B. I. Lembrikov

Theoretical analysis of gain-recovery time and chirp in QD-SOA

We present a theoretical analysis of the gain recovery and chirp characteristics of quantum-dot semiconductor optical amplifier (QD-SOA). We have derived an analytical expression for the frequency chirp in QD-SOA. The values of chirp and gain recovery time (GRT) for various signal power levels are calculated by numerical solution of the rate equations. The simulation results show that the chirp value in QD-SOA is approximately one order of magnitude lower than that in a bulk SOA. The dependences of the GRT and the chirp on the pump power level are studied.

Ultrafast All-Optical Processor Based on Quantum-Dot Semiconductor Optical Amplifiers

We have developed a theoretical model of an ultra- fast all-optical signal processor based on the Mach-Zehnder interferometer with quantum-dot semiconductor optical amplifiers in both its arms. It is shown that such a processor under different conditions may realize wavelength conversion, XOR logic operation, and optical 3R regeneration.

Acceleration of gain recovery and dynamics of electrons in QD-SOA

We propose a new method for reducing the patterning effect in quantum-dot semiconductor optical amplifier (QD-SOA) by using an additional light beam. A detailed theoretical analysis of the carrier dynamics in QD-SOA is presented. It is shown that the increase of the bias current only partially improves the QD-SOA temporal behavior. The additional light beam drastically reduces the patterning effect.

Specific Features of XGM in QD-SOA

The peculiarities of a cross-gain modulation (XGM) in quantum-dot semiconductor optical amplifier (QD SOAs) related to the inhomogeneous broadening are theoretically studied. We have solved numerically the electron rate equations for the QD SOA model including an excited state, a ground state and a continuum wetting layer (WL), and the propagation equations for the pump and the signal lightwaves. It is shown that XGM in QD SOA is possible for a comparatively large detuning close to the inhomogeneous broadening because in such a case QDs with substantially different resonant frequencies interact directly through WL.

Ultra-Wideband Radio-Over-Optical Fiber Concepts, Technologies and Applications

We have developed novel ultra-wideband (UWB) radio-over-optical-fiber (UROOF) concepts and technologies for a number of important in-house applications characterized by a high data rate. We propose the novel components, architecture, and realization of UWB UROOF systems. We present new experimental results related to UWB signal up-conversion, photonic radio impulse generation, and digital and analog signal coexistence. We also discuss future trends in the field of UWB UROOF technologies.

Proposal for All-Optical Generation of Ultra-Wideband Impulse Radio Signals in Mach–Zehnder Interferometer With Quantum-Dot Optical Amplifier

We developed a theoretical analysis of a novel method of ultra-wideband impulse radio signals all-optical generation based on cross-phase modulation and cross-gain modulation in a nonsymmetric integrated Mach-Zehnder interferometer (MZI) containing quantum-dot semiconductor optical amplifier. The proposed method is promising due to the advantages of compact, easily controlled, and low energy integrated MZI structures as compared to optical fiber systems.

Observation of excimer luminescence from electron-excited liquid xenon

This letter presents an experimental study of vacuum-ultraviolet luminescence from low-energy electron-excited liquid xenon. Our experimental results provide strong support for the theory by [E. B. Gordon, V. V. Khmelenko and O. S. Rzhevskii, Chem. Phys. Lett. 217, 605 (1994)] which considers the rare-gas-atom excitations to be the main reason for the electron drift-velocity saturation occurring at high-electric fields in the condensed rare gases. Furthermore, our results prove the existence of hot electrons in liquid xenon and show that electron-excited liquid xenon could serve as the active medium for a novel type of excimer laser as proposed by [E. B. Gordon, O. S. Rzhevsky, and V. V. Khmelenko, Quantum Electron. 24, 227 (1994)].

All-Optical AGC of EDFA Based on SOA

We propose a novel all-optical method for automatic gain controlling of transients in erbium-doped fiber amplifiers (EDFAs) using a semiconductor optical amplifier (SOA)-based negative feedback loop for adjusting the EDFA pump power. A dynamic model for the EDFA-SOA system is developed and used for numerical simulation of the transient behavior of this system. Simulation results for EDFA-SOA performance of the proposed method are presented. It is shown that using this method, it is possible to significantly reduce the transient effects, without producing power oscillations on the surviving channels

Synchronized Carrier Dynamics in Quantum Dot-in-a-Well (QDWELL) Laser Under an Optical Injection

We used the Lüdge-Schöll (LS) model of the optically injected quantum dot (QD) in a well (QDWELL) laser and carried out the numerical simulations for the LS rate equation system. We have shown that due to the optical injection, the electron and hole dynamics in QDs is synhcronized, the modulation frequency is enhanced, and the QDWELL laser manifests a high performance at the repetition frequency of 20 Hz, drastically deteriorating at 30 GHz .

Semiconductor Optical Amplifier Based on a Quantum Dot-in-a-Well (QDWELL) Structure Under Optical Pumping

We investigated theoretically dynamics of a semiconductor optical amplifier (SOA) based on the quantum dot-in-a-well (QDWELL) structure. We modified the QDWELL laser rate equations for the case of SOA and solved the modified equation system numerically. We have shown that a strong pumping optical wave in the QDWELL SOA synchronizes the QD carrier dynamics, which results in the enhancement of the QDWELL SOA bandwidth and repetition frequency, fast gain recovery, cross-gain modulation, and chirp decrease.