Nonlinear Radiation Reflection

H. V. Pikichyan

Werner H. Lauterborn, Thomas Kurz, Martin Wiesenfeldt

Aleksandr Akimov, Salavat A. Guzairov, Valery V. Ivakhnik

The influence of feedback for both signal and object waves on the amplitude reflection coefficient of a four-wave radiation converter on thermal nonlinearity has been considered. The dependences of the reflection coefficient of a four-wave converter on the parameters of a ring-type resonator, which provides the feedback, and the pump intensity have been obtained and analyzed. It was shown that the use of a ring-type resonator allows one to increase the reflection coefficient of a four-wave radiation converter on thermal nonlinearity by several times.

Александр Александрович Акимов, Valery V. Ivakhnik, Kseniya G. Kazakova

Background. The need to create highly efficient four-wave radiation converters in order to use them in adaptive optics systems, for real-time processing of complex spatio-temporal fields, in interferometry, quantum cryptography, etc. requires along with the use of traditional methods to increase the efficiency of such converters by increasing the interaction length, radiation power density, effective value of the nonlinear susceptibility of the development of new methods. One of these methods is a method based on the imposition of feedback on one or more interacting waves. Aim. The influence of feedback on the amplitude reflection coefficient of the degenerate four-wave radiation converter on thermal and resonant nonlinearities has been considered. Methods. The amplitude reflection coefficient of a degenerate four-wave radiation converter on thermal and resonant nonlinearities in the presence of feedback for both object and signal waves has been analyzed by a numerical method based on the multiple passage of the signal and object waves of the nonlinear layer in the ring resonator. Results. It was shown, that the difference in the reflection coefficients in the presence and absence of feedback for both object and signal waves increase monotonically with a growth in the pumping waves intensity and does not depend on the parameter characterizing the relationship between thermal and resonant nonlinearities at the approximation of a small reflection coefficient. Conclusion. The range of values of the absorption coefficient in which the imposition of feedback for both object and signal waves leads to an increase in the efficiency of the four-wave radiation converter has been established.

Werner H. Lauterborn, Thomas Kurz

P. I. Khadzhi, S L Gaivan

A theoretical investigation is reported of the coherent nonlinear response of excitons and biexcitons in a thin semiconductor film subjected to resonant laser radiation. It is shown that saturation of an exciton transition results in an abrupt qualitative change in the nature of film transmission from total reflection of the incident pulse at low pump amplitudes to oscillatory reflection at high amplitudes. A new area theorem is derived for ultrashort pulses: it establishes a correspondence between the areas of the incident, transmitted, and reflected pulses. Anomalous transmission and reflection (area 'quantisation') is predicted for large values of the nonlinear parameter. The equations of state, describing bistable behaviour of the amplitudes of the fields of the transmitted and reflected radiation, are derived for quasi-cw operation.