Coherent optical control of the ultrafast dephasing and mobility in a polar semiconductor

Abstract

Using the nonperturbative many-body time-dependent approach, we investigate the nonequilibrium dynamics of the coherent longitudinal optical phonon-plasmon coupled ͑LOPC͒ modes in a polar semiconductor and explore their coherent optical control and eventually the carrier mobility of the semiconductor. The basic idea for a control of the carrier mobility is to manipulate the ultrafast dephasing of the coherent carrier-relevant LOPC mode. We theoretically propose two possible options to realize the idea and reach the final goal. One is to optimize a semiconductor by finely balancing two kinds of carrier densities by chemical doping and optical doping ͑or photodoping͒, where the relaxation of the coherent carrier-relevant LOPC mode would respond in a ͑weak͒ singular way. It is found that, in this way, the carrier mobility could be enhanced by a few tens of percent. The other is to optimize the optical pumping laser. In this option, the pulse train creating pure virtual carriers through the below-band-gap excitation would be incorporated for an optical pumping, which can make possible the dephasing-free dynamics of the coherent carrier-relevant LOPC mode. The carrier mobility can then be efficiently controlled and dramatically enhanced by synchronizing the pulse train with its coherent oscillation. This might imply one of ultimate ways to control the carrier mobility of the semiconductor.

Control of carrier transport in GaAs by longitudinal-optical phonon-carrier scattering using a pair of laser pump pulses

“…In this paper, we report experimentally on the coherent control of the relaxation time of the plasma-relevant coherent LO phonon-plasmon coupled mode using a femtosecond pump-pulse pair in n-GaAs under nearly belowgap excitation condition. The relaxation time of the plasma-relevant LOPC mode is directly linked to the carrier transport, 12,16,17 and therefore, our results are suggestive to a possibility of realization of near-ballistic regime as a consequence of the reduction of the electronphonon scattering.…”

“…[13][14][15] One can enhance the amplitude of a phonon mode by applying in-phase pulses, or suppress it by applying out-of-phase pulses, both of which are observed in real time-domain. Recently, it has been theoretically pointed out that coherent control of relaxation of carrier plasma is possible by the irradiation of THz-rate trains of laser pulses with below-gap excitation condition, 16,17 while most of the pump-probe experiments and time-domain simulations have been made with above-gap excitation in GaAs, 7,[18][19][20][21][22] where the pump-pulse generates substantial nonequilibrium carriers in the conduction band with excess energy. In this condition, one expects that the firstly generated coherent LOPC modes may be always suppressed by the secondly pump-pulse if the separation time between the pump-pulses is several hundred femtoseconds.…”

Modeling and Deciphering on Two Spin-polariton Entanglement Experiments in NV Centers of Diamond

“…And OSE can cause energy band structure adjust and luminescence spectrum shift if an ultrafast (usually in femtosecond scale) laser pulse is applied on the sample. The OSE has been investigated both theoretically and experimentally in QDs of semiconductor systems (see, for example, the first experimental observation of OSE in semiconductor QD [62]) and other solid optical systems [36,57,65], and has been used as a tool to control single electron and photon or phonon interaction in solid nanostructures in recent years [32,33]. These two effects are important for quantum operations (see for example [50] [9]).…”