No abstract

A means of reproducibly fabricating stable cw lasers in rare-earth-doped Ti:LiNb0 3 has been demonstrated through judicious choice of waveguide orientation. Z-propagating waveguides have been fabricated in Nd-and Er-diffused Ti:LiNb0 3 and room-temperature laser operation with greatly reduced photorefractive instability has been obtained. The reduced photorefractive damage susceptibility in this waveguide configuration has led to the realization of a 980 nm pumped laser in Er:Ti:LiNb0 3 , with a threshold of 10.5 mW of absorbed pump power and a slope efficiency of 8.5%. © 1996 American Institute of Physics. [S0003-6951(96)0315 l-8] The success of fiber amplifiers and lasers has recently stimulated a great deal of interest in rare-earth-doped planar waveguide devices for providing signal-processing functions on a local scale both in optical communications and sensor systems. In particular, rare-earth-doped LiNb0 3 is extremely attractive since it potentially permits a high degree of integration through a combination of the mature waveguide fabrication techniques that exist in this host material, it has in·trinsically good material properties, and the gain is introduced by the rare-earth ions. Moreover, the incorporation of rare-earth ions in this crystal by indiffusion demonstrates a degree of versatility not readily available in bulk rare-earth-doped planar waveguide systems. Numerous integrated laser and amplifier devices have been demonstrated over the past few years in Nd-and Er-diffused LiNb0 3 . 1. 2 The most common method of waveguide fabrication in rareearth-diffused LiNb0 3 is by Ti-indiffusion, as this technique allows for low propagation losses and does not alter the spectral characteristics of the rare-earth ions. However. an inherent problem with Ti:LiNb0 3 guided wave devices is their relative instability at visible and near-infrared wavelengths as a result of photorefractive damage induced by the high power densities in these guides. This has limited the demonstration of cw room-temperature operating Nd-doped devices almost exclusively to annealed proton exchange waveguides in MgO:LiNb0 3 , with the exception of the device reported in Ref. I. This device constituted a Y-branch. Ti-indiffused waveguide, in a y-propagating configuration, and the reason behind the stable cw operation at room temperature obtained in that case is still not clear. Photorefractive damage has also been one of the main reasons that the majority of Er:Ti:LiNb0 3 devices have been pumped at 1480 nm. The only report of a 980 nm pumped Er:Ti:LiNb0 3 device thus far. to our knowledge, has been made by Huang and McCaughan. 3 In that report the detrimental effect of photorefractive damage on the amplifier gain was evident, and it is unclear as to whether net gain was obtained in the device.It is widely accepted that the photorefractive effect is due to photogeneration of electrons through ionization of F 1 + .. .. e-1mpunt1es to t e e· state, an t e su sequent m1gra-JIElectronic mail: jamin@boulder.nist.gov tion of these electron...

No abstract

No abstract

No abstract