Semiconductor Photonic Crystals Research Articles

160 Gb/s photonic crystal semiconductor optical amplifier-based all-optical logic NAND gate

The performance of an ultra-fast all-optical logic NOT-AND gate using photonic crystal semiconductor optical amplifiers (PCSOA)-based Mach–Zehnder interferometers is numerically analysed and investigated. The dependence of the quality factor (Q-factor) on the input signals’ and PCSOA operating parameters is examined, with the impact of amplified spontaneous emission included so as to obtain realistic results. The achieved Q-factor is 18 at 160 Gb/s, which is higher than when using conventional SOAs.

A multi-channel optical filter by means of one dimensional n doped semiconductor dielectric photonic crystals

In this paper, I have designed a multi-channel optical filter through a broad band of IR regions using one dimensional n doped semiconductor dielectric photonic crystals. The modeling is essentially based on the plasma model and the characteristic matrix method. The numerical results investigate the significant effect of the doping impurity concentration on the permittivity of the semiconductor layer. Thus, the transmittance characteristics of my design could be significantly controlled by means of such parameter. The role played with some parameters such as the thickness of the semiconductor layer, the thickness of the dielectric material and the index of refraction of the dielectric material on the transmittance properties of the proposed filter is considered here. The designed structure may be useful in the field of photonics and the optical communications as a multi-channel optical filter especially through a broad band of IR regions.

All optical switching and associated technologies: a review

Optical computation is the most desirable technology that enhances the speed, data transmission rate and processing power by replacing the electronics with the optical switches. Optical switching is efficiently performed in high speed signal processing by all optical gates. This paper reviews the progressive development of the optical switching technology, highlights the different technologies of all optical gates and other switching circuits in all optical processing. Basic gates and other logic circuits in optical computing based on nonlinear regimes using semiconductor optical amplifier (SOA), fiber and photonic crystals are discussed, compared and the challenges along with future direction is outlined.

Effects of hydrostatic pressure, temperature and angle of incidence on the transmittance spectrum of TE mode in a 1D semiconductor photonic crystal

In this paper, we study the effects of hydrostatic pressure, temperature and angle of incidence on the transmittance spectrum of TE mode of a one-dimensional photonic crystal, using the transfer-matrix method. We consider that the crystal is formed by alternated layers of air and GaAs, with the dielectric constant of GaAs as a function of the temperature and pressure applied. We found that the spectrums dependence on temperature is negligible, the optical response of the system is due mainly to the pressure applied. When increasing the hydrostatic pressure, the spectrum shifts to a short-wavelength, which is caused by the decrease of the dielectric constant of GaAs. These results agree with the electromagnetic variational theorem. We also found if the angle of incidence of the modes increases, the band width increases compared to the normal incidence modes.

The Effect of the Electron Tunneling on the Photoelectric Hot Electrons Generation in Metallic-Semiconductor Nanostructures

Semiconductor photonic crystals (MSPhC) were used to convert solar energy into hot electrons. An experimental model was designed by using metallic semiconductor photonic crystals (MSPhC). The designed MSPhC is based on TiO2/Au schottky contact. The model has similar nanocavity structure for broad gold absorption, but the materials on top of the cavity were changed to a metal and a semiconductor in order to collect the hot electrons. Detailed design steps and characterization have shown a broadband sub-bandgap photoresponse at a wavelength of 590 nm. This is due to the surface plasmon absorption by the wafer-scale Au/TiO2 metallic-semiconductor photonic crystal. Analytical calculation of the hot electron transport from the Au thin layer to the TiO2 conduction band is discussed. This theoretical study is based on the quantum tunneling effect. The photo generation of the hot electrons was undertaken at different wavelengths in Au absorber followed by tunneling through a schottky barrier into a TiO2 collector. The presence of a tunnel current from the absorber to the collector under illumination, offers a method to extract carriers from a hot-electron distribution at few bias voltages is presented in this study. The effects of doping different concentrations of the semiconductor on the evolution of the current characteristics were also investigated and discussed. The electrical characteristics were found to be sensitive to any change in the thickness of the barrier.

Performance analysis of all-optical XOR gate with photonic crystal semiconductor optical amplifier-assisted Mach–Zehnder interferometer at 160 Gb/s

The photonic crystal (PC) can be used to prohibit, confine, or control the propagation of light in a photonic band-gap. The performance of an ultrafast exclusive disjunction (XOR) gate-implemented with a photonic crystal semiconductor optical amplifier (PC-SOA)-assisted Mach–Zehnder interferometer (MZI) is numerically investigated and analyzed at a data rate of 160 Gb/s. The impact of the data signals and PC-SOA’s critical parameters on the output quality factor (Q-factor) is examined and assessed. The simulation results demonstrate that the XOR gate which is based on the proposed scheme is capable of operating at the target data rate with logical correctness and high quality. This is achieved with better performance than when having conventional SOAs in the MZI, which justifies employing PC-SOAs as nonlinear elements.

低垂直发散角高亮度光子晶体半导体激光器

低垂直发散角高亮度光子晶体半导体激光器

Simulation Studies on Semiconductor Photonic Crystal Using Photonic Bandgap Analysis: A Realization of Optical Mirror

In this research, we attempt to envisage the mirror application using semiconductor photonic crystal with the help of photonic bandgap analysis. The photonic bandgap of photonic crystal structure is simulated using plane wave expansion method, where photonic crystal is realized by 2D triangular photonic crystal structure with gallium arsenide as background material having periodic air holes. Simulation result revealed that both lattice spacing of crystal structure and radius of air holes play vital role in realizing optical mirror. It is observed that photonic band gap of the above structure is found, if radius of air hole varies from 16 nm to 50 nm for lattice constant of 100 nm . It is also seen that photonic band gap is found if lattice spacing varies from 200 nm to 650 nm for radius of air hole of 100 nm.

Characteristics of strain-sensitive photonic crystal cavities in a flexible substrate

High-index semiconductor photonic crystal (PhC) cavities in a flexible substrate support strong and tunable optical resonances that can be used for highly sensitive and spatially localized detection of mechanical deformations in physical systems. Here, we report theoretical studies and fundamental understandings of resonant behavior of an optical mode excited in strain-sensitive rod-type PhC cavities consisting of high-index dielectric nanorods embedded in a low-index flexible polymer substrate. Using the three-dimensional finite-difference time-domain simulation method, we calculated two-dimensional transverse-electric-like photonic band diagrams and the three-dimensional dispersion surfaces near the first Γ-point band edge of unidirectionally strained PhCs. A broken rotational symmetry in the PhCs modifies the photonic band structures and results in the asymmetric distributions and different levels of changes in normalized frequencies near the first Γ-point band edge in the reciprocal space, which consequently reveals strain-dependent directional optical losses and selected emission patterns. The calculated electric fields, resonant wavelengths, and quality factors of the band-edge modes in the strained PhCs show an excellent agreement with the results of qualitative analysis of modified dispersion surfaces. Furthermore, polarization-resolved time-averaged Poynting vectors exhibit characteristic dipole-like emission patterns with preferentially selected linear polarizations, originating from the asymmetric band structures in the strained PhCs.

Chaos in the honeycomb optical-lattice unit cell.

Natural and artificial honeycomb lattices are of great interest because the band structure of these lattices, if properly constructed, contains a Dirac point. Such lattices occur naturally in the form of graphene and carbon nanotubes. They have been created in the laboratory in the form of semiconductor 2DEGs, optical lattices, and photonic crystals. We show that, over a wide energy range, gases (of electrons, atoms, or photons) that propagate through these lattices are Lorentz gases and the corresponding classical dynamics is chaotic. Thus honeycomb lattices are also of interest for understanding eigenstate thermalization and the conductor-insulator transition due to dynamic Anderson localization.

Epitaxial growth of three dimensionally structured III-V photonic crystal via hydride vapor phase epitaxy

Three-dimensional (3D) photonic crystals are one class of materials where epitaxy, and the resultant attractive electronic properties, would enable new functionalities for optoelectronic devices. Here we utilize self-assembled colloidal templates to fabricate epitaxially grown single crystal 3D mesostructured GaxIn1−xP (GaInP) semiconductor photonic crystals using hydride vapor phase epitaxy (HVPE). The epitaxial relationship between the 3D GaInP and the substrate is preserved during the growth through the complex geometry of the template as confirmed by X-ray diffraction (XRD) and high resolution transmission electron microscopy. XRD reciprocal space mapping of the 3D epitaxial layer further demonstrates the film to be nearly fully relaxed with a negligible strain gradient. Fourier transform infrared spectroscopy reflection measurement indicates the optical properties of the photonic crystal which agree with finite difference time domain simulations. This work extends the scope of the very few known methods for the fabrication of epitaxial III-V 3D mesostructured materials to the well-developed HVPE technique.

Tunability of two dimensional n-doped semiconductor photonic crystals based on the Faraday effect.

In this paper, we theoretically investigate the effect of an external magnetic field on the properties of photonic band structures in two-dimensional n-doped semiconductor photonic crystals. We used the frequency-dependent plane wave expansion method. The numerical results reveal that the external magnetic field has a significant effect on the permittivity of the semiconductor materials. Therefore, the photonic band structures can be strongly tuned and controlled. The proposed structure is a good candidate for many applications, including filters, switches, and modulators in optoelectronics and microwave devices.

Long-range surface plasmon amplification with current injection on a one-dimensional photonic crystal surface.

A one-dimensional (1D) semiconductor photonic crystal (PC) structure with a terminal metal nanofilm, supporting propagation of long-range surface plasmons (LRSPs), is considered as an LRSP amplifier with current pumping. Current is injected to an active region through the metal nanofilm from one side and doped semiconductor layers from the other side. The propagation length of LRSP waves in such 1D PC structures reaches several millimeters, and therefore, a gain as low as 10 cm(-1) is enough to compensate for attenuation and amplify LRSPs. A unique advantage of this structure is that the refractive index of LRSP wave is very close to unity. As a result, no return reflection to semiconductor occurs during the edge-emission of LRSP to air, and this enhances the light extraction efficiency from semiconductor light sources such as edge-emitting superluminescent diodes and light-emitting diodes (LEDs). Optical feedback may be incorporated in this LRSP amplifier by grating deposition on the external side of the metal nanofilm, and LRSP lasing (i.e., long-range SPASER) may be realized without the use of complicated "etch-and-regrow" processes.

Tunable omnidirectional absorber and mode splitter based on semiconductor photonic crystal

In this paper, the properties of one-dimensional (1D) photonic crystals (PCs) composed of the semiconductor (GaAs) and dielectric layers are theoretically investigated by the transfer matrix method (TMM). The absorption of semiconductor layers is investigated theoretically. Due to the magneto-optical Voigt effect, the dielectric constant of the semiconductor is modified differently in different modes and frequency ranges. If the frequency range of the incident wave is larger than the plasma frequency, TE and TM modes of the incident wave will be absorbed in a wide incident angle. TM wave will be absorbed but TE wave will be reflected while the frequency range is less than the plasma frequency. The absorption of semiconductor can also be tuned by varying the external magnetic field. The proposed PCs have a reconfigurable application to design a tunable omnidirectional absorber and mode splitter at same time.

Enhanced backscattering for infrared detection using photonic crystal based flat lens

An n=-1 flat lens based on photonic crystal semiconductor technology is evaluated for infrared detection purposes. The idea consists in exploiting the backscattered waves of an incident plane wave impinging on a target placed in the focal region of a flat lens. It is shown that subwavelength detection of micronic dielectric targets can be obtained at 1.55 μm using the double focus of reflected waves induced by negative refraction. Complex relations among the intrinsic nature, the shape and size of the target, and detection efficiency are interpreted in terms of target eigenmode excitation. Reflectivity is modulated by the intrinsic mode nature, transverse, circular, or longitudinal, with an enhancement of the detection sensitivity in the case of whispering-gallery modes. It is believed that such a study paves the way to the definition of original noninvasive infrared sensors.

Magnetooptical Effects in Wave Properties for a Semiconductor Photonic Crystal at Near-Infrared

We investigate the magnetooptical effects in near-infrared wave properties for a semiconductor-based photonic crystal (PC) containing <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> -type InSb. We find that the static magnetic field serves as an externally switching and tuning agent in the wave transmission near 1.54 μm. With the applied static magnetic field, an additional small transmission gap, which does not appear in the absence of static magnetic field, can be opened up. The position of this gap can also be further tuned by the variation in this static field. The analytical results near this wavelength reveal that such a semiconductor PC can work as a magnetically tunable notch filter, which will be informative and of technical use to signal processing in optical communications.

Ultrafast all-optical switching in one-dimensional semiconductor–polymer hybrid nonlinear photonic crystals with relaxing Kerr nonlinearity

The achievement of ultrafast all-optical switching on chip is a fundamental issue of all-optical integration. A feasible and promising method for this is to combine semiconductor photonic crystals with highly nonlinear polymer materials to form the hybrid nonlinear photonic crystal. In this paper we numerically investigate the femtosecond dynamic response of all-optical switching based on the effect of band gap edge shift in one-dimensional (1D) semiconductor–polymer hybrid nonlinear photonic crystal (NPC) structures. Taking into account the Kerr relaxation time of the polymer and semiconductor materials simultaneously, the introduction of highly nonlinear polymer materials with femtosecond relaxation time can realize all-optical switching in the femtosecond range in spite of the low response speed of the semiconductor materials. The physical origin is the large and ultrafast response Kerr nonlinearity of the polymer materials and this is proved by examining the dependence of switching time on the relaxation speed of the polymer materials. The results can be extended to 2D and 3D NPC structures.

Pressure, temperature and plasma frequency effects on the band structure of a 1D semiconductor photonic crystal

In this work using the transfer-matrix formalism we study pressure, temperature and plasma frequency effects on the band structure of a 1D semiconductor photonic crystal made of alternating layers of air and GaAs. We have found that the temperature dependence of the photonic band structure is negligible, however, its noticeable changes are due mainly to the variations of the width and the dielectric constant of the layers of GaAs, caused by the applied hydrostatic pressure. On the other hand, by using the Drude's model, we have studied the effects of the hydrostatic pressure by means of the variation of the effective mass and density of the carriers in n-doped GaAs, finding firstly that increasing the amount of n-dopants in GaAs, namely, increasing the plasma frequency, the photonic band structure is shifted to regions of higher frequencies, and secondly the appearance of two regimes of the photonic band structure: one above the plasma frequency with the presence of usual Bragg gaps, and the other, below this frequency, where there are no gaps regularly distributed, with their width diminishing with the increasing of the plasma frequency as well as with the appearance of more bands, but leaving a wide frequency range in the lowest part of the spectrum without accessible photon states. Also, we have found characteristic frequencies in which the dielectric constant equals for different applied pressures, and from which to higher or lower values the photonic band structure inverts its behavior, depending on the value of the applied hydrostatic pressure. We hope this work may be taken into account for the development of new perspectives in the design of new optical devices.

Optical amplification based on slow light effects in the photonic crystal waveguide

AbstractOptical amplification is demonstrated in a slab photonic crystal waveguide (PCW). Nonlinear dispersive gain FDTD and traveling‐wave rate equation method (TWRE) are used to design a photonic crystal semiconductor optical amplifier (PC‐SOA). Optical amplification based on slow light of PCW can be obtained not only in theory but also in experiment. In the C band, the gain of more than 10 dB is obtained in a 20‐μm long PC‐SOA sample. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2997–3001, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26419

Design of Photonic Crystal Semiconductor Optical Amplifier With Polarization Independence

Slow-light effects in photonic crystal (PC) waveguides can enhance light-mater interaction near the photonic band edge, which can be used to design a short cavity length semiconductor optical amplifier (SOA). In this paper, a novel SOA based on slow-light effects in PC waveguides (PCSOA) is presented. To realize the amplification of the optical signal with polarization independence, a PCSOA is designed with a compensated structure. The cascaded structure leads to a balanced amplification to the TE and TM polarized light.