Nonlinear optical phenomena in coherent phase of 2D exciton system

✍ Scribed by Yu.E. Lozovik; I.L. Kurbakov; I.V. Ovchinnikov

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 145 KB
• Volume: 126
• Category: Article
• ISSN: 0038-1098
• DOI: 10.1016/s0038-1098(03)00128-5

✦ Synopsis

We show that spatial many-particle coherence of condensed 2D exciton system, which is represented by anomalous averages

; can be transferred to exciton luminescence via the processes of coherent (simultaneous) recombination of many correlated excitons with production of the same number of correlated photons (â † k is exciton creation operator). In high-quality samples 2D momentum conservation dictates the requirement P i k i ¼ 0 for 2D exciton momenta. Due to momentum conservation, the photons coherently produced in such a process possess zero sum 2D momentum as well. Analyzing such a many-photon spatial coherence of the luminescence we predict new nonlinear optical effects in a coherent phase of 2D exciton system. The effects are the above-mentioned processes stimulated by external laser beams. They effectively look as if the stimulated exciton system irradiates a unidirectional beam with recoil momentum. 'Recoil' beams constitute a photon 'fan' in case of single stimulating laser beam and a photon 'lattice' in case of two stimulating laser beams. Quantitative estimations for exciton system in GaAs/AlGaAs double quantum wells point to possible experimental observability of the effects.