Transmission and control of bright solitons in parity-time symmetric waveguide

Based on the theoretical model of optical wave propagation in parity-time (PT) symmetric waveguide, the transmission and control of bright solitons in PT symmetric Kerr nonlinear planar waveguide with Gaussian distribution are studied numerically. The PT symmetric waveguide requires that the refractive index distribution of waveguide should have to be an even symmetry, whereas the gain/loss distribution should be odd. The results show that when the strength of refractive index distribution of waveguide is positive, the refractive index has a maximum value in the center of the PT symmetric waveguide. Without the self-focusing Kerr nonlinear effect, the waveguide can also restrict optical wave to form the wavy light beam and transmit with long distance. When the strength of refractive index distribution is negative, the refractive index has a minimum value in the center of the PT symmetric waveguide. The transmission direction of optical wave is shifted. The gain/loss distribution can control the transmission direction of optical wave: if the strength of gain/loss distribution is positive, the optical wave is shifted toward the left; if the strength is negative, the optical wave is shifted toward the right; if the strength equals zero, the optical wave is divided into two beams. And when the refractive index distribution is negative, the interaction between adjacent bright solitons can be suppressed very well. The results of this research can provide a theoretical basis for the application of PT symmetric waveguide in all-optical control in the future.