All-Optical Switching Property of an MQW-Sandwich Nonlinear Directional Coupler with Nonlinear Losses

Naomichi OKAMOTO  Xue Jun MENG  Okihiro SUGIHARA  

IEICE TRANSACTIONS on Electronics   Vol.E78-C   No.3   pp.299-303
Publication Date: 1995/03/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Opto-Electronics
nonlinear directional coupler,  strong coupling,  MQW coupling layer,  nonlinear losses,  all-optical switching,  

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We analyze all-optical switching property of a nonlinear directional coupler (NLDC) having an MQW coupling layer with both nonlinear and linear losses, and examine the effect of nonlinear losses. We use the Galerkin finite element method accompanied by a prodictor-corrector algorithm. The propagation loss along the strongly-coupled NLDC decreases with increasing nonlinear absorption coefficient due to saturation in absorption. A propagation loss of 8.18 dB or 2.38 dB in the bar state of the cross state is much smaller than the bulk loss of MQW structure which exceeds 50 dB. The nonlinear losses lengthen the coupling length and bring it close to that of a lossfree NLDC, while the linear losses shorten. It is found that the property of the cross state is greatly improved by counting the nonlinear losses: The cross-state output power and the output power ratio of two waveguides increase, and the cross state input power, that is, the switching power decreases.