Very few nonlinear optical materials are actually useful for high throughput all-optical devices. However, AlGaAs does satisfy all of the nonlinear optical figures of merit when used with photons of energy less than one half the semiconductor bandgap. Here we review our measurements of the pertinent nonlinear coefficients in waveguides and various device applications to all-optical switching in the communications band around 1550 nm.
The wavelength dependence of the nonlinear refractive index and two-photon absorption coefficient near half the band gap was measured in an AlGaAs waveguide. The two photon figure of merit for efficient nonlinear optics in AlGaAs is shown to be quite favorable for photon energies less than one half the band gap.
The hybrid recurrent fuzzy neural network (HRFNN) control permanent magnet synchronous motor (PMSM) drive system using rotor flux estimator is developed to control electric motorcycle in this paper. First, the dynamic models of a PMSM drive system and electric motorcycle are built through experimental tests and parameter measurements. Then, a HRFNN control system using rotor flux estimator is developed to control PMSM drive system in order to drive electric motorcycle. The rotor flux estimator consists of the estimation algorithm of rotor flux position and speed based on the back electromagnetic force (EMF). Moreover, the HRFNN controller consists of the supervisor control, RFNN and variable structure control (VSC) is applied to PMSM drive system using rotor flux estimator. The parameters of RFNN are trained to control command current in order to achieve different output torque of various speeds. The electric motorcycle is operated to provide constant disturbance torque. Finally, the effectiveness of the proposed control schemes is demonstrated by experimental results.
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