Ultranarrow linewidth and high gain of an optical cavity with enhanced self-Kerr nonlinearity in quantum dot molecules

Abstract

The enhanced self-Kerr nonlinearity of quantum dot molecules may be used to realize optical cavities with an ultranarrow linewidth and high gain. The resonant tunneling induces constructive interference for the self-Kerr nonlinearity, and then a narrow gain window with large normal dispersion appears with frequency detuning. The competition between linear and nonlinear dispersion leads to strong normal dispersion of the total susceptibility, which significantly narrows the cavity linewidth; the nonlinear gain introduces the total gain effects contributing to high transmission. Simulation results show that the cavity linewidth could be narrowed by nearly 30 times and the transmission peak enhanced about 40 times compared with a linear case.

Tunneling induced transparency and giant Kerr nonlinearity in multiple quantum dot molecules

“…And in the later case, giant Kerr nonlinearity with vanishing absorption can be achieved. Compared with QDMs with two or three dots [45,46], in multiple QDMs Kerr nonlinearity can be greatly enhanced for probe fields with different frequencies.…”

“…And it is also possible to induce quantum interference and coherence in QDMs only by the tunneling [34][35][36]. Therefore, QDMs with two or three dots can be used in the field of EIT [37,38] or tunneling induced transparency (TIT) [39], optical bistability [40,41], entanglement [42], resonance fluorescence spectrum [43], coherent population transfer [44], Kerr nonlinearity [45,46] and cavity transmission spectrum [47].…”

“…With proper values of the energy splitting of the excited states and the tunneling intensity, giant Kerr nonlinearity accompanied by vanishing absorption can be realized. Compared with QDMs with two or three dots [45,46], one than one probe fields with different frequencies can acquire giant Kerr simultaneously.…”

Control of optical bistability and third-order nonlinearity via tunneling induced quantum interference in triangular quantum dot molecules

“…19 With the help of an external electric field, [20][21][22] the tunneling between the dots can induce quantum interference and coherence. [23][24][25] Therefore, fundamental studies such as electromagnetically induced transparency (EIT), 26,27 coherent population transfer, [28][29][30][31] optical bistability, [32][33][34][35] entanglement, 36,37 narrowing of fluorescence spectrum 38 and enhanced self-Kerr nonlinearity 39 are studied. Furthermore, triple quantum dots (TQDs) are receiving much attention, due to its multilevel structure and extra controlling parameters which can not be found in DQDs.…”

Influence of the asymmetric excited state decay on coherent population trapping

“…For the QDM, the control laser beam is replaced by the electron tunneling between the quantum dots (with tunneling rate T e ), which can be controlled by an external electric field [17]. This effect is known as tunneling induced transparency (TIT) due to the critical role of tunneling in the appearance of transparency in QDM's [18,19] and allows for applications similar to those we find in atomic systems, e.g., slow down of light pulses [18] or cavity linewidth narrowing [20,21].Our results show a notable difference in the optical response of these systems when the Rabi frequency of the probe laser is comparable or larger than the Rabi frequency of the control field (tunneling rate), i.e., Ω P Ω C (T e ). Besides, we note a very appreciable difference in the transmission spectrum of the cavity when we have atom or QDM coupled to it and when we are in the limit Ω C → 0 or T e → 0, respectively.…”