Wide-band steady-state numerical model and parameter extraction of a tensile-strained bulk semiconductor optical amplifier

A wide-band steady-state model of a tensile-strained bulk InGaAsP semiconductor optical amplifier is described. An efficient numerical algorithm of the steady-state model and a parameter extraction algorithm based on the Levenberg–Marquardt method are described. The parameter extraction technique is used to determine the material Auger recombination coefficient, effective intraband lifetime, the average strain and molar fraction of Arsenic in the active region. Simulations and comparisons with experiment are given which demonstrate the accuracy and versatility of the model

Wideband semiconductor optical amplifier steady-state numerical model

A wideband steady-state model and efficient numerical algorithm for a bulk InP–InGaAsP homogeneous buried ridge stripe semiconductor optical amplifier is described. The model is applicable over a wide range of operating regimes. The relationship between spontaneous emission and material gain is clarified. Simulations and comparisons with experiment are given which demonstrate the versatility of the model

Reflective semiconductor optical amplifier pulse propagation model

A simple time-domain model for optical pulse propagation in a reflective semiconductor optical amplifier (RSOA) is described. The RSOA saturation energy, effective carrier lifetime and spectral hole-burning parameters used in the model are determined using experimental measurements of the input and output pulse temporal profiles to the RSOA and least mean-square fitting. The model accurately predicts the propagation of 39.6 ps pulsewidth variable energy pulses in the RSOA. The model is used to predict the RSOA gain dynamics, spatial dependence of the pulse shape and dynamic chir

Wideband dynamic numerical model of a tapered buried ridge stripe semiconductor optical amplifier gate

A wideband dynamic numerical model of a tapered buried ridge stripe semiconductor optical amplifier is described. The model is based on a carrier density rate equation and a set of travelling-wave equations describing the amplified signal fields and spontaneous emission photon rates. These equations are solved in time and space using a computationally efficient numerical algorithm. The model is used to predict the switching properties of an optical gate. A simple equivalent circuit model of the gate, including package parasitics, is derived that can be used in conventional electrical circuit simulation tools

Band-gap shrinkage calculations and analytic model for strained bulk InGaAsP

Band-gap shrinkage is an important effect in semiconductor lasers and optical amplifiers. In the former it leads to an increase in the lasing wavelength and in the latter an increase in the gain peak wavelength as the bias current is increased. The most common model used for carrier-density dependent band-gap shrinkage is a cube root dependency on carrier density, which is strictly only true for high carrier densities and low temperatures. This simple model, involves a material constant which is treated as a fitting parameter. Strained InGaAsP material is commonly used to fabricate polarization insensitive semiconductor optical amplifiers (SOAs). Most mathematical models for SOAs use the cube root bandgap shrinkage model. However, because SOAs are often operated over a wide range of drive currents and input optical powers leading to large variations in carrier density along the amplifier length, for improved model accuracy it is preferable to use band-gap shrinkage calculated from knowledge of the material bandstructure. In this letter the carrier density dependent band-gap shrinkage for strained InGaAsP is calculated by using detailed non-parabolic conduction and valence band models. The shrinkage dependency on temperature and both tensile and compressive strain is investigated and compared to the cube root model, for which it shows significant deviation. A simple power model, showing an almost square-root dependency, is derived for carrier densities in the range usually encountered in InGaAsP laser diodes and SOAs

Repetition rate and wavelength tunable all-optical actively mode-locked fiber ring laser based on a reflective semiconductor optical amplifier

A repetition rate and wavelength tunable fiber ring laser that utilises a reflective semiconductor optical amplifier as both a gain and mode-locking element is presented. 10.3 ps pulses at 10 GHz repetition rate are obtained across a 30 nm tuning range covering the entire C-band. The repetition rate is tunable up to 30 GHz via rational harmonic mode-locking. A comparison is made with using a conventional semiconductor optical amplifier as the gain and mode-locking element. It is shown that the reflective semiconductor optical amplifier requires in excess of 5 dB less average pump pulse power in order to achieve the optimum mode-locking condition, for achieving the narrowest output pulse width, thereby relaxing the requirement for a complex and expensive pump pulse source

Signal-induced birefringence and dichroism in a tensile-strained bulk semiconductor optical amplifier and its application to wavelength conversion

Signal-induced birefringence and dichroism in a tensile-strained bulk semiconductor optical amplifier (SOA) are demonstrated in a counterpropagation scheme. The polarization azimuth rotation and the change of ellipticity angle of the probe light are presented on the Poincaré sphere and can be calculated by the Stokes parameters. All-optical wavelength conversion (inverted/noninverted and upconversion/downconversion) based on cross polarization modulation (XPolM) in SOAs are investigated. It is shown that a bit error rate (BER) of 9 dB can be obtained at a bit rate of 2.488 Gb/s with a 231 − 1 non-return-to-zero (NRZ) pseudorandom bit sequence (PRBS). Because of the larger birefringence effect induced by the pump light in the longer wavelength range, upconversion shows better performance than downconversion. Compared with the noninverted case, inverted wavelength conversion shows better performance due to the positive contribution from cross gain modulation (XGM), which takes place simultaneously with XPolM

All-optical AND gate with improved extinction ratio using signal induced nonlinearities in a bulk semiconductor optical amplifier

An all-optical AND gate based on optically induced nonlinear polarization rotation of a probe light in a bulk semiconductor optical amplifier is realized at a bit rate of 2.5Gbit/s. By operating the AND gate in an up and inverted wavelength conversion scheme, the extinction ratio is improved by 8dB compared with previously published work

A Mueller-matrix formalism for modeling polarization azimuth and ellipticity angle in semiconductor optical amplifiers in a pump–probe scheme

This paper presents a Mueller-matrix approach to simulate the azimuth and ellipticity trajectory of a probe light in a tensile-strained bulk semiconductor optical amplifier (SOA) in a conventional pump–probe scheme. The physical mechanisms for the variations of polarization azimuth and ellipticity angle of the probe originate from the significant nonuniform distributions of carrier density across the active region in the presence of an intense pump light. Due to this carrier-density nonuniformity, the effective refractive indexes experienced by transverse-electric (TE) and transverse-magnetic (TM) modes of the probe are different. This results in a phase shift between TE and TM modes of the probe upon leaving the SOA. Simulations of the carrier distributions along the cavity length at different pump-light levels are demonstrated using multisection rate equations, which take into account the longitudinal nonuniform carrier density. The optical gain is considered via the parabolic band approximation. The influences of the spontaneous recombination and carrierdependent material loss on the amplifier performance are included. The Mueller-matrix formalism is utilized to predict the variations of azimuth and ellipticity angle, which greatly reduces the complexity of the simulations in comparison with Jones-matrix formalism. The suggested approach is beneficial to experimental investigations due to the fact that during the optical-tuning process, Stokes parameters are virtually measurable on the Poincaré sphere, and the Stokes vector of the incoming probe can be adjusted by a polarization controller and monitored by a polarization analyzer. Based on these carrier-induced nonlinearities in SOAs, an optical AND gate with extinction ratio larger than 14 dB and Q-factor larger than 25 is presented at a bit rate of 2.5 Gb/s

On the correct modeling of semiconductor optical amplifier RIN and phase noise for optical phase shift keyed communication systems

Phase modulation schemes are attracting much interest for use in ultra-fast optical communication systems because they are much less affected by fiber nonlinearities than conventional modulation formats. Semiconductor optical amplifiers (SOAs) can be used to amplify and process phase modulated signals. However, existing SOA nonlinear phase noise (NLPN) models are simplistic and, sometimes, inaccurate. It is, therefore, important to correctly model their behavior since NLPN is the main drawback in these applications. In this paper we show that a more accurate model can be used leading to simple nonlinear noise expressions at the SOA output of differential phase shift keying systems. To demonstrate the utility of this model, we have used it to calculate the optical signal to noise ratio penalties introduced by a power booster SOA and the first inline amplifier of a 40 Gb/s NRZ-DQPSK single channel link. The model parameters have been estimated from measurements taken of a commercial SOA