High power LDA's in general have an emitter line dimension of 1cmx1μm and a beam divergence of 40°x10°, which could not be delivered or focused effectively with common optics. With the ever-increasing needs of high power diode laser sources, it is crucial to obtain high power high brightness diode laser beam with improved optical quality. Although it has been known that beam shaping techniques can be used to achieve this aim, it has been challenging to shape the laser beam effectively and efficiently to deliver it through an optical fiber with high brightness. By using a new beam shaping technology developed recently, however, brightness over 2.4 MW/cm2-str has been achieved by delivering 28W from a 0.1mm multimode fiber. Diode lasers are the most efficient laser comparing with other lasers, and its application in various industrial sectors will become more and more extensive.
The fiber laser's excellent focus and efficiency, small size and light weight makes it highly promising not only for telecommunication, but also for industry and medical applications. In a double clad fiber laser, the inner cladding for guiding the pump light is provided around a core doped with active ion (e.g. YB3+, Nd3+, Er3+, etc.). The recent progress of fiber laser is reviewed at first in this paper. Different shapes of inner cladding are investigated to increase the pumping efficiency. Beam-shaping optics deliver high-power beams as the pumping source is discussed. Finally, a 4.9W cw double-clad fiber laser demonstration experiment in SIOM is described.