Abstract Optical properties including absorption, dispersion, group index, Kerr nonlinearity, and optical bistability of a three-level V-type atomic medium have modified by varying an external magnetic field. By changing the magnitude or the sign of the external magnetic field, the transparency window with normal dispersion transfers to the enhanced absorption with anomalous dispersion at the line center, and hence the light propagation switches between subluminal and superluminal modes. The magnitude and the sign of the Kerr nonlinearity are controlled with the strength and the sign of the magnetic field. As a consequence, the behaviors of optical bistability are also made to appear or disappear when switching on/off the magnetic field. Moreover, the threshold intensity and width of optical bistability are also changed by the magnetic field and the coupling field. The results can be used to control the working characteristics of applied devices and study the related effects.
Abstract Optical properties including absorption, dispersion, group index, Kerr nonlinearity, and optical bistability of a three-level V-type atomic medium have modified by varying an external magnetic field. By changing the magnitude or the sign of the external magnetic field, the transparency window with normal dispersion transfers to the enhanced absorption with anomalous dispersion at the line center, and hence the light propagation switches between subluminal and superluminal modes. The magnitude and the sign of the Kerr nonlinearity are controlled with the strength and the sign of the magnetic field. As a consequence, the behaviors of optical bistability are also made to appear or disappear when switching on/off the magnetic field. Moreover, the threshold intensity and width of optical bistability are also changed by the magnetic field and the coupling field. The results can be used to control the working characteristics of applied devices and study the related effects.
We investigated control of optical bistability behavior based on the probe absorption and Kerr nonlinearity properties in a tripod-type degenerate four-level atom system under an external magnetic field. This excitation configuration can provide two transparent spectral regions on the probe absorption profile. It can be transitioned between the transparency and absorption regimes by turning on or off the magnetic field in different frequency domains. We can effortlessly transform one into two transparency windows, and vice versa, by modifying the intensity of the magnetic field. The investigations showed the enhancement of the Kerr nonlinearity around one/two-EIT windows, thereby forming one/two-channel optical bistability in these frequency regions. In addition, the coupling field intensity, the probe frequency detuning, and the atomic cooperation parameter have also significantly influenced the absorption spectrum, Kerr nonlinearity, and optical bistability. The proposed model has useful applications for storage and optical switching, and nonlinear logic gates in optical communications processing.
In this work, we proposed a simple model for control of subluminal and superluminal light propagation via an external magnetic field in a lambda configuration degenerate two-level atomic medium. We show that the absorption-dispersion properties and group index under the influence of the strength of coupling laser and external magnetic fields are controlled. By changing the direction and magnitude of the magnetic field, the medium switches from transparency with normal dispersion to enhanced absorption with anomalous dispersion at the line center, corresponding with the transfer from slow light to fast light. This work may provide for the application realization of magneto-optic switches and storage devices in quantum information processing.
In this work, we investigate subluminal and superluminal light propagation in a vee-type three-level atomic medium under an external magnetic field. The dispersion and absorption behaviors are studied for the cases of absence and presence of a magnetic field. It is found that under an electromagnetically induced transparency condition, the light pulse can be switched between subluminal and superluminal propagation by ON-OFF switching of the magnetic field. Finally, the transient response of the medium is discussed, which shows that the considered scheme has potential applications in magneto-optic switching devices. Full Text: PDF ReferencesBoller K J, Imamoglu A, Harris S E, "Observation of electromagnetically induced transparency", Phys. Rev. Lett. 66 (1991) 2593. CrossRef Fleischhauer M, Imamoglu A, Marangos J P, "Electromagnetically induced transparency: Optics in coherent media", Rev. Mod. Phys. 77 (2005) 633. CrossRef L.V. Hau, S. E. Harris, Z. Dutton, C.H. Bejroozi, "Light speed reduction to 17 metres per second in an ultracold atomic gas", Nature, 397 (1999) 594. CrossRef Z. Dutton, N.G.C. Slowe, L.V. Hau, "The art of taming light: ultra-slow and stopped light", Europhysics News, 35 (2004) 33. CrossRef V. Bharti, V. Natarajan, "Sub- and super-luminal light propagation using a Rydberg state", Opt. Commun. 392 (2017) 180-184. CrossRef Khoa D X, Doai L V, Son D H and Bang N H, "Enhancement of self-Kerr nonlinearity via electromagnetically induced transparency in a five-level cascade system: an analytical approach", J. Opt. Soc. Am. B. 31 (2014) 1330. CrossRef Hamedi H R, Gharamaleki A H, and Sahrai M, "Colossal Kerr nonlinearity based on electromagnetically induced transparency in a five-level double-ladder atomic system", Appl. Opt 22 (2016) 5892. CrossRef A. Fountoulakis, A.F. Terzis, E. Paspalakis, "All-optical modulation based on electromagnetically induced transparency", Phys. Lett. A 374, (2010) 3354. CrossRef Khoa D X, Doai L V, Mai Anh L. N, Trung L. C, Thuan P. V, Dung N. T, and Bang N. H, J. "Optical bistability in a five-level cascade EIT medium: an analytical approach", Opt. Soc. Am. B, 33 (2016) 735. CrossRef Hoang Minh Dong, and Nguyen Huy Bang, "Controllable optical switching in a closed-loop three-level lambda system", Phy. Scr. 94, (2019) 115510. CrossRef Dong H M, Doai L V, Sau V N, Khoa D X and Bang N H, "Propagation of a laser pulse in a three-level cascade atomic medium under conditions of electromagnetically induced transparency", Photonics Letter of Poland, 3 (2016) 73. CrossRef Khoa D X, Dong H M, Doai L V and Bang N H, "Propagation of laser pulse in a three-level cascade inhomogeneously broadened medium under electromagnetically induced transparency conditions", Optik 131 (2017) 497. CrossRef H. M. Dong, L.V. Doai, and N.H. Bang, "Pulse propagation in an atomic medium under spontaneously generated coherence, incoherent pumping, and relative laser phase", Opt. Commun. 426 (2018) 553-557. CrossRef Jiahua Li, Rong Yu, Liugang Si, and Xiaoxue Yang, "Propagation of twin light pulses under magneto-optical switching operations in a four-level inverted-Y atomic medium", J. Phys. B: At. Mol. Opt. Phys. 43 (2010) 065502. CrossRef S. H. Asadpour, H. R. Soleimani, "Polarization dependence of optical bistability in the presence of external magnetic field", Opt. Commun 310 (2014) 120-124. CrossRef H.M. Dong, L.T.Y. Nga, and N.H. Bang, "Optical switching and bistability in a degenerated two-level atomic medium under an external magnetic field", App. Opt. 58, (2019) 4192. CrossRef H. M. Dong, L. T. Y. Nga, D. X. Khoa, N. H. Bang, "Controllable ultraslow optical solitons in a degenerated two-level atomic medium under EIT assisted by a magnetic field", Sci. Rep. 10 (2020) 15298. CrossRef Daniel A. Steck, "Rubidium 87D Line Data," http://steck.us/alkalidata. CrossRef
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Abstract We propose a degenerate V-type inhomogeneously broadening atomic model for Kerr nonlinear control under the support of an external magnetic field. The magnetic field is used as a control knob to convert the medium from transparency to absorption at the resonance center. It is shown that the magnitude and sign of the Kerr nonlinearity index are manipulated by the magnetic field. Especially, we can easily convert the Kerr nonlinearity index from the positive peak into a negative peak, and from zero value can be transferred to enhanced positive or negative peaks simply only by changing the direction or strength of the magnetic field. In addition, the Kerr nonlinearity index under the influence of the temperature, the intensity, and detuning of the control field is also considered. The proposed model can be useful for applications in optical switching and nonlinear optical devices as well as possible experimental implementations.
We investigate the behavior of optical bistability in a degenerate two-level atomic medium using an external magnetic field to separate the lower level into two distinct levels that both connect to an upper level by the probe and coupling laser fields. Based on analytical solutions, the absorption spectrum and behavior of optical bistability in an electromagnetically induced transparency regime under an external magnetic field are investigated. By controlling the external magnetic field, we find that the appearance and disappearance of the optical bistability can be easily controlled according to the strength of the magnetic field in the transparent window domain. Furthermore, the effects of the intensity of the coupling laser field and the parameters of the system on the behavior of optical bistability are also considered. The proposed model is useful for applications in all-optical switches and magneto-optic storage devices.