Optimal parameters of monolithic high-contrast grating mirrors

In this Letter a fully vectorial numerical model is used to search for the construction parameters of monolithic high-contrast grating (MHCG) mirrors providing maximal power reflectance. We determine the design parameters of highly reflecting MHCG mirrors where the etching depth of the stripes is less than two wavelengths in free space. We analyze MHCGs in a broad range of real refractive index values corresponding to most of the common optoelectronic materials in use today. Our results comprise a complete image of possible highly reflecting MHCG mirror constructions for potential use in optoelectronic devices and systems. We support the numerical analysis by experimental verification of the high reflectance via a GaAs MHCG designed for a wavelength of 980 nm

Concept of Inverted Refractive-Index-Contrast Grating Mirror and Exemplary Fabrication by 3D Microprinting

Highly reflective mirrors are indispensable components in a variety of state-of-the-art photonic devices. Typically used, bulky, multi-layered distributed Bragg (DBR) reflectors are limited to lattice-matched semiconductors or nonconductive dielectrics. Here, we introduce an inverted refractive-index-contrast grating (ICG), as compact, single layer alternative to DBR. In the ICG, a subwavelength one-dimensional grating made of a low refractive index material is implemented on a high refractive index cladding. Our numerical simulations show that the ICG provides nearly total optical power reflectance for the light incident from the side of the cladding whenever the refractive index of the grating exceeds 1.75, irrespective of the refractive index of the cladding. Additionally, the ICG enables polarization discrimination and phase tuning of the reflected and transmitted light, the property not achievable with the DBR. We experimentally demonstrate a proof-of-concept ICG fabricated according to the proposed design, using the technique of 3D microprinting in which thin stripes of IP-Dip photoresist are deposited on a Si cladding. This one-step method avoids laborious and often destructive etching-based procedures for grating structuration, making it possible to implement the grating on any arbitrary cladding material

Time-dependent laser cavity perturbation theory: Exploring future nano-structured photonic devices in semi-analytic way

We present a theoretical framework, which successfully combines two different fields of photonics: i) the laser rate equations and ii) the cavity perturbation theory, focusing particularly on micro-cavity lasers with optical anisotropies. Our approach is formally analogous to quantum-mechanical time-dependent perturbation theory, in which however the gain medium and permittivity tensor distribution are perturbed instead of the Hamiltonian. Using the general vectorial Maxwell-Bloch equations as a starting point, we derive polarization-resolved coupled-mode equations, in which all relevant geometric and anisotropy-related laser parameters are imprinted in its coefficients. Closed-form coupled-mode equations offer physical insights like rate equations approaches and the precision comparable to brute-force numeric routines, thus being the time-saving alternative to finite-difference time-domain methods. The main advantage is that one calculates numerically the shapes of cold-cavity modes used to derive coupled-mode equations for one set of parameters and the broad landscape of parameters of interest is further studied in a perturbative way. This makes the method particularly interesting for semi-analytic studies of state-of-art devices such as the photonic crystal lasers, the liquid-crystal lasers or specifically spin-lasers, in which the interplay between injected spin and cavity birefrigence creates very promising platform for ultrafast data transfer technologies.Web of Science40144745473

Spatial-Mode Discrimination in Guided and Antiguided Arrays of Long-Wavelength VCSELs

Three means of optical confinement imposed on InAlGaAs/InP 1.3 mu m VCSEL arrays are investigated with self-consistent numerical model of laser operation. Laterally patterned tunnel junction (TJ), in-build guiding realized with air-gap patterning, and antiguiding schemes are investigated and optimized to achieve single-mode operation. The analysis shows that mode discrimination in laterally patterned TJ is very responsive to the injected current, the air-gap patterning reduces influence of the working conditions and supports multimode operation, and finally, antiguiding schemes provide single-mode operation for prescribed geometrical design

Multi-dimensional modeling and simulation of semiconductor nanophotonic devices

Self-consistent modeling and multi-dimensional simulation of semiconductor nanophotonic devices is an important tool in the development of future integrated light sources and quantum devices. Simulations can guide important technological decisions by revealing performance bottlenecks in new device concepts, contribute to their understanding and help to theoretically explore their optimization potential. The efficient implementation of multi-dimensional numerical simulations for computer-aided design tasks requires sophisticated numerical methods and modeling techniques. We review recent advances in device-scale modeling of quantum dot based single-photon sources and laser diodes by self-consistently coupling the optical Maxwell equations with semiclassical carrier transport models using semi-classical and fully quantum mechanical descriptions of the optically active region, respectively. For the simulation of realistic devices with complex, multi-dimensional geometries, we have developed a novel hp-adaptive finite element approach for the optical Maxwell equations, using mixed meshes adapted to the multi-scale properties of the photonic structures. For electrically driven devices, we introduced novel discretization and parameter-embedding techniques to solve the drift-diffusion system for strongly degenerate semiconductors at cryogenic temperature. Our methodical advances are demonstrated on various applications, including vertical-cavity surface-emitting lasers, grating couplers and single-photon sources

Numerical modeling of arrow-VCSELs with oxide island

International audienceWe study optical properties of ARROWVCSEL, in which the anti-resonant effect is provided by an oxide island located inside the optical cavity manufactured with planar oxidation. We show how this effect alters the nature of the laser modes, by providing qualitative change in the optical field profile. Such strong change can be used to improve laser modal discrimination in order to achieve single-mode emission

Porównanie metod symulacji właściwości optycznych laserów VCSEL

Institute of Physics, Lodz University of TechnologyInstytut Fizyki, Politechnika ŁódzkaThis paper presents the differences arising from the use of scalar (Effective Frequency Method) and vector (Fourier’s and Bessel’s Admittance Methods) calculation methods in optical analysis of arsenide Vertical-Cavity Surface-Emitting Lasers (VCSELs). Discussed results demonstrate that the vector methods are more accurate than the scalar one, but also they are more time consuming. By comparing two vector methods, it can be seen that the Bessel’s Admittance Method allows to obtain similar qualitatively and quantitatively results in a slightly shorter time. The calculations were performed for structures with varied aperture radius and its location in the resonant cavity. Moreover, this paper includes the comparison of calculation results for a structure in which there are layers with gradually changing refractive index, and the structure in which these layers are replaced by a layer with a constant average refractive index.W niniejszej pracy przedstawiono wyniki obliczeń propagacji emitowanej fali elektromagnetycznej (jej długości i czasu życia fotonów) dla arsenkowego lasera typu VCSEL. Celem pracy jest przedstawienie różnic płynących z zastosowania skalarnych i wektorowych metod obliczeniowych. Omówione wyniki pokazują, iż metody wektorowe są dużo dokładniejsze od metody skalarnej, ale jednocześnie bardziej czasochłonne. Obliczenia przeprowadzono dla struktur różniących się wartością średnicy apertury oraz jej położeniem wzdłuż wnęki rezonansowej. Ponadto metodą skalarną wykonano obliczenia dla struktury, w której występują warstwy o gradientowo zmieniającym się współczynniku załamania, oraz dla struktury, w której warstwy te zastąpiono warstwą pośrednią o stałym współczynniku załamania. Celem pracy jest również pokazanie różnic w wynikach otrzymanych dla powyższych przypadków

Podfalowe siatki dyfrakcyjne o wysokim kontraście współczynnika załamania światła jako sensory optyczne

Subwavelength high contrast gratings (HCG) can be used as high reflective mirrors and can be used as mirrors of vertical-cavity surface-emitting lasers. HCG mirrors can be designed in such a way that they are extremely sensitive to environmental changes - changes in the refractive index of ambient substance or changes in the absorption coefficient may cause changes in mirror reflectivity. This phenomenon can be used to detect liquids and gases. In this paper we present analysis of HCG properties. We consider the various HCG mirror designs and the possibilities of detecting gases and liquids.Zwierciadła HCG to podfalowe siatki dyfrakcyjne wykonane z materiału o wysokim współczynniku załamania światła. Mogą one zostać wykorzystane jako zwierciadła o wysokiej odbijalności w laserach typu VCSEL. Zwierciadła HCG można zaprojektować w taki sposób, że będą wyjątkowo czułe na zmiany współczynnika załamania światła lub współczynnika absorpcji w otoczeniu zwierciadła. Zmiana tych parametrów powoduje zmianę odbijalności zwierciadła HCG. Zjawisko to może być wykorzystane w sensorach optycznych. W niniejszej pracy prezentujemy analizę właściwości zwierciadeł HCG. Rozważamy różne struktury zwierciadeł HCG i pokazujemy, że mogą być one wykorzystane do detekcji gazów i cieczy

Numerical Methods for modeling Photonic-Crystal VCSELs

We show comparison of four different numerical methods for simulating Photonic-Crystal (PC) VCSELs. We present the theoretical basis behind each method and analyze the differences by studying a benchmark VCSEL structure, where the PC structure penetrates all VCSEL layers, the entire top-mirror DBR, a fraction of the top-mirror DBR or just the VCSEL cavity. The different models are evaluated by comparing the predicted resonance wavelengths and threshold gains for different hole diameters and pitches of the PC. The agreement between the models is relatively good, except for one model, which corresponds to the effective index method. The simulation results elucidate the strength and weaknesses of the analyzed methods; and outline the limits of applicability of the different models