The spectral bandwidth of a broad-area laser diode is effectively suppressed by use of an off-axis external-cavity technique. The external cavity consisted of a rod lens, a cylindrical lens and a volume Bragg grating. The laser beam has 5.8-fold improvement in spectral bandwidth and its peak power versus wavelength is effectively enhanced. On the basis of this technique, we focus the beam of the high-power laser diode to effectively end pump a solid-state laser.
