Enhancing Kerr nonlinearity via spontaneously generated coherence

Abstract

A theoretical investigation is carried out into the effect of spontaneously generated coherence on the Kerr nonlinearity of general three-level systems of ⌳, ladder, and V-shape types. It is found, with spontaneously generated coherence present, that the Kerr nonlinearity can be clearly enhanced. In the ⌳and ladder-type systems, the maximal Kerr nonlinearity increases and at the same time enters the electromagnetically induced transparency window as the spontaneously generated coherence intensifies. As for the V-type system, the absorption property is significantly modified and therefore enhanced Kerr nonlinearity without absorption occurs for certain probe detunings. We attribute the enhancement of Kerr nonlinearity mainly to the presence of an extra atomic coherence induced by the spontaneously generated coherence.

Nonlinear effects in pulse propagation through Doppler-broadened closed-loop atomic media

“…A particular example is the occurrence of an intensity dependent refractive index, with applications such as beam focussing, pulse compression, selfphase-or cross-phase modulation or optical switching [23,24,25,26,27,28,29,30]. Here, the connection to coherence properties is the following.…”

“…Laser driven atomic media are also known to exhibit significant nonlinear optical properties [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30].…”

Electromagnetically induced transparency and nonlinear pulse propagation in a combined tripod and Λ atom-light coupling scheme

“…By making a transition between the two limiting cases, one can switch from the EIT regime to the absorption for the probe field propagation. Laser-driven atomic media, on the other hand, can be exploited to exhibit various nonlinear optical properties [15,16,18,20,24,26,28,31,[56][57][58]. A particular example is formation of optical solitons with applications for optical buffers, phase shifters [59], switches [60], routers, transmission lines [61], wavelength converters [62], optical gates [63] and others.…”

“…The absorption is suppressed due to a quantum mechanical interference between different excitation pathways of atomic energy levels leading to the EIT. The EIT has various important applications in quantum and nonlinear optics, such as slow and stored light [7][8][9][10][11][12], stationary light [13,14], multiwave mixing [15][16][17], optical solitons [18][19][20][21][22][23], optical bistability [24,25] and Kerr nonlinearity [26][27][28][29][30]. Using the slow light greatly enhances the light-matter interaction and enables nonlinear optical processes to achieve significant efficiency even at a singlephoton level [26,[31][32][33][34][35][36][37][38].…”

Uniform phase modulation via control of refractive index in a thermal atom vapor with vanishing diffraction or absorption

“…In order to achieve such phase shifts, there have been extensive studies by utilizing nonlinear effects enhanced by quantum coherences and interferences. For example, self- [6,7] or cross- [8][9][10][11] phase modulation based on Kerr effect have been proposed using electromagnetically induced transparency (EIT) [12][13][14][15], spontaneously generated coherences [16] or active Raman gain [17,18] media, not only in gaseous-phase such as atomic alkali atoms, but also in solid-state media including optical fibers [3,19,20], quantum wells [21,22], and superconducting qubits [23][24][25]. Several schemes have been experimentally tested in cold [2, 11,26] or thermal atomic systems [6,10,27,28], where small nonlinear phase shifts up to the order of one radian are achieved.…”