An Overview on Yb-Doped Transparent Polycrystalline Sesquioxide Laser Ceramics

Fabrication and laser operation of Yb:Lu2O3 transparent ceramics from co‐precipitated nano‐powders

“…In the laser tests, the sample was then carefully aligned with its faces perpendicular to the cavity axis, so that the Fresnel reflections are superimposed to the laser mode of the cavity and contribute to the laser feedback. This approach was used in previous laser tests with a similar setup . As it will be shown in the following part, this strongly reduces the actual losses induced by the Fresnel reflection.…”

“…In this way, the average thermal path length between the pumped volume and the cooled surface is only about 1.5 mm, thus ensuring an adequate heat dissipation. This cooling scheme was used in previous laser experiments, and it was found effective up to average pumping power of some tens of watts . The sample was pumped by a fiber‐coupled laser diode which emits at 929.4 nm with a Gaussian pump intensity distribution in the region of the focal plane (ie, waist radius around 65 µm at 1/e 2 , measured with a CCD camera, numerical aperture of the pump beam 0.22).…”

“…This cooling scheme was used in previous laser experiments, and it was found effective up to average pumping power of some tens of watts. 8,9,15 The sample was pumped by a fiber-coupled laser diode which emits at 929.4 nm with a Gaussian pump intensity distribution in the region of the focal plane (ie, waist radius around 65 µm at 1/e 2 , measured with a CCD camera, numerical aperture of the pump beam 0.22). The laser cavity is composed by the following elements: End-Mirror (EM), dichroic (high transmission for the pump wavelength, high reflection for the laser wavelength); Folding-Mirror (FM, spherical, ROC 100 mm); Flat Output Coupler mirror (OC).…”

Submicron‐grained Yb:Lu2O3 transparent ceramics with lasing quality

“…Based on the open literatures, so far Konoshima Chemical Co. has produced the best quality rare‐earth ions doped sesquioxide laser ceramics. Together with their collaborators they have reported a series of results on the high efficiency laser oscillations with their Er:Lu 2 O 3, Er:Y 2 O 3, Yb:Y 2 O 3, Tm:Lu 2 O 3, Yb:Lu 2 O 3, and Yb:Sc 2 O 3 laser ceramics. However, no detailed information on their powder synthesis and sintering technologies were disclosed.…”

“…It is well known that grain size affects the mechanical strength of a ceramic following the Hall‐Petch equation. Smaller grain size implies higher mechanical strength and higher thermal shock resistence . For the high‐energy lasers, thermal shock resistance would be another important factor of the gain media to consider.…”