Photonic-bandgap microcavities in optical waveguides

Physical Review B, 1999

We investigate the existence of defect modes in the photonic band structure of a comblike waveguide geometry made of dangling side branches grafted periodically along an infinite monomode waveguide. This one-dimensional photonic crystal exhibits forbidden bands that originate both from the periodicity of the system and the resonance states of the grafted branches. The defect modes result from the presence of defective branches in the comb and may occur in these stop bands. The localized states appear as very narrow peaks in the transmission spectrum of finite comblike waveguides composed of a finite number of grafted branches. The behavior of the localized states is analyzed as a function of the length, of the position, and of the number of the defective branches. These theoretical results are confirmed by experiments using coaxial cables in the frequency range of a few hundreds of MHz.

Applied Physics Letters, 2009

A two dimensional silicon-on-insulator based photonic crystal structure is used to enhance the emission from colloidal HgTe nanocrystal quantum dots embedded in a thin polymer film. The enhancement is resonant to the leaky eigenmodes of the photonic crystals due to coherent scattering effects. Transmittance and photoluminescence experiments are presented to map the leaky mode dispersion and the angle dependence of the emission enhancement factor, which reaches values up to 80 ͑650͒ for vertical ͑oblique͒ emission in the telecommunication wavelength range.

Applied Physics Letters, 2004

We investigate the response of photonic crystal (PC) atoms with Kerr nonlinearity to the excitation of ultrashort optical pulses. Surprisingly, it is found that PC atoms with sharp resonant peaks in frequency spectrum (or with large quality factors) can respond to ultrashort pulses very ...

Applied Physics Letters, 2005

We investigate the dynamics of nonlinear photonic crystal ͑PC͒ atoms by use of numerical simulations in a pump-probe scheme based on a finite-difference time-domain technique. A two-dimensional nonlinear PC atom with multimode is intentionally employed for the numerical simulations. The use of the multimode PC atom makes it possible that the pump and probe waves are set at different frequencies, ensuring the clear identification of the dynamics of the nonlinear PC atom. The physical model for the dynamics of nonlinear PC atoms has been established and very good agreement between the analytical and simulation results has been achieved.

Optics Letters, 2014

Photonic crystal cavity-based switching is studied both theoretically and experimentally in order to identify the best configuration to maximize "wavelength conversion" efficiency. In particular, it is shown that an enhanced contrast can be reached when the probe is blueshifted with respect to the resonance. The use of an InP/SOI hybrid photonic crystal nanocavity is reported for the first time for all-optical error-free "wavelength conversion" at 20 Gbit∕s with a nonreturn to zero on-off keying signal.

Optics express, 2011

Characteristic analyses are given for a bent silicon hybrid plasmonic waveguide, which has the ability of submicron bending (e.g., R = 500 nm) even when operating at the infrared wavelength range (1.2 μm~2 μm). A silicon hybrid plasmonic submicron-donut resonator is then presented by utilizing the sharp-bending ability of the hybrid plasmonic waveguide. In order to enable long-distance optical interconnects, a pure dielectric access waveguide is introduced for the present hybrid plasmonic submicron-donut resonator by utilizing the evanescent coupling between this pure dielectric waveguide and the submicron hybrid plasmonic resonator. Since the hybrid plasmonic waveguide has a relatively low intrinsic loss, the theoretical intrinsic Q-value is up to 2000 even when the bending radius is reduced to 800 nm. By using a three-dimensional finite-difference time-domain (FDTD) method, the spectral response of hybrid plasmonic submicron-donut resonators with a bending radius of 800 nm is simu...

Applied Physics Letters, 2013

Applied Physics Letters, 2004

We demonstrate the use of a micron-size planar silicon photonic device for the detection of ultralow concentrations of metal nanoparticles. The high detection sensitivity is achieved by using a strong light confining structure that enhances the effective extinction cross section of metal nanoparticles. We demonstrate the detection of 10 nm diameter gold particles with a density of fewer than 1.25 particles per 0.04 m 2 . Using such a device one could detect the presence of single metal nanoparticles specifically bound to various analytes, enabling ultrasensitive detection of analytes including DNA, RNA, proteins, and antigens.

Applied Physics B: Lasers and Optics, 2004

We investigate four wave mixing in photonic crystal wire microresonators realized in an isotropic medium. Onedimensional optical parametric oscillators are numerically analyzed by solving Maxwell's equations in all dimensions and including material dispersion as well as nonlinear polarization.

Physical Review B, 2012

We map out the band structure of a one-dimensional photonic crystal while a 12-fs control pulse activates ultrastrong interaction with quantized electronic transitions in semiconductor quantum wells. Phase-locked multi-terahertz transients trace the buildup of a large vacuum Rabi splitting and an unexpected asymmetric formation of the upper and lower polariton bands. The pronounced flattening of the photonic bands causes a slow-down of the group velocity by one order of magnitude on the time scale of the oscillation period of light.

Optics Letters, 2013

We have demonstrated what we believe to be the first waveguide photonic crystal cavity operating in the midinfrared. The devices were fabricated from Ge 23 Sb 7 S 70 chalcogenide glass (ChG) on CaF 2 substrates by combing photolithographic patterning and focused ion beam milling. The waveguide-coupled cavities were characterized using a fiber end fire coupling method at 5.2 μm wavelength, and a loaded quality factor of ∼2000 was measured near the critical coupling regime.

Microwave and Optical Technology Letters, 2003

Guided wave propagation in a parallel-plate waveguide with Kronig-Penney morphology is analyzed. Modes in the photonic band-gap (PBG) structure can be classified as either transverse electric or transverse magnetic with respect to the propagation direction. Above the modal cut-off frequencies, band gaps exist where in propagation is ABSTRACT: The error control of local interpolation for a 2D MLFMA will be discussed. The way to select proper parameters is proposed in terms of both numerical accuracy and computational cost. Satisfying the conditions derived in this paper, error can be controlled at the same level as global interpolation, and the computational cost becomes less expensive than the global one.

Journal of Applied Physics, 2002

We studied photonic-band-gap properties of two-dimensional lattices of Si nanopillars by theoretical calculation and measurement of reflection and transmission spectra. We focused on advantages of these photonic crystals compared to other Si photonic crystals, which usually operate in the range of transparency of bulk Si ͑wavelengths longer than ϳ1.1 m͒. We showed that the available spectral range for the photonic crystals of Si nanopillars can be extended to the submicron wavelengths, light absorption by Si nanopillars being insignificant. Another important advantage of Si nanopillar lattices is the ability to incorporate luminescent materials into the huge free space of this photonic crystal. We demonstrate the inhibition of spontaneous emission of dye incorporated into the nanopillar lattice.

Journal of Nonlinear Optical Physics & Materials, 2002

An alternative experimental technique for the determination of weak localization of light in partially ordered nanostructured materials is proposed. The technique is based on the criterion for weak localization of light that the transport mean free path length of multiply scattered photons is reduced down to shorter than the wavelength of the light. This mean free path is calculated from the experimental dwell time of the photons in the scattering structure and by applying the photon random walk model using the diffusion approximation. The dwell time is experimentally determined by multifrequency phasefluorimetry. This technique is capable of providing corroborative intensity demodulation data that can be linked to the wavelength dependent transmission (optical bandgap) of colloidal crystals.

Physical Review B, 2014

We study the fluorescence emission from single dye molecules in coplanar plasmonic cavities composed of a thin gold film surrounded by two in-plane surface plasmon Bragg mirrors. We first discuss the effect of the presence of Bragg mirrors on the radiation diagram of surface plasmon coupled emission. Then, we investigate the role of the planar cavity size by single-molecule fluorescence lifetime imaging. Experimental data are compared to numerical simulations of the decay rates calculated as a function of the molecule orientation and position within the cavity. The creation of new decay channels by coupling to the cavity modes is also discussed. We measure a plasmonic Purcell factor up to five, attributed to the enhancement of the radiative rate.

Physical Review B

We present a systematic comparison between guided modes supported by slab waveguides and Bloch Surface Waves (BSWs) propagating at the surface of truncated periodic multilayers. We show that, contrary to common belief, the best surface field enhancement achievable for guided modes in a slab waveguide is comparable to that observed for BSWs. At the same time, we demonstrate that, if one is interested in maximizing the electromagnetic energy density at a generic point of a dielectric planar structure, BSWs are often preferable to modes in which light is confined uniquely by total internal reflection. Since these results are wavelength independent and have been obtained by considering a very wide range of refractive indices of the structure constituent materials, we believe they can prove helpful in the design of future structures for the control and the enhancement of the light-matter interaction.

Annalen der Physik

Till now the nanoscale focussing and imaging in the sub-diffraction limit is achieved mainly with the help of plasmonic field enhancement assisted with noble metal nanoparticles. Using far field imaging technique, we have recorded polarized spectroscopic photoluminescence (PL) imaging of a single AlGaN nanowire (NW) of diameter ~ 100 nm using confinement of polarized light. The nanowires on the substrate have a nematic ordering. It is found that the PL from a single NW is influenced by the proximity to other NWs with the PL intensity scaling as 1/(ld), where l and d are the NW length and the separation from the neighbouring NW, respectively. We show that this proximity induced PL intensity enhancement can be understood, if we assume the existence of reasonably long lived photons in the intervening space between the NWs. A nonzero non-equilibrium population of such photons causes stimulated emission leading to the enhanced PL emission with the intensity scaling as 1/(ld). The effect is analogous to the Purcell enhancement of polarized optical emissions induced by confined photons in micro-cavities. The enhancement of PL emission facilitated the far field spectroscopic imaging of a single semiconducting nanowire in the sub-diffraction regime.

Physical Review A

In this paper we present universal broadband multi-resonator quantum memory (MR-QM) based on the spatial-frequency combs of the microresonators coupled with a common waveguide. Here we found new Bragg-type impedance matching condition for the coupling of the microresonators with a waveguide field which provides an efficient broadband quantum storage. The obtained analytical solution for the microresonator fields enables sustainable parametric control of all the memory characteristics.

Scientific Reports

In this paper we experimentally demonstrated a broadband scheme of the multiresonator quantum memory-interface. The microwave photonic scheme consists of the system of mini-resonators strongly interacting with a common broadband resonator coupled with the external waveguide. We have implemented the impedance matched quantum storage in this scheme via controllable tuning of the mini-resonator frequencies and coupling of the common resonator with the external waveguide. Proof-of-principal experiment has been demonstrated for broadband microwave pulses when the quantum efficiency of 16.3% was achieved at room temperature. By using the obtained experimental spectroscopic data, the dynamics of the signal retrieval has been simulated and promising results were found for high-Q mini-resonators in microwave and optical frequency ranges. The results pave the way for the experimental implementation of broadband quantum memory-interface with quite high efficiency η > 0.99 on the basis of modern technologies, including optical quantum memory at room temperature.

Physical Review Letters

Mode-locking is predicted in a nanolaser cavity forming an effective photonic harmonic potential. The cavity is substantially more compact than a Fabry-Perot resonator with comparable pulsing period, which is here controlled by the potential. In the limit of instantaneous gain and absorption saturation, mode-locking corresponds to a stable dissipative soliton, which it very well approximated by the coherent state of a quantum mechanical harmonic oscillator. This property is robust against non-instantaneous material response and non-zero phase-intensity coupling.

Advanced Functional Materials, 2013

Physical Review B

The transmission and phase-shift spectra for millimeter electromagnetic waves are obtained for a twodimensional ͑2D͒ square lattice array made of Si 3 N 4 spheres of diameter Ӎ3.2 mm. The results are compared with the theoretical 2D photonic-band structures that take account of the lifetime effect due to the radiative energy decay. It is found that the incidence-angle dependence of the observed transmission spectra is in excellent agreement with the calculated in-plane dispersion curves of the photonic bands and that the frequency dependence of the phase shift agrees well with the calculated lifetime-broadened density of states. The radiative lifetimes of the photonic bands are estimated to be about ten times longer than those of whispering gallery modes of an isolated sphere, though the magnitudes depend rather strongly on the wave vector and band index.

Applied Physics Letters, 2000

Radiation losses occurring in photonic crystals etched into planar waveguides are analyzed using a first-order perturbation approximation. Assuming the incoherent scattering limit, the model indicates that losses diminish as the cladding index approaches the core index. A simple scheme is devised to include these losses into purely two-dimensional calculations by using an imaginary index. Such calculations are shown to agree with corresponding experimental transmission through near-infrared photonic crystals, reproducing the contrasting behavior of the ''dielectric'' and ''air'' band edges.

Physical Review B, 2010

One dimensional nanobeam photonic crystal cavities are fabricated in silicon dioxide with silicon nanocrystals. Quality factors of over 9 × 10 3 are found in experiment, matching theoretical predictions, with mode volumes of 1.5(λ/n) 3. Photoluminescence from the cavity modes is observed in the visible wavelength range 600-820 nm. Studies of the lossy characteristics of the cavities are conducted at varying temperatures and pump powers. Free carrier absorption effects are found to be significant at pump powers as low as a few hundred nanowatts.

Applied Physics Letters, 2000

Applied Physics Letters, 2006

The authors have investigated the optical characteristics of a one-dimensional hybrid photonic crystal ͑1D HPC͒ containing cholesteric liquid crystal ͑CLC͒ as a defect by theoretical calculation and predicted the appearance of additional modes at the band edges of the CLC defect, whose Q factor was higher than those of the other defect modes. They have confirmed the appearance of the additional mode experimentally. Single-mode laser action with low pumping threshold was observed in a 1D HPC with a dye-doped CLC defect, which is based on the additional defect mode with a high Q factor peculiar to the CLC defect having periodic structure.

Electronics and Communications in Japan (Part II: Electronics), 2004

The localized state in a one-dimensional photonic crystal having a liquid crystal defect layer can be controlled by applying a voltage. We used the light confinement effect of the photonic crystal and the shift in the localized state wavelength due to the introduction of a liquid crystal defect layer and tried to control the laser emission by optical pumping of the one-dimensional photonic crystal having a liquid crystal defect layer and control the lasing wavelength upon applying an electric field. First, we used a dielectric multilayer of periodically stacked TiO 2 and SiO 2 layers as the one-dimensional photonic crystal, introduced a nematic liquid crystal having excellent responsiveness to an external electric field as the defect layer that disrupts the periodicity, and verified that the peak wavelength can be controlled by applying a voltage based on the localized state in the one-dimensional photonic band. These results agreed well with the numerical analysis results. Furthermore, we excited the dye-doped liquid crystal by a pulse laser and measured the laser emission from the localized state wavelength. In addition, the emission wavelength was successfully modulated upon applying electric field.

Electronics and Communications in Japan (Part II: Electronics), 2005

It is possible by the application of voltage to control the local level in a one-dimensional photonic crystal with a liquid crystal defect layer. In the present paper, a nematic liquid crystal is used and high-speed switching is attempted on the basis of the shift of the localized state wavelength by the photonic bandgap and liquid crystal orientation control. First, by the finite-difference time-domain method, the optical propagation characteristics inside a one-dimensional photonic crystal with a liquid crystal defect layer are analyzed. It is shown that optical switching by control of the localized state wavelength is possible. TiO 2 and SiO 2 are periodically laminated as a one-dimensional photonic crystal. A nematic liquid crystal layer is introduced as a defect layer to disturb the periodicity, resulting in a one-dimensional photonic crystal with a liquid crystal defect layer. By application of a voltage, the orientation of the liquid crystal defect layer is varied in an attempt to perform optical switching by electric field control of the localized state. High-speed optical switching of microsecond order is successful with nematic liquid crystals.

Optical and Quantum Electronics, 2012

An electro-optic modulator based on a 1-dimensional photonic crystal in a Fabry-Perot structure in a silicon on insulator waveguide with a comb like diode structure is proposed. By placing the doped regions of the p-in diode into the minima of the standing wave inside the resonator, the modulation bandwidth is increased compared to a conventional stripe diode. The highly doped regions inside the waveguide induce only low additional losses. Keywords Electro-optic modulator • SOI waveguide • Micro-cavity • Photonic crystal • Silicon photonics • CMOS

Physical Review B, 2015

We experimentally and theoretically demonstrate subwavelength scale localization of spoof surface plasmon polaritons at a point defect in a two-dimensional groove metal array. An analytical expression for dispersion relation of spoof surface plasmon polaritons substantiates the existence of a band gap where a defect mode can be introduced. A waveguide coupling method allows us to excite localized spoof surface plasmon polariton modes and measure their resonance frequencies. Numerical calculations confirm that localized modes can have a very small modal volume and a high Q factor both of which are essential in enhancing light-matter interactions. Interestingly, we find that the localized spoof surface plasmon polariton has a significant toroidal dipole moment, which is responsible for the high Q factor, as well as an electric quadrupole moment. In addition, the dispersion properties of spoof surface plasmon polaritons are analyzed using a modal expansion method and numerical calculations.

2019

We report on the design and the fabrication of 1D photonic crystal nanobeam cavities with optical resonances around 800 nm, compatible with rubidium, cesium, or argon atomic transitions. The cavities are made of indium gallium phosphide material, a III-V semi-conductor compound which has a large index of refraction (n≃3.3) favoring strong optical confinement and small mode volumes. Nanobeam cavities with inline and side coupling have been designed and fabricated, and quality factors up to 2×104 have been measured.

Microwave and Optical Technology Letters, 2002

Demonstration of aluminum-free metamorphic InP/In 0.53 Ga 0.47 As/InP double heterojunction bipolar transistors on GaAs substrates. IEEE Electron Device Lett EDL-21 (2000),

Journal of Materials Science, 2015

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Fifteenth Conference on Education and Training in Optics and Photonics: ETOP 2019, 2019

Silicon-based photonics is mobilizing into a manufacturing industry with specialized integrated circuit design requirements for applications in low power cloud computing, high speed wireless, smart sensing, and augmented imaging. The AIM Photonics Manufacturing USA Institute, which operates the world's most advanced 300mm semiconductor research fab, has co-developed a Process Design Kit (PDK) in fabless circuit design for these expanding digital and analog applications; however, there currently isn't available an in-depth curriculum to train engineers (academia, industry) in the AIM PDK process and Electronic Photonic Design Automation (EPDA) software. AIM Photonics Academy, an education initiative of AIM Photonics based at MIT, has collaborated with faculty to create three online MOOC edX courses that (1) introduce integrated photonics devices, and applications performance needs and metrics; and (2) train into the AIM PDK and specialized EPDA tools in a six week design project to lay out an application-specific photonic transceiver. The courses are structured around asynchronous video lectures and exploratory design problems that involve Python and Matlab-based first-principles calculations (systems modeling) or advanced EPDA tools (circuit design and layout). The online MOOC courses can optionally form a tandem blended learning component with two AIM Photonics Academy on-site training programs: the annual AIM Summer Academy one-week intensive program (held every July at MIT), or a photonic integrated circuit testing workshop (the first workshop is planned for fall 2019). These courses are a cornerstone effort at AIM to found and support a specialized cohort community of future integrated photonics designers.

Physical Review B, 2000

Linear waveguides in photonic-crystal slabs. Steven G. Johnson, Pierre R. Villeneuve, Shanhui Fan, and JD Joannopoulos Department of Physics and the Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139. ...

Journal of Applied Physics, 2000

Physical Review E, 2005

We show analytically, and numerically that highly-dispersive media can be used to drastically increase lifetimes of high-Q microresonators. In such a resonator, lifetime is limited either by undesired coupling to radiation, or by intrinsic absorption of the constituent materials. The presence of dispersion weakens coupling to the undesired radiation modes and also effectively reduces the material absorption. Microcavities with long lifetimes , and very small modal volumes (i.e. very narrow transmission resonance widths Γ TRANS

Journal of Applied Physics, 2011

We investigated numerically and experimentally the transmission of terahertz (THz) waves through single and multiple metallic defects created in a one-dimensional (1D) photonic crystal (PC) by inserting single metallic wires or arrays of parallel metallic wires into the air-gap defect of the 1D PC. The transmission properties of the metallic defect modes generated in the photonic bandgap (PBG) were characterized by using THz time-domain spectroscopy. For single metallic defects, it was found that the appearance the defect mode depends not only on the diameter of the metallic wires but also on the polarization of the THz wave. For transverse magnetic (TM) polarized waves whose electric fields are parallel to the metallic wires, the incident THz wave is generally split into two identical parts. In sharp contrast, the excitation of surface plasmon polaritons (SPPs) with enhanced field intensity is observed for transverse electric (TE) polarized waves whose electric fields are perpendicular to the metallic wires. In both cases, two resonant modes with reduced transmittance are observed in the PBG. While the resonant mode related to SPPs is found at the long-wavelength side of the original defect mode, the resonant mode without the excitation of SPPs appears at the short-wavelength side. Numerical simulation based on the finite-difference time-domain (FDTD) technique revealed that the electric field of SPPs is more tightly confined at the surface of the metallic wire when it is placed in the PC, implying that the confinement of a THz wave in the propagation direction will facilitate the localization of SPPs in the transverse direction. For two parallel metallic wires, the defect mode was found to depend on the separation between them. If they are widely separated, then the excitation of SPPs is similar to that observed in single metallic wires. However, the excitation of dipole-like SPPs does not occur for two closely packed metallic wires because of their large lateral size. It was also revealed that two parallel metallic wires with a small diameter and a narrow separation could be employed to achieve a significant enhancement, as large as 21.6, for the electric field in between them. More interestingly, the enhancement factor becomes larger when the confinement of the electric field in the propagation direction is increased. For an array of four widely separated wires whose lateral dimension is wider than the diameter of the THz beam, only one resonant mode is observed at the long-wavelength side of the original defect mode. The experimental observations are in good agreement with the simulation results based on the FDTD technique. The enhanced concentration of the electric field of SPPs at the surfaces of metallic defects may be useful for focusing and sensing of THz waves. V

Journal of the Optical Society of America B, 2009

A cross-waveguide resonator structure is proposed for silicon electro-optic modulators operating around the near-infrared (NIR) communication wavelength of 1550 nm. The device is modeled based on a silicon-oninsulator wafer with a compact surface area of 16 m 2 ͑4 m ϫ 4 m͒ and the modulation is achieved by resonance peak shift caused by carrier injection-based refractive index perturbation. It is shown via numerical study that the modulation speed of the device hits 2.9 GHz and 3 dB frequency around 4 GHz, while the DC power consumption is only 17.3 mW. An optimum modulation depth of 5.7 dB was found after tuning the optical confinement of the cavity.

Nature nanotechnology, 2017

Monolayer transition-metal dichalcogenides (TMDs) have the potential to become efficient optical-gain materials for low-energy-consumption nanolasers with the smallest gain media because of strong excitonic emission. However, until now TMD-based lasing has been realized only at low temperatures. Here we demonstrate for the first time a room-temperature laser operation in the infrared region from a monolayer of molybdenum ditelluride on a silicon photonic-crystal cavity. The observation is enabled by the unique combination of a TMD monolayer with an emission wavelength transparent to silicon, and a high-Q cavity of the silicon nanobeam. The laser is pumped by a continuous-wave excitation, with a threshold density of 6.6 W cm(-2). Its linewidth is as narrow as 0.202 nm with a corresponding Q of 5,603, the largest value reported for a TMD laser. This demonstration establishes TMDs as practical materials for integrated TMD-silicon nanolasers suitable for silicon-based nanophotonic appli...

Journal of Applied Physics, 2007

We analyze the dynamic response and optical properties of a high-speed defect mode switching that is based on a tunable defect mode in a one-dimensional photonic crystal with a nematic liquid crystal defect layer. The electro-optic responses of the defect mode switching are calculated considering the director distributions in the defect layer, which are determined using continuum theory. The calculated defect mode switching exhibits a response on the order of microseconds in spite of the use of the reorientation of nematic liquid crystal molecules. From the calculation, it is found that the fast response is realized using a narrow peak shift and a fast part of the molecular reorientation. Furthermore, the dependences of the switching response are clarified on several physical parameters.

Crystals, 2015

Polarization characteristics of defect mode peaks in a one-dimensional (1D) photonic crystal (PC) with a nematic liquid crystal (NLC) defect layer have been investigated. Two different polarized defect modes are observed in a stop band. One group of defect modes is polarized along the long molecular axis of the NLC, whereas another group is polarized along its short axis. Polarizations of the defect modes can be tuned by field-induced in-plane reorientation of the NLC in the defect layer. The polarization properties of the 1D PC with the NLC defect layer is also investigated by the finite difference time domain (FDTD) simulation.

Physical Review B, 2017

We propose a concept of chiral photonic limiters utilizing topologically protected localized midgap defect states in a photonic waveguide. The chiral symmetry alleviates the effects of structural imperfections and guarantees a high level of resonant transmission for low intensity radiation. At high intensity, the light-induced absorption can suppress the localized modes, along with the resonant transmission. In this case the entire photonic structure becomes highly reflective within a broad frequency range, thus increasing dramatically the damage threshold of the limiter. Here we demonstrate experimentally the loss-induced reflection principle of operation which is at the heart of reflective photonic limiters using a waveguide consisting of coupled dielectric microwave resonators.

Plasmonics, 2016

In silicon, the presence of two photon absorption (TPA) and the generated free carriers can strongly perturb any Kerr-related nonlinear performance. Special consideration about the geometry and applied input power is needed to reduce undesirable free carrier effects (FCE). In our study, a plasmonic photonic crystal structure consisting of a central metal-coated silicon nanowire is proposed. The photonic crystal cladding and plasmonic nature of the guided modes provide the efficient wave propagation in the subwavelength core radius size of 150 nm, well beyond the diffraction limit at λ = 1.55 μm. Considerable increase of the threshold powers (approximate increment of 42dBW and 12dBW for the free carrier absorption and dispersion threshold powers at r Si = 500 nm) for the observation of FCE is a distinguished feature of the proposed structure which guarantee the safe launch of high input powers for full development of Kerr-based phenomena. An excellent agreement between the numerical solution of the nonlinear schrödinger equation and the calculated threshold powers confirms the obtained results. The proposed structure has potential applications in the areas regarding the Kerr-related

Physical Review E, 1999

It is generally believed that the spatial periodic variation of a dielectric constant ⑀ or refractive index ͱ⑀ can give rise to photonic band gaps. However, through microwave experiments of microstrip lines with a periodic array of holes, we demonstrate that the wave impedance, which depends on ͱ/⑀, is an essential parameter, giving photonic band gaps rather than the refractive index. We explain physically the effect of the magnetic permeability on photonic band gaps, already reported. ͓S1063-651X͑99͒08904-7͔

Physical Review Letters, 2006

We report the first experimental demonstration of band-gap guidance of light in an optically induced two-dimensional photonic lattice with a single-site negative defect (akin to a low-index core in photoniccrystal fibers). We discuss the difference between spatial guidance at a regular and a defect site, and show that the guided beam through the defect displays fine structures such as vortex cells that arise from defect modes excited at higher band gaps. Defect modes at different wavelengths are also observed.

Journal of the Optical Society of America B, 1999

We present a three-dimensional finite-difference time-domain analysis of localized defect modes in an optically thin dielectric slab that is patterned with a two-dimensional array of air holes. The symmetry, quality factor, and radiation pattern of the defect modes and their dependence on the slab thickness are investigated.

Physical Review A, 2002

This paper presents a detailed analysis, based on the first-principles finite-difference time-domain method, of the resonant frequency, quality factor (Q), mode volume (V), and radiation pattern of the fundamental (HE 11) mode in a three-dimensional distributed-Bragg-reflector ͑DBR͒ micropost microcavity. By treating this structure as a one-dimensional cylindrical photonic crystal containing a single defect, we are able to push the limits of Q/V beyond those achievable by standard micropost designs, based on the simple rules established for planar DBR microcavities. We show that some of the rules that work well for designing large-diameter microposts ͑e.g., high-refractive-index contrast͒ fail to provide high-quality cavities with small diameters. By tuning the thicknesses of mirror layers and the spacer, the number of mirror pairs, the refractive indices of high-and low-refractive index regions, and the cavity diameter, we are able to achieve Q as high as 10 4 , together with a mode volume of 1.6 cubic wavelengths of light in the high-refractive-index material. The combination of high Q and small V makes these structures promising candidates for the observation of such cavity-quantum-electrodynamics phenomena as strong coupling between a quantum dot and the cavity field, and single-quantum-dot lasing.

Carbon Letters, 2022

Nonporous materials have nano-sized pores. High specific surface area and size and shape selectivity (size and shape Selectivity) are the most important features of these materials that have led to their widespread use in various industries, such as catalysts, water treatment and separation of pollutants. The development of properties and applications of these materials depends on the fabrication of nanoporous materials with optimal and controlled structures. In this paper, porous nanostructures and supermolecular chemistry are introduced in detail. Then, a number of common nanoporous materials, such as activated carbon, metal–organic frameworks and zeolites, then various types of mineral and organic nanoporous materials as well as methods of synthesis, characterization and applications of these materials will be studied in detail.

Applied Physics Letters, 2001

Applied Physics Letters, 2002

Fiber and Integrated Optics, 2019

Ring resonators have always been referred to as a highly flexible structure for designing optical devices. In this paper, we have designed and evaluated two 8-channel optical demultiplexers using photonic crystal ring resonators. The purpose of this study is to investigate the flexibility of this type of resonator for designing and manufacturing optical devices based on photonic crystals. To the extent that we have investigated the literature, there is no report so far on such a study. For this purpose, two structures with the same structural parameters, but only with a difference in the type of lattice constant (square or triangular) are used. Both structures have a common photonic band gap within a proper range for telecommunication applications used in wavelengthdivision multiplexing (WDM) systems. Both designed structures have an average crosstalk of −26 dB. For the demultiplexer structure with a square lattice constant, the quality factor and the transmission coefficient are 3,046 and 93.7% respectively, and its channel spacing is 1.97 nm. For the structure with a triangular lattice constant, the quality factor and the transmission coefficient are 1577.7 and 94.5%, respectively and its channel spacing is equal to 4 nm. To obtain the photonic band gap of the structures, the plane wave expansion (PWE) method is used and the output spectrum of the structures is obtained using the finite-difference time-domain (FDTD) method. The good results obtained in this study is through designing and simulating optical demultiplexer structures only by creating a change in the type of lattice constant used. This undoubtedly justifies the high flexibility of ring resonators, when used in the design of optical devices, as well as their suitability for the use in WDM systems ARTICLE HISTORY

Physical Review B, 1998

Optically thick metal films perforated with a periodic array of subwavelength holes show exceptional transmission properties. The zero-order transmission spectra exhibit well-defined maxima and minima of which the positions are determined by the geometry of the hole array. We show that the minima are the collection of loci for Wood's anomaly, which occurs when a diffracted beam becomes tangent to the film, and that the maxima are the result of a resonant excitation of surface plasmons ͑SP's͒. SP's from both surfaces of the metal film are apparent in the dispersion diagram, independent of which side of the film is illuminated, indicating an anomalously strong coupling between the two sides. This leads to wavelength-selective transmission with efficiencies that are about 1000 times higher than that expected for subwavelength holes.

Applied Physics Letters, 1999

Physical Review Applied, 2018

Optical microcavities are key elements in many photonic devices, and those based on distributed Bragg reflectors (DBRs) enhance dramatically the end reflectivity, allowing for higher quality factors and finesse values. Besides, they allow for wide wavelength tunability, needed for nano-and microscale light sources to be used as photonic building blocks in the micro-and nanoscale. Understanding the complete behavior of light within the cavity is essential to obtaining an optimized design of properties and optical tunability. In this work, focused ion-beam fabrication of high refractive-index contrast DBR-based optical cavities within Ga 2 O 3 ∶Cr microwires grown and doped by the vapor-solid mechanism is reported. Room-temperature microphotoluminescence spectra show strong modulations from about 650 nm up to beyond 800 nm due to the microcavity resonance modes. Selectivity of the peak wavelength is achieved for two different cavities, demonstrating the tunability of this kind of optical system. Analysis of the confined modes is carried out by an analytical approximation and by finite-difference-time-domain simulations. A good agreement is obtained between the reflectivity values of the DBRs calculated from the experimental resonance spectra, and those obtained by finite-difference-time-domain simulations. Experimental reflectivities up to 70% are observed in the studied wavelength range and cavities, and simulations demonstrate that reflectivities up to about 90% could be reached. Therefore, Ga 2 O 3 ∶Cr high-reflectivity optical microcavities are shown as good candidates for single-material-based, widely tunable light emitters for micro-and nanodevices.

Laser & Photonics Reviews, 2020

Photonic crystal (PhC) nanocavities have demonstrated unique capabilities in terms of light confinement and manipulation. As such, they are becoming attractive for the design of novel resonance-based photonic integrated circuits (PICs). Here two essential challenges arise however − how to realize ultrahigh-Q PhC cavities using standard fabrication processes compatible with large volume fabrication, and how to efficiently integrate them with other standard building blocks, available in exiting PIC platforms. In this work, we demonstrate ultrahigh-Q 1D PhC nanocavities fabricated on a 300 mm SOI wafer by optical lithography, with a record Q factor of up to 0.84 million. Moreover, we show efficient mode management in those oxide embedded cavities by coupling them with an access waveguide and realize two critical components: notch filters and narrow-band reflectors. In particular, they allow both single-wavelength and multi-wavelength operation, at the desired resonant wavelengths, while suppressing all other wavelengths over a broad wavelength range (>100 nm). Compared to traditional cavities, this offers a fantastic strategy for implementing resonances precisely in PIC designs with more freedom in terms of wavelength selectivity and the control of mode number. Given their compatibility with optical lithography and compact footprint, the realized 1D PhC nanocavities will be of profound significance for designing compact and novel resonance-based photonic components on large scale.

Physical review. E, Statistical, nonlinear, and soft matter physics, 2003

In this study, two fast and accurate methods of inverse iteration with multigrid acceleration are developed to compute band structures of photonic crystals of general shape. In particular, we report two-dimensional photonic crystals of silicon air with an optimal full band gap of gap-midgap ratio Deltaomega/omega(mid)=0.2421, which is 30% larger than ever reported in the literature. The crystals consist of a hexagonal array of circular columns, each connected to its nearest neighbors by slender rectangular rods. A systematic study with respect to the geometric parameters of the photonic crystals was made possible with the present method in drawing a three-dimensional band-gap diagram with reasonable computing time.

Physical Review E, 2000

The Green dyadic formalism is applied to the study of the optical properties of dielectric subwavelength structures integrated in coplanar geometry. We first consider homogeneous wires with high refractive index featuring subwavelength cross sections. We show that such wires may have guiding properties and that they may be coupled with a local illumination produced by a focused Gaussian beam totally reflected at the substrate interface. When excited by the focused beam, these subwavelength optical waveguides ͑SOW's͒ provide a confined source of light that could be used to excite a single nanoscopic object. Well designed heteregeneous wires resulting from the alignment of dielectric particles separated from each other by a subwavelength distance are also found to propagate a Gaussian beam excitation over several micrometers. This propagation occurs with reasonable damping for incident beams in the visible frequency range. The computed transmission spectra of these heterowires may exhibit narrow gaps. Finally, we discuss the relation between the optical properties of the SOW and the calculated electromagnetic local density of states.

Physical Review B, 2004

The photonic band structures in certain two-and three-dimensional periodic networks made of one-dimensional waveguides are studied by using the Floquet-Bloch theorem. We find that photonic band gaps exist only in those structures where the fundamental loop exhibits anti-resonant transmission. This is also true for quasi-periodic networks in two and three dimensions, where the photonic band structures are calculated from the spectra of total transmission arising from a source inside the samples. In all the cases we have studied, it is also found that the gap positions in a network are dictated by the frequencies at which the anti-resonance occurs.

Physical Review B, 1998

Extraordinary angle-sensitive light propagation, which we call a superprism phenomenon, was demonstrated at optical wavelength in photonic crystals with three-dimensional-periodic structure fabricated on Si substrate. The propagation beam was swung from Ϫ90°to ϩ90°with a slight change in the incident angle within Ϯ12°. This effect together with wavelength sensitivity is at least two orders of magnitude stronger than that of the conventional prism. The incident-angle dependence including negative refraction and multiple beam branching was interpreted from highly anisotropic dispersion surfaces derived by photonic band calculation. These phenomena will be available to fabricate microscale light circuits on Si with LSI-compatible lithography techniques. ͓S0163-1829͑98͒51840-1͔

Nature, 2000

A two-dime~iorial (2D) photonic crystal is an attractive alternative and complimentary to its 3D counterpart [1-5], due to fabrication simplicity. A 2D crystal, however, confines light only in the 2D plane [6], but not in the third direction, the zdirection. Earlier experiments show that such a 2D system can exist [7-10], providing that the boundary effect in z-direction is negligible and that light is collimated in the 2D plane. Nonetheless, the usefulness of such 2D crystals is limited because they are incapable of guiding light in z-direction, which leads to diffraction loss. This drawback presents a major obstacle for realizing low-loss 2D crystal waveguides, bends and thresholdless lasers. A recent theoretical calculation, though, suggests añ oveI way to eIiminate such a loss with a 2D photonic crystal slab [11,12]. The concept of a Iightcone is introduced as a criterion for fully guiding and controlling light. Although the leaky modes of a crystal slab have been studied [13], there have until now no experimental reports on probing its guided modes and band gaps. In this paper, a waveguide-coupled 2D photonic crystal slab is successfully fabricated from a GaAs/AIXOY material system and its intrinsic transmission properties are studied. The crystal slab is shown to have a strong 2D band gap at Z-1.5 pm. Light attenuates as much as-5dB per period in the gap, the strongest ever reported for any 2D photonic crystal in optical k. More importantly, for the first time, the crystal slab is shown to be capable-of controlling light fully in all three-dimensions. The lightcone criterion is also experimentally confirmed.

Nature, 1998

Data collection was performed on a Rigaku AFC-5R diffractometer with graphite monochromated Mo Ka radiation (l = 0.71069) and a rotating anode generator. Intensities were collected to a maximum 2y value of 60.0 by the o±2y scan technique. The total number of independent reflections measured was 4353, of which 1760 were considered to be observed [I > 3.00s(I)]. The structure was solved by direct methods (SHELXS86). The non-hydrogen atoms were refined anisotropically. Hydrogen atoms were included but not refined. Full-matrix leastsquares refinement gave R = 0.064, R w = 0.063. [10] H. Kobayashi, A. Kobayashi, Y. Sasaki, G. Saito, H. Inokuchi, Bull. Chem. Soc. Jpn. 1986, 59, 301. [11] Crystal data for the BF ± 4 salt: (C 10 H 6 N 2 S 2 Se 4) 3 (BF 4) 1.5 (CH 2 Cl 2) 0.6, M r = 1783.56, monoclinic, space group C2/c, a = 35.119(9), b = 12.578(7), c = 21.985(8) , b = 99.37(3), V = 9581(6) 3 , Z = 8, D calc = 2.473 g/ cm 3. Data collection was performed on a Rigaku AFC-7R diffractometer with graphite monochromated Mo Ka radiation (l = 0.71069) and a rotating anode generator. Intensities were collected to a maximum 2y value of 60.1 by the o±2y scan technique. The total number of independent reflections measured was 12 709, of which 2395 were considered to be observed [I > 3.00s(I) ]. The structure was solved by direct methods (SHELXS86). The sulfur and selenium atoms were refined anisotropically. Boron atoms were fixed. The other non-hydrogen atoms were refined isotropically. Hydrogen atoms were included but not refined. Full-matrix least-squares refinement gave = 0.064, R w = 0.056. [12] Crystal data for the ClO ± 4 salt: (C 10 H 6 N 2 S 2 Se 4) 3 (ClO 4) 1.5 (CH 2 Cl 2) 0.6, M r = 1802.53, monoclinic, space group C2/c, a = 35.308(5), b = 12.600(4), c = 21.996(7) , b = 99.36(2), V = 9655(6) 3 , Z = 8, D calc = 2.480 g/cm 3. Data collection was performed on a Rigaku AFC-7R diffractometer with graphite monochromated Mo Ka radiation (l = 0.71069) and a rotating anode generator. Intensities were collected to maximum 2y value of 60.0 by the o±2y scan technique. The total number of independent reflections measured was 12 490, of which 2090 were considered to be observed [I > 3.00s(I)]. The structure was solved by direct methods (SHELXS86). The sulfur, selenium and chlorine (of anions) atoms were refined anisotropically. The other non-hydrogen atoms were refined isotropically. Hydrogen atoms were included but not refined. Full-matrix least-squares refinement gave R = 0.068, R w = 0.065. [13] a) T.

Scientific Reports, 2013

Particles manipulation with optical forces is known as optical tweezing. While tweezing in free space with laser beams was established in the 1980s, integrating the optical tweezers on a chip is a challenging task. Recent experiments with plasmonic nanoantennas, microring resonators, and photonic crystal nanocavities have demonstrated optical trapping. However, the optical field of a tweezer made of a single microscopic resonator cannot be shaped. So far, this prevents from optically driven micromanipulations. Here we propose an alternative approach where the shape of the optical trap can be tuned by the wavelength in coupled nanobeam cavities. Using these shapeable tweezers, we present micromanipulation of polystyrene microspheres trapped on a silicon chip. These results show that coupled nanobeam cavities are versatile building blocks for optical near-field engineering. They open the way to much complex integrated tweezers using networks of coupled nanobeam cavities for particles or bio-objects manipulation at a larger scale.

Applied Physics Letters, 2011