Research on all-solid-state blue lasers

Blue lasers have many important applications such as high-density optical data storage, biological and medical diagnostics, color displays, and submarine laser imaging and communication. High efficiency, high brightness and compactness all-solid-state blue lasers have attracted much attention for their merits. In this paper, four main ways for achieving all-solid-state blue lasers are reviewed and compared in detail, such as the semiconductor laser, the frequency-doubling of the semiconductor laser, the up-conversion blue laser, the nonlinear optical frequency conversion of Nd³⁺-doped or optical parametric oscillating lasers and so on. Results show that the nonlinear optical frequency conversion of the Nd³⁺-doped lasers is a potential way to realize a high power, high efficiency cw or pulsed blue laser output.