Time-domain Traveling-wave Method Research Articles

Computation of ion exchange buried microring resonator waveguide for THz communication applications

Abstract The ion exchange creates the optical buried waveguides, whereas it is the method that the glass doping occurs with the condition of existence of the mobile metal ions. The most common ion used is silver (Ag+) due to its broad variation in the refractive index. The proposed application presented in this work is to use the microring resonator (MRR) system based on the buried waveguides simulated by the ion exchange method. The passive MRRs are realized as the multi-wavelength transceiver, applicable in optical technologies such as the optical sensing, Terahertz (THz) communication and optical switching. The cross-sectional view of the simulated buried optical waveguide for the Ag+ concentrations of 0.8 mol/m3 is presented. The fundamental mode propagation is simulated using the time-domain traveling wave method, where the simulation of the optical power flow density and the electric field distributions of the buried waveguides were performed. The two coupled MRRs are used to generate tunable dual-wavelength with spacing in the range of Terahertz (THz). As results, the dual wavelengths in the range between 0.25 and 0.96 THz were generated at the throughput and drop port of the MRRs system.

Simulation of mode lock lasers using microring resonators integrated with InGaAsP saturable absorbers

Add-drop microring resonators (MRRs) are used in a wide variety of practical applications. To add or drop special wavelength division multiplexing, an optical wavelength selective ring resonator can be used. This paper presents a system of multiple mode lock lasers consisting of an add-drop MRR integrated into a smaller ring with a saturable absorber (SA). In the case of mode-locking, a semiconductor is presented as the SA. This study uses an InGaAsP/InP semiconductor with an InP substrate and a direct bandgap as the MRR. The time-domain traveling wave method is utilized to model the presented photonic circuits. The generated multi-wavelength mode lock lasers have a bandwidth and free spectral range (FSR) of 1.1 and 30.24 nm, corresponding to 0.137 and 3.77 THz, respectively. The drop port output signals have a bandwidth and FSR of 1.5 and 30.24 nm, corresponding to 0.187 and 3.77 THz in the frequency domain. A finesse of 20.16 is obtained, and the Q-factor is ~1 × 103. The side bands of the mode lock lasers have an FSR of 0.86 nm.

Silicon-based microring resonators for multi-solitons generation for THz communication

Silicon-based microring resonator (SMRR) is required to select the specific channels in a wavelength division multiplexing systems. SMRRs also have applications in optical filters, data storages and bio-sensors, due to their significant advantages such as versatile wavelength-selective elements, compact size, fast operation and compatibility with current optical infrastructure, as well as being able to divert groups of inputs light and synthesize a wide class of filter functions. Here, we proposed a system for multiple mode-locked soliton generation, where the photonic circuits simulator PICWave software made by photon design based on the time-domain travelling wave method is used for modeling passive and active photonic circuits. A mode-locked spectrum possessing a spacing of 30 ps and a full width at half maximum (FWHM) of 10 ps was generated and input into the ring system. The subsequent multiple mode-locked soliton pulses had a free spectral range of 25 GHz and FWHM of 630 MHz, which corresponded to 0.2 nm and 5 pm respectively, with a 40 ps pulse duration and 200 GHz repetition. The obtained finesse was approximately 39.7, and the Q-factor was approximately 3 × 105.

Modeling of widely tunable V-cavity semiconductor laser using time-domain traveling-wave method

We investigate the static and dynamic characteristics of the widely tunable V-cavity semiconductor laser using the time-domain traveling-wave method. The theoretical model is presented. The simulation results are compared with experimental data for an all-active V-cavity laser, and good agreements are obtained. To improve the device performance, a new device structure with passive tuning waveguides is designed. The numerical results show that 21 channels can be achieved by single electrode tuning using carrier injection effect with two cavities of 420 and 440 μm long. Dynamic wavelength switching between different channels is simulated. Mode competition is observed during the transient and the switching delay time varies from 3 to 18.5 ns for different switching paths. A simple algorithm for quasi-continuous tuning is developed for the first time by varying the injection currents on the channel selector electrode and the fine-tuning electrode synchronously. A quasi-continuous tuning of 16.8 nm is achieved with a current variation of less than 20 mA on each electrode. For direct modulation characteristics, small signal response simulation is carried out by an impulse current injection with a fast Fourier transform algorithm, and a 3 dB bandwidth of 7 GHz is obtained when biased at 100 mA. Moreover, 2.5 and 10 Gb/s direct intensity modulation are also demonstrated. The simulation results show great potential for the compact and low-cost tunable laser to be used for wavelength-agile access and data center networks, as well as biomedical applications.

Modeling Widely Tunable Sampled-Grating DBR Lasers Using Traveling-Wave Model With Digital Filter Approach

A theoretical model for simulating widely tunable sampled-grating distributed Bragg reflector (SGDBR) lasers has been developed. The model integrates both time-domain traveling-wave method and frequency-domain transfer-matrix method into a single procedure. The active region of the device is still operated in the conventional time domain, while the passive parts are firstly performed by the transfer-matrix method and then transformed to the time domain via digital filters. Both the static and dynamic characteristics of SGDBR lasers, such as L-I curve, output spectrum, tuning characteristics, large-signal modulation, and dynamic wavelength switching, can be clearly visible in our model and in qualitative agreement with the published experimental results.

Numerical simulation on pulsed operation of an all-semiconductor optical amplifier nonlinear loop device

Pulsed-signal self- and cross-switching operations in an all-semiconductor-optical-amplifier (SOA) nonlinear optical loop device are numerically investigated. The device consists of a loop amplifier, a multimode-interference waveguide amplifier (MMIWA), an input leg, and an output leg. With the combined mechanisms, including nonlinear coupling in the MMIWA, lateral field redistribution and amplification by the loop, and asymmetric gain-phase modulation between two counterpropagating signals in the loop, the device operates with efficient power-dependent switching. Simulations were conducted using a modified time-domain traveling-wave method for the interplay between the two counterpropagating signals in MMIWA and loop. Typical parameter values of GaAs-AlGaAs multiple quantum-well (MQW) optical amplifiers were adopted for simulating separately published experimental conditions. Numerical results of simulation agreed well in physical trend with the reported experimental data.