mit

Nonlinear Optics in Three Level Atomic Systems

Shaoul Ezekiel

Published Dec 1, 1992• 0 citations

Abstract

The nonlinear optical properties of three-level atomic systems in the resonance Raman configuration are investigated both theoretically and experimentally. Special emphasis is placed on the optical properties which are unique to three-level systems, and have potential device applications. In particular, microwave-phase-dependent optical absorption is demonstrated experimentally. This is of interest because of potential applications to microwave circuit phase mapping, and mm-wave to FIR beam steering and image conversion. Optical data storage with Raman excited microwave spin echoes is also demonstrated experimentally. This technique has potential for increasing storage densities in optical echo memories and may lead to near-room-temperature materials for echo storage and processing. Finally, the optical forces on three- level atoms in Raman resonant standing waves are studied to investigate the potential for using trapped neutral atoms as nonlinear optical elements.

Related papers

First observation of forces on three-level atoms in Raman resonant standing-wave optical fields

Philip Hemmer, M. S. Shahriar, Mara Goff Prentiss +4 more

A sodium atomic beam is deflected by two optical standing-wave fields which excite near resonance Raman transitions. Observed deflections are consistent with theoretical predictions of a long-range dc component of the force on a three-level atom in the \ensuremath{\Lambda} configuration. The low laser intensities (and small detunings) used, combined with observed evidence of damping in the three-level \ensuremath{\Lambda} system, may ultimately lead to the design of high-density, all optical traps wherein the atoms would be mostly in the dark state.

Physical Review LettersMay 25, 199225 citations

Nonlinear optical effects manifested by electromagnetic induced transparency in cold atoms

Jiepeng Zhang

This dissertation reports experimental studies of nonlinear optical effects manifested by electromagnetically induced transparency (EIT) in cold Rb atoms. The cold Rb atoms are confined in a magneto-optic trap (MOT) obtained with the standard laser cooling and trapping technique. Because of the near zero Doppler shift and a high phase density, the cold Rb sample is well suited for studies of atomic coherence and interference and related applications, and the experiments can be compared quantitatively with theoretical calculations. It is shown that with EIT induced in the multi-level Rb system by laser fields, the linear absorption is suppressed and the nonlinear susceptibility is enhanced, which enables studies of nonlinear optics in the cold atoms with slow photons and at low light intensities. Three independent experiments are described and the experimental results are presented. First, an experimental method that can produce simultaneously co-propagating slow and fast light pulses is discussed and the experimental demonstration is reported. Second, it is shown that in a three-level Rb system coupled by multi-color laser fields, the multi-channel two-photon Raman transitions can be manipulated by the relative phase and frequency of a control laser field. Third, a scheme for all-optical switching near single photon levels is developed. The scheme is based on the phase-dependent multi-photon interference in a coherently coupled four-level system. The phase dependent multi-photon interference is observed and switching of a single light pulse by a control pulse containing ∼20 photons is demonstrated. These experimental studies reveal new phenomena manifested by quantum coherence and interference in cold atoms, contribute to the advancement of fundamental quantum optics and nonlinear optics at ultra-low light intensities, and may lead to the development of new techniques to control quantum states of atoms and photons, which will be useful for applications in quantum measurements and quantum photonic devices.

Oct 1, 20080 citations

SOME FUNDAMENTAL ASPECTS OF NONLINEAR OPTICS

Y. R. Shen

Selected topics related to the fundamentals of nonlinear optics are discussed. First, a brief description on the theory of nonlinear optical susceptibilities is given. Emphasis is on the basic properties, on the recently developed bond theory, and on the dispersion of nonlinear susceptibilities. Then the coupled wave approach is discussed. It is shown that the transverse resonant excitation in material can be treated as a material excitational wave, and most nonlinear optics problems can be understood as results of coupling between em waves or em and material excitational waves. A number of examples of current interest are presented. These include sum- and difference-frequency generation, Raman scattering by coherent excitation, stimulated Raman and stimulated polariton scattering, four-wave mixing, and vibrational relaxation measurements. Finally, the physical distinction between laser emission and resonant stimulated Raman scattering in an optically pumped three-level system are considered. A similar problem on the distinction of hot luminescence and resonant Raman scattering has recently attracted much attention. It is shown that the hot laser action is connected directly with the population inversion, while the resonant stimulated Raman scattering is connected with transverse excitation. The problem is, however, more complicated for a multi-level system. (auth)

Sep 1, 19750 citations

Enhanced Kerr Nonlinearity via Atomic Coherence in a Three-Level Atomic System

Hai Wang, David J. Goorskey, Min Xiao

We measure the Kerr-nonlinear index of refraction of a three-level Lambda-type atomic system inside an optical ring cavity. The Kerr nonlinearity is modified and greatly enhanced near atomic resonant conditions for both probe and coupling beams. The Kerr nonlinear coefficient n(2) changes sign when the coupling beam frequency detuning switches sign, which can lead to interesting applications in optical devices such as all-optical switches.

Physical Review LettersJul 26, 2001497 citations

Phase-dependent atomic coherence and interference in multi-level atomic systems

Jiepeng Zhang, Yifu Zhu

Atomic coherence and interference manifested by electromagentically induced transparency (EIT) and coherent population trapping (CPT) plays an important role in the current studies of atom-photon interactions and has found numerous applications in optical physics. EIT is created in a three-level atomic system by a coupling field and results in destructive interference between two excitation paths of a weak probe laser interacting with the atomic medium. This leads to suppressed linear absorption and rapidly varying atomic dispersion for the probe laser near the atomic resonance, which provides the platform for a variety of applications such as nonlinear optics at low light levels, slow light manipulation, and quantum state engineering for photons and atoms. Here we extend the simple three-level EIT system to more complicated and versatile configurations in a multi-level atomic system coupled by multiple laser fields. We show that with multiple excitation paths provided by different laser fields, phase-dependent quantum interference is induced: either constructive or destructive interference can be realized by varying the relative phases among the laser fields. Two specific examples are discussed. One is a three-level system coupled by bichromatic coupling and probe fields, in which the phase dependent interference between the resonant two-photon Raman transitions can be initiated and controlled. Another is a four-level system coupled by two coupling fields and two probe fields, in which a double-EIT configuration is created by the phase-dependent interference between three-photon and one-photon excitation processes. We analyze the coherently coupled multi-level atomic system and discuss the control parameters for the onset of constructive or destructive quantum interference. We describe two experiments performed with cold Rb atoms that can be approximately treated as the coherently coupled three-level and four-level atomic systems respectively. The experimental results show the phase-dependent quantum coherence and interference in the multi-level Rb atomic system, and agree with the theoretical calculations based on the coherently coupled three-level or four-level model system.

BENTHAM SCIENCE PUBLISHERS eBooksJan 1, 20090 citations

Phase dependent atom optics

Aline Vernier

Quantum interference in atomic media has elicited interest for a very wide range of investigations and applications. As well as being a fascinating effect in itself, it also found applications in spectroscopy, nonlinear optics and has recently been drawing attention in the field of quantum optics for the realisation of sources of entangled photons, optical switching, and quantum information storage. The work presented in this thesis consists of two main projects centred around the theme of quantum interference in atomic processes. As cooled atomic vapours provide favourable conditions for the investigation of coherent phenomena, a magneto-optical trap was built for the future study of quantum interference in four-level link- ages. The number of trapped atoms is estimated to be ≈ 8 × 10^8, and the density to be ≈ 10^9 atoms per cubic centimetre. This represents the first stage of an ongoing study of quantum interference in four-level linkages. However, coherent effects can also be observed in hot vapours. A spontaneous, highly efficient, frequency up-conversion arising from four-wave mixing can indeed be observed in Rubidium. This complex phenomenon was investigated experimentally and theoretically so as to improve the conversion efficiency, and understand the underlying physics. The optimum conditions found in this study yield 1 mW of converted light for 40 mW of pumping light. As part of the study of the phase coherence of the process, the conversion of spatial modes in the four-wave mixing process was also examined. The observation of the transfer of orbital angular momentum in the process is reported, and a preliminary theoretical interpretation is presented.

Jan 1, 20110 citations