Photosensitive Er/Yb optical fibers for efficient single-frequency fiber lasers

The absence of highly photosensitive Er/Yb fibers has been the main obstacle in the implementation of short efficient single-frequency fiber lasers. An earlier report of an Er/Yb single-frequency distributed Bragg reflector (DBR) laser demonstrated the promising properties of such lasers over their Er-doped counterpart due to their very high pump absorption (~0.2 dB/mm at 980 nm). A fiber grating was spliced onto a short section of Er/Yb fiber and the splice contributed to a substantial part of the cavity loss. In this paper a highly photosensitive Er/Yb fiber is presented for easy implementation of these devices and novel designs