Polycrystalline ceramic lasers

Abstract

Polycrystalline ceramic laser rods, composed of a cubic solid solution of 89 mole% Y2O3, 10% ThO2, and 1% Nd2O3, were made by a conventional ceramic sintering approach. Rods of this material, called Nd-doped Yttralox (NDY) ceramic, have lasing thresholds between 16 and 30 J when employing a 95% output mirror reflectivity and a pump pulse of 150 μsec; the lasing slope efficiencies are approximately 0.1%. As a reference for comparison, a commercially available Nd-doped glass laser exhibits a threshold energy of 9 J and a lasing slope efficiency of 0.44% under the same testing conditions. Active attenuation coefficients for the NDY rods examined were between 5 and 7% cm−1. The lower values are within a factor of 6 of that found for laser glass. The major contribution to the attenuation coefficients for NDY laser rods, as currently produced, is a result of unidentified submicroscopic scattering centers. Direct observation of the pore size distributions in these highly transparent sintered ceramics reveals that (i) the volume fraction of pores is of the order of 1 ppm, (ii) there is a peak in the pore size distribution between 1 and 2 μm, (iii) pore growth to this size most likely occurs during the sintering process, and (iv) pores are not the major scattering centers responsible for high scattering losses.

Laser crystals and ceramics: recent advances

“…The second ceramic laser was demonstrated only ten years later (Y 2 O 3 -ThO 2 :Nd 3+ [297] Analysis has shown also that the probability of spontaneous transitions for the various 4 F 3/2 → 4 I (J =9/2−15/2) channels of Nd 3+ ions in different crystalline hosts depends primarily on the well-known intensity parameters Ω t of the fourth and sixth rank, because the matrix elements 4 F 3/2 U (2) 4 I J for ed transitions between the 4 F 3/2 and 4 I J manifolds are equal to zero (see Table 3.2 in [18]). It should be particularly emphasized here that Ω t parameters describe the efficiency of the interaction between the Nd 3+ ions and their surrounding crystal field.…”

Highly Transparent BaAl4O7 Polycrystalline Ceramic Obtained by Full Crystallization from Glass

“…Advances in ceramic processing have recently produced fully dense transparent polycrystalline ceramics with competitive optical properties. [ 3 ] Commercially successful polycrystalline materials are currently used as gain media for ceramic lasers [ 4 ] (e.g., Nd:YAG, Yb:Y 2 O 3 , Yb:Sc 2 O 3 and Yb:Lu 2 O 3 ), in transparent armour applications [ 5 ] (e.g., MgAl 2 O 4 ), and as optical lenses [ 6 ] (e.g., Lu 3 NbO 7 and ZrO 2 ). In these examples, cubic symmetry of the ceramic crystal structure is exploited to achieve highly transparent materials with limited birefringent light scattering at grain boundaries.…”

Phase Separation in Garnet Solid Solutions and its Effect on Optical Properties

“…The use of Y 3 Al 5 O 12 (YAG) doped with Er 3+ (YAG:Er 3+ ) is well established in applications such as planar waveguide amplifi ers, [ 1,2 ] near-infrared (NIR) lasers for biomedical use, [3][4][5][6][7] and up-conversion phosphors for IR detection by conversion to visible light. [8][9][10] The YAG:Er 3+ system has several absorption bands at around 490, 800, 970 and 1480 nm, [ 11,12 ] which allows the use of various pumping sources.…”