Phase-sensitive modulation instability in asymmetric coupled quantum wells

This paper presents a theoretical investigation of the phase-sensitive modulation instability of a continuous or quasicontinuous probe beam in an asymmetric coupled quantum well (ACQW) system facilitated by electromagnetically induced transparency. The dispersive properties of the probe beam can be controlled not only by the Rabi frequency of the control field but by the relative phase between them as well. The ACQW system exhibits large Kerr and quintic nonlinearities which could be controlled by controlling the relative phase of the probe beam. The probe beam is modulation unstable, and the gain and the bandwidth of unstable frequencies could be controlled by the phase of the probe beam. The gain of the instability disappears at certain values of phase and at certain other values of the phase the gain of the instability, and the bandwidth of unstable frequencies could be made large. Similarly, at certain values of the probe phase, the interplay of fourth-order dispersion and nonlinearity leads to the creation of discrete sidebands of the modulation instability. Both the fourth-order dispersion and quintic nonlinearity considerably reduces the growth and bandwidth of unstable frequencies.