Simulation of mode deflection and reshaping in lithium niobate planar waveguide with serrated array electrodes
In this paper, we establish a lithium niobate (LN) thin film planar waveguide model with serrated array electrode configuration to reshape the optical mode. The refractive index profile of the waveguide can be slightly electro-optically manipulated, so the optical beam can be deflected and reshaped in the transmitted direction of waveguide. When the beam deflection can be modulated via the high speed electro-optic effect of LN, the temporally and spatially beam smoothing can be potentially achieved for the application of inertial confinement fusion system.
Beam smoothing by lens array with spectral dispersion
A scheme of combining technology of lens array (LA) and smoothing by spectral dispersion (SSD) is introduced to improve the irradiation uniformity in laser fusion based on the earlier works on LA. The feasibility of the scheme is also analyzed by numerical simulation. It shows that a focal pattern with flat-top and sharp-edge profile could be obtained, and the irradiation nonuniformity can fall down from 14% with only LA to 3% with both SSD and LA. And this smoothing scheme is depended less on the incidence comparing to other smoothing methods. The preliminary experiment has demonstrated its effectiveness.
Use of induced spatial incoherence for uniform illumination on laser fusion targets. Memorandum report
We report a technique to achieve very uniform illumination of laser irradiated targets by inducing a controlled amount of transverse spatial incoherence in the output beam of a broadband laser. The spatial incoherence is created by imposing different optical delays upon different transverse sections of the beam, and choosing the delay increments to be larger than the laser coherence time tc = 1 delta. This technique may allow easy attainment of the pellet illumination uniformity required for laser fusion.