Mechanical oscillators are at the heart of many sensor applications. Recently several groups have developed oscillators that are probed optically, fabricated from high-stress silicon nitride films. They exhibit outstanding force sensitivities of a few aN/Hz$^{1/2}$ and can also be made highly reflective, for efficient detection. The optical read-out usually requires complex experimental setups, including positioning stages and bulky cavities, making them impractical for real applications. In this paper we propose a novel way of building fully integrated all-optical force sensors based on low-loss silicon nitride mechanical resonators with a photonic crystal reflector. We can circumvent previous limitations in stability and complexity by simulating a suspended focusing photonic crystal, purely made of silicon nitride. Our design allows for an all integrated sensor, built out of a single block that integrates a full Fabry-Pérot cavity, without the need for assembly or alignment. The presented simulations will allow for a radical simplification of sensors based on high-Q silicon nitride membranes. Our results comprise, to the best of our knowledge, the first simulations of a focusing mirror made from a mechanically suspended flat membrane with subwavelength thickness. Cavity lengths between a few hundred $μ$m and mm should be directly realizable.
We study nonlinear coupling of mutually incoherent beams associated with different Floquet-Bloch waves in a one-dimensional optically-induced photonic lattice. We demonstrate experimentally how such interactions lead to asymmetric mutual focusing and, for waves with opposite diffraction properties, to simultaneous focusing and defocusing as well as discreteness-induced beam localization and reshaping effects.
The physical origin of subwavelength photonic nanojet in retrograde-reflection mode (retro-PNJ) is theoretically considered. This specific type of photonic nanojet emerges upon sequential double focusing of a plane optical wave by a transparent dielectric microparticle located near a flat reflecting mirror. For the first time to the best of our knowledge, we report a unique property of retro-PNJ for increasing its focal length and intensity using microparticles with the optical contrast exceeding limiting value (n > 2) that fundamentally distinguishes retro-PNJ from regular PNJ behavior. This …
Resistance thermometry is a time-tested method for taking temperature measurements. In recent years fundamental limits to resistance-based approaches spurred considerable interest in developing photonic temperature sensors as a viable alternative. In this study we demonstrate that our photonic thermometer, which consists of a silicon waveguide integrated with a Bragg grating, can be used to measure temperature changes over the range from 5 C to 160 C with a combined expanded uncertainty [k = 2 ; 95% confidence level] of 1.25 degree C. The computational modeling of the sensor predicts the reson…
We present the key results from a comprehensive study of the refraction and focusing properties of a two-dimensional dodecagonal photonic ``quasicrystal'' (PQC), carried out via both full-wave numerical simulations and microwave measurements on a slab made of alumina rods inserted in a parallel-plate waveguide. We observe anomalous refraction and focusing in several frequency regions, confirming some recently published results. However, our interpretation, based on numerical and experimental evidence, differs substantially from the one in terms of ``effective negative refractive-index'' that w…
We study the focusing of light through random photonic materials using wavefront shaping. We explore a novel approach namely binary amplitude modulation. To this end, the light incident to a random photonic medium is spatially divided into a number of segments. We identify the segments that give rise to fields that are out of phase with the total field at the intended focus and assign these a zero amplitude, whereas the remaining segments maintain their original amplitude. Using 812 independently controlled segments of light, we find the intensity at the target to be 75 +/- 6 times enhanced ov…
We study the sensitivity of fiber grating sensors in the applications of strain, temperature, internal label-free biosensing, and internal refractive index sensing. It is shown that optical dispersion plays a central role in determining the sensitivity, and the dispersion may enhance or suppress sensitivity as well as change the sign of the resonant wavelength shifts. We propose a quality factor, $Q$, for characterizing LPGs.
Optofluidic sensors based on highly dispersive two-dimensional photonic crystal waveguides are theoretically studied. Results show that these structures are strongly sensitive to the refractive index of the infiltrated liquid (nl), which is used to tune dispersion of the photonic crystal waveguide. Waveguide mode-gap edge shifts about 1.2 nm for dnl=0.002. The shifts can be explained well by band structure theory combined with first-order perturbation theory. These devices are potentially interesting for chemical sensing applications.
We demonstrate an amplitude-based micro-displacement sensor that uses a plastic photonic bandgap Bragg fiber with one end coated with a silver layer. The reflection intensity of the Bragg fiber is characterized in response to different displacements (or bending curvatures). We note that the Bragg reflector of the fiber acts as an efficient mode stripper for the wavelengths near the edge of the fiber bandgap, which makes the sensor extremely sensitive to bending or displacements at these wavelengths. Besides, by comparison of the Bragg fiber sensor to a sensor based on a regular multimode fiber…
We present a sensor capable of detecting solution-based nanoparticles using an optical fiber tip functionalized with a photonic crystal cavity. When sensor tips are retracted from a nanoparticle solution after being submerged, we find that a combination of convective fluid forces and optically-induced trapping cause an aggregation of nanoparticles to form directly on cavity surfaces. A simple readout of quantum dot photoluminescence coupled to the optical fiber shows that nanoparticle presence and concentration can be detected through modified cavity properties. Our sensor can detect both gold…
We report on the fabrication and characterization of photonic-based nanothermometers, a silicon photonic Bragg grating and photonic crystal cavity. When cladded with silicon dioxide layer the sensors have at least eight times better sensitivity compared to the sensitivity of conventional fiber Bragg grating sensors. We demonstrate that these photonic thermometers are a viable temperature sensing solution.
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…
Resistance thermometry provides a time-tested method for taking temperature measurements that has been painstakingly developed over the last century. However, fundamental limits to resistance-based approaches along with a desire to reduce the cost of sensor ownership and increase sensor stability has produced considerable interest in developing photonic temperature sensors. Here we demonstrate that silicon photonic crystal cavity-based thermometers can measure temperature with uncertainities of 175 mK (k = 1), where uncertainties are dominated by ageing effects originating from the hysteresis …
A Bragg waveguide-based resonant fluidic sensor operating in THz band is studied. A fused deposition modeling 3D printing technique is employed to fabricate the sensor where the liquid analyte is flowing in the microfluidic channel integrated into the waveguide cladding. The analyte refractive index-dependent resonant defect state supported by the fluidic channel is probed by tracking the resulting absorption dip and phase change of the core-guided mode on waveguide transmission spectra. The proposed fluidic sensor can open new opportunities in applied chemical and biological sensing as it off…
Compact Photonic Fibre-based Deformation Sensor Fabricated by Two-Photon Polymerization
Aston Institute of Photonic Technologies, Aston University（阿斯顿光子技术研究所，阿斯顿大学）；Laser nanoFab GmbH（激光纳米制造有限公司）；Leibniz Universität Hannover（汉诺威莱布尼茨大学）；Bruker Nano GmbH（布鲁克纳米有限公司）
We propose an improved structure of an optical biosensor based on a photonic crystal (PC) with a defect layer (DL), which can detect the concentration of SARS-CoV-2 in water by defect mode (DM) shift. We investigated 4 types of defective PCs with different arrangements of layers inside the perfect PCs and their impact on the performance of the sensor. The sensitivity and amplitude of DM were examined as a function of DL thickness. Also, the peculiarities of edge modes in the presence of DL were investigated. Finally, we obtained a characteristic equation to determine the wavelengths of DMs for…
In this work, we proposed a high resolution D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor based on gold grating. Gold grating is introduced to modulate the resonance wavelength and enhance the refractive index (RI) sensitivity. Structure parameters of PCF and gold grating are analyzed by finite element method (FEM) for optimizing the SPR sensor. The simulation results indicate that air hole pitch, air hole diameter and gold thickness and grating constant have little influence on the sensitivity of refractive index, which reduces the requirement of precise process…
We report a very high precision interferometric sensor with resolution up to ~λ/1024, exploiting hollow photonic bandgap waveguide-based geometry for the first time. Here sensing has been measured by a complete switching in the direction of the outgoing beam, owing to transverse momentum oscillation phenomena. Using a 1.32 μm source and core-width of 7.25 μm, a complete switching cycle is obtained even due to a small change of ~1 nm in the core-width. Using hollow-core photonic bandgap waveguide, Talbot effect, revivals of the initial phase, oscillation in the transverse momentum along with mu…
We present a novel differential refractive index sensor based on arrays of photonic molecules (PM) of dielectric cylinders and two structural defect cavities. The transmission spectrum of the photonic proposed structure as sensor shows a wide photonic stop band with two localized states. One of them, the reference state, is bound to a decagonal ring of cylinders and the other, the sensing state, to the defect cavities of the lattice. It is shown that defect mode is very sensitive to the presence of materials with dielectric permittivity different from that of the surrounding cylinders while th…
In recent years there has been considerable interest in exploiting the temperature dependence of sapphire whispering gallery mode frequency to develop a mechanically stable, high accuracy temperature sensor. Disk-resonator-based devices have been demonstrated to measure temperature with .01 K or better accuracy in the temperature range of 273 K to 373 K. Here we have utilized automated data acquisition and processing to rapidly evaluate a mechanically-stabilized sapphire whispering gallery mode resonator based on a hollow cylinder configuration.
The development of highly-sensitive and miniaturized sensors that capable of real-time analytes detection is highly desirable. Nowadays, toxic or colorless gas detection, air pollution monitoring, harmful chemical, pressure, strain, humidity, and temperature sensors based on photonic crystal fiber (PCF) are increasing rapidly due to its compact structure, fast response and efficient light controlling capabilities. The propagating light through the PCF can be controlled by varying the structural parameters and core-cladding materials, as a result, evanescent field can be enhanced significantly …
Flexible microelectronics has shown tremendous promise in a broad spectrum of applications, especially those that cannot be addressed by conventional microelectronics in rigid materials and constructions1-3. These unconventional yet important applications range from flexible consumer electronics to conformal sensor arrays and biomedical devices. A recent successful paradigm shift in implementing flexible electronics is to physically transfer and bond highly integrated devices made in high-quality, crystalline semiconductor materials on to plastic materials4-8. Here we demonstrate a flexible fo…
We report a high performance relative humidity (RH) microsensor by coating a few-layer graphene oxide (GO) flake over a photonic crystal (PC) cavity. Since the GO layer has a high water-activity and interacts with the evanescent cavity mode strongly, the exposure of GO-PC cavity in varied humidity levels results in significant resonant wavelength shifts, showing a slope of 0.68 nm/%RH in the range of 60%-85% RH. By interrogating the power variation of the cavity reflection, the microsensor presents an ultrahigh sensitivity exceeding 3.9 dB/%RH. Relying on the unimpeded permeation of water mole…
Photonic-crystal-based integrated optical systems have been used for a broad range of sensing applications with great success. This has been motivated by several advantages such as high sensitivity, miniaturization, remote sensing, selectivity and stability. Many photonic crystal sensors have been proposed with various fabrication designs that result in improved optical properties. In parallel, integrated optical systems are being pursued as a platform for photonic quantum information processing using linear optics and Fock states. Here we propose a novel integrated Fock state optical sensor a…
We have discovered and studied the effect of the asymmetric deformation of a photonic crystal in the form of a change in the slope of the crystal planes as it is filled with a gaseous analyte. We have demonstrated that the use of a new effect leading to the displacement of the stop band against the unchanged spectrum of diffracted white light at the (glass-thin opal film) interface can be used as fast, compact, high sensitive and reproducible optical chemical sensor for ammonia. Low cost and simplicity of sensor fabrication, the response of which can be easily observed without resorting to spe…
We present the design of a compact and highly sensitive electric field sensor based on a bowtie antenna-coupled slot photonic crystal waveguide (PCW). An electro-optic (EO) polymer with a large EO coefficient, r33=100pm/V, is used to refill the PCW slot and air holes. Bowtie-shaped electrodes are used as both poling electrodes and as receiving antenna. The slow-light effect in the PCW is used to increase the effective in-device r33>1000pm/V. The slot PCW is designed for low-dispersion slow light propagation, maximum poling efficiency as well as optical mode confinement inside the EO polymer. T…
We report a theoretical study of clusters of evanescently-coupled 2D whispering-gallery (WG) mode optical micro-cavities (termed "photonic molecules") as chemosensing and biosensing platforms. Photonic molecules (PMs) supporting modes with narrow linewidths, wide mode spacing, and greatly enhanced sensitivity to the changes in the dielectric constant of their environment and to the presence of individual sub-wavelength sized nanoparticles in the PM evanescent-field region are numerically designed. This type of optical biosensor can be fabricated in a variety of material platforms and integrate…
Portable and cost-effective gas sensors are gaining demand for a number of environmental, biomedical and industrial applications, yet current devices are confined into specialized labs and cannot be extended to general use. Here, we demonstrate a part-per-billion-sensitive refractive index gas sensor on a photonic chip based on silicon nitride waveguides functionalized with a mesoporous silica top-cladding layer. Low-concentration chemical vapors are detected by monitoring the output spectral pattern of an integrated Mach-Zehnder interferometer having one coated arm exposed to the gas vapors. …
Controlling artificial Pearcey and swallowtail beams allows realizing caustic lattices in nonlinear photosensitive media at very low light intensities. We examine their functionality as 2D and 3D waveguiding structures, and show the potential of exploiting these lattices as a linear beam splitter, which we name a Pearcey-Y-splitter. For symmetrized Pearcey beams as auto-focusing beams, the formation of solitons in focusing nonlinearity is observed. Our original approach represents the first realization of caustic photonic lattices and can directly be applied in signal processing, microscopy an…
Micro-sized spheres can focus light into subwavelength spatial domains: a phenomena called photonic nanojet. Even though well studied in three-dimensional (3D) configurations, only a few attempts have been reported to observe similar phenomena in two-dimensional (2D) systems. This, however, is important to take advantage of photonic nanojets in integrated optical systems. Usually, surface plasmon polaritons are suggested for this purpose, but they suffer notoriously from the rather low propagation lengths due to intrinsic absorption. Here, we solve this problem and explore, theoretically, nume…
Dielectric microspheres or microbeads can squeeze light into the subwavelength scale via photonic nanojet (PNJ) focusing. This enables strong light-matter interactions within its focus and induces extraordinary effects such as enhancements in light emission, signal collection and various other applications. However, critical challenges exist on how to efficiently and precisely loading the studied objects into the desired location of the PNJ focusing, and subsequently measure the field and signal of interests precisely and reliably. Such technique is currently missing. We present for the first …
We study analytically and numerically the optical analogue of the Jackiw-Rebbi states in quantum field theory. These solutions exist at the interface of two binary waveguide arrays which are described by two Dirac equations with opposite sign masses. We show that these special states are topologically robust not only in the linear regime, but also in nonlinear regimes (with both focusing and de-focusing nonlinearity). We also reveal that one can generate the Jackiw-Rebbi states starting from Dirac solitons.
The field of optical metrology with its high precision position, rotation and wavefront sensors represents the basis for lithography and high resolution microscopy. However, the on-chip integration - a task highly relevant for future nanotechnological devices - necessitates the reduction of the spatial footprint of sensing schemes by the deployment of novel concepts. A promising route towards this goal is predicated on the controllable directional emission of the fundamentally smallest emitters of light, i.e. dipoles, as an indicator. Here we realize an integrated displacement sensor based on …
Quantum metrology takes advantage of nonclassical resources such as entanglement to achieve a sensitivity level below the standard quantum limit. To date, almost all quantum-metrology demonstrations are restricted to improving the measurement performance at a single sensor, but a plethora of applications require multiple sensors that work jointly to tackle distributed sensing problems. Here, we propose and experimentally demonstrate a reconfigurable sensor network empowered by continuous-variable (CV) multipartite entanglement. Our experiment establishes a connection between the entanglement s…
The six-fold rotational symmetry of photonic crystal fibers has important manifestations in the radiated fields in terms of i) a focusing phenomena at a finite distance from the end-facet and ii) the formation of low-intensity satellite peaks in the asymptotic far field. For our study, we employ a surface equivalence principle which allows us to rigorously calculate radiated fields starting from fully-vectorial simulations of the near field. Our simulations show that the focusing is maximal at a characteristic distance from the end-facet. For large-mode area fibers the typical distance is of t…
Goos-Hanchen-Shift Photonic Sensor for Nanometer-Scale Delayering and Tamper Detection in Semiconductor Packages
Bangladesh Army International University of Science and Technology（孟加拉国陆军国际科学技术大学）；James C. Wyant College of Optical Sciences, University of Arizona（亚利桑那大学詹姆斯·C·怀恩特光学科学学院）
We propose that a photonic array of resonant circular dielectric waveguides with subwavelength grating can be designed as a robust and sensitive topological chemical sensor. The device can detect trace amounts of a given chemical species through photonic edge modes that are impervious to most sources of disorder. We perform a simulation in the mid-infrared that accounts for the absorption loss introduced by chemical molecules in contact with a strongly coupled photonic lattice of resonators. Due to the topological nature of the device, its chemical sensitivity scales linearly with the system s…
Silicon photonics (SiP) integrated coherent image sensors offer higher sensitivity and improved range-resolution-product compared to direct detection image sensors such as CCD and CMOS devices. Previous generation of SiP coherent imagers suffer from relative optical phase fluctuations between the signal and reference paths, which results in random phase and amplitude fluctuations in the output signal. This limitation negatively impacts the SNR and signal acquisition times. Here we present a coherent imager system that suppresses the optical carrier signal and removes non-idealities from the re…
Integrated photonic sensors can provide large scale, flexible detection schemes. Photonic crystal slabs (PCS) offer a miniaturized platform for wideband, sensitive ultrasound detection by exploiting the photoelastic effect in water. However, poor modal overlap with the sensing medium and non-negligible absorption loss of the aqueous medium have previously limited PCS sensor performance. In this study, we detail the development and optimization of a PCS-based acoustic sensor, by adding to it a low-loss high-index polymer cladding layer. Exploiting a mode-optimized TM-like optical resonance pres…
Whispering-gallery mode (WGM) resonators combine small optical mode volumes with narrow resonance linewidths, making them exciting platforms for a variety of applications. Here we report a flying WGM microlaser, realized by optically trapping a dye-doped microparticle within a liquid-filled hollow-core photonic crystal fiber (HC-PCF) using a CW laser and then pumping it with a pulsed excitation laser whose wavelength matches the absorption band of the dye. The laser emits into core-guided modes that can be detected at the endfaces of the HC-PCF. Using radiation forces, the microlaser can be fr…
Visible surface plasmon resonances (SPRs) could be excited by TE wave polarization in one-dimensional photonic crystals (PCs) coated by a graphene layer under the Kretschmann configuration. In this work, the plasmonic Bloch wave properties beyond Dirac points in a one-dimensional graphene-based photonic sensing structure have been numerically studied. We demonstrate that emergent plasmonic dips in the reflectance spectra of the suggested photonic device in the visible region exhibit tunable characteristics upon modulation of the chemical potential and the hopping parameter. The sensitivity of …
On-chip measurement of thermo-optic coefficient (TOC) of samples along with on-chip temperature measurements can be used to compensate for thermal fluctuation induced noise in refractometry using integrated photonic sensors. In this article we demonstrate a device design and describe the method to extract TOCs of liquid samples using resonant wavelength shifts of a silicon microring resonator. The TOCs of three standard fluids; De-ionized water, Ethanol and Isopropanol, were determined using our sensor and show a good agreement with values reported in literature. A mechanism for tracking of on…
We investigate theoretically and numerically the photonic band structure in the optical domain of an array of core-shell metal-semiconductor nanowires. Corresponding negative-index photonic bands are calculated, showing isotropic equifrequency surfaces. The effective (negative) electric permittivity and magnetic permeability, retrieved from S parameters, are used to compare the performance of such nanowire arrays with homogeneous media in canonical examples, such as refraction through a prism and flat-lens focusing. Very good agreement is found, indeed confirming the effective medium behavior …
This chapter presents a brief overview of photonic sensor and standards development that is currently undergoing in the thermodynamic metrology group at NIST in the areas of temperature, pressure, vacuum and time-resolved pressure measurements.
We demonstrate that multiple topological transitions can occur, with high-sensitivity, by continuous change of the geometry of a simple 2D dielectric-frame photonic crystal consisting of circular air-holes. By changing the radii of the holes and/or the distance between them, multiple transitions between normal and topological photonic band gaps (PBGs) can appear. The time-reversal symmetric topological PBGs resemble the quantum spin-Hall insulator of electrons and have two counter-propagating edge states. We search for optimal topological transitions, i.e., sharp transitions sensitive to the g…
We present a study of the lensing properties of two-dimensional (2-D) photonic quasicrystal (PQC) slabs made of dielectric cylinders arranged according to a 12-fold-symmetric square-triangle aperiodic tiling. Our full-wave numerical analysis confirms the results recently emerged in the technical literature and, in particular, the possibility of achieving focusing effects within several frequency regions. However, contrary to the original interpretation, such focusing effects turn out to be critically associated to local symmetry points in the PQC slab, and strongly dependent on its thickness a…
We present the design, fabrication and characterization of high-\emph{Q} (\emph{Q}=36,000) polymeric photonic crystal nanobeam cavities made of two polymers that have an ultra-low index contrast (ratio=1.15) and observed thermo-optical bistability at hundred microwatt power level. Due to the extended evanescent field and small mode volumes, polymeric nanobeam cavities are ideal platform for ultra-sensitive biochemical sensing. We demonstrate that these sensors have figures of merit (FOM=9190) two orders of magnitude greater than surface plasmon resonance based sensors, and outperform the comme…
