Large Signal Modulation Characteristics in the Transition Regime for Two-State Lasing Quantum Dot Lasers

Large-signal modulation capability, as an important performance indicator, is directly related to the high-speed optical communication technology involved. We experimentally and theoretically investigate the large-signal modulation characteristics of the simultaneous ground-state （GS） and the excited-state （ES） lasing in InAs/OaAs quantum dot laser diodes. The large-signal modulation capability of total light intensity in the transition regime from OS lasing to two-state lasing is unchanged as the bias-current increases. However, GS and ES large-signal eye diagrams show obvious variations during the transition. Relaxation oscillations and large-signal eye diagrams for OS, ES, and total light intensities are numerically simulated and analyzed in detail by using a rate-equation model. The -ndings show that a complementary relationship between the light intensities for OS and ES lasing exists in both the transition regime and the two-state lasing regime, leading to a much smaller overshooting power and a shorter settling time for the total light intensity. Therefore, the eye diagrams of GS or ES lasing are diffuse whereas those of total light intensity are constant as the bias-current increases in the transition regime.

Design and development of module management controller for MicroTCA.4 standard

Objective The MicroTCA.4(MTCA.4)standard systems have been widely used in large-scale scientific facilities such as synchrotron radiation light sources and FELs over the world,covering RF control,beam instrumentation,timing,machine protection,and so on.The MTCA.4 module management controller(MMC)realizes intelligent management of the boards in the chassis through bus protocol and system interaction.It is an important functional module in MTCA.4 standard system.Methods In order to meet the requirements of the large scientific facilities,an MMC module was designed and developed.This design can realize power management of Advanced Mezzanine Card(AMC)and Rear Transition Module(RTM)boards,as well as monitoring the temperature,voltage,and current during operation.The core part of this module is limited into an area of 3 cm 3 cm on the AMC board,leaving large space for subsequent development of functional circuit.Results An AMC board was developed to verify functions of the MMC.Test results indicate that this board is compatible with existing MTCA.4 standard system.Conclusions This MMC solution can be directly and modularly applied to the design of MTCA.4 standard hardware.

On Smash Products of Transitive Module Algebras

Let H be a semisimple Hopf algebra over a field of characteristic 0, and A a finite-dimensional transitive H-module algebra with a l-dimensional ideal. It is proved that the smash product A#H is isomorphic to a full matrix algebra over some right coideal subalgebra N of H. The correspondence between A and such N, and the special case A = k（X） of function algebra on a finite set X are considered.