Resonant Photonic Structures Research Articles

Light‐Induced Tuning and Reconfiguration of Nanophotonic Structures

AbstractInteraction of light pulses of various durations and intensities with nanoscale photonic structures plays an important role in many applications of nanophotonics for high‐density data storage, ultra‐fast data processing, surface coloring and sensing. A design of optically tunable and reconfigurable structures made from different materials is based on many important physical effects and advances in material science, and it employs the resonant character of light interaction with nanostructures and strong field confinement at the nanoscale. Here we review the recent progress in physics of tunable and reconfigurable nanophotonic structures of different types. We start from low laser intensities that produce weak reversible changes in nanostructures, and then move to the discussion of non‐reversible changes in photonic structures. We focus on three platforms based on metallic, dielectric and hybrid resonant photonic structures such as nanoantennas, nanoparticle oligomers and nanostructured metasurfaces. Main challenges and key advantages of each of the approaches focusing on applications in advanced photonic technologies are also discussed.

Coupled mode theory of microtoroidal resonators with a one-dimensional waveguide

We study the transmission of light through a system consisting of an arbitrary number N of microtoroidal resonators coupled to a one-dimensional (1D) waveguide. The transmission T through such a system and its full-width at half-maximum (FWHM) are calculated for various values of N and mutual-mode coupling coefficients. We found that at small mutual-mode coupling, the minimum transmission vanishes exponentially with N while the FWHM is proportional to N. At big mutual-mode coupling, as the number of resonators increases, the mode-splitting is reduced. Our findings contribute to better understanding of novel interfaces between quantum emitters and resonant photonic structures for quantum information processing.

Photodetectors: A heated junction.

Resonant photonic structures made of thermoelectric materials can convert light into electricity without wavelength limitations.

Atomically Thin MoS2 Narrowband and Broadband Light Superabsorbers.

We present a combined theoretical and experimental effort to enable strong light absorption (>70%) in atomically thin MoS2 films (≤4 layers) for either narrowband incidence with arbitrarily prespecified wavelengths or broadband incidence like solar radiation. This is achieved by integrating the films with resonant photonic structures that are deterministically designed using a unique reverse design approach based on leaky mode coupling. The design starts with identifying the properties of leaky modes necessary for the targeted strong absorption, followed by searching for the geometrical features of nanostructures to support the desired modes. This process is very intuitive and only involves a minimal amount of computation, thanks to the straightforward correlations between optical functionality and leaky modes as well as between leaky modes and the geometrical feature of nanostructures. The result may provide useful guidance for the development of high-performance atomic-scale photonic devices, such as solar cells, modulators, photodetectors, and photocatalysts.

Topological lasing in resonant photonic structures

The use of virtually lossless topologically isolated edge states may lead to a novel class of thresholdless lasers operating without inversion. One needs however to understand if topological states may be coupled to external radiation and act as active cavities. We study a two-level topological insulator and show that self-induced transparency pulses can directly excite edge states. We simulate laser emission by a suitable designed topological cavity, and show that it can emit tunable radiation. For a configuration of sites following the off-diagonal Aubry-Andre-Harper model we solve the Maxwell-Bloch equations in the time domain and provide a first principle confirmation of topological lasers. Our results open the road to a new class of light emitters with topological protection for applications ranging from low-cost energetically-effective integrated lasers sources, also including silicon photonics, to strong coupling devices for studying ultrafast quantum processes with engineered vacuum.

Reflection of short polarized optical pulses from periodic and aperiodic multiple quantum well structures

We study the reflection of polarized optical pulses from resonant photonic structures formed by periodic, Fibonacci, and gradient sequences of quantum wells. The form and polarization of the reflected pulse are shown to be determined by the structure design and optical length. In structures with periodic quantum well arrangement, the response to ultrashort pulse is an optical signal with a sharp rise followed by an exponential decay or Bessel beats depending on the structure length. The duration of reflected pulses non-monotonically depends on the number of quantum wells reaching the minimum for a certain structure length which corresponds to the transition from superradiant to photonic-crystalline regime. We also study the conversion of pulse polarization in the longitudinal external magnetic field which splits the exciton resonance. Comparing periodic, Fibonacci, and gradient structures we show that the latter are more efficient for the conversion from linear to circular polarization.

Optical pulse propagation in dynamic Fabry–Perot resonators

We present a simple and intuitive model based on the impulse response of linear electrical systems for describing the propagation of optical pulses through a dynamic Fabry–Perot resonator whose refractive index changes with time. Our model shows that the adiabatic wavelength conversion process in resonators results from a scaling of the round-trip time with index changes. For pulses longer than the cavity round-trip time, we find that more energy can be transferred to the new wavelength when the input pulses are slightly detuned from the cavity resonance and the refractive index does not change too rapidly. In fact, the optimum duration of index changes scales with the photon lifetime of the resonator. We describe the evolution of the shape and spectrum of picosecond pulses inside a resonator under a variety of input conditions and with the magnitude and duration of index variations. We also apply our general theory to the case of pulses whose widths are shorter than the round-trip time and derive an analytical expression for the output field under quite general conditions. This analysis reveals a shifting of the spectral comb as well as compression of the temporal pulse train that depends on the both the magnitude and sign of the index change. Our results should find applications in the area of optical signal processing using resonant photonic structures.

Loss compensation in metal-dielectric structures in negative-refraction and super-resolving regimes

We study the influence of gain on negative refraction and super-resolution in transparent resonant metal-dielectric photonic band gap structures in the visible and near infrared ranges. We find that while the introduction of gain can compensate for losses caused by the excitation of surface waves, it also improves the resolving characteristics of the lens and leads to gain-tunable super-resolution.

Photonic valence/conduction subbands in optically generated photonic quantum wells: Tunable optical-delay line application

It has been shown that, in the absence of a control laser field, functional photonic superstructures can act as homogeneous photonic band gap structures formed via uniform corrugations of their background refractive indexes. When some sections of these structures are illuminated with such a laser, those sections become resonant (active) photonic band structures with higher refractive index contrast, forming photonic heterostructures. In this paper we study how by controlling the phase of quantum interference processes in such structures one can control alignment of such heterostructures, coherently generating photonic quantum wells with either conduction- or valencelike subbands (resonant transmission states). We show the energies of these subbands can be tuned by the control laser and demonstrate that their longitudinal mode profiles follow one-by-one correspondence with the envelope functions of the electron or hole subbands in electronic quantum well structures. In particular, we show how such photonic quantum wells can act as optically tunable time-delay lines, capable of increasing delay of a signal passing through them significantly via laser-induced control of optical confinements of the photonic subbands.

Infrared switching from resonant to passive photonic bandgaps: transition from purelyphotonic to hybrid electronic/photonic systems

Coherently controlled optical processes have been extensively studied in various systemsincluding atoms, quantum wells and quantum dots. In this study we investigate suchprocesses in Bragg multi-quantum well resonant (active) photonic bandgaps,wherein the dipole–dipole interwell interaction couples different quantum wellstogether, forming supperradiant exciton modes. Our results show that in suchsystems one can use an infrared laser beam to replace the collective superradiantmode with an electromagnetically induced transparency mode, demonstratinginfrared switching of an active photonic bandgap to a hybrid system. Such a hybridsystem consists of a passive photonic bandgap and an electromagnetically inducedtransparency band window superimposed on each other. A detailed study of the interplaybetween the collective and infrared-induced exciton excitations of quantum wells inBragg multi-quantum well resonant photonic bandgap structures is presented.

All-optical signal amplification in multiple-quantum-well resonant photonic bandgap structures

Using a microscopic many-particle theory, we predict all-optical amplification of low-intensity light pulses in resonant photonic bandgap structures realized by Bragg-spaced semiconductor multiple quantum wells. The discussed scheme is based on mirrorless parametric amplification.

Stopping, storing, and releasing light in quantum-well Bragg structures

We present a theoretical analysis of light propagation in one-dimensional resonant photonic bandgap structures (RPBGs). The analysis is aimed at evaluating the feasibility of controlled stopping, storing, and releasing of light pulses by parametric manipulation of the RPBG's bandstructure. First we lay the conceptual foundation of light-pulse delay by means of band structure control in infinite RPBGs, and then we contrast the idealized concepts with numerical results for realistic, finite-sized RPBGs. For a physical model for RPBGs, we use semiconductor quantum-well Bragg structures, but the general analysis is valid for a wider class of RPBG. We show that the usefulness of RPBGs for optical delay lines depends critically on the number of quantum wells and the dephasing and loss mechanisms in each unit cell of the RPBG, and we also outline optimization strategies in terms of spectral light characteristics as well as quasi-antireflection coating of the RPBGs.

All-optical spin-dependent polarization switching in Bragg-spaced quantum well structures

All-optical polarization switching is demonstrated in a resonant photonic band-gap structure consisting of Bragg-spaced quantum wells (BSQWs). The switch takes advantage of the large spin-dependent optical nonlinearities and the ultrafast recovery present in BSQWs to produce large throughputs (greater than 40%), high contrast ratios (greater than 40 dB), and large optical bandwidths (∼0.6THz), where both switching time and sample recovery time are control-pulse-width limited.