Semiconductor Photonic Crystals Research Articles

Temperature Dependence of Optical Bistability in Superconductor–Semiconductor Photonic Crystals Embedded with Graphene

We theoretically investigate the optical bistability in superconductor–semiconductor photonic crystals composed of graphene. The photonic crystals are symmetric to the center and arranged alternately by the superconductor (HgBa2Ca2Cu3O8+δ) and semiconductor (GaAs) layers. The system supports a defect mode, and graphene is located at the layer interface where the local electric field is the strongest. Consequently, the optical nonlinearity of graphene has been greatly enhanced, and low-threshold optical bistability can be achieved with an incident wavelength red-detuning to the defect mode. The upper and lower thresholds of bistability increase with the increase in the value of low environmental temperature, while the interval between the upper and lower thresholds decreases. This research has a potential application in temperature-controlled optical switches and temperature-controlled optical memory.

Pressure Sensing of Symmetric Defect Photonic Crystals Composed of Superconductor and Semiconductor in Low-Temperature Environment

We theoretically investigate the defect mode transmittance of light waves in superconductor–semiconductor photonic crystals and its pressure-sensing dependence. The photonic crystal is composed of alternating superconducting and semiconducting slabs and a defect locates at the center of this structure. Two trapezoid waveguides are fixed at both sides of the crystal, which induces the hydrostatic pressure applied and beams transmitted simultaneously. The resonant wavelength variation in the defect mode is directly proportional to the pressure applied on the system in the near-IR region, which can be utilized for linear pressure sensors in the cryogenic environment. Pressure sensitivity reaches a high value of 2.6 nm/GPa, which is higher than that in the study based on the reflection spectra. The sensitivity coefficient may be modulated by the environment temperature as well. This study has potential regarding pressure-light-wave sensors.

Design and analysis of Tbps all-optical gray code converter using photonic crystal-semiconductor optical amplifier-Mach–Zehnder interferometric structure

Future communication networks require the entire communication system to be all-optical to overcome the bandwidth constraints of electronics. All-optical devices play a vital role in supporting future networks, which demand a high speed of up to Tbps. An all-optical gray code converter operation was demonstrated numerically using a photonic crystal semiconductor optical amplifier (PhC-SOA) in a Mach–Zehnder interferometric (MZI) configuration at 1 Tbps for M-ary differential phase shift keying modulated binary and BCD inputs. The design achieved a very high extinction ratio of about 123.8 dB with a good quality factor value of about 45. The results show that PhC-SOA-based XOR and OR gates in the gray code converter design exhibits improved modulation features compared with traditional SOAs in our previous works.

Computational study of wavelength conversion based on XGM by photonic crystal semiconductor optical amplifier

In this paper, a numerical study of wavelength conversion based on cross-gain modulation (XGM) has been conducted for the first time using the photonic crystal semiconductor optical amplifier (PC-SOA). A PC-SOA and an optical filter have been used in this design. Nonlinear effects, such as carrier depletion (CD), carrier heating (CH), and spectral hole burning (SHB), have been included in the PC-SOA. The rate and propagation equations have been solved using the finite difference method (FDM). The optimal wavelength conversion based on XGM has been obtained in the PC-SOA through the application of 3.2fJ and 1.0pJ energies for the input and the continuous wave (CW) signals, respectively, and a 15mA injection current for the biasing. The effects of the injection current and input signal energies on wavelength conversion have also been investigated for further examination of the impact of the XGM mechanism on wavelength conversion. It has finally been demonstrated that the PC-SOA exhibits better conditions and performance than the conventional bulk SOA in wavelength conversion based on XGM. Furthermore, the PC-SOA provides a far more appropriate alternative than the bulk SOA for all-optical integrated circuits due to the smaller length of the device and the lower value of injected current.

Design and analysis of an all-optical NAND logic gate using a photonic crystal semiconductor optical amplifier based on the Mach–Zehnder interferometer structure

In this study, a high-speed all-optical NAND logic gate (AO-NAND-LG) was designed and numerically simulated. The simulation was performed using the photonic crystal-semiconductor optical amplifier (PC-SOA) structure based on the Mach–Zehnder interferometer and nonlinear cross-phase modulation mechanism. The input optical pulse sequence used in the design was the return-to-zero type. Moreover, two PC-SOAs were utilized in the design of the NAND-LG. The rate and propagation equations were solved using the finite difference method. The optimal mode was achieved for NAND-LG with an energy value of 2.2 fJ for input pulse trains A and B, and an injection current of 1 mA at a bit rate of 80 Gbps. Furthermore, the impacts of the pattern effect, conversion efficiency, extinction ratio, and gain recovery on the design of the AO-NAND-LG were analyzed for the first time in simulations to enhance the performance and efficiency of the PC-SOA. Furthermore, the results demonstrated that the PC-SOA exhibited better logical performance than the ordinary SOA, and it is a suitable candidate for integrated optical circuits because it is much shorter than the SOA.

Design and simulation of the all-optical XOR logic gate by XPM mechanism using photonic crystal semiconductor optical amplifier based on Mach–Zehnder interferometer

In the presented structure, the performance of the all-optical XOR logic gate (AO-XOR-LG) is investigated. The XOR-LG is designed and simulated using a photonic crystal semiconductor optical amplifier (PC-SOA) based on Mach–Zehnder interferometer (MZI) and cross-phase modulation (XPM) nonlinear mechanism. The input optical pulse train used in this simulation is the type of RZ (Return-to-Zero). The finite difference method (FDM) has been used to solve the rate and propagation equations. The effect of input signal energy, bias current, and group refractive index on the output signal and gain of the XOR-LG is studied. The optimal mode is obtained for the XOR-LG with a bit rate of 80 Gbps. Furthermore, for the first time, the effects of quality factor (QF), conversion efficiency (CE), extinction ratio (ER), pattern effect (PE), and gain recovery are simultaneously analyzed in the simulation to increase PC-SOA performance. According to the results, PC-SOA has a more reasonable logic performance than conventional SOA, and due to its much shorter length than SOA, it can be a much better choice for integrated optical circuits.

Fully integrated 3-bit all-optical analog to digital converter based on photonic crystal semiconductor optical amplifier

Integrating a photonic crystal based semiconductor optical amplifier (PhC-SOA) composed of InP/InGaAsP/InP heterostructure with eight PhC based channel drop filters (CDFs) based on an InGaAsP platform, we have designed a fully integrated all-optical 3-bit analog to digital converter (AO-ADC). A probe signal after passing through a 9-µm long PhC-SOA in the presence of an amplitude-modulated Gaussian pulse of 1.422 ps width and maximum energy of 37.2 fJ exhibited a 4.8-nm wavelength shift. The eight appropriately designed PhC-CDFs have coded the chirped signal into eight quantization levels. The numerical results show that the proposed structure can convert analog photonic signals into 3-bit digital output with no missing code at 10Gs/s. The proposed AO-ADC structure with a small footprint of 455 μm2, along with its ultra-low power consumption, can pave the way for the further development of the next-generation integrated photonic chips.

Recent Advances in Preparation and Applications of 3D Transition Metal Oxides Semiconductor Photonic Crystal

Nanostructured transition metal oxides (TMOs) semiconductor materials, whose photoelectric properties are significantly improved due to their nanostructures, have attracted more and more attention in recent years. As a functional material with periodic nanostructures and unique optical properties, photonic crystals (PhCs) have become an important option for nanostructuring semiconductor materials. The TMO semiconductor PhC (TMOPC), which is integrated by combining TMO with PhC, not only has the sensitivity of the TMO semiconductor to environmental stimulus, but also can improve the utilization rate of light and make the material have the optical response due to the optical modulation of PhC, such as slow light effect. The application of TMOPCs is widely promoted and expanded due to the improvement of its performance. Herein, this review summarizes the preparation methods of 3D TMOPCs in recent years and their main applications. The limitation and potential development of 3D TMOPCs in preparation and application are also discussed and prospected.

Use of four-wave mixing for designing and simulating an all-optical AND logic gate in a photonic crystal semiconductor optical amplifier

A simple method has been proposed to use four-wave mixing to design and simulate the all-optical AND logic gate in a photonic crystal semiconductor optical amplifier (PC-SOA) that is integrated with an ideal optical bandpass filter. The preferred logical function could be carried out in the proposed scheme with no use of a continuous-wave signal. Nonlinearities including carrier depletion, carrier heating, and spectral hole burning have been considered in the presented simulations. Furthermore, for improvement of the AND logic gate performance, the impacts of the pattern effect of the signals propagating in the PC-SOA medium, the input signal bit rate effects, and gain recovery have been extensively investigated. The findings demonstrated that the optimal output signal featuring 3-fJ energy and 2-mA injection current could be achieved at a bit rate of 50 Gbps.

An integrated 2-bit all optical analog to digital converter based on photonic crystal semiconductor optical amplifier

In this paper, by integrating InP/InGaAsP/InP Photonic crystal semiconductor optical amplifier (PhC-SOA) with photonic crystal channel drop filters (PhC-CDF), we present a novel fully integrated ultra-small low-power all-optical analog to digital converter (AO-ADC). The self-phase modulation in the PhC-SOA can shift the frequency of the Gaussian input pulse. The two output PhC-CDFs are designed in a way that appropriately codes the frequency-shifted pulse by the PhC-SOA, which consequently converts them to four desired digital output levels. The numerical results indicated that the center wavelength of an amplitude modulated Gaussian pulse with a center wavelength of 1551.228 nm, temporal pulse-width of 10.6 ps, and energy of 74.4 fJ can be shifted by 1.652 nm. This shift is accommodated by utilizing a PhC-SOA with a length of 9 µm and an injection current of 6.5 mA. The shifted pulse is then quantized and coded to the four digital levels of (00, 01, 10, 11) by two point-defect PhC-CDFs. The PhC-CDFs minimize the AO-ADC integral and differential nonlinearity (INL/DNL) errors by compensating for the effect of the nonlinear frequency shift induced by PhC-SOA. The proposed design offers a footprint of 142 µm2 AO-ADC working at 10 Gs/s.

Recent progress in topological waveguides and nanocavities in a semiconductor photonic crystal platform [Invited

Topological photonics provides a novel route for designing and realizing optical devices with unprecedented functionalities. Topological edge states, which are supported at the boundary of two photonic systems with different band topologies, enable robust light transport immune to structural imperfections and/or sharp bends in waveguides. Furthermore, the topological edge states are expected to revolutionize cavity-based optical devices such as lasers. Optical devices with built-in topological protection with a small footprint are fascinating as on-chip optical devices for low-loss and functional photonic integrated circuits. Semiconductor photonic crystals are promising platforms enabling the miniaturization of topological optical devices. Herein, we review the recent realizations of semiconductor topological photonic crystals. In particular, we discuss topological waveguides in valley photonic crystals, which have received increasing attention because of their simple realization. In addition, we provide recent demonstrations of topological nanocavities, which are another key component of topological nanophotonics. Progress in semiconductor topological photonic crystals will propel the use of topological photonic devices in various applications as well as deepen the understanding of topological photonic phenomena at the wavelength scale.

Photonic Crystal Optical Parametric Oscillator.

We report a new class of Optical Parametric Oscillators, based on a 20μm-long semiconductor Photonic Crystal Cavity and operating at Telecom wavelengths. Because the confinement results from Bragg scattering, the optical cavity contains a few modes, approximately equispaced in frequency. Parametric oscillation is reached when these high Q modes are thermally tuned into a triply resonant configuration, whereas any other parametric interaction is strongly suppressed. The lowest pump power threshold is estimated to 50 - 70μW. This source behaves as an ideal degenerate Optical Parametric Oscillator addressing the needs in the field of quantum optical circuits, paving the way to the dense integration of highly efficient nonlinear sources of squeezed light or entangled photons pairs.

Engineering of Broadband Nanoporous Semiconductor Photonic Crystals for Visible-Light-Driven Photocatalysis.

A new class of semiconductor photonic crystals composed of titanium dioxide (TiO2)-functionalized nanoporous anodic alumina (NAA) broadband-distributed Bragg reflectors (BDBRs) for visible-light-driven photocatalysis is presented. NAA-BDBRs produced by double exponential pulse anodization (DEPA) show well-resolved, spectrally tunable, broad photonic stop bands (PSBs), the width of which can be precisely tuned from 70 ± 6 to 153 ± 9 nm (in air) by progressive modification of the anodization period in the input DEPA profile. Photocatalytic efficiency of TiO2-NAA-BDBRs with tunable PSB width upon visible-NIR illumination is studied using three model photodegradation reactions of organics with absorbance bands across the visible spectral regions. Analysis of these reactions allows us to elucidate the interplay of spectral distance between red edge of TiO2-NAA-BDBRs' PSB, electronic bandgap, and absorbance band of model organics in harnessing visible photons for photocatalysis. Photodegradation reaction efficiency is optimal when the PSB's red edge is spectrally close to the electronic bandgap of the functional semiconductor coating. Photocatalytic performance decreases dramatically when the red edge of the PSB is shifted toward visible wavelengths. However, a photocatalytic recovery is observed when the PSB's red edge is judiciously positioned within the proximity of the absorption band of model organics, indicating that TiO2-NAA-BDBRs can harness visible electromagnetic waves to speed up photocatalytic reactions by drastically slowing the group velocity of incident photons at specific spectral regions. Our advances provide new opportunities to better understand and engineer light-matter interactions for photocatalysis, using TiO2-NAA-BDBRs as model nanoporous semiconductor platforms. These high-performing photocatalysts could find broad applicability in visible-NIR light harvesting for environmental remediation, green energy generation, and chemical synthesis.

A review on all-optical logic adder: Heading towards next-generation processor

In this paper few literatures on all-optical adders, reported approximately in last fifteen years, have been reviewed. Being the key element of arithmetic and logic unit (ALU), adder has attracted stirring attention of the researchers. The reviewed articles are primarily categorized into three broad sections based on the platforms utilized in designing all-optical adder namely semiconductor optical amplifier (SOA), plasmonics and photonic crystal (PhC). SOA based designs offer high contrast ratio between the output logic levels, however; at the cost of high response time and operating power. Plasmonic based designs provide miniaturized physical footprint of the devices owing to the tight optical confinement. Nevertheless, the process of fabrication involved with the plasmonic based designs along with the loss incurred at the metal are among the limiting features. In contrast, PhC based designs are much more advantageous owing to the notable characteristics of light propagation. The operating power and bandwidth of operation are also higher as compared to the other designs. Photonic crystal-based designs are further categorized into linear and nonlinear domains based on their operating principle. The design structures and performances have been summarized and a comparison is made. Some insights have been discussed leading to design of more efficient PhC based all-optical adders for next generation ultra-first optical processors.

Tunable filter based on the 1D photonic crystal within ultraviolet radiations

In the present study, we develop a one-dimensional semiconductor photonic crystal to control ultraviolet radiation. We study the transmittance spectra of incident light on the proposed structure in the ultraviolet regime. A photonic bandgap appears with a width of 95.2 nm. by changing the thickness parameters, it can reach up to 125.6 nm with appearing of new band gaps. The incident angle effect on the band gap’s width is apparent. The bandgap shifted to a lower wavelength region. So the proposed structure could be useful in preventing UV radiation from passing through it.

Ultrafast performance of all-optical AND and OR logic operations at 160 Gb/s using photonic crystal semiconductor optical amplifier

The light confined and controlled by photonic crystals (PCs) can be exploited to enhance the performance and reduce the size of semiconductor optical amplifiers (SOAs) in which they are embedded. By incorporating PCSOAs in a Mach-Zehnder interferometer, or using a PCSOA followed by a delayed interferometer, Boolean AND and OR gates are formed, respectively, whose performance when executed all-optically (AO) is thoroughly analyzed at 160 Gb/s. For this purpose, the variation of the quality factor against the critical data signal and PCSOA operating factors is examined and assessed when the effects of amplified spontaneous emission and working temperature are included to make the simulation more realistic. The results obtained from the conducted theoretical study suggest that leveraging the PCSOAs benefits of low absorption loss, suppressed undesirable nonlinear effects, low power consumption, and high power transmission favors realizing the considered AO gates at the target data rate. Compared to conventional SOAs, PCSOAs advanced technology allows to obtain better logic performance, as quantified by the achieved higher metrics values, and to render the practical implementation of the AO gates more feasible, since the requirements for the PCSOAs structural parameters and driving conditions become more relaxed.

One-way edge modes in truncated semiconductor photonic crystal at terahertz frequencies

Terahertz one-way edge modes in truncated photonic crystals (PhCs) are investigated theoretically. The PhC consists of a square array of air columns in a semiconductor. By applying an external dc magnetic field in the PhC, a band gap is generated by lifting the degeneracy point of the lowest two bands. Based on this band gap, the edge mode always exists in the truncated PhC for any boundary cutting, and it may propagate unidirectionally or bidirectionally, closely depending on the PhC boundary shape. It is shown that for the one-way edge mode, the PhC boundary cutting has a remarkable influence on the propagation length when the semiconductor loss is taken into account. A boundary structure is introduced into the PhC system for weakening the loss effect, and the propagation length of the one-way edge mode can be increased nearly by twice by optimizing the boundary parameters.

Surface and bulk plasmon-polaritons in semiconductor photonic crystals with embedded graphene sheets

A theoretical study is made for the bulk and surface plasmon-polaritons in one-dimensional semi-infinite layered semiconductor photonic crystals with graphene interlayers. The retarded dispersion relations are calculated in a general way and applied to two cases, depending on whether a graphene sheet is present or absent at the first interface of the semi-infinite structure. We apply the result to doped GaAs as the constituent material, considering the layers to be arranged in a periodic fashion with alternating layer thicknesses. Both s- and p-polarized modes are evaluated with the effects of retardation on the polaritons being included in the general expressions. Simplifications, particularly for the surface modes, are studied for the case when retardation effects are small. Through numerical examples, we illustrate the important role of the graphene sheets in modifying the plasmon-polariton properties (focusing on the region near the bulk plasma frequency). A strong dependence on the mode polarization is found.

Numerical analysis of four wave mixing in photonic crystal semiconductor optical amplifier

Abstract In this paper, we present a theoretical analysis of four-wave mixing (FWM) between short optical pulses in a photonic crystal semiconductor optical amplifier (PC-SOA). The proposed model is based on a nonlinear propagation equation by taking into account self-phase modulation (SPM), carrier density pulsations (CDP), carrier heating (CH), and spectral-hole burning (SHB). To analyse the FWM in a PC-SOA, pulse evolution in a temporal and spectral domain are investigated. Also, the optical fluid method is used in the photonic structure for design and engineering an appropriate bandwidth with constant group index to analyse the FWM mechanism. The bandwidth is designed in the L-Band region of telecommunication optical networks. Based on calculated results, it is depicted that for low energy short pulses, the conversion efficiency (CE) of PC-SOA is higher than conventional SOA. Furthermore, it is shown that, by increasing the injection current the CE is increased.

Computational study of pulse propagation in photonic crystal semiconductor optical amplifier

A theoretical analysis of photonic crystal semiconductor optical amplifier (PC-SOA) is presented. The proposed model is based on rate and propagation equations. The analysis is carried out using two input signal regimes of constant and Gaussian waves. To the best of the authors’ knowledge, temporal and spatial variation of picosecond pulses have not been previously investigated in active PC medium. The effect of injection current, group index, and amplifier length variation on the output signal and amplifier gain is investigated. Based on the results, temporal peak shift, chirp, and spectral width increased in low current regime compared to conventional SOAs. It is also demonstrated that short length PC-SOA can be used as a preamplifier in photonic integrated circuits.