Omnidirectional emission from micro-notched Bragg fiber

A micro-notched Bragg fiber is proposed as a simplified method to achieve omnidirectional emission. The output beam can retain Gauss-like distribution when the size of the notch is appropriate. Simulation results show that the width and the depth of the notch significantly affect the features of the radial beam, such as the divergence angle and output energy. According to the result that the initial phase can directly control the phase of the output beam, the notched Bragg fiber is suggested as being suitable for simplifying a Cassegrain optical antenna system, and making up for the energy loss (about 25%) caused by the central obstruction of the secondary mirror.