Abstract
We propose and analyze an efficient way to enhance four-wave mixing (FWM) signals in a four-subband semiconductor quantum well via Fano-type interference. By using Schrödinger-Maxwell formalism, we derive explicitly analytical expressions for the input probe pulse and the generated FWM field in linear regime under the steady-state condition. With the aid of interference between two excited subbands tunneling to the common continuum, the efficiency to generate FWM field is found to be significantly enhanced, up to 35%. More interestingly, a linear growth rate in the FWM efficiency is demonstrated as the strength of Fano-type interference increases in presence of the continuum states, which can be maintained for a certain propagation distance (i.e., 50μm).
Highlights
A linear growth rate in the four-wave mixing (FWM) efficiency is demonstrated as the strength of Fano-type interference increases in presence of the continuum states, which can be maintained for a certain propagation distance (i.e., 50μm)
One can see that the amplitude of two cw pump fields and the Fano-type interference caused by the tunneling from the excited subbands to the continuum both have an obvious influence on the FWM conversion efficiency
It is the Fano-type interference that suppresses the population in the subbands |3 and |4, resulting in the reduction of the corresponding absorption in the generated FWM field
Summary
The FWM efficiency ρ is plotted as a function of the amplitude Ωc2 of the cw pump field c2, for the different cw pump fields c1 without and with including the continuum states, shown in Fig. 5(a) and 5(b), respectively. One can see that the amplitude of two cw pump fields and the Fano-type interference caused by the tunneling from the excited subbands to the continuum both have an obvious influence on the FWM conversion efficiency. In the presence of the Fano-type interference caused by tunneling from the excited subbands to the continuum, in Fig. 7, we show the conversion efficiency ρ as a function of the strength of the Fano-type interference p for the different amplitudes of two pump fields.
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