Frequency Doubling In Raman Fiber Lasers

摘要

CW fiber lasers pumped by laser diodes (LD) become the most reliable powerful systems for the wavelengths around 1.5 micron (Er-) and 1 micron (Yb- doped fiber lasers - YFL) as well as for tunable 1.1-1.7 micron radiation (Raman fiber lasers - RFLs). The main advantages of fiber lasers compared to conventional ones are obvious: efficient heat removal and high beam quality due to specific fiber geometry (thin and long fiber core in silica cladding), efficient and reliable LD pump injection, compact design of fiber bobbin, direct fiber delivery and hands-free operation due to special cavity mirrors, fiber Bragg gratings (FBGs), imprinted directly into the fiber. Recently 10 kW CW YFL system appears on the market (ILR-10000 by IPG Photonics Corp., USA). In spite of the outstanding advances in the IR region, the fiber lasers have not been yet applied for the visible and UV spectral range, where powerful ion lasers and DPSS (diode pumped solid state) lasers with frequency doubling remain to be the main laser sources at fixed lines and Ti:Sapphire and dye lasers as high-power tunable sources.