# Oral51 Videos

We theoretically investigate cascade Raman generation in bismuth-modified tungsten-tellurite glass microlasers, for the first time for microcavities based on TeO2 glasses. The calculated results demonstrate the opportunities of CW Raman generation in the near-IR and mid-IR ranges with CW pump at the wavelength of 1.55 μm. The predicted wavelengths are 1.81 µm, 2.17 µm, 2.70 […]

### LD02 – Microscopic modeling of interface roughness scattering and application to the simulation of quantum cascade lasers

The theory of interface roughness (IFR) scattering in semiconductor heterostructures is well established in the case of idealized abrupt interfaces. However, in reality, interfaces have a finite width, i.e. interfaces are graded. In such case, the effect of interface roughness, i.e. the breaking of in-plane invariance, a general framework has been lacking to describe the […]

### IS02 – Exploring modern alternatives to the Whittaker-Shannon-Nyquist sampling theorem in THz Spectroscopy

We present simulations for a THz cross-correlation spectroscopy (THz-CCS) optical system. The aim is using compressed sensing (CS) to reconstruct the THz signal from a random under sampling of the signal and potentially replacing a delay stage unit of the THz-CCS system to increase robustness and cost-effectiveness of the optical system. We present results from […]

### IS01 – Network Authentication with Synchronized Chaotic Lasers

We numerically study a hardware method for network authentication, where a pair of matched (twins) chaotic lasers generate the same chaos when they synchronize, being subject to the same optical injection from a third chaotic laser. One of the lasers is in the secure environment, the other in the unsecure environment, and authorization is granted […]

### LD09 – Simulation of the Spectral Behavior in High-Power Distributed Feedback Lasers above Threshold

We report on the simulations of mode hopping behavior in semiconductor distributed feedback lasers with asymmetric facet reflectivities above threshold and its dependence on the phase between the grating and the high reflective facet.

### LED01 – First-principles computation of charge-carrier recombination coefficients in optoelectronic materials

Charge-carrier recombination plays a decisive role in determining the efficiency of optoelectronic materials and devices, but their accurate experimental measurements and interpretation are challenging. In this context, first-principles computation of charge-carrier recombination coefficients is particularly useful. It allows not only rigorous computation of the recombination rates, but also intuitive interpretation of the microscopic recombination mechanisms […]

### MM01 – Rigorous modal analysis of micro or nanoresonators

The most general motion of a system is a superposition of its normal modes, or eigenstates. We report our recent developments of a rigorous modal analysis of electromagnetic resonators, which is accurate even for geometries that have not been analyzed so far, e.g. 3D resonators made of dispersive media and placed in non-homogeneous backgrounds (on […]

### P02 – Modal properties of dielectric bowtie cavities with deep sub-wavelength confinement

We present a quasinormal mode analysis of a dielectric bowtie cavity with deep sub-wavelength confinement. The cavity – which is based on an inverse design by topology optimization – exhibits a remarkable sensitivity to local shape deformations, which we show to be well described by perturbation theory.

### D05 – Mode-Guided Infrared Absorption in Ge/SiO2 Grating for Large-Angle and Broadband Photodetection

The numerical simulation of the electromagnetic properties of the Ge/SiO2 grating structure with bottom distributed Bragg reflector. With mode guiding in Ge, the structure exhibits an absorption angle of 100° and broadband behavior from 1300 to 1500 nm.

### D03 – 3D multiphysics transient modeling of vertical Ge-on-Si pin waveguide photodetectors

We report transient simulations of Ge-on-Si vertical pin waveguide photodetectors (WPDs), where the optical generation term used by the time-domain model is the FDTD solution of the electromagnetic problem treated as a spatially-distributed pulsed signal. This approach, validated against experimental measurements of the frequency response, paves the way to future studies of the dynamic response […]

### IS04 – All-optical AND Logic Gate Based on Semiconductor Optical Amplifiers for Implementing Deep Recurrent Neural Networks

The development of optical logic gates is a key factor for enabling next generation of computations in the context of Deep Learning and Quantum Computing. In this work, we introduce a scheme for the implementation of an all-optical AND logic gate, which makes use of semiconductor optical amplifiers (SOA) in cross-phase modulation configuration combined with […]

### MM06 – Dual-Potential Finite-Difference Technique for Computational Electrodynamics

We present a finite-difference time-domain (FDTD) technique suitable for coupling with quantum-transport solvers. We derive first-order equations for the electric and magnetic vector potentials and the electric scalar potential which, upon the adoption of the Coulomb gauge, decouple into solenoidal and irrotational equation sets and are sourced by the solenoidal and irrotational parts of the […]

### LD08 – Modeling of THz Comb Emission in Difference-Frequency Quantum Cascade Lasers

The generation of terahertz (THz) frequency comb emission by intracavity difference frequency generation (DFG) in a mid-infrared (mid-IR) quantum cascade laser (QCL) is a promising alternative to direct THz QCL frequency comb generation. Concerning their room temperature operation capabilities, these devices are well suited for applications in rotational molecular spectroscopy and sensing. In order to […]

### SC01 – Built-in electric field in irregular morphologies of bulk-heterojunction solar cells

This paper theoretically analyzes the built-in electric field distribution in bulk heterojunction solar cells. The approach proposed leads to explore the impact of regular and irregular morphologies on the performance of these devices. The width of the depletion region at the donor-acceptor interface is set by the doping concentration. The proposed analysis resulted in the […]

### MM03 – Implementation of Partially Reflecting Boundary Conditions in the Generalized Maxwell-Bloch Equations

Perfectly matched layer (PML) boundary conditions have been used for several decades for the simulation of open domains within the finite difference time domain (FDTD) method. In this paper, we report on a new PML-based partially reflecting boundary condition for the generalized Maxwell-Bloch equations that enables setting a certain value of reflectance R at the […]

### MM04 – Simulation of ac conductivity of monolayer MoS2 at terahertz frequencies

We present a multiphysics numerical tool for calculating the terahertz (THz) conductivity of transition-metal dichalcogenides (TMDs). The tool combines the ensemble Monte Carlo (EMC) technique for carrier transport with a three-dimensional finite-difference-time-domain (FDTD) solver for electromagnetic fields. We use the coupled EMC–FDTD technique to calculate the frequency-dependent conductivity in the terahertz range for monolayer MoS2, […]

### MM02 – Carrier transport in (In,Ga)N quantum well systems: Connecting atomistic tight-binding electronic structure theory to drift-diffusion simulations

Understanding the impact of the alloy microstructure on carrier transport in (In,Ga)N/GaN quantum well systems is important for aiding device design. We study the impact that alloy fluctuations have on uni-polar carrier transport for both electrons (n-i-n junction) and holes (p-i-p junction) using a multiscale framework. To do so we connect an atomistic tight-binding model […]

### MM05 – Comparison of flux discretizations for varying band edge energies

Recently, a multiscale framework was developed where drift-diffusion is combined with atomistic tight-binding models. A naive flux discretization was proposed to tackle the problem of heavily fluctuating band edge energies which does not take into account mathematical complications. Here we would like to present several alternatives and compare them.

### P03 – Numerical Simulations on Quantum Noise Squeezing for Soliton-like Pulses in Optical Fiber

Generation of light with nonclassical properties, such as squeezed light, has gathered a lot of attention because of possible uses in such areas as quantum state engineering, quantum imaging, continuous variable quantum computing, and detection of gravitational waves. Squeezed light is generally produced by transporting light through a nonlinear medium. One such media is Kerr-nonlinear […]

### MM10 – Full-Vectorial Meshfree Finite Cloud Mode Solver for Fused Fiber-Optic Couplers

A novel full-vectorial meshfree finite cloud mode solver is proposed for analysis of fused optic-fiber couplers, in which the curvilinear coordinate mapping technique is used to map a cloud with curved interface onto a unit square. Numerical results are compared with prior analysis using the finite difference method, showing the validity and utility of the […]

### LD06 – Relative intensity noise of injection-locked epitaxial quantum dot laser on silicon

This work investigates the relative intensity noise (RIN) characteristics of quantum dot (QD) lasers epitaxially grown on silicon subject to the optical injection. The effect of threading dislocation (TD), which acts as nonradiative recombination centers in the Shockley-Read-Hall (SRH) process, is considered in the rate equation model. The results reveal that the RIN is enhanced […]

### D01 – Non-Uniform Time-Stepping For Fast Simulation of Photodetectors Under High-Peak-Power, Ultra-Short Optical Pulses

A novel non-uniform time-stepping procedure is developed to reduce the memory usage and simulation time—by two orders of magnitude—of photodetectors when detecting high-peak-power, ultra-short optical pulses. The proposed procedure can be used in other marching-on-in-time solvers to achieve the same for the simulations dealing with ultra-short pulses.

### MM08 – Data-driven doping reconstruction

To reconstruct doping profiles via opto-electronic techniques (e.g. LBIC and LPS), we formulate an inverse problem based on the van Roosbroeck system. To solve it, we use neural networks fed with data created from efficient implementations of the forward model. We discuss errors of the reconstructed doping profiles as well as their robustness with respect […]

### NM02 – Impact of random alloy fluctuations on the electronic and optical properties of c-plane AlxGa1−xN/AlN quantum wells

We present a theoretical study of the electronic and optical properties of c-plane AlxGa1−xN/AlN quantum wells emitting in the ultraviolet-A (UV-A) to UV-C spectral range. Special attention is paid to the impact of alloy fluctuations on the results. We find that random alloy fluctuations in (Al,Ga)N are already sufficient to cause strong carrier localization effects. […]

### IS05 – Thermal crosstalk mitigation in a dual-drive Mach-Zehnder Modulator

Dual-drive, PIN-diode based Mach-Zehnder modulators are pivotal for power-efficient and cost-effective CMOS compatible optical transceivers with small footprints. However, the basic chip materials have substantial thermal conductance resulting in thermal crosstalk, which eventually deteriorates the modulator performance in terms of bandwidth and data transmission capabilities. In this work, we simulate and analyze the influence of […]

### N04 – An Efficient Workflow of Modeling Single-Nanowire Based Single-Photon Avalanche Detectors

Single-photon detector (SPD) as an essential building block for detecting and counting photons, plays a fundamental role in quantum technologies. In this work, we propose an efficient workflow of modeling SPDs based on emerging one-dimensional materials, i.e. nanowires, utilizing avalanche breakdown in reverse biased condition. Comparing to another extensively studied platform, superconducting nanowire SPDs, avalanche […]

### NM04 – Semi-Analytic Modelling of Slot Waveguides in Silicon-Organic Hybrid Mach-Zehnder Modulators

A semi-analytic approach for modelling the distributed capacitance and the elecro-optic confinement factor of the slot waveguide in a silicon-organic hybrid Mach-Zehnder modulator using the principle of conformal mapping is presented. The results show a deviation of less than 1.3% compared with numerical field simulations.

### LED04 – Development of time-dependent Exciton diffusion solver for modeling Triplet-Triplet Fusion Mechanism in OLEDs

In this work, we developed a both stable and time-dependent exciton diffusion model including singlet and triplet exciton coupled with a modified Poisson & drift-diffusion solver to demonstrate the mechanism of triplet-triplet fusion (TTF) OLEDs. Using this modified simulator, we can demonstrate the characteristics of OLEDs including current-voltage curve, quantum efficiency performance, time-resolved electroluminescence spectrum, […]

### P04 – Numerical modeling and experimental verification of advanced methods for characterization of broadband optical pulses and optical frequency combs

We propose novel linear method for measuring ultrafast pulse trains with extremely high pulse repetition rates that are commonly generated in nonlinear microresonators. The method combines single-shot spectral interferometry with the reference pulses and an advanced version of the frequency resolved optical gating algorithm to reconstruct the initially unknown reference pulses.

### IS08 – Flat-band 8-Channel Optical MUX/DeMUX for Long Reach 400GbE Applications

We propose novel optical demultiplexer scheme for LR-8 applications, and theoretically verify flatband spectral response with the discrete 8-channel wavelengths. By the additional band rejection filter, non-continuous wavelength filtering response was achieved with spectral flatness and low crosstalk of < -15dB within an entire LR-8 targeted spectral range.