巴伊兰大学）
Photonic crystal slabs have been widely used in nanophotonics for light confinement, dispersion engineering, nonlinearity enhancement, and other unusual effects arising from their structural periodicity. Sub-micron device sizes and mode volumes are routine for silicon-based photonic crystal slabs, however spectrally they are limited to operate in the near infrared. Here, we show that two single-layer graphene sheets allow silicon photonic crystal slabs with submicron periodicity to operate in the terahertz regime, with an extreme 100x wavelength reduction and excellent out-of-plane confinement…
We investigate an integrated optical chip immersed in atomic vapor providing several waveguide geometries for spectroscopy applications. The narrow-band transmission through a silicon nitride waveguide and interferometer is altered when the guided light is coupled to a vapor of rubidium atoms via the evanescent tail of the waveguide mode. We use grating couplers to couple between the waveguide mode and the radiating wave, which allow for addressing arbitrary coupling positions on the chip surface. The evanescent atom-light interaction can be numerically simulated and shows excellent agreement …
We report fabrication of low loss single mode waveguides on lithium niobate on insulator (LNOI) cladded by a layer of SiO2. Our technique, termed photolithography assisted chemo-mechanical etching (PLACE), relies on patterning of a chromium film into the mask shape by femtosecond laser micromachining and subsequent chemo-mechanical etching of the lithium niobate thin film. The high-index-contrast single mode waveguide is measured to have a propagation loss of 0.13 dB/cm. Furthermore, waveguide tapers are fabricated for boosting the coupling efficiency.
Quantum-dot (QD) nanolasers integrated on a silicon photonic circuit are demonstrated for the first time. QD nanolasers based on one-dimensional photonic crystal nanocavities containing InAs/GaAs QDs are integrated on CMOS-processed silicon waveguides cladded by silicon dioxide. We employed transfer-printing, whereby the three-dimensional stack of photonic nanostructures is assembled in a simple pick-and-place manner. Lasing operation and waveguide-coupling of an assembled single nanolaser are confirmed through micro-photoluminescence spectroscopy. Furthermore, by repetitive transfer-printing,…
Silicon nitride (Si3N4) has emerged as a promising material for integrated nonlinear photonics and has been used for broadband soliton microcombs and low-pulse-energy supercontinuum generation. Therefore understanding all nonlinear optical properties of Si3N4 is important. So far, only stimulated Brillouin scattering (SBS) has not been reported. Here we observe, for the first time, backward SBS in fully cladded Si3N4 waveguides. The Brillouin gain spectrum exhibits an unusual multi-peak structure resulting from hybridization with with high-overtone bulk acoustic resonances (HBARs) of the silic…
Highly confining waveguides without degraded nonlinear coefficient and low propagation losses have been fabricated in lithium niobate by a new process that we called High Vacuum Vapor-phase Proton Exchange (HiVac-VPE). Index contrast, index profile, nonlinearity and crystallographic phases are carefully investigated. Original analysis of index profiles indicates that the waveguides contains sub-layers whose depths are depending on the exchange durations. Propagation behavior, propagation losses and Second Harmonic Generation (SHG) response of HiVac-VPE channel waveguides are investigated at te…
In recent years we are witnessing a flourish in research aimed to facilitate alkali vapors in guided wave configurations. Owing to the significant reduction in device dimensions, the increase in density of states, the interaction with surfaces and primarily the high intensities carried along the structure, a rich world of light vapor interactions can be studied, and new functionalities, e.g. low power nonlinear light-matter interactions can be achieved. One immense remaining challenge is to study the effects of quantum coherence and shifts in such nano-scale waveguides, characterized by ultra-…
Chemical vapor deposition-based growth techniques allow flexible design of CMOS-compatible materials. Here, we report the deuterated silicon-rich nitride films grown using plasma-enhanced chemical vapor deposition. The linear and nonlinear properties of the films are characterized. We compare the absorption at 1550nm wavelength region for films grown with $SiH_4$ and $SiD_4$, and experimentally confirm that the silicon-rich nitride films grown with $SiD_4$ eliminates Si-H related absorption. Waveguides fabricated on the films are further shown to possess a linear and nonlinear refractive index…
Photonic integrated circuits currently use platform intrinsic thermo-optic and electro-optic effects to implement dynamic functions such as switching, modulation and other processing. Currently, there is a drive to implement field programmable photonic circuits, a need which is only magnified by new neuromorphic and quantum computing applications. The most promising non-volatile photonic components employ phase change materials such as GST and GSST, which had their origin in electronic memory. However, in the optical domain, these compounds introduce significant losses potentially preventing a…
We propose an efficient scheme for the generation of tunable optical waveguide based on atomic vapor in N -type configuration. We exploit both control field induced transparency and Kerr field induced absorption to produce a flexible probe transparency window otherwise not feasible. We employ a suitable spatial profile of control and Kerr beams to create a high contrast refractive in- dex modulation that holds the key to guiding a weak narrow probe beam. Further we numerically demonstrate that high contrast tunable waveguide permits the propagation of different modes of probe beam to several R…
We theoretically demonstrate an efficient scheme to build a microwave (MW) assisted optical waveguide in an inhomogeneously broadened vapor medium that is made of active 87 Rb atoms and inactive buffer gas atoms. We exploit the sensitive behaviour of MW field coupled between highly excited Rydberg states to create distinctly responsive and tunable atomic waveguide. The buffer gas induced collision further manipulates the features of the waveguide by widening the spatial transparency window and enhancing the contrast of the refractive index. We numerically solve Maxwell's equations to demonstra…
We study an integrated silicon photonic chip, composed of several sub-wavelength ridge waveguides, and immersed in a micro-cell with rubidium vapor. Employing two-photon excitation, including a telecom wavelength, we observe that the waveguide transmission spectrum gets modified when the photonic mode is coupled to rubidium atoms through its evanescent tail. Due to the enhanced electric field in the waveguide cladding, the atomic transition can be saturated at a photon number $\approx$ 80 times less than a free-propagating beam case. The non-linearity of the atom-clad Si-waveguide is about 4 o…
Beam propagation beyond the paraxial approximation is studied in an optically written waveguide structure. The waveguide structure that leads to diffractionless light propagation, is imprinted on a medium consisting of a five-level atomic vapor driven by an incoherent pump and two coherent spatially dependent control and plane-wave fields. We first study propagation in a single optically written waveguide, and find that the paraxial approximation does not provide an accurate description of the probe propagation. We then employ coherent control fields such that two parallel and one tilted Gauss…
Silicon nitride is awell-established material for photonic devices and integrated circuits. It displays a broad transparency window spanning from the visible to the mid-IR and waveguides can be manufactured with low losses. An absence of nonlinear multi-photon absorption in the erbium lightwave communications band has enabled various nonlinear optic applications in the past decade. Silicon nitride is a dielectric material whose optical and mechanical properties strongly depend on the deposition conditions. In particular, the optical bandgap can be modified with the gas flow ratio during low-pr…
We report the first demonstration of a 1555 nm stepped-height ridge waveguide polarization mode converter monolithically integrated with a side wall grating distributed-feedback (DFB) laser using the identical epitaxial layer scheme. The device shows stable single longitudinal mode (SLM) operation with the output light converted from TE to TM polarization with an efficiency of >94% over a wide range of DFB injection currents (IDFB) from 140 mA to 190 mA. The highest TM mode purity of 98.2% was obtained at IDFB=180 mA. A particular advantage of this device is that only a single step of metalorg…
This paper reports the first demonstration of beta-phase gallium oxide as optical waveguides on sapphire substrates grown by metal-organic chemical vapor deposition (MOCVD). The propagation losses from visible to ultraviolet spectra were comprehensively studied. By optimizing the fabrication processes, minimum propagation loss was identified to be 3.7 dB/cm at the wavelength of 810 nm, which is comparable to other wide bandgap materials within the III-N family (GaN, AlN). To further reveal the underlying loss mechanisms, several physical mechanisms such as two-photon absorption, sidewall scatt…
Enhanced selfphase modulation in silicon nitride waveguides with integrated 2D MoS2 films
Swinburne University of Technology（斯威本科技大学）；INL, Institut des Nanotechnologies de Lyon UMR CNRS 5270, Ecole Centrale de Lyon, INSA Lyon, Universite Claude Bernard Lyon 1, CPE Lyon（里昂纳米技术研究所）；RMIT University（皇家墨尔本理工大学）；Peking University（北京大学）；CEA-LETI, Université Grenoble Alpes（格勒诺布尔阿尔卑斯大学）；ARC Centre of Excellence in Optical Microcombs for Breakthrough Science (COMBS)（光学微梳突破科学卓越中心）
Strong light-induced interactions between atoms are known to cause nonlinearities at a few-photon level which are crucial for applications in quantum information processing. Compared to free space, the scattering and the light-induced dipolar interaction of atoms can be enhanced by a dielectric environment. For this \emph{Purcell effect}, either a cavity or a waveguide can be used. Here, we combine the high densities achievable in thermal atomic vapors with an efficient coupling to a slot waveguide. In contrast to free-space interactions, atoms aligned within the slot exhibit repulsive interac…
We study the propagation of light beams through optical media with competing nonlocal nonlinearities. We demonstrate that the nonlocality of competing focusing and defocusing nonlinearities gives rise to self-organization and stationary states with stable hexagonal intensity patterns, akin to transverse crystals of light filaments. Signatures of this long-range ordering are shown to be observable in the propagation of light in optical waveguides and even in free space. We consider a specific form of the nonlinear response that arises in atomic vapor upon proper light coupling. Yet, the general…
We report an AlGaInAs multiple quantum well integrated source of polarization controlled light consisting of a polarization mode converter PMC, differential phase shifter(DPS), and a side wall grating distributed-feedback DFB laser. We demonstrate an asymmetrical stepped-height ridge waveguide PMC to realize TE to TM polarization conversion and a symmetrical straight waveguide DPS to enable polarization rotation from approximately counterclockwise circular polarization to linear polarization. Based on the identical epitaxial layer scheme, all of the PMC, DPS, and DFB laser can be integrated mo…
Atomically thin transition metal dichalcogenides are highly promising for integrated optoelectronic and photonic systems due to their exciton-driven linear and nonlinear interaction with light. Integrating them into optical fibers yields novel opportunities in optical communication, remote sensing, and all-fiber optoelectronics. However, scalable and reproducible deposition of high quality monolayers on optical fibers is a challenge. Here, we report the chemical vapor deposition of monolayer MoS2 and WS2 crystals on the core of microstructured exposed core optical fibers and their interaction …
