All passive architecture for high efficiency cascaded Raman conversion

Cascaded Raman fiber lasers have offered a convenient method to obtain scalable, high-power sources at various wavelength regions inaccessible with rare-earth doped fiber lasers. A limitation previously was the reduced efficiency of these lasers. Recently, new architectures have been proposed to enhance efficiency, but this came at the cost of enhanced complexity, requiring an additional low-power, cascaded Raman laser. In this work, we overcome this with a new, all-passive architecture for high-efficiency cascaded Raman conversion. We demonstrate our architecture with a fifth-order cascaded Raman converter from 1117nm to 1480nm with output power of similar to 64W and efficiency of 60%. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

A Diode Drive Mechanism for ``Always Resonant'' Pumping with Laser Diodes without Wavelength Locking

We demonstrate a simple to implement, drive scheme for standard laser diode modules ( without wavelength locking) used for pumping rare-earth doped lasers and amplifiers. This scheme enables an ``always-resonant'' mode of operation. The deleterious effect accompanying power/current tuning - drifts of emission wavelength of the diodes from the peak absorption band of the gain medium is completely avoided. In this work, we demonstrate the drive mechanism and its performance in a fiber amplifier. We anticipate this scheme to have significant impact in enabling a cost-effective solution which achieves an optimal balance of efficiency, nonlinearity and reliability in laser systems