Impulse irradiation of layered medium by the open end of circular waveguide
The radiation of impulse signal from the open end of a circular waveguide is considered by analytical and direct numerical methods. The radiation of short pulse from the aperture is considered by calculation of special time form of field by means of modal basis method that permits to transform the nonstationary three-dimensional electrodynamic problem into the problem for one-dimensional evolutionary equations by means of the construction of modal basis for electromagnetic field with arbitrary time dependence. The method is applied to solve the problem of pulse evolution for positive and negative time with the use of Laplace transform by construction of operator of propagation. The approach is employed to form the short pulse on aperture of circular waveguide for irradiation of layered medium with losses.
Transient radiation from the open end of circular waveguide
The transient radiation from the open end of a circular waveguide is considered by simple analytical and direct numerical methods. The radiation of short pulse from the aperture is provided by calculation of special time form of field by means of modal basis method that permits to solve the problem of pulse evolution for positive and negative time with the use of Laplace transform. The radiation of the short pulse is calculated in Kirchhoff approximation and simulated by FDTD method. The frequency characteristics of the radiated field are considered.
Coherent pulsed injection seeding of two gain-switched semiconductor lasers
High-power, narrow-spectrum, short pulses at a wavelength near 830 nm are needed for optical logic applications. The authors report the generation of two coherent trains of pulses by pulsed injection seeding of two gain-switched semiconductor lasers with one mode-locked master oscillator. The available power was doubled and both lasers emit in nearly identical spectral lines. Short pulses (30-50 ps) are generated at a repetition rate of 1.9 GHz. The spectrum is reduced to a single mode cluster and shows a 1.7 AA wide chirp suitable for pulse compression. The peak power is 0.1 W for each pulse train. The capability of this technique for coherent power combining is demonstrated.<<ETX>>