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Laser Physics

Birefringence in a chiral medium, via temporal cloaking

Humayun Khan, Muhammad Haneef

Published Mar 28, 2017• 27 citations
Publisher

Abstract

Abstract This paper reports theoretical investigation of birefringence in a chiral medium for the creation of temporal cloaking. The chiral medium splits the input probe beam into left/right circular polarized beams. These left/right circular polarized beams are then controlled and modified within the chiral medium. The left circular polarized beam delays by 24 ns whereas the right circular polarized beam advances by −23 ns at a control field of rabbi frequency 6 γ . This opens a 47 ns time gap for temporal cloaking to hide information without noise corruption and energy loss. The results have potential applications in communication devices for secure propagation of light pulse.

DOI
10.1088/1555-6611/aa658f

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Physica Scripta•Feb 11, 2021•19 citations
Abstract This paper reports theoretical investigation of birefringence in a chiral medium for the creation of temporal cloaking. The chiral medium splits the input probe beam into left/right circular polarized beams. These left/right circular polarized beams are then controlled and modified within the chiral medium. The left circular polarized beam delays by 24 ns whereas the right circular polarized beam advances by −23 ns at a control field of rabbi frequency 6 γ . This opens a 47 ns time gap for temporal cloaking to hide information without noise corruption and energy loss. The results have potential applications in communication devices for secure propagation of light pulse.
Abstract We propose a scheme for distortion free left/right circularly polarized beams in a chiral atomic medium in a tripod-type configuration using the superposition of atomic states. We measure and control the group index, group velocity and delay and advance times for left/right circularly polarized beams in a transparent chiral atomic medium by varying the population distribution probability in the superposition states. For the left and right circularly polarized beams of the probe field, delay and advance times have been observed at resonance and away from resonance. A negligible distortion and large phase shift in the left/right circularly polarized beams is theoretically investigated in the system. The results show potential applications in telecommunication, cloaking base technology and information processing.
Abstract We examine propagation of the linear polarized pulse through a medium containing four-level double V-type atoms. The medium is made chiral by the cross coupling of the applied electromagnetic fields. We show that such medium can be used as a polarization splitter of the probe pulse where the spatially refracted left and right circular polarized components propagate independently due to their distinct phase velocities. We find that dispersion characteristics of the chiral medium can be manipulated by the controlling parameters of the system. Consequently, both the left and right circular polarized components exhibit sub and superluminal propagation characteristics for suitable choices of the probe field detuning and external control fields. It is found that for both polarized components a switching from sub to superluminal behavior may be achieved by adjusting the probe field detuning. In addition, splitting of the left and right circular polarized components and hence peak value of the group time delay and advance may be tuned via the strengths of the control fields. Our results may find applications in spintronics, magnetic quantum optics, images coding and cloaking technology.
Abstract The birefringence characteristics of reflection and transmission of light pulse are explored in chiral medium driving by two probe electric and magnetic fields, while four control fields. The proposed medium show significant birefringence behaviors in reflection/transmission and Goos-Hänchen (GH) shifted beams. The birefringent GH-reflected and GH-transmitted pulses show significant contribution in the space time gap creation for secure communication and invisibility. A space-time gap has been observed in the reflection, transmission and corresponding GH-shifted reflection and transmission birefringent beams. The theoretical results may be useful for noise free secure communication in invisible radar technology.
Abstract The absorption coefficients, refractive/group indices, phase shifts and fractional change of birefringence beams through dynamic chiral atomic medium are investigated under the effect of quantum tunnelling. The birefringence of phase indices Δ n = n r ( + ) − n r ( − ) and group indices Δ n g = n g ( + ) − n g ( − ) are controlled and modified through induced dynamic chiral medium by tunnelling effect. The group indices n g ( ± ) = ± 500 and group velocities v g ( ± ) = ± c / 500 are reported with the tunnelling effect. The maximum change in birefringent phase shifts is calculated to 5 microradian with tunnelling frequency at a speed of v = 10 cm/s of the chiral medium in the right circularly polarized (RCP) and left circularly polarized (LCP) beams. A 60% fractional change in the phase shift of RCP and LCP beams are investigated through induced chiral medium when the medium is at rest and when it is moving with the speed of v = 10 cm/s. These results will play an important role in scatterplate phase shifting interferometry.
We propose a new scheme for the coherent control of birefringent light pulses propagation in a four-level atomic medium. We modify the splitting of a light pulse by controlling the electric and magnetic responses. The Doppler broadening effect is also noted on the propagation of the birefringent pulses. The dispersions of the birefringence beams are oppositely manipulated for delay and advancement of time at a Doppler width of 10 γ . A time gap is created between the birefringence beams, which protects from hacking of information. The time gap is then closed to restore the pulse into the original form by a reverse manipulation of the dispersion of the birefringence beams, i.e., introducing another medium whose transfer function is the complex conjugate of that of the original medium. The results are useful for secure communication technology.
Abstract The control and modification of divergence angle and birefringent rotary photon drags under the effect of quantum tunnelling is investigated in this article. The circularly birefringence Δ n = n r ( + ) − n r ( − ) , divergence angle θ d and rotary photon dragging angles θ r ( ± ) are found to have modified with the strength of tunnelling frequencies. The left and right circularly polarized beams show superlominality of group velocities − c /150 and − c /50, respectively, and the divergence angle of 0.050 radian per increment of tunnelling frequency. The maximum of rotary photon drags for both beams is measured θ r ( ± ) = ± 2 micro radian with fractional change of 2%. The output pulses intensities ∣ E out + ( t ) ∣ 2 and ∣ E out − ( t ) ∣ 2 show uniform undistorted shapes with tunnelling frequencies and no energy losses. The results could have significant applications in the fields of quantum optics, photonics, plasmonics and special mode imaging coding technology.