Four-level inverted-Y Research Articles

Narrowing the absorption linewidth and its limitation in a four-level inverted-Y atomic system

Depending on a four-level inverted-Y atomic system, we demonstrate the limitation of linewidth-narrowing for the probe absorption spectrum in the electromagnetic induced absorption platform. Thanks to the use of an auxiliary control field which couples one hyperfine ground state and one middle-excited state we show that the linewidth limitation can be constrained by a coherence decay rate between two hyperfine ground states, rather than by the decay rate between the ground and the excited states as in previous Ladder schemes. That fact makes the theoretically-predicted absorption linewidth at least two orders of magnitude narrower. By using a suitable adjustment for the control-field amplitude and the detuning we numerically show that an extremely-narrowed probe absorption spectrum accompanied by a higher spectra contrast can be obtained, which confirms well with our theoretical predictions. We study the transient time response to the absorption spectrum and show that a relatively longer response time arises due to the small coherence decay rate between two hyperfine ground states. Furthermore, we reduce the influence on linewidth-narrowing from the Doppler effect via an optimized design of lasers, and reveal that no Doppler-free effect exists due to the lack of three-photon process. Our results may pave a route to the development of high-resolution spectroscopy in current experiments.

Negative Refractive Index in an Inhomogeneously Broadened Four-Level Inverted-Y Atomic Medium

In this paper, we present the study on negative refractive index in an inhomogeneously broadened four-level inverted-Y atomic medium based on electromagnetically induced transparency (EIT). The expressions of the relative permittivity and the relative permeability are derived under Doppler broadening. For this four-level system, we have found two frequency bands of negative refractive index in an optical region corresponding to two EIT windows. The influences of coupling and signal laser fields as well as temperature on frequency bands of negative refractive index are investigated. Our research can be convenient for experimental implementation with real atomic media under different temperatures.

Giant cross-Kerr nonlinearity in a four-level Y-type atomic system

We found the analytical expression for cross-Kerr nonlinear coefficient in a four-level Y-type atomic system. The analytical model is applied to 85Rb atoms and shown that under electromagnetically induced transparency, cross-Kerr nonlinear coefficient is enhanced by several orders of magnitude. At the same time, the amplitude and the sign of cross-Kerr nonlinear coefficient are controlled with respect to the intensity and the frequency of the coupling laser field. The analytical model can be useful to explain the experimental results and to study related effects in nonlinear optics. Full Text: PDF ReferencesC. Ottaviani, D. Vitali, M. Artoni, F. Cataliotti, P. Tombesi, "Polarization Qubit Phase Gate in Driven Atomic Media", Phys. Rev. Lett. 90, 197902 (2003). CrossRef C. Zhu, G. Huang, "Giant Kerr Nonlinearity, Controlled Entangled Photons and Polarization Phase Gates in Coupled Quantum-Well Structures", Opt. Express 19, 23364 (2011). CrossRef C. Hang, G. Huang, "Giant Kerr nonlinearity and weak-light superluminal optical solitons in a four-state atomic system with gain doublet", Opt. Express 18(3), 2952 (2010). CrossRef M. Fleischhauer, I. Mamoglu, and J. P. Marangos, "Electromagnetically induced transparency: Optics in coherent media", Rev. Mod. Phys. 77, 633 (2005). CrossRef H. Schmidt, And A. Imamogdlu, "Giant Kerr nonlinearities obtained by electromagnetically induced transparency", Opt. Lett., 21(23), 1936 (1996). CrossRef H. Kang And Y. Zhu, Phys. "Observation of Large Kerr Nonlinearity at Low Light Intensities", Rev. Lett., 91, 093601 (2003). CrossRef J. Kou, R. G. Wan, Z. H. Kang, H. H. Wang, L. Jiang, X. J. Zhang, Y. Jiang, and J. Y. Gao, "EIT-assisted large cross-Kerr nonlinearity in a four-level inverted-Y atomic system", J. Opt. Soc. Am. B. 27(10), 2035 (2010). CrossRef X. Yang, S. Li, C. Zhang, and H. Wang, "Enhanced cross-Kerr nonlinearity via electromagnetically induced transparency in a four-level tripod atomic system", J. Opt. Soc. Am. B. 26(7), 1423 (2009). CrossRef C. Ottaviani, D. Vitali, M. Artoni, F. Cataliotti and P. Tombesi, "Polarization Qubit Phase Gate in Driven Atomic Media", Phys. Rev. Lett. 90, 197902 (2003). CrossRef H. Sun, Y. Niu, S. Jin and S. Gong, "Phase control of cross-phase modulation with electromagnetically induced transparency", J. Phys. B: At. Mol. Opt. Phys. 40, 3037 (2007). CrossRef L.V. Doai, P.V. Trong, D.X. Khoa, and N.H. Bang, "Electromagnetically induced transparency in five-level cascade scheme of 85Rb atoms: An analytical approach", Optik, 125, 3666 (2014). CrossRef D. X. Khoa, P. V. Trong, L. V. Doai and N. H. Bang, "Electromagnetically induced transparency in a five-level cascade system under Doppler broadening: an analytical approach", Phys, Scr. 91, 035401 (2016). CrossRef D.X. Khoa, L.C. Trung, P.V. Thuan, L.V. Doai and N.H. Bang, "Measurement of dispersive profile of a multiwindow electromagnetically induced transparency spectrum in a Doppler-broadened atomic medium", J. Opt. Soc. Am. B 34 (6), 1255 (2017). CrossRef D. X. Khoa, L. V. Doai, D. H. Son, and N. H. Bang, "Enhancement of self-Kerr nonlinearity via electromagnetically induced transparency in a five-level cascade system: an analytical approach", J. Opt. Soc. Am. B., 31, 1330 (2014). CrossRef L.V. Doai, N.L.T. An, D.X. Khoa, V.N. Sau and N.H. Bang, "Manipulating giant cross-Kerr nonlinearity at multiple frequencies in an atomic gaseous medium", J. Opt. Soc. Am. B 36, 2856 (2019). CrossRef D. X. Khoa, L. V. Doai, L. N. M. Anh, L. C. Trung, P. V. Thuan, N. T. Dung, and N. H. Bang, "Optical bistability in a five-level cascade EIT medium: an analytical approach", J. Opt. Soc. Am. B, Vol. 33, 735 (2016). CrossRef N. T. Anh, L. V. Doai, and N. H. Bang, "Manipulating multi-frequency light in a five-level cascade-type atomic medium associated with giant self-Kerr nonlinearity", J. Opt. Soc. Am. B 35, 1233 (2018). CrossRef N. T. Anh, L. V. Doai, D. H. Son, and N. H. Bang, "Manipulating multi-frequency light in a five-level cascade EIT medium under Doppler broadening", Optik 171, 721 (2018). CrossRef D.A. Steck, Rb85 D Line Data: http://Steck.Us/Alkalidata/rubidium85numbers.pdf CrossRef

Subluminal and superluminal light pulse propagation under external magnetic field in a vee-type three-level atomic medium

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

Microwave assisted gain in inverted-Y type atomic system

The probe response in four-level inverted-Y configuration showsgainwithout population inversionin presence of microwave field.At on-resonant probe field, switching between superluminal and subluminal probe propagation under the influence of microwave field is discussed in details.Both the bandwidth and sharpness of optical switching can easilybe controlled by varying the microwave power. The switching action improves immensely if the control transition is chosen to be a Rydberg transition. The transient behavior of the atomic system ultimately settles into probe gain under the influence of the microwave field.A way of transferring population to the highest excited state through the application of microwave field is also discussed.

Local modulation of double electromagnetically induced transparency in an inverted-Y atomic system

A four-level inverted-Y configuration driven by two control fields is considered to demonstrate the phenomenon of electromagnetically induced transparency (EIT). It is shown that the double EIT can be realized in this system. Such double transparency spectra can be locally modulated by changing the detunings as well as the Rabi frequencies of the control fields.

Influence of Doppler broadening on cross-Kerr nonlinearity in a four-level inverted-Y system: An analytical approach

In this work, we study the influence of Doppler broadening on cross-Kerr nonlinearity in a four-level inverted-Y atomic system under electromagnetically induced transparency (EIT) condition. The first- and third-susceptibilities in the presence of Doppler effect are derived as a function of probe, signal and coupling beams and temperature of medium. Under EIT condition, cross-Kerr nonlinearity is enhanced several orders of magnitude compared to that without EIT. The Doppler effect leads to a reduction in the transparent efficiency and thus reduces the amplitude of cross-Kerr nonlinear coefficient. For hot atomic gaseous medium, such consideration of the Doppler effect may be useful for experimental observations and apply to photonic devices operating at different temperature conditions.

An optical narrowband switch between subluminal and superluminal light propagation in the inverted-Y configuration

The propagation of a weak probe field through a four-level inverted-Y type atomic system driven by two additional coherent fields, namely the control field and the repump field, is studied. The simulated probe absorption shows that electromagnetically induced transparency and the line shape of the transparency window under a Doppler-broadened condition are dependent on the residual Doppler averaging due to the wavelength mismatch between the control and probe fields. For 87Rb the probe propagation changes from subluminal on-resonance under a Doppler-free condition to superluminal on-resonance under a Doppler-broadened condition. For both 87Rb and 133Cs, the narrow subluminal window occurring in the group index profile in a Doppler-free environment offers an excellent delay bandwidth for probe field propagation. Under this condition, the order of the delay in probe field propagation can be as long as a few hundred µs and seems quite promising in the field of optical delay generation and light storage. The analysis shows that the residual Doppler averaging has a greater impact on the switching window under the variation of the Rabi frequency of the control field as compared to that of the repump field.

Laser-induced diffraction grating in asymmetric double quantum well nanostructure

We analyze the electromagnetically induced grating in a four-level inverted-Y double quantum well system. Based on the electromagnetically induced transparency, the Fraunhofer diffraction of a weak probe laser field is theoretically investigated. It is shown that the diffraction patterns are sensitive to both the absorptive and dispersive properties of the system. The effect of coupling and pumping fields intensity, frequency detuning, the relative phase of fields and the sample interaction length on diffraction pattern is then discussed. Our scheme may find potential applications in designing the semiconductor quantum well-based photonic devices, such as all-optical switches at low light levels.

Sub-luminal and super-luminal light propagation in inverted-Y system with wavelength mismatching effects

We investigate the electromagnetically induced transparency phenomenon in a four-level inverted-Y system, i.e. composite of three-level Λ and Ξ systems, using the density matrix formalism theoretically in stationary as well as moving atoms. Most of the EIT studies have taken the probe and coupling fields with wavelength matched condition to minimize the effect of Doppler-broadening. In this work we show a variation of absorption and dispersion profiles with wavelength mismatching factor because in real atoms for multilevel system the matched wavelength condition is difficult to obtain. This mismatching results in Doppler-broadening. We show that for moving atoms at the room temperature, a narrow window is also present within the wide transparency window for the probe absorption and dispersion for the mismatched cases. The group index modifies the probe propagation from super-luminal to sub-luminal within a very small detuning range near resonance. The variation of the group index with the coupling fields shows optical switching behavior when one of the coupling field is slightly detuned.

Sub-half-wavelength atom localization via two standing waves

We present a simple scheme of high-efficiency one-dimensional (1D) atom localization via manipulation of excited state population in a four-level inverted-Y atomic system. Because of the joint quantum interference induced by the two standing-wave fields, the 100% detecting probability of the atom in the subwavelength domain appears when the corresponding conditions are satisfied. The proposed scheme may open a promising way to achieve high-precision and high-efficiency 1D atom localization, which provides some potential applications to spatially selective single-qubit phase gate, entangling gates, and quantum error correction for quantum information processing.

Revisiting the four-level inverted-Y system under both Doppler-free and Doppler-broadened conditions: an analytical approach

We report the occurrence of electromagnetically induced transparency (EIT) in the simulated probe response signal for a four-level inverted-Y type system that is being acted upon by a weak coherent probe field, a strong coherent pump field and a coherent repump field. There are two ground energy levels, one intermediate energy level and one uppermost energy level. The weak probe field couples the lowest ground level to the intermediate level whereas the repump field connects the other ground level with the intermediate level. The strong control field couples the intermediate level with the uppermost energy level, thereby forming an inverted-Y type system. The density matrix based theoretical model has been developed and solved analytically for this four-level system and the probe response signal has been simulated at different values of the control and repump Rabi frequencies, control and repump frequency detunings and under both Doppler-free and Doppler-broadened conditions using the parameters of 87Rb D2 transition. Extremely low line width (few tens of kHz) for the EIT signal has been noticed under thermal averaging for copropagating probe, control and repump field configuration. The EIT signal is found to be immune to the variation in the control Rabi frequency.

Phase control of two-dimensional probe gain-absorption spectra in semiconductor quantum wells

We investigate the two-dimensional gain and absorption of a weak probe field via two orthogonal standing-wave lasers in a four-level inverted-Y asymmetric quantum well system. We find that, due to the spatial-dependent quantum interference effect, the spatial distribution of the 2D gain and absorption spectra can be easily controlled by adjusting the system parameters. More importantly, the probe gain-absorption spectrum can be controlled at a particular position and the 2D localization effect is indeed achieved efficiently. Thus, our scheme shows the underlying probability for the formation of the 2D localization effect by using a QW structure.

Phase-dependent high refractive index without absorption in a four-level inverted-Y atomic system

We consider a closed four-level inverted-Y system in the presence and the absence of a microwave field. It is found that due to the quantum coherence between the two lower levels, either induced by the spontaneous decay or by the microwave field, the refraction – absorption properties of the system can be modulated by controlling the relative phase of the applied fields in both driven ways. In particular, by properly setting the values of the relative phase, the desirable high index of refraction without absorption can be achieved.

Refractive index enhancement without absorption in a quantum well system

We investigated the absorptive–dispersive property of a weak field in a four-level inverted-Y quantum well system. We find that the cycling field and relative phase of the applied fields can affect the absorptive–dispersive property of a weak field dramatically, which can be used to manipulate efficiently the ultrahigh index of refraction without absorption. Our study is much more practical than its atomic counterpart due to its flexible design and controllable quantum-interference effect. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state optical communication

Coexisting four-wave mixing and six-wave mixing in three-level atomic system

We demonstrate the coexisting four-wave mixing (FWM) signal and six-wave mixing (SWM) signal which can be enhanced both by electromagnetically induced transparency (EIT) and optical pumping effect in a common three-level and open four-level inverted-Y type systems of 85Rb. We also analyze the effect of optical pumping in different energy level systems by arranging laser beams and comparing the strength of the increased and reduced absorption caused by optical pumping.

Inhibition and enhancement of two-photon absorption in a four-level inverted-Y semiconductor quantum well system

We theoretically investigate the features of two-photon absorption in a four-level inverted-Y quantum well system. We find that not only the strengths of applied laser fields but also the total closed interaction phase can affect the two-photon absorption dramatically, which can be used to suppress or enhance two-photon absorption. More importantly, the double electromagnetically induced two-photon transparency can be achieved in this system. Thus, it may provide some new possibilities for technological applications in the two-photon lasing, the pulse propagation, and the two-photon entanglement in solid-state quantum information processing.

Double dark resonances and the dispersion properties in a four-level inverted-Y atomic system

The electromagnetically induced transparency (EIT) and its dispersion properties in a four-level inverted-Y atomic system are investigated. The absorption spectrum of a weak probe field shows two EIT windows (dark resonances) whose location, width, and depth can be controlled by manipulating the parameters of the coupling fields; the corresponding dispersion properties are also measured by using a Mach–Zehnder interferometer. The experimental measurements agree well with the theoretical calculations. This kind of system can find important applications in two-channel quantum communication and information storage.

EIT-assisted large cross-Kerr nonlinearity in a four-level inverted-Y atomic system

A four-level inverted-Y scheme with an electromagnetically induced transparency (EIT) core is investigated for the enhancement of cross-Kerr effect in rubidium atoms. When detunings of the coupling and control fields are appropriately set, an enhanced EIT window is observed, and the induced phase shift of the probe field due to cross-phase modulation (XPM) is obtained by measuring the dispersive property of the probe transition. The maximal XPM phase shift is about 12° under the current experimental conditions. The experimental measurements agree well with the theoretical calculations. The enhanced XPM phase shift in such an atomic system has applications in quantum nonlinear optics and quantum information science.

Controllable Kerr nonlinearity with vanishing absorption in a four-level inverted-Y atomic system

The giant enhancement of Kerr nonlinearity in a four-level inverted-Y atomic system is investigated theoretically. Compared with that generated in a generic three-level system, the Kerr nonlinearity can be enhanced by several orders of magnitude with vanishing linear absorption. The physical mechanism leading to the giant enhancement of Kerr nonlinearity is also discussed.