Page 227 - Introduction to Information Optics

212 4. Switching with Optics

Fig. 4.9. Dependence of output power from waveguides A and B as a function of nonlinear phase
mismatch A.

the output intensity from an interferometer is

, - n 2r 2) (4.19)
where /j and I 2 are the intensity for beams 1 and 2 respectively. The required
phase shift in <5 in this case is only n to switch the total intensity from
constructive to destructive interference, whereas it is 2n as in a NLDC,
However, the response of an interferometer follows a squared sinusoid function
of the phase shift and is less sharp than an NLDC.

4.2.4.1. Self-switching Nonlinear Optical Loop Mirror
Phase shift can be induced by changing n l5 r t , n 2, or r 2. This can be achieved
using nonlinear optical media. However, if the nonlinear effect is small, long
nonlinear interaction length is needed for the arm of an interferometer, in order
to reduce switching energy. Since the interferometer has to be stable to within