Phase-conjugate four-wave mixing in a waveguide has many advantages over that in a bulk medium due to the waveguiding effect . It is also relatively easy to introduce an optical gain in the waveguide to amplify the weak signal. For sufficient image resolution, a multimode waveguide with a large number of guided modes is needed. For high fideIiy image replication, the nonlinear phase conjugate efficiency has to be mode-independent. These requirements are examined for two types of multimode waveguides: the cylindrical fiber waveguide without carrier diffusion and the rectangular semiconductor waveguide with carrier diffusion. In the fiber waveguide, the cylindrical geometry and the tensorial nature of makes the nonlinear coupling coefficient quite mode-dependent. In the semiconductor waveguide, carrier diffusion severely limits the efficiency of coupling the power in a particular pump mode to other modes in the conjugate signal. The existence of a gain will further aggravate these problems. In order to avoid these problems while maintaining the advantages of the waveguiding effect, we propose to use an array of single-mode waveguides. In this case, the only requirements are that the elements are identical and equally pumped and that there is no cross-talk between individual elements. A high-fidelity signal can be generated with an optical gain for amplification. In addition, the signal beam can be steered by changing the incident direction of one of the pump beams.

Date Published: 1 May 1990
PDF: 9 pages
Proc. SPIE 1220, Nonlinear Optics, (1 May 1990); doi: 10.1117/12.18303

Published in SPIE Proceedings Vol. 1220:
Nonlinear Optics
Robert A. Fisher; John F. Reintjes, Editor(s)